ORCID Profile
0000-0002-6062-0450
Current Organisations
Monash University
,
University of Technology Sydney
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In Research Link Australia (RLA), "Research Topics" refer to ANZSRC FOR and SEO codes. These topics are either sourced from ANZSRC FOR and SEO codes listed in researchers' related grants or generated by a large language model (LLM) based on their publications.
Carbon capture engineering (excl. sequestration) | Chemical and thermal processes in energy and combustion | Industrial Chemistry | Chemical engineering | Nanotechnology | Organic Chemistry | Nanotechnology | Organic Green Chemistry | Electrochemistry | Diagnostic Applications | Bioprocessing bioproduction and bioproducts | Bioprocessing, Bioproduction and Bioproducts |
Management of Solid Waste from Plant Production | Metals (composites, coatings, bonding, etc.) | Inorganic Industrial Chemicals | Organic Industrial Chemicals (excl. Resins, Rubber and Plastics) | Chemical sciences | Physical sciences
Publisher: Royal Society of Chemistry (RSC)
Date: 26-04-2002
DOI: 10.1039/B201026G
Publisher: American Chemical Society (ACS)
Date: 04-05-2004
DOI: 10.1021/JP049890L
Publisher: Royal Society of Chemistry (RSC)
Date: 1997
DOI: 10.1039/A703639F
Publisher: American Chemical Society (ACS)
Date: 16-12-2005
DOI: 10.1021/LA052055Q
Abstract: In this paper, we demonstrate the effect of halide ions on the formation of biogenically prepared gold nanotriangles using the leaf extract of lemongrass (Cymbopogon flexuosus) plant. We have also studied the effect of halide ions on the morphology of biogenic nanotriangles. It has been shown that iodide ions have a greater propensity to transform flat gold nanotriangles into circular disk-like structures as compared to other halide ions. The study also suggests that the presence of Cl- ions during the synthesis promotes the growth of nanotriangles, whereas the presence of I- ions distorts the nanotriangle morphology and induces the formation of aggregated spherical nanoparticles. The change in the morphology of gold nanotriangles has been explained in terms of the ability of the halide ions to stabilize or inhibit the formation of (111) faces to form [111] oriented gold nanotriangles. Last, we have also shown that the temperature is an important parameter for controlling the aspect ratio and the relative amounts of gold nanotriangles and spherical particles. The results show that, by varying the temperature of reaction condition, the shape, size, and optical properties of anisotropic nanoparticles can be fine-tuned.
Publisher: Wiley
Date: 02-2005
Publisher: American Chemical Society (ACS)
Date: 24-08-2004
DOI: 10.1021/LA0495837
Abstract: Liquid foams have been used as a template to prepare iron oxyhydroxide nanoparticles. This is achieved by a process of electrostatic entrapment of Fe2+/Fe3+ ions in the foam stabilized by the surfactant sodium dodecyl sulfate followed by the in situ hydrolysis of the metal ions. Infrared and selected area electron diffraction measurements suggest the formation of a mixture of beta-FeO(OH) and gamma-FeO(OH) crystallographic phases after the in situ hydrolysis of the metal ions in the foam template. Transmission electron microscopy analysis of the powders obtained from the foam indicates that the particles are fairly monodisperse with an average size of around 50 nm. Scanning electron microscopy pictures reveal that the particles form loosely bound aggregates of around 300 nm. After the powders obtained in the foam are annealed at 400 degrees C, X-ray diffraction measurements show that the FeO(OH) particles are converted to alpha-Fe2O3. The mechanistic aspects of metal ion hydrolysis in a foam are discussed, and some of the advantages of this method vis-à-vis the normal solution-based methods are outlined.
Publisher: American Physical Society (APS)
Date: 15-03-1990
Publisher: American Chemical Society (ACS)
Date: 04-2003
DOI: 10.1021/LA0268202
Publisher: American Chemical Society (ACS)
Date: 10-1992
DOI: 10.1021/LA00046A002
Publisher: Wiley
Date: 05-09-2008
DOI: 10.1021/BP034236T
Abstract: The formation of biocomposite films of the industrially important enzyme invertase and fatty lipids under enzyme-friendly conditions is described. The approach involves a simple beaker-based diffusion protocol wherein invertase diffuses into the cationic lipid octadecylamine during immersion of the lipid film in the enzyme solution. Entrapment of invertase in the octadecylamine film is highly pH-dependent, underlining the role of attractive electrostatic interactions between the enzyme and the lipid in the biocomposite film formation. The kinetics of formation of the enzyme-lipid biocomposites has been studied by quartz crystal microgravimetry (QCM) measurements. The stability of the enzyme in the lipid matrix was confirmed by fluorescence spectroscopy and biocatalytic activity measurements. The biocatalytic activity of the invertase-lipid biocomposite films was comparable to that of the free enzyme in solution and showed marginally higher temperature stability. Particularly exciting was the excellent reuse characteristics of the biocomposite films, indicating potential industrial application of these films.
Publisher: American Chemical Society (ACS)
Date: 16-08-2001
DOI: 10.1021/BC0001241
Abstract: We present herein details pertaining to the preparation of bioconjugates of colloidal gold with aspartic protease from the fungus Aspergillus saitoi (F-prot) and their characterization and enzymatic activity. Simple mixing of the colloidal gold and protein solutions under protein-friendly conditions (pH = 3) followed by centrifugation (to remove uncomplexed gold nanoparticles and protein molecules) results in the formation of the fungal protease-gold nanoparticle conjugates. The protein-gold nanoparticle bioconjugate was redispersed in buffer solution and indicated the formation of efficient bioconjugates with intact native protein structures. The bioconjugates in solution were characterized by UV-vis spectroscopy, fluorescence spectroscopy, and biocatalytic activity measurements while drop-dried bioconjugate films on Si (111) substrates were characterized by scanning electron microscopy (SEM), energy dispersive analysis of X-rays (EDAX), and X-ray diffraction (XRD) measurements. Microscopy images do show some aggregate formation, but the intactness of the native structure of the enzyme in the bioconjugate material was verified by fluorescence and biocatalytic activity measurements. The enzyme retains substantial biocatalytic activity in the bioconjugate material and was comparable to that of free enzyme in solution.
Publisher: Elsevier BV
Date: 07-1997
Publisher: American Chemical Society (ACS)
Date: 02-07-2004
DOI: 10.1021/LA049244D
Abstract: The total biological synthesis of SrCO3 crystals of needlelike morphology arranged into higher order quasi-linear superstructures by challenging microorganisms such as fungi with aqueous Sr2+ ions is described. We term this procedure "total biological synthesis" since the source of carbonate ions that react with aqueous Sr2+ ions is the fungus itself. We believe that secretion of proteins during growth of the fungus Fusarium oxysporum is responsible for modulating the morphology of strontianite crystals and directing their hierarchical assembly into higher order superstructures.
Publisher: Wiley
Date: 16-12-2004
Publisher: American Chemical Society (ACS)
Date: 31-10-2018
Abstract: Lithium metal is strongly recognized as a promising anode material for next-generation high-energy-density systems. However, unstable solid electrolyte interphase and uncontrolled lithium dendrites growth induce severe capacity decay and short cycle life accompanied by high security risks. Here, we propose a simple method for constructing an artificial solid electrolyte interphase layer on the surface of lithium metal through spontaneous reaction, where ammonium persulfate and lithium nitrate are exploited as oxidants. The satisfactory artificial protective layer with uniform and dense morphology is composed of mixed lithium compounds, mainly including Li
Publisher: American Scientific Publishers
Date: 11-2009
Abstract: Nanostructured metals with hollow interiors are of technological importance due to their unique optoelectronic properties and enhanced surface area. We describe herein, a novel method for the synthesis of anisotropic gold and palladium nanoparticles through a simple galvanic replacement reaction across a semi-permeable dialysis membrane. The control over the reaction kinetics achieved by the presence of membrane enables one to tune the bimetal composition, particle porosity and morphology. Rapid outward diffusion of silver ions generated from the sacrificial silver nanoparticles even at room temperatures prevents the precipitation of high quantities of silver chloride, thereby circumventing the need for product purification. The porous anisotropic nanostructures have potential applications in catalysis, cell imaging and therapeutics.
Publisher: Royal Society of Chemistry (RSC)
Date: 2009
DOI: 10.1039/B9NR00004F
Abstract: DNA has been successfully used as a scaffold for the fabrication of metallic nanowires, primarily based on the electrostatic complexation and reduction of the metal cations on the negatively charged sugar-phosphate backbone. Here, we probe the differential binding affinities of nucleobases for silver ions using sensitive isothermal titration calorimetry (ITC) measurements of the reaction enthalpies, which go in order: C > G > A > or = T. Using the disparity between the interaction of cytosine (strong binding) and thymine (weak binding) with silver ions, we have successfully generated silver nanoparticle doublets and triplets on custom-made oligonucleotides, C(30)-T(40)-C(30) and C(20)-T(20)-C(20)-T(20)-C(20), respectively. Thus, a new and simple method of generating metallized DNA wires is presented, based entirely on the nucleotide sequence of DNA. The concept could be extended to other cations and complex DNA sequences in order to achieve intricately patterned DNA constructs.
Publisher: American Chemical Society (ACS)
Date: 21-06-2003
DOI: 10.1021/JA034972T
Abstract: Keggin ion-mediated synthesis of Au core-Ag shell bimetallic nanoparticles is described. Exposure of photochemically reduced aqueous (PW12O40)3- Keggin ions to AuCl4- ions leads to the formation of stable gold nanoparticles capped by the Keggin ions. The surface-bound Keggin ions may then be activated by UV irradiation and, upon exposure to Ag+ ions, reduce the metal ions to form a silver shell around the gold core. That the capping agent not only stabilizes the metal nanoparticles but also plays the role of a switchable reducing agent is a highlight of this approach with important implications in nanomaterials synthesis and catalysis.
Publisher: Royal Society of Chemistry (RSC)
Date: 2002
DOI: 10.1039/B210346J
Publisher: Elsevier BV
Date: 08-2003
Publisher: Elsevier BV
Date: 05-2009
DOI: 10.1016/J.JCIS.2008.12.076
Abstract: The paper presents a time-dependent study of shape-dependent preferential complexation of gold nanoparticles to the octadecyl amine (ODA) monolayers at the air-water interface. Room temperature reduction of chloroaurate ions using lemon grass leaf extract yields a mixture of spherical and triangular nanoparticles, which were used for this study. These nanoparticles have a net negative charge on their surface due to the presence of biomolecules from plant extract and thus a strong attractive electrostatic interaction with the positively charged ODA monolayers drives the complexation process. The extent of preferential complexation of the gold nanoparticles to the ODA monolayers is a function of the charge on the particles and the relative mobility of the nanoclusters in the medium. The complexation process has been followed in real time by a host of techniques such as surface pressure-area (pi-A) isotherms, UV-vis-NIR spectroscopy and Brewster angle microscopy. The charge and mobility of the gold nanoparticles was confirmed by measurement of their electrophoretic mobility. Langmuir-Blodgett films of the nanogold-ODA composites have been characterized by UV-vis-NIR spectroscopy, Fourier transform infrared spectroscopy, and transmission electron microscopy. These measurements clearly indicate that the cluster mobility and complexation increase with decreasing cluster size. In the competitive complexation process of large and small gold particles, it was observed that some bigger gold particles were also incorporated into the amine matrix even though the cluster mobility is higher for smaller gold particles.
Publisher: Royal Society of Chemistry (RSC)
Date: 2004
DOI: 10.1039/B404391J
Publisher: Royal Society of Chemistry (RSC)
Date: 2005
DOI: 10.1039/B510398C
Publisher: American Scientific Publishers
Date: 04-2002
DOI: 10.1166/JNN.2002.106
Abstract: The assembly of silver nanoparticles into quasi-linear superstructures in solution has been demonstrated. A small dc voltage applied to fine-tipped, L-shaped copper electrodes immersed in aqueous carboxylic acid-derivatized silver nanoparticle solution leads to the anodic dissolution of copper ions. The controlled release of Cu2+ ions within the gaps results in local screening of repulsive coulombic interactions between the silver nanoparticles and the consequent formation of aggregates that are extremely stable in time. Atomic force and transmission electron microscopy images of the silver nanoparticle solution after application of an electric field showed the presence of a large number of silver nanoparticle assemblies in open, quasi-linear structures. Such open structures do not form if Cu2+ ions are added directly to the silver nanoparticle solution.
Publisher: American Chemical Society (ACS)
Date: 18-02-2005
DOI: 10.1021/LA047717A
Abstract: Development of simple and reliable protocols for the synthesis of organically soluble catalytically active metal nanoparticles is an important aspect of research in nanomaterials. We demonstrate herein the formation of Pd nanoparticles by reduction of aqueous Pd(NO(3))(2) by photoexcited Keggin ions (phosphotungstate anions). This results in the formation of Pd nanoparticles capped with with Keggin ions that render the particles negatively charged. The Keggin ion capped Pd nanoparticles may then be phase transferred into nonpolar organic solvents such as toluene by electrostatic complexation with cationic surfactants such as octadecylamine at the liquid-liquid interface. This results in a new class of catalyst wherein both the Pd core and Keggin ion shell may be used in a range of catalytic reactions leading to a truly multifunctional catalyst dispersible in organic solvents.
Publisher: American Chemical Society (ACS)
Date: 17-08-2000
DOI: 10.1021/AC000099S
Abstract: Encapsulation of an aspartic protease from the fungus Aspergillus saitoi (F-prot) in thermally evaporated fatty acid films by a simple beaker-based immersion technique under enzyme-friendly conditions is described. The approach is based on diffusion of the enzyme from aqueous solution, driven primarily by attractive electrostatic interaction between charged groups on the enzyme surface and ionized lipid molecules in the film. The encapsulated enzyme molecules could be "pumped out" of the biocomposite film into solution by modulating the electrostatic interaction between the enzyme and fatty acid molecules via solution pH variation. The kinetics of F-prot diffusion into the acid films was followed using quartz crystal microgravimetry measurements while the secondary and tertiary structure of the enzyme in the lipid matrix was studied using Fourier transform infrared (FT-IR) and fluorescence spectroscopies. FT-IR and fluorescence measurements indicated little perturbation to the native structure of the enzyme. A chemical analysis of the F-prot-fatty acid biocomposite film was also performed using X-ray photoelectron spectroscopy. The encapsulated F-prot molecules showed catalytic activity (as estimated by reaction with hemoglobin) comparable to free enzyme molecules in solution, indicating facile access of biological analytes/reactants in solution to the enzyme molecules. The advantages/disadvantages of this approach vis-à-vis methods currently used for encapsulation of biomolecules are briefly discussed.
Publisher: Elsevier BV
Date: 08-2004
Publisher: Elsevier BV
Date: 2004
DOI: 10.1016/S0021-9797(03)00616-7
Abstract: The synthesis of water-dispersible amino-acid-protected gold nanoparticles by the spontaneous reduction of aqueous chloroaurate ions by tryptophan is described. Water-dispersible gold nanoparticles may also be obtained by the sequential synthesis of the gold nanoparticles by borohydride reduction of chloroauric acid followed by capping with tryptophan. Comparison of the proton NMR spectroscopic signatures from the tryptophan-protected gold nanoparticles obtained by the two processes indicated that the indole group in tryptophan is responsible for reduction of the aqueous chloroaurate ions. The reduction of the metal ions is accompanied by oxidative polymerization of the indole group of the tryptophan molecules and, consequently, some degree of cross-linking of the gold nanoparticles.
Publisher: American Chemical Society (ACS)
Date: 17-02-1999
DOI: 10.1021/LA981335L
Publisher: Elsevier BV
Date: 03-2008
Publisher: AIP Publishing
Date: 15-05-1989
DOI: 10.1063/1.343337
Abstract: Presented in this communication are the results of aging experiments carried out on copper island films deposited on fused quartz substrates held at 380 K in a vacuum of 1×10−5 Torr. Ion-bombardment cleaning of the substrates prior to deposition of the films was found to significantly alter the aging rates in the films. The mobility coalescence model was operative during the aging process, and it is inferred from the data that adsorbed gases on the substrate surface affect the nucleation and reduce the mobility of copper islands, which reduces the aging rate. The mean island sizes were determined for some of the films from activation energy measurements.
Publisher: Royal Society of Chemistry (RSC)
Date: 2012
DOI: 10.1039/C2AN35162E
Abstract: Mercury is a serious environmental pollutant known to have detrimental health effects in all life forms. Here, we report the use of biologically synthesized aqueous gold nanotriangles for sensitive and selective optical detection of femto-molar levels of mercury ions by exploiting the high amalgamation tendency of mercury metal towards gold. Aqueous chloroaurate ions were reduced using lemongrass (Cymbopogon flexuosus) leaf extract at room temperature to form gold nanotriangles. Mercuric (Hg(2+)) ions were reduced in the presence of these triangles to facilitate amalgamation and the optical properties were monitored. We observe a significant change in the longitudinal plasmon absorption band of the nanotriangles even at femto-molar concentrations of mercuric ions. High-resolution transmission electron microscopy confirms changes in particle morphology at such low concentrations. This protocol shows no sensitivity to other environmentally relevant metal ions, including Pb(2+), Zn(2+), Cd(2+), Fe(2+), Ni(2+), Sr(2+), Ca(2+), Mn(2+), and Cu(2+), confirming further that change in the optical properties of gold nanotriangles in the presence of reduced mercuric ions is solely due to the strong amalgamation tendency of mercury metal.
Publisher: Wiley
Date: 03-12-2004
DOI: 10.1021/BP049792H
Abstract: Preparation of chemically functionalized biocompatible surfaces is of current interest, with application in the immobilization of various bioactive species such as DNA, enzymes, whole cells, etc. We report herein the one-step synthesis of a self-supporting gold nanoparticle membrane, its surface modification, and application in the immobilization of Candida bombicola (yeast) cells. The gold nanoparticle membrane is prepared by the spontaneous reduction of aqueous chloroaurate ions by a diamine at a liquid-liquid interface. The gold nanoparticles in the polymeric membrane may be capped with octadecylamine (ODA) molecules, thereby rendering the nanoparticle membrane hydrophobic. Exposure of the hydrophobized organic-gold nanoparticle membrane to C. bombicola yeast cells results in their binding to the membrane, possibly through nonspecific interactions such as hydrophobic interactions between the yeast cell walls and the ODA molecules. The enzyme cytochrome P450 present in the yeast cells immobilized on the organic-gold nanoparticle membrane was then used in the transformation of the arachidonic acid (AA) to sophorolipids followed by acid hydrolysis to form 20-hydroxyeicosatetraneoic acid (20-HETE). The organic-gold nanoparticle membrane-C. bombicola bioconjugate could be easily separated from the reaction medium and reused a number of times.
Publisher: Royal Society of Chemistry (RSC)
Date: 2004
DOI: 10.1039/B311771P
Publisher: Elsevier BV
Date: 10-2001
Publisher: IOP Publishing
Date: 14-02-1987
Publisher: American Chemical Society (ACS)
Date: 11-07-2002
DOI: 10.1021/LA025755T
Publisher: IOP Publishing
Date: 06-09-2002
Publisher: American Chemical Society (ACS)
Date: 22-03-2002
DOI: 10.1021/CG0155447
Publisher: American Chemical Society (ACS)
Date: 03-02-2001
DOI: 10.1021/LA001164W
Publisher: Elsevier BV
Date: 15-06-2001
Publisher: American Chemical Society (ACS)
Date: 06-03-2003
DOI: 10.1021/LA026906V
Publisher: American Scientific Publishers
Date: 08-2007
DOI: 10.1166/JNN.2007.618
Abstract: This study describes the synthesis of a free-standing nanogold membrane by the spontaneous reduction of aqueous chloroaurate ions by the diamine molecule DAEE at a liquid-liquid interface. The free standing nanogold membrane, provides a biocompatible surface for the immobilization of proteins. F-Protease (F-Prot) was then bound to the nanogold membrane via interaction with the gold nanoparticles leading to a new class of biocatalyst. A highlight of the new biocatalyst wherein the enzyme is bound to the nanogold membrane is the ease with which separation from the reaction medium may be achieved by simple filtration. In relation to the free enzyme in solution, the F-Prot in the bioconjugate material exhibited a slightly higher biocatalytic activity and significantly enhanced pH and temperature stability. The F-Prot nanogold membrane bioconjugate material also exhibited excellent biocatalytic activity over ten successive reuse cycles.
Publisher: Royal Society of Chemistry (RSC)
Date: 2000
DOI: 10.1039/B000182L
Publisher: American Chemical Society (ACS)
Date: 06-1994
DOI: 10.1021/LA00018A011
Publisher: American Chemical Society (ACS)
Date: 30-08-2001
DOI: 10.1021/NL0155274
Publisher: Elsevier BV
Date: 05-1988
Publisher: American Chemical Society (ACS)
Date: 03-05-2008
DOI: 10.1021/LA704019P
Abstract: The bacterium Actinobacter sp. has been shown to be capable of extracellularly synthesizing iron based magnetic nanoparticles, namely maghemite (gamma-Fe2O3) and greigite (Fe3S4) under ambient conditions depending on the nature of precursors used. More precisely, the bacterium synthesized maghemite when reacted with ferric chloride and iron sulfide when exposed to the aqueous solution of ferric chloride-ferrous sulfate. Challenging the bacterium with different metal ions resulted in induction of different proteins, which bring about the specific biochemical transformations in each case leading to the observed products. Maghemite and iron sulfide nanoparticles show superparamagnetic characteristics as expected. Compared to the earlier reports of magnetite and greigite synthesis by magnetotactic bacteria and iron reducing bacteria, which take place strictly under anaerobic conditions, the present procedure offers significant advancement since the reaction occurs under aerobic condition. Moreover, reaction end products can be tuned by the choice of precursors used.
Publisher: American Chemical Society (ACS)
Date: 09-02-2021
DOI: 10.1021/JP048766Z
Publisher: Elsevier BV
Date: 02-2005
Publisher: Wiley
Date: 2002
DOI: 10.1021/BP025538I
Abstract: In an earlier report on fungal protease (F-prot)-fatty acid biocomposite film formation [Gole et al. Anal. Chem. 2000, 72, 4301], it was observed that the biocatalytic activity of the immobilized enzyme was comparable to that of the free enzyme in solution. However, a somewhat negative aspect of the protocol was the steady loss in activity during reuse and storage of the biocomposite film. In this paper, we address the latter issues and demonstrate successful attempts toward the realization of efficient biocomposite films with enhanced biological activity, temporal stability, and excellent reusability. The improved performance of the F-prot-stearic acid biocomposite is accomplished by preordering the fatty acid film by incorporation of Pb(2+) ions into the lipid matrix prior to enzyme immobilization. The lead cation induces lamellar ordering in the lipid film and thus facilitates diffusion of the F-prot molecules into the lipid matrix and accessibility of the substrate molecules (hemoglobin, Hb) to the entrapped F-prot enzyme molecules. The preordering consequently leads to effective control of the "mass transport" problem and might be responsible for the enhanced biological activity ( approximately 36%) of the enzyme molecules in the biocomposite in comparison with the free enzyme in solution, as well the excellent reusability of the composite film. In addition to biocatalytic activity measurements, the formation and characterization of the F-prot-lead stearate biocomposite films was done by quartz crystal microgravimetry and X-ray diffraction.
Publisher: Springer Science and Business Media LLC
Date: 23-03-2007
DOI: 10.1007/S11095-007-9257-9
Abstract: Colloidal metallic systems have been recently investigated in the area of nanomedicine. Gold nanoparticles have found themselves useful for diagnostic and drug delivery applications. Herein we have reported a novel method for synthesis of gold nanoparticles using a natural, biocompatible and biodegradable polymer chitosan. Use of chitosan serves dual purpose by acting as a reducing agent in the synthesis of gold nanoparticles and also promotes the penetration and uptake of peptide hormone insulin across the mucosa. To demonstrate the use of chitosan reduced gold nanoparticles as carriers for drug delivery, we report herein the transmucosal delivery of insulin loaded gold nanoparticles. Gold nanoparticles were prepared using different concentrations of chitosan (from 0.01% w/v up to 1% w/v). The gold nanoparticles were characterized for surface plasmon band, zeta potential, surface morphology, in vitro diffusion studies and fluorescence spectroscopy. The in vivo studies in diabetic male Wistar rats were carried out using insulin loaded chitosan reduced gold nanoparticles. Varying concentrations of chitosan used for the synthesis of gold nanoparticles demonstrated that the nanoparticles obtained at higher chitosan concentrations (>0.1% w/v) were stable showing no signs of aggregation. The nanoparticles also showed long term stability in terms of aggregation for about 6 months. Insulin loading of 53% was obtained and found to be stable after loading. Blood glucose lowering at the end of 2 h following administration of insulin loaded gold nanoparticles to diabetic rats was found to be 30.41 and 20.27% for oral (50 IU/kg) and nasal (10 IU/kg), respectively. Serum gold level studies have demonstrated significant improvement in the uptake of chitosan reduced gold nanoparticles. The synthesis of gold nanoparticles using a biocompatible polymer, chitosan would improve its surface properties for binding of biomolecules. Our studies indicate that oral and nasal administration of insulin loaded chitosan reduced gold nanoparticles has led to improved pharmacodynamic activity. Thus, chitosan reduced gold nanoparticles loaded with insulin prove to be promising in controlling the postprandial hyperglycemia.
Publisher: Elsevier BV
Date: 06-2004
Publisher: Elsevier BV
Date: 09-1992
Publisher: American Chemical Society (ACS)
Date: 10-01-2003
DOI: 10.1021/LA026486+
Publisher: American Scientific Publishers
Date: 12-2005
DOI: 10.1166/JNN.2005.401
Abstract: Certain surfactant-stabilized aqueous foams provide a potentially efficient and simple chemical route for the synthesis of various nanomaterials with controllable structure, size, and shape. In the present work, a one-step process for the synthesis of CdS and Cd1-xMn(x)S (0 < x < 10) nanocrystals has been described. Aqueous CdCl2 and the aerosol-OT solutions are homogeneously mixed together and thereafter, nitrogen is bubbled through this solution to produce stable aqueous foam. After drainage of the foam, the freestanding dry foam consisting of cadmium cations electrostatically complexed with the anionic aerosol-OT molecules at the liquid-gas interface is treated with H2S vapor. The foam turns yellowish-orange and collapses, in the process yielding CdS nanoclusters of variable morphology. This morphology variation is appropriately attributed to growth of the CdS as well as alloyed Cd1-xMn(x)S nanoparticles in different regions of the foam contributing to the varying topological structure. Optical absorption spectra of both CdS and Cd1-xMn(x)S nanoparticles clearly show a well-defined exciton absorption feature around 450 nm due to quantum confinement effects. The interesting band edge emission characteristics of these AOT-capped CdS and Cd1-xMn(x)S nanoparticles produced in the foam are discussed with respect to their size and shape. Particular interest in the present novel aqueous foam approach arises due to the fact that the cubic zincblende CdS and alloyed Cd1-xMn(x)S nanocrystals could easily be obtained even under ambient experimental conditions itself.
Publisher: Royal Society of Chemistry (RSC)
Date: 2008
DOI: 10.1039/B719528A
Publisher: Elsevier BV
Date: 08-2002
Publisher: AIP Publishing
Date: 10-07-2006
DOI: 10.1063/1.2210080
Abstract: We report on the synthesis of La0.7Sr0.3MnO3 (LSMO) nanoparticles having perovskite structure and particle size of the order of 30nm. The process involves citrate-gel synthesis, size filtering, and surface coating with a shell of octadecyl amine (ODA) using electrostatic interaction-assisted novel chemical route. Magnetic measurements show the Curie temperature of ∼360K establishing the desired stoichiometry and phase. Fourier transform infrared studies bring out that the amine group of ODA interacts with the LSMO surface. Refluidization yields uniform redispersion of the coated and dried powder.
Publisher: Wiley
Date: 16-08-1986
Publisher: American Chemical Society (ACS)
Date: 07-12-2002
DOI: 10.1021/CM0256920
Publisher: American Chemical Society (ACS)
Date: 31-08-2001
DOI: 10.1021/LA010536D
Publisher: Royal Society of Chemistry (RSC)
Date: 23-05-2002
DOI: 10.1039/B203438G
Publisher: American Chemical Society (ACS)
Date: 08-12-2004
DOI: 10.1021/CG0341858
Publisher: American Chemical Society (ACS)
Date: 07-1999
DOI: 10.1021/LA981139E
Publisher: American Scientific Publishers
Date: 10-2005
DOI: 10.1166/JNN.2005.192
Abstract: Gold nanoparticles of triangular morphology possess interesting optical properties with potential application in medicine and infrared absorbing coatings, however, little is known about conditions that favor their growth. In this paper, we have reinvestigated a time-tested recipe for the formation of gold nanospheres by citrate reduction of aqueous gold ions under boiling conditions (Turkevich recipe). Our principle findings are that gold nanotriangle formation is kinetically controlled and is highly favored at low temperatures. Furthermore, the presence of chloride ions from the precursor chloroaurate ions plays a major role in promoting the growth of oriented triangular/truncated triangular particles. The presence of bromide and iodide ions that possess the ability to replace surface-bound chloride ions inhibits triangle formation to varying degrees.
Publisher: Royal Society of Chemistry (RSC)
Date: 2007
DOI: 10.1039/B614934K
Publisher: American Chemical Society (ACS)
Date: 03-09-2005
DOI: 10.1021/CM051165F
Publisher: Wiley
Date: 16-05-1988
Publisher: American Chemical Society (ACS)
Date: 1993
DOI: 10.1021/JA00055A063
Publisher: American Chemical Society (ACS)
Date: 10-08-2001
DOI: 10.1021/LA010597B
Publisher: Elsevier BV
Date: 03-2007
Publisher: Royal Society of Chemistry (RSC)
Date: 2001
DOI: 10.1039/B106564E
Publisher: American Chemical Society (ACS)
Date: 25-06-2003
DOI: 10.1021/LA034209C
Abstract: In addition to alkanethiols and phosphine derivatives, alkylamines have been investigated as capping agents in the synthesis of organically dispersible gold nanoparticles. However, reports pertaining to gold nanoparticle derivatization with alkylamines are relatively scarce and their interaction with the underlying gold support is poorly understood. In this paper, we attempt a more detailed examination of this problem and present results on the Fourier transform infrared spectroscopy, thermogravimetry, nuclear magnetic resonance, and X-ray photoemission (XPS) characterization of gold nanoparticles capped with the alkylamines laurylamine (LAM) and octadecylamine (ODA). The capping of the gold nanoparticles with the alkylamines was accomplished during phase transfer of aqueous gold nanoparticles to chloroform containing fatty amine molecules. Thermogravimetry and XPS analysis of purified powders of the amine-capped gold nanoparticles indicated the presence of two different modes of binding of the alkylamines with the gold surface. The weakly bound component is attributed to the formation of an electrostatic complex between protonated amine molecules and surface-bound AuCl
Publisher: Wiley
Date: 17-06-2004
Publisher: Springer Science and Business Media LLC
Date: 1987
DOI: 10.1007/BF01160582
Publisher: AIP Publishing
Date: 05-07-1993
DOI: 10.1063/1.109735
Abstract: Excellent quality thin TiO2 films have been obtained by the thermal decomposition of n-octadecyl amine-titanyl oxalate complex multilayer Langmuir–Blodgett films. The films were characterized by x-ray diffraction and x-ray photoemission studies. X-ray diffraction studies suggest a preferred orientation of the TiO2 films.
Publisher: IOP Publishing
Date: 22-01-2002
Publisher: Wiley
Date: 03-12-2004
DOI: 10.1021/BP0499000
Abstract: The synthesis of polyurethane microsphere-gold nanoparticle "core-shell" structures and their use in the immobilization of the enzyme endoglucanase are described. Assembly of gold nanoparticles on the surface of polymer microspheres occurs through interaction of the nitrogens in the polymer with the nanoparticles, thereby precluding the need for modifying the polymer microspheres to enable such nanoparticle binding. Endoglucanse could thereafter be bound to the gold nanoparticles decorating the polyurethane microspheres, leading to a highly stable biocatalyst with excellent reuse characteristics. The immobilized enzyme retains its biocatalytic activity and exhibits improved thermal stability relative to free enzyme in solution. The high surface area of the host gold nanoparticles renders the immobilized enzyme "quasi free", while at the same time retaining advantages of immobilization such as ease of reuse, enhanced temporal and thermal stability, etc.
Publisher: Wiley
Date: 31-03-2005
Publisher: Springer Science and Business Media LLC
Date: 05-02-2019
DOI: 10.1038/S41467-019-08422-8
Abstract: Due to the high theoretical specific energy, the lithium–oxygen battery has been heralded as a promising energy storage system for applications such as electric vehicles. However, its large over-potentials during discharge–charge cycling lead to the formation of side-products, and short cycle life. Herein, we report an ionic liquid bearing the redox active 2,2,6,6-tetramethyl-1-piperidinyloxy moiety, which serves multiple functions as redox mediator, oxygen shuttle, lithium anode protector, as well as electrolyte solvent. The additive contributes a 33-fold increase of the discharge capacity in comparison to a pure ether-based electrolyte and lowers the over-potential to an exceptionally low value of 0.9 V. Meanwhile, its molecule facilitates smooth lithium plating/stripping, and promotes the formation of a stable solid electrolyte interface to suppress side-reactions. Moreover, the proportion of ionic liquid in the electrolyte influences the reaction mechanism, and a high proportion leads to the formation of amorphous lithium peroxide and a long cycling life ( 200 cycles). In particular, it enables an outstanding electrochemical performance when operated in air.
Publisher: Elsevier BV
Date: 03-2003
Publisher: American Chemical Society (ACS)
Date: 27-09-2005
DOI: 10.1021/LA0513712
Abstract: Macrophages are one of the principal immune effector cells that play essential roles as secretory, phagocytic, and antigen-presenting cells in the immune system. In this study, we address the issue of cytotoxicity and immunogenic effects of gold nanoparticles on RAW264.7 macrophage cells. The cytotoxicity of gold nanoparticles has been correlated with a detailed study of their endocytotic uptake using various microscopy tools such as atomic force microscopy (AFM), confocal-laser-scanning microscopy (CFLSM), and transmission electron microscopy (TEM). Our findings suggest that Au(0) nanoparticles are not cytotoxic, reduce the production of reactive oxygen and nitrite species, and do not elicit secretion of proinflammatory cytokines TNF-alpha and IL1-beta, making them suitable candidates for nanomedicine. AFM measurements suggest that gold nanoparticles are internalized inside the cell via a mechanism involving pinocytosis, while CFLSM and TEM studies indicate their internalization in lysosomal bodies arranged in perinuclear fashion. Our studies thus underline the noncytotoxic, nonimmunogenic, and biocompatible properties of gold nanoparticles with the potential for application in nanoimmunology, nanomedicine, and nanobiotechnology.
Publisher: American Chemical Society (ACS)
Date: 19-11-2004
DOI: 10.1021/JP0465581
Publisher: Elsevier BV
Date: 1999
Publisher: Elsevier BV
Date: 05-1989
Publisher: Elsevier BV
Date: 05-2002
DOI: 10.1016/S0167-7799(02)01939-X
Abstract: The immobilization of biomacromolecules such as proteins, enzymes and DNA in various inert matrices is a problem that attracts considerable attention and is motivated by fundamental, biomedical and industrial interests. In addition to several other entrapping matrices, lipids in the form of monolayers and bilayers are versatile hosts owing to their membrane-mimicking capability, bio-friendliness, flexibility and inertness. Here, we discuss the immobilization of proteins, enzymes and DNA via electrostatic interactions in films of thermally evaporated fatty lipids. The role of the lipid in preserving the natural conformation of the biomolecule, protection against harsh environmental conditions and accessibility to substrates and reagents is an important feature of the protocol and is highlighted.
Publisher: American Chemical Society (ACS)
Date: 18-07-2000
DOI: 10.1021/LA000452P
Publisher: IOP Publishing
Date: 06-06-2003
Publisher: American Chemical Society (ACS)
Date: 11-10-2006
DOI: 10.1021/JA062113+
Abstract: Rice husk is a cheap agro-based waste material, which harbors a substantial amount of silica in the form of amorphous hydrated silica grains. However, there have been no attempts at harnessing the enormous amount of amorphous silica present in rice husk and its room-temperature biotransformation into crystalline silica nanoparticles. In this study, we address this issue and describe how naturally deposited amorphous biosilica in rice husk can be bioleached and simultaneously biotransformed into high value crystalline silica nanoparticles. We show here that the fungus Fusarium oxysporum rapidly biotransforms the naturally occurring amorphous plant biosilica into crystalline silica and leach out silica extracellularly at room temperature in the form of 2-6 nm quasi-spherical, highly crystalline silica nanoparticles capped by stabilizing proteins that the nanoparticles are released into solution is an advantage of this process with significant application and commercial potential. Calcination of the silica nanoparticles leads to loss of occluded protein and to an apparently porous structure often of cubic morphology. The room-temperature synthesis of oxide nanomaterials using microorganisms starting from potential cheap agro-industrial waste materials is an exciting possibility and could lead to an energy-conserving and economically viable green approach toward the large-scale synthesis of oxide nanomaterials.
Publisher: Elsevier BV
Date: 03-2001
Publisher: Royal Society of Chemistry (RSC)
Date: 2000
DOI: 10.1039/A909385K
Publisher: Wiley
Date: 2003
DOI: 10.1021/BP034065S
Abstract: Preparation of biocompatible surfaces for immobilization of enzymes and whole cells is an important aspect of biotechnology due to their potential applications in biocatalysis, biosensing, and immunological applications. In this report, patterned thermally evaporated octadecylamine (ODA) films are used for the immobilization of Candida bombicola cells. The attachment of the cells to the ODA film surface occurs possibly through nonspecific interactions such as hydrophobic interactions between the cell walls and the ODA molecules. The enzyme cytochrome P450 present in the immobilized yeast cells on the ODA film surface was used for the transformation of the arachidonic acid to 20-hydroxyeicosatetraenoic acid (20-HETE). The assembly of cells on the hydrophobic ODA surface was confirmed by quartz crystal microgravimetry (QCM), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). SEM images confirmed the strong binding of the yeast cells to the ODA film surface after biocatalytic reactions. Moreover, the biocomposite films could be easily separated from the reaction medium and reused.
Publisher: Springer Science and Business Media LLC
Date: 20-06-2004
DOI: 10.1038/NMAT1152
Publisher: Royal Society of Chemistry (RSC)
Date: 2001
DOI: 10.1039/B101110N
Publisher: Wiley
Date: 09-09-2020
Publisher: Royal Society of Chemistry (RSC)
Date: 2004
DOI: 10.1039/B315022B
Publisher: Springer Science and Business Media LLC
Date: 1997
Publisher: Elsevier BV
Date: 10-1997
Publisher: Elsevier BV
Date: 02-2004
DOI: 10.1016/J.JCIS.2003.10.018
Abstract: We report on the reduction of aqueous chloroaurate ions by glucose to form gold nanoparticles of uniform size. We further demonstrate the complexation of these particles with octadecylamine (ODA) monolayers at the air-water interface. Pressure-area (pi-A) isotherms as a function of time of complexation revealed a significant expansion of the monolayer. Surface pressure variation with time for constant areas after spreading of the monolayer was carried out to observe the kinetics of complexation of the colloidal particles at the interface. The kinetics of complexation of the particles at the interface was also monitored by Brewster angle microscopy (BAM) measurements. Langmuir-Blodgett films of the particles complexed with ODA were formed at a subphase pH of 9 onto different substrates. Quartz crystal microgravimetry (QCM) was used to quantify the amount of particles deposited per immersion cycle of the quartz crystal. The LB films were further characterized by UV-vis and transmission electron microscopy (TEM) measurements. TEM measurements indicate a close packed and equidistant arrangement of colloidal particles in the LB film, probably due to hydrogen-bonding interactions.
Publisher: American Physical Society (APS)
Date: 15-04-1990
Publisher: Elsevier BV
Date: 2014
Publisher: Royal Society of Chemistry (RSC)
Date: 2003
DOI: 10.1039/B311010A
Publisher: Informa UK Limited
Date: 12-2010
Publisher: Royal Society of Chemistry (RSC)
Date: 2004
DOI: 10.1039/B409033K
Publisher: American Chemical Society (ACS)
Date: 20-12-2001
DOI: 10.1021/JP013468C
Publisher: American Chemical Society (ACS)
Date: 05-12-2019
DOI: 10.1021/JACS.9B09352
Abstract: Designing atomically dispersed metal catalysts for oxygen reduction reaction (ORR) is a promising approach to achieve efficient energy conversion. Herein, we develop a template-assisted method to synthesize a series of single metal atoms anchored on porous N,S-codoped carbon (NSC) matrix as highly efficient ORR catalysts to investigate the correlation between the structure and their catalytic performance. The structure analysis indicates that an identical synthesis method results in distinguished structural differences between Fe-centered single-atom catalyst (Fe-SAs/NSC) and Co-centered/Ni-centered single-atom catalysts (Co-SAs/NSC and Ni-SAs/NSC) because of the different trends of each metal ion in forming a complex with the N,S-containing precursor during the initial synthesis process. The Fe-SAs/NSC mainly consists of a well-dispersed FeN
Publisher: American Chemical Society (ACS)
Date: 04-08-2001
DOI: 10.1021/LA010571K
Publisher: MDPI AG
Date: 29-05-0010
Abstract: The severe “shuttle effect” of dissolved polysulfide intermediates and the poor electronic conductivity of sulfur cathodes cause capacity decay of lithium–sulfur batteries and impede their commercialization. Herein, we synthesized a series of well-designed yolk-shelled Fe3O4@carbon (YS-Fe3O4@C) nanocavities with different proportions of Fe3O4 as efficient sulfur hosts to stabilize polysulfide intermediates. The yolk-shelled nanocavity architectures were prepared through a facile method, which could effectively confine the active materials and achieve high conductivity. The polysulfide intermediate shuttle was successfully suppressed by a physiochemical synergism effect combining the retention of carbon shells and the adsorption of Fe3O4 nanoparticle cores. The highly conductive carbon shell provides efficient pathways for fast electron transportation. Meanwhile, the visible evolution of active materials and a reversible electrochemical reaction are revealed by in situ X-ray diffraction. With the balanced merits of enhanced electrical conductivity of carbon shell and optimal adsorption of Fe3O4 cores, the S/YS-27Fe3O4@C cathode (Fe3O4 accounts for 27 wt% in YS-Fe3O4@C) had the best electrochemical performance, exhibiting a high reversible specific capacity of 731.9 mAh g−1 and long cycle performance at 1 C (capacity fading rate of 0.03% over 200 cycles).
Publisher: Elsevier BV
Date: 11-2004
Publisher: American Chemical Society (ACS)
Date: 22-03-2007
DOI: 10.1021/LA062535X
Abstract: One of the important routes for the production of zirconia is by chemical treatment and removal of silica from zircon sand (ZrSixOy). We present here a completely green chemistry approach toward enrichment of zirconia in zircon sand this is based on the reaction of the fungus Fusarium oxysporum with zircon sand by a process of selective extracellular bioleaching of silica nanoparticles. Since this reaction does not result in zirconia being simultaneously leached out from the sand, there is a consequent enrichment of the zirconia component in zircon sand. We believe that fungal enzymes specifically hydrolyze the silicates present in the sand to form silicic acid, which on condensation by certain other fungal enzymes results in room-temperature synthesis of silica nanoparticles. This fungus-mediated twofold approach might have vast commercial implications in low-cost, ecofriendly, room-temperature syntheses of technologically important oxide nanomaterials from potentially cheap naturally available raw materials like zircon sand.
Publisher: American Chemical Society (ACS)
Date: 03-12-2005
DOI: 10.1021/LA051982U
Abstract: Nanomaterials have gained tremendous importance in biology and medicine because they can be used as carriers for delivering small molecules such as drugs, proteins, and genes. We report herein the binding of the hormone insulin to gold nanoparticles and its application in transmucosal delivery for the therapeutic treatment of diabetes mellitus. Insulin was loaded onto bare gold nanoparticles and aspartic acid-capped gold nanoparticles and delivered in diabetic Wistar rats by both oral and intranasal (transmucosal) routes. Our principle observations are that there is a significant reduction of blood glucose levels (postprandial hyperglycemia) when insulin is delivered using gold nanoparticles as carriers by the transmucosal route in diabetic rats. Furthermore, control of postprandial hyperglycemia by the intranasal delivery protocol is comparable to that achieved using the standard subcutaneous administration used for type I diabetes mellitus, thus showing considerable promise for further development.
Publisher: AIP Publishing
Date: 15-01-1993
DOI: 10.1063/1.464288
Abstract: The inelastic scattering of electrons in Langmuir–Blodgett films of cadmium arachidate [(C19H39COO)2Cd] deposited on glass substrates has been studied by reflection electron energy loss spectroscopy (REELS) and by monitoring the loss features of the C 1s and O 1s core levels by x-ray photoemission spectroscopy (XPS). REELS studies with a primary beam of energy 95 eV revealed some vibrational modes of the cadmium arachidate molecules and features due to transition of valence electrons to the conduction band. Similar structures were also identified in the C 1s and O 1s loss spectra and interpreted as reflecting the density of states of the conduction band, in agreement with earlier findings using secondary electron emission spectroscopy. In contrast to the monolayer film, the 5 ML film showed reduced order as inferred from the lack of features in the loss spectra.
Publisher: American Chemical Society (ACS)
Date: 28-04-2005
DOI: 10.1021/LA048541F
Abstract: Inorganic composites are of special interest for biomedical applications such as in dental and bone implants wherein the ability to modulate the morphology and size of the inorganic crystals is important. One interesting possibility to control the size of inorganic crystals is to grow them on nanoparticles. We report here the use of surface-modified gold nanoparticles as templates for the growth of hydroxyapatite crystals. Crystal growth is promoted by a monolayer of aspartic acid bound to the surface of the gold nanoparticles the carboxylate ions in aspartic acid are excellent binging sites for Ca(2+) ions. Isothermal titration calorimetry studies of Ca(2+) ion binding with aspartic acid-capped gold nanoparticles indicates that the process is entropically driven and that screening of the negative charge by the metal ions leads to their aggregation. The aggregates of gold nanoparticles are believed to be responsible for assembly of the platelike hydroxyapatite crystals into quasi-spherical superstructures. Control experiments using uncapped gold nanoparticles and pure aspartic acid indicate that the amino acid bound to the nanogold surface plays a key role in inducing and directing hydroxyapatite crystal growth.
Publisher: Elsevier BV
Date: 04-2003
DOI: 10.1016/S0021-9797(03)00047-X
Abstract: The organization of hydrophobized colloidal gold nanoparticles at air-water interface and the formation thereafter of lamellar, multilayer films of the gold nanoparticles by the Langmuir-Blodgett technique is described in this paper. The hydrophobization of the colloidal particles was accomplished by the direct chemisorption of laurylamine molecules on aqueous colloidal gold nanoparticles during a phase-transfer process. While monolayers of the laurylamine-capped gold nanoparticles at the air-water interface were not amenable to layer-by-layer transfer onto solid supports, it was observed that addition of the water-insoluble hiphile octadecanol to the gold nanoparticle solution improved the stability of the monolayer at the interface as well as the multilayer assembly protocol. The organization of the gold nanoparticles at the air-water interface was followed by surface pressure-area isotherm measurements while the formation of multilayer films of the nanoparticles by the Langmuir-Blodgett technique was monitored by quartz crystal microgravimetry, UV-vis spectroscopy, Fourier transform infrared spectroscopy, and transmission electron microscopy.
Publisher: Wiley
Date: 25-01-2019
Publisher: American Chemical Society (ACS)
Date: 06-05-2003
DOI: 10.1021/CG0255671
Publisher: Elsevier BV
Date: 2004
Publisher: Wiley
Date: 10-2001
DOI: 10.1002/1521-3773(20011001)40:19<3585::AID-ANIE3585>3.0.CO;2-K
Publisher: American Chemical Society (ACS)
Date: 15-04-2008
DOI: 10.1021/LA0346797
Publisher: Elsevier BV
Date: 2000
Publisher: Wiley
Date: 08-06-2009
Abstract: A facile method for the synthesis of porous platinum nanoparticles by transmetallation reactions between sacrificial nickel nanoparticles and chloroplatinic acid (H(2)PtCl(6)) in solution, as well as at the constrained environment of the air-water interface, using a Langmuir-Blodgett instrumental setup is presented. To carry out the transmetallation at the air-water interface hydrophobized nickel nanoparticles are assembled as a monolayer on the sub phase containing platinum ions. The porous Pt nanoparticles obtained as a result of the reaction are found to act as extremely good catalysts for hydrogenation reaction. The products are well characterized by TEM, HRTEM, EDAX, and STEM. Attempts are made to postulate the plausible mechanism of this reaction to generate this kind of nanoparticle with controllable geometric shape and structure. This simple strategy has the potential to synthesize other nanomaterials of interest too.
Publisher: Springer Science and Business Media LLC
Date: 06-2000
DOI: 10.1007/BF02719902
Publisher: Elsevier BV
Date: 07-0009
Publisher: The Chemical Society of Japan
Date: 08-2000
DOI: 10.1246/BCSJ.73.1757
Publisher: AIP Publishing
Date: 05-1986
DOI: 10.1063/1.336899
Abstract: The aging of island silver films deposited on glass at room temperature and at a pressure of 2×10−5 Torr was studied by monitoring the dc electrical resistance of the films. Films in the resistance range 1–11 MΩ/⧠ were studied under different conditions to ascertain the role of the residual gases and surface contaminants on the agglomeration rate. It was found that residual gases do not significantly affect the agglomeration rate, but a film of water vapor adsorbed on the glass surface retards the agglomeration to a great extent. An expression is arrived at for the functional dependence of the interisland spacing with time for the different conditions of study, assuming that the conduction in these island films is by quantum mechanical tunneling.
Publisher: Informa UK Limited
Date: 12-06-2023
Publisher: American Physical Society (APS)
Date: 15-05-1986
Publisher: American Chemical Society (ACS)
Date: 1998
DOI: 10.1021/JP971423Z
Publisher: AIP Publishing
Date: 04-11-2025
DOI: 10.1063/1.114298
Abstract: Free-standing powder of zinc sulphide quantum particles has been synthesized using a chemical route. X-ray diffraction analysis shows that the diameter of the particles is ∼21±2 Å which is smaller than the Bohr exciton diameter for zinc sulphide. UV absorption shows an excitonic peak centered at ∼300 nm corresponding to an energy gap of 4.1±0.1 eV. These particles show a luminescence band at ∼424 nm. The quantum particles could be doped with copper during synthesis without altering the UV absorption or x-ray diffraction pattern. However, doping shifted the luminescence to 480 nm, green wavelength in the visible region.
Publisher: American Chemical Society (ACS)
Date: 09-03-2002
DOI: 10.1021/CM010372M
Publisher: Springer Science and Business Media LLC
Date: 04-2003
DOI: 10.1007/BF02707447
Publisher: Royal Society of Chemistry (RSC)
Date: 2005
DOI: 10.1039/B405599N
Abstract: The liquid-liquid interface has been used with considerable success in the synthesis of advanced materials ranging from (bio)minerals to inorganic membranes to nanoparticles. In almost all such cases, the interface is static. The Hele-Shaw cell in which a viscous fluid is displaced by a less viscous one in a constrained manner has been invaluable in the study of dynamic instabilities at interfaces and in the study of viscous fingering pattern formation. However, the potential of the Hele-Shaw cell in carrying out reactions at the interface between the two fluids leading to the formation of inorganic materials has been largely unrecognized and underexploited. Realizing that the dynamic liquid-liquid interface in a Hele-Shaw cell would provide opportunities to control a variety of time-scales associated with material formation, we have started a program on the use of the Hele-Shaw cell in materials synthesis. In this discussion paper, we present some of our recent results on the growth of calcium carbonate crystals in the Hele-Shaw cell by the reaction of Ca2+ ions electrostatically complexed with carboxylate ions pinned to the interface with carbonate ions present in the aqueous part of the biphasic reaction medium. We show that both polymorph selectivity and the morphology of the crystals may be modulated by varying the experimental conditions in the cell. We also discuss the possibility of using the dynamic interface in the Hele-Shaw cell to cross-link gold nanoparticles in water through bifunctional linkers present in the oil phase and investigate the nature of the structures formed.
Publisher: Elsevier BV
Date: 08-2007
DOI: 10.1016/J.JCIS.2007.03.032
Abstract: A seed mediated procedure for the synthesis of hydrophobic Au(core)Ag(shell) nanoparticles in toluene is demonstrated. The reaction proceeds by way of the interfacial reduction of silver ions by 3-pentadecylphenol followed by their deposition on hydrophobized Au nanoparticles. Such a hitherto unreported interfacial seeded growth reaction leads to the formation of phase pure Au(core)Ag(shell) nanoparticles that retain the hydrophobicity of the seed particles and remain stable in toluene. Such core-shell structures are however not formed in the aqueous phase. The core-shell architecture was verified using TEM analysis and the formation process was studied by recording the UV-vis spectra of the organic phase nanoparticles as a function of time. TEM kinetics also showed gradual increase in the silver layer thickness. Conclusive evidence was however obtained on examination of the HRTEM images of the products formed. Elemental analysis using X-ray photoelectron spectroscopy of the Au(core)Ag(shell) nanostructure revealed the presence of metallic silver. Moreover changing the surface capping of the Au seed does not affect the formation of the Au(core)Ag(shell) nanostructure.
Publisher: American Physical Society (APS)
Date: 15-12-0015
Publisher: IOP Publishing
Date: 09-1999
Publisher: Royal Society of Chemistry (RSC)
Date: 19-11-2001
DOI: 10.1039/B107727A
Publisher: IOP Publishing
Date: 28-08-2022
Publisher: Royal Society of Chemistry (RSC)
Date: 2001
DOI: 10.1039/B101056P
Publisher: American Chemical Society (ACS)
Date: 18-02-2004
DOI: 10.1021/CM035004S
Publisher: Wiley
Date: 22-02-2007
Abstract: Spider silk is being viewed with interest by materials scientists due to its excellent resilience and mechanical properties. In this paper we show that spider silk is an excellent scaffold for the one-step synthesis and assembly of gold nanoparticles. Formation of a gold nanoparticle-spider-silk bioconjugate material is accomplished by simple reaction of the fibers with aqueous chloroauric acid. The gold nanoparticles thus formed are strongly bound to the spider-silk fiber surface enabling study of the electrical properties of the nanobioconjugate. Using the well-known contraction/expansion behavior of the fibers in solvents of varying polarity, we show that exposure of the gold nanoparticle-spider silk bioconjugate to vapors of methanol and chloroform leads to changes in electrical transport through the nanoparticles and thus, the possibility of developing a vapor sensor. The bioconjugate shows excellent response time and cycling efficiency to methanol vapors. The activation energy of electron transport from one gold nanoparticle to another in the nanobiocojugate was determined from temperature-dependent electron-transport measurements to be approximately 1.7 eV.
Publisher: Wiley
Date: 2005
DOI: 10.1021/BP050144N
Abstract: Current strategies for bone tissue regeneration focus on the development of implantable matrices that mimic biological tissues. Inorganic composites are of special interest for bone substitute applications. It is necessary to create an artificial three-dimensional scaffold-like porous material with certain geometrical structure to induce bone growth. We report here the growth of calcium phosphate crystals on free-standing carboxylic acid functionalized gold nanoparticle membranes. The gold nanoparticle membrane is synthesized by the spontaneous reduction of aqueous chloroaurate ions by a diamine molecule at a liquid-liquid interface. This membrane is robust and malleable, and most importantly, the gold nanoparticles in the membrane may be functionalized with suitable ligands. In this study, the amino acids aspartic acid and cysteine together with an aromatic bifunctional molecule, anthranilic acid, were used to modify the surface of the gold nanoparticles in the membrane. The free carboxylic acid groups on the gold nanoparticles further to functionalization with these molecules were then used to bind Ca(2+) ions and reacted with phosphate ions to yield calcium phosphate. The nature of the nanogold surface modifier directed the formation of either crystalline hydroxyapatite or amorphous calcium phosphate. The nanogold membrane thus suggests potential biomedical application as biocompatible implants and grafts.
Publisher: Wiley
Date: 2001
DOI: 10.1002/BIT.1107
Abstract: In this article we demonstrate a versatile method for the generation of patterned protein films by encapsulation in arrays of the lipids, octadecylamine (ODA, cationic), and arachidic acid (AA, anionic). A simple 2 x 2 array of ODA and AA was vacuum deposited on different substrates using appropriate masks. Thereafter, the enzymes pepsin and fungal protease as well as the heme-proteins cytochrome c and hemoglobin were encapsulated in the different elements of the array by sequential immersion (combined with judicious masking) of the array elements in the different protein solutions. The proteins are incorporated into the lipid elements by electrostatic interaction between charged amino acid residues on the protein surface and charged functional groups in the lipid matrix. This procedure leads to spatially distinct regions of the different proteins on one substrate and shows promise for single-chip multianalyte immunoassay/multiplex, high-throughput biosensor and catalysis applications. Fourier transform infrared spectroscopy (FTIR) was used to monitor the incorporation of the proteins in the different elements of the array as well as to ascertain whether intermixing of the proteins in a particular array element had occurred. The heme-protein composite regions were further characterized using UV-VIS spectroscopy.
Publisher: Elsevier BV
Date: 03-1994
Publisher: Wiley
Date: 08-07-2019
Abstract: It is essential to develop a facile and effective method to enhance the electrochemical performance of lithium metal anodes for building high-energy-density Li-metal based batteries. Herein, we explored the temperature-dependent Li nucleation and growth behavior and constructed a dendrite-free Li metal anode by elevating temperature from room temperature (20 °C) to 60 °C. A series of ex situ and in situ microscopy investigations demonstrate that increasing Li deposition temperature results in large nuclei size, low nucleation density, and compact growth of Li metal. We reveal that the enhanced lithiophilicity and the increased Li-ion diffusion coefficient in aprotic electrolytes at high temperature are essential factors contributing to the dendrite-free Li growth behavior. As anodes in both half cells and full cells, the compact deposited Li with minimized specific surface area delivered high Coulombic efficiencies and long cycling stability at 60 °C.
Publisher: Elsevier BV
Date: 03-2004
Publisher: Elsevier BV
Date: 05-1997
Publisher: American Chemical Society (ACS)
Date: 31-05-2002
DOI: 10.1021/AR010094X
Abstract: The controlled assembly of nanoparticles in thin film form on solid supports, both as monolayers and as superlattice structures, is a problem of considerable topical interest. Among the many interactions used to program the assembly of nanoparticles, electrostatic forces are particularly interesting for many reasons. This Account deals with assembling surface-modified nanoparticles in thin film form using electrostatic interactions at the air-water interface and in thermally evaporated lipid films. The generality of the electrostatic assembly protocol is demonstrated in the immobilization of DNA and proteins in lipid films.
Publisher: Wiley
Date: 09-1993
Publisher: American Vacuum Society
Date: 11-2006
DOI: 10.1116/1.2366606
Abstract: The authors report a highly controlled approach, based on electron-beam lithography, to interconnect in idual nano-objects for transport experiments. The process is based on a three-step procedure, consisting of fabrication of four alignment markers, localization of the nano-object after its immobilization onto functionalized surfaces, and interconnection of the single nanostructure by patterning two nanoelectrodes on its sides. The approach is highly reproducible and widely applicable and allows an alignment accuracy of 15–20nm. Here they demonstrate the reliability of such technique by using a thin triangular gold nanoprism as the active element and show the I-V characteristics of the single nanostructure.
Publisher: American Chemical Society (ACS)
Date: 19-12-2003
DOI: 10.1021/LA0350352
Publisher: SAGE Publications
Date: 10-2011
Publisher: Wiley
Date: 29-12-2019
Abstract: Benefiting from the natural abundance and low standard redox potential of potassium, potassium-ion batteries (PIBs) are regarded as one of the most promising alternatives to lithium-ion batteries for low-cost energy storage. However, most PIB electrode materials suffer from sluggish thermodynamic kinetics and dramatic volume expansion during K
Publisher: Royal Society of Chemistry (RSC)
Date: 2003
DOI: 10.1039/B303919F
Publisher: Elsevier BV
Date: 07-2007
Publisher: Royal Society of Chemistry (RSC)
Date: 2003
DOI: 10.1039/B307000J
Publisher: Walter de Gruyter GmbH
Date: 2002
Abstract: Nanotechnology is witnessing impressive advances on many different fronts. One of the key areas with important commercial implications concerns the assembly of nanoparticles to form thin films and superstructures by what is commonly known as the "bottom-up" approach. This paper covers some of the more recent developments in this fascinating field with particular emphasis on the work from the author's laboratory on assembly of nanoparticles using electrostatic interactions. The use of electrostatic interactions enables extension of the assembly protocols to the immobilization of biomacromolecules such as proteins/enzymes and DNA with exciting application potential.
Publisher: American Chemical Society (ACS)
Date: 26-10-2002
DOI: 10.1021/LA026206Q
Publisher: Royal Society of Chemistry (RSC)
Date: 2004
DOI: 10.1039/B407904C
Publisher: Royal Society of Chemistry (RSC)
Date: 2004
DOI: 10.1039/B405335B
Publisher: Informa UK Limited
Date: 03-2006
Publisher: American Chemical Society (ACS)
Date: 18-09-1999
DOI: 10.1021/LA990170T
Publisher: American Chemical Society (ACS)
Date: 21-10-2000
DOI: 10.1021/LA000623Q
Publisher: AIP Publishing
Date: 12-1991
DOI: 10.1063/1.461241
Abstract: Attenuation lengths in cadmium arachidate [(C19H39COO)2Cd] multilayer Langmuir–Blodgett films deposited on thick lead arachidate [(C19H39COO)2Pb] films have been determined in this communication. A discrete layer model appropriate to the ordered structure of these built-up films is proposed and applied for the first time to the measurements of the x-ray photoemission intensity variation with electron takeoff angle and attenuation lengths for 950–1350 eV electrons are evaluated. These lengths agree with earlier attenuation length measurements in Langmuir–Blodgett films and are higher than in most inorganic materials.
Publisher: Elsevier BV
Date: 11-2010
Publisher: Wiley
Date: 09-06-2008
Abstract: There has been significant progress in the biological synthesis of nanomaterials. However, the molecular mechanism of synthesis of such bio-nanomaterials remains largely unknown. Here, we report the extracellular synthesis of crystalline silver nanoparticles (AgNPs) by using Morganella sp., and show molecular evidence of silver resistance by elucidating the synthesis mechanism. The AgNPs were 20+/-5 nm in diameter and were highly stable at room temperature. The kinetics of AgNPs formation was investigated. Detectable particles were formed after an hour of reaction, and their production remained exponential up to 18 h, and saturated at 24 h. Morganella sp. was found to be highly resistant to silver cations and was able to grow in the presence of more than 0.5 mM AgNO(3). Three gene homologues viz. silE, silP and silS were identified in silver-resistant Morganella sp. The homologue of silE from Morganella sp. showed 99 % nucleotide sequence similarity with the previously reported gene, silE, which encodes a periplasmic silver-binding protein. The homologues of silP and silS were also highly similar to previously reported sequences. Similar activity was totally absent in closely related Escherichia coli this suggests that a unique mechanism of extracellular AgNPs synthesis is associated with silver-resistant Morganella sp. The molecular mechanism of silver resistance and its gene products might have a key role to play in the overall synthesis process of AgNPs by Morganella sp. An understanding of such biochemical mechanisms at the molecular level might help in developing an ecologically friendly and cost-effective protocol for microbial AgNPs synthesis.
Publisher: American Chemical Society (ACS)
Date: 29-09-2005
DOI: 10.1021/JP0530552
Abstract: The transmetalation reaction between a sacrificial nanoparticle and more noble metal ions in solution has emerged as a novel method for creating unique hollow and bimetallic nanostructures. In this report, we investigate the possibility of carrying out the transmetalation reaction between hydrophobic silver nanoparticles assembled and constrained at the air-water interface and subphase gold ions. We observe that facile reduction of the subphase gold ions by the sacrificial silver nanoparticles occurs resulting in the formation of elongated gold nanostructures that appear to cross-link the sacrificial silver particles. This transmetalation reaction may be modulated by the insertion of an electrostatic barrier in the form of an ionizable lipid monolayer between the silver nanoparticles and the aqueous gold ions that impacts the gold nanoparticle assembly. Transmetalation reactions between nanoparticles constrained into a close-packed structure and appropriate metal ions could lead to a new strategy for metallic cross-linking of nanoparticles and generation of coatings with promising optoelectonic behavior.
Publisher: Elsevier BV
Date: 05-2003
Publisher: Springer Science and Business Media LLC
Date: 10-2002
DOI: 10.1007/BF02704195
Publisher: Wiley
Date: 10-10-2020
Abstract: Sodium-based batteries have attracted considerable attention and are recognized as ideal candidates for large-scale and low-cost energy storage. Sodium (Na) metal anodes are considered as one of the most promising anodes for next-generation, high-energy, Na-based batteries owing to their high theoretical specific capacity (1166 mA h g
Publisher: American Chemical Society (ACS)
Date: 11-03-2003
DOI: 10.1021/LA026772L
Publisher: Royal Society of Chemistry (RSC)
Date: 2005
DOI: 10.1039/B503008K
Publisher: American Chemical Society (ACS)
Date: 26-04-2003
DOI: 10.1021/CM020784A
Publisher: Wiley
Date: 2002
DOI: 10.1021/BP015504V
Abstract: The formation of biocomposite films of the pharmaceutically important enzyme penicillin G acylase (PGA) and fatty lipids under enzyme-friendly conditions is described. The approach involves a simple beaker-based diffusion protocol wherein the enzyme diffuses into the lipid film during immersion in the enzyme solution, thereby leading to the formation of a biocomposite film. The incorporation of the enzyme in both cationic as well as anionic lipids suggests the important role of secondary interactions such as hydrophobic and hydrogen bonding in the enzyme immobilization process. The kinetics of formation of the enzyme-lipid biocomposites has been studied by quartz crystal microgravimentry (QCM) measurements. The stability of the enzyme in the lipid matrix was confirmed by Fourier transform infrared spectroscopy (FTIR) and biocatalytic activity measurements. Whereas the biological activity of the lipid-immobilized enzyme was marginally higher than that of the free enzyme, the biocomposite film exhibited increased thermal/temporal stability. Particularly exciting was the observation that the biocomposite films could be reused in biocatalysis reactions without significant loss in activity, which indicates potentially exciting biomedical/industrial application of these films.
Publisher: IOP Publishing
Date: 19-04-2006
Publisher: American Chemical Society (ACS)
Date: 10-2001
DOI: 10.1021/LA0108353
Publisher: American Chemical Society (ACS)
Date: 30-06-2005
DOI: 10.1021/LA047132G
Abstract: We show here that reaction of the fungus, Fusarium oxysporum, with the aqueous heavy-metal ions Pb2+ and Cd2+ results in the one-step formation of the corresponding metal carbonates. The metal carbonates are formed by reaction of the heavy-metal ions with CO2 produced by the fungus during metabolism and thus provide a completely biological method for production of crystals of metal carbonates. The PbCO3 and CdCO3 crystals thus produced have interesting morphologies that are shown to arise because of interaction of the growing crystals with specific proteins secreted by the fungus during reaction. An additional advantage of this approach is that the reaction leads to detoxification of the aqueous solution and could have immense potential for bioremediation of heavy metals. Under conditions of this study, the metal ions are not toxic to the fungus, which readily grows after exposure to the metal ions.
Publisher: Royal Society of Chemistry (RSC)
Date: 2000
DOI: 10.1039/B002419H
Publisher: Elsevier BV
Date: 1990
Publisher: Elsevier BV
Date: 1988
Publisher: American Physical Society (APS)
Date: 15-04-1992
Publisher: Royal Society of Chemistry (RSC)
Date: 2000
DOI: 10.1039/A910343K
Publisher: American Chemical Society (ACS)
Date: 14-01-2000
DOI: 10.1021/LA990103Z
Publisher: American Chemical Society (ACS)
Date: 23-09-2004
DOI: 10.1021/JA046785G
Abstract: An isothermal titration calorimetric (ITC) investigation of the interaction of DNA bases and PNA base monomers with gold nanoparticles is described revealing a binding sequence in the order C > G > A > T. Direct measurement of the strength of interaction of ligands with nanogold by ITC has important implications in surface modification strategies for biomedical, catalysis, and nanoarchitecture applications.
Publisher: American Physical Society (APS)
Date: 15-05-1989
Publisher: Elsevier BV
Date: 09-2015
Publisher: Royal Society of Chemistry (RSC)
Date: 2005
DOI: 10.1039/B418566H
Abstract: Transmetallation reaction between hydrophobized silver nanoparticles with hydrophobized chloroaurate and chloroplatinate ions in chloroform results in the formation of hollow gold and platinum shell nanoparticles respectively.
Publisher: American Chemical Society (ACS)
Date: 11-05-2001
DOI: 10.1021/LA0015765
Publisher: AIP Publishing
Date: 07-1988
DOI: 10.1063/1.341213
Abstract: In this communication, we report the results of the investigations carried out on the stability of discontinuous Cu films deposited on polymethylmethacrylate coated substrate heated to a temperature above the glass transition temperature of the polymer. It was reported that evaporated materials on such substrates form a subsurface particulate structure. It was found that in Cu films post-deposition instability persisted on a softenable substrate similar to the behavior of Cu on glass. On exposure to atmosphere, the resistance increased due to the interaction of atmospheric gases and water vapor. A film deposited at room temperature and and heated also behaved in a similar fashion when exposed to atmosphere.
Publisher: Wiley
Date: 03-2001
DOI: 10.1002/1521-4095(200103)13:5<341::AID-ADMA341>3.0.CO;2-X
Publisher: American Chemical Society (ACS)
Date: 30-05-2003
DOI: 10.1021/CM0342344
Publisher: Wiley
Date: 04-04-2005
Publisher: American Chemical Society (ACS)
Date: 21-09-2002
DOI: 10.1021/JA027296O
Abstract: The biosynthesis of Q-state CdS nanoparticles by reaction of aqueous CdSO4 solution with the fungus, Fusarium oxysporum, is demonstrated. Nanoparticle formation proceeds by release of sulfate reductase enzymes by the fungus, conversion of sulfate ions to sulfide ions that subsequently react with aqueous Cd2+ ions to yield highly stable CdS nanoparticles. Elucidation of an enzymatic pathway using fungi opens up the exciting possibility of developing a rational, biosynthesis strategy for nanomaterials over a range of chemical compositions which is currently not possible.
Publisher: American Chemical Society (ACS)
Date: 28-02-2002
DOI: 10.1021/NL015676M
Publisher: American Chemical Society (ACS)
Date: 04-1995
DOI: 10.1021/LA00004A009
Publisher: American Chemical Society (ACS)
Date: 10-2003
DOI: 10.1021/LA0352063
Publisher: Wiley
Date: 2003
DOI: 10.1021/BP034070W
Abstract: Development of biologically inspired experimental processes for the synthesis of nanoparticles is evolving into an important branch of nanotechnology. In this paper, we report on the use of Geranium (Pelargonium graveolens) leaf extract in the extracellular synthesis of silver nanoparticles. On treating aqueous silver nitrate solution with geranium leaf extract, rapid reduction of the silver ions is observed leading to the formation of highly stable, crystalline silver nanoparticles in solution. Transmission electron microscopy analysis of the silver particles indicated that they ranged in size from 16 to 40 nm and were assembled in solution into quasilinear superstructures. The rate of reduction of the silver ions by the geranium leaf extract is faster than that observed by us in an earlier study using a fungus, Fusarium oxysporum, thus highlighting the possibility that nanoparticle biosynthesis methodologies will achieve rates of synthesis comparable to those of chemical methods. This study also represents an important advance in the use of plants over microorganisms in the biosynthesis of metal nanoparticles.
Publisher: American Scientific Publishers
Date: 08-2007
DOI: 10.1166/JNN.2007.636
Abstract: A seed mediated approach for the synthesis of anisotropic rod shaped gold nanoparticles in organic media (toluene) is demonstrated. Pre-formed gold nanoparticles stabilized in toluene by 4-hexadecylaniline (HDA) are used as seeds. These when reacted with 1-octadecylamine (ODA) hydrophobised chloroaurate ions in toluene lead to the formation of gold nanorods. ODA or alkylamines of different chain lengths which are the chloroaurate ion phase transfer agent have been found to play a key role in the formation of the nanorods. The gold nanorods that have a five-fold symmetry evolve from multiply twinned particles and are bound at the tips by [1 11] faces and at the sides by [100] faces. The gold nanorods have been shown to grow under the shape directing effect of the alkylamines which stabilize the high energy [100] faces. The concentration of the alkylamines has been found to play a critical role in the formation of the gold nanorods. Higher concentrations of the alkylamines lead to formation of spherical particles, at times of narrow size distribution.
Publisher: American Chemical Society (ACS)
Date: 25-07-2002
DOI: 10.1021/LA025827G
Publisher: Wiley
Date: 03-05-2002
DOI: 10.1002/1439-7633(20020503)3:5<461::AID-CBIC461>3.0.CO;2-X
Publisher: Elsevier BV
Date: 2004
DOI: 10.1016/J.JCIS.2003.07.013
Abstract: We demonstrate the synthesis of zirconia nanoparticles in a lipid matrix by a simple, low temperature beaker-based process. This is accomplished by electrostatic entrapment of ZrF6(2-) ions within thermally evaporated octadecylamine (ODA) thin films followed by the low-temperature in situ hydrolysis of the entrapped metal ion complexes. The zirconia particles thus formed were of the monoclinic phase and were fairly monodisperse with particles of average size 40 nm. The zirconia crystallites appeared to exhibit preferred orientation indicating epitaxial growth of the crystals within the lipid matrix. The formation of zirconia nanoparticles in the lipid matrix was investigated using quartz crystal microgravimetry (QCM), optical absorption spectroscopy, X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and X-ray diffraction (XRD) techniques.
Publisher: Springer Science and Business Media LLC
Date: 06-2003
DOI: 10.1007/BF02704258
Publisher: American Chemical Society (ACS)
Date: 28-06-2003
DOI: 10.1021/LA034128G
Publisher: Elsevier BV
Date: 03-2018
Publisher: American Scientific Publishers
Date: 10-2005
DOI: 10.1166/JNN.2005.184
Abstract: The design, synthesis and characterization of biologically synthesized nanomaterials have become an area of significant interest. In this paper, we report the extracellular synthesis of gold and silver nanoparticles using Emblica Officinalis (amla, Indian Gooseberry) fruit extract as the reducing agent to synthesize Ag and Au nanoparticles, their subsequent phase transfer to an organic solution and the transmetallation reaction of hydrophobized silver nanoparticles with hydrophobized chloroaurate ions. On treating aqueous silver sulfate and chloroauric acid solutions with Emblica Officinalis fruit extract, rapid reduction of the silver and chloroaurate ions is observed leading to the formation of highly stable silver and gold nanoparticles in solution. Transmission Electron Microscopy analysis of the silver and gold nanoparticles indicated that they ranged in size from 10 to 20 nm and 15 to 25 nm respectively. Ag and Au nanoparticles thus synthesized were then phase transferred into an organic solution using a cationic surfactant octadecylamine. Transmetallation reaction between hydrophobized silver nanoparticles and hydrophobized chloroaurate ions in chloroform resulted in the formation of gold nanoparticles.
Publisher: Elsevier BV
Date: 07-1999
Publisher: American Scientific Publishers
Date: 10-2003
DOI: 10.1166/JNN.2003.214
Abstract: Protocols for the synthesis of gold nanoparticles are increasingly focusing on controlling the morphology of the nanocrystals. We demonstrate in this article the facile, one-step synthesis of gold nanotapes that are readily dispersible in organic media. This is accomplished by the spontaneous reduction of aqueous chloroaurate ions by hexadecylaniline molecules present in chloroform at the static interface between water and chloroform. The hexadecylaniline molecules cap the gold nanotapes thus formed, rendering them hydrophobic and dispersible in a range on nonpolar and weakly polar organic solvents. Possible reasons for the growth of gold nanotapes are discussed.
Publisher: Wiley
Date: 05-12-2006
Abstract: The development of synthetic processes for oxide nanomaterials is an issue of considerable topical interest. While a number of chemical methods are available and are extensively used, the collaborations are often energy intensive and employ toxic chemicals. On the other hand, the synthesis of inorganic materials by biological systems is characterized by processes that occur at close to ambient temperatures and pressures, and at neutral pH (ex les include magnetotactic bacteria, diatoms, and S-layer bacteria). Here we show that nanoparticulate magnetite may be produced at room temperature extracellularly by challenging the fungi, Fusarium oxysporum and Verticillium sp., with mixtures of ferric and ferrous salts. Extracellular hydrolysis of the anionic iron complexes by cationic proteins secreted by the fungi results in the room-temperature synthesis of crystalline magnetite particles that exhibit a signature of a ferrimagnetic transition with a negligible amount of spontaneous magnetization at low temperature.
Publisher: American Chemical Society (ACS)
Date: 02-1993
DOI: 10.1021/LA00026A021
Publisher: Springer Science and Business Media LLC
Date: 06-2008
Publisher: Elsevier BV
Date: 11-1997
Publisher: Elsevier BV
Date: 02-2005
Publisher: American Scientific Publishers
Date: 09-2001
DOI: 10.1166/JNN.2001.046
Abstract: The formation of cadmium sulfide nanoparticle assemblies in a patterned manner on suitable substrates is described. The protocol for realizing such structures comprises the following steps. In the first step, patterned films of a fatty acid are thermally evaporated onto solid supports using suitable masks (e.g., a transmission electron microscope grid). Thereafter, the fatty acid film is immersed in cadmium sulfate solution and Cd2+ ions entrapped in the lipid matrix by electrostatic complexation with the carboxylate ions of the fatty acid molecules. The final step involves reaction of the entrapped Cd2+ ions with Na2S, leading to the in situ generation of cadmium sulfide nanoparticles within the patterned lipid matrix. This approach shows promise for generating patterned nanoparticle assemblies of different chemical compositions.
Publisher: American Chemical Society (ACS)
Date: 14-01-2005
DOI: 10.1021/CM048292G
Publisher: Elsevier BV
Date: 12-2017
Publisher: Wiley
Date: 16-01-1989
Publisher: Elsevier BV
Date: 07-2004
Publisher: American Chemical Society (ACS)
Date: 24-09-2005
DOI: 10.1021/LA051595K
Abstract: An easy and convenient method for the synthesis of cobalt and magnesium ferrite nanoparticles is demonstrated using liquid foams as templates. The foam is formed from an aqueous mixture of an anionic surfactant and the desired metal ions, where the metal ions are electrostatically entrapped by the surfactant at the thin borders between the foam bubbles and their junctions. The hydrolysis is carried out using alkali resulting in the formation of desired nanoparticles, with the foam playing the role of a template. However, in the formation of ferrites with the formula MFe(2)O(4), where the metal ion and iron possess oxidation states of +2 and +3, respectively, forming a foam from a 1:2 mixture of the desired ionic solutions would lead to a foam composition at variance with the original solution mixture because of greater electrostatic binding of ions possessing a greater charge with the surfactant. In our procedure, we circumvent this problem by preparing the foam from a 1:2 mixture of M(2+) and Fe(2+) ions and then utilizing the in situ conversion of Fe(2+) to Fe(3+) under basic conditions inside the foam matrix to get the desired composition of the metal ions with the required oxidation states. The fact that we could prepare both CoFe(2)O(4) and MgFe(2)O(4) particles shows the vast scope of this method for making even multicomponent oxides. The magnetic nanoparticles thus obtained exhibit a good crystalline nature and are characterized by superparamagnetic properties. The magnetic features observed for CoFe(2)O(4) and MgFe(2)O(4) nanoparticles are well in accordance with the expected behaviors, with CoFe(2)O(4) particles showing higher blocking temperatures and larger coercivities. These features can easily be explained by the contribution of Co(2+) sites to the magnetocrystalline anisotropy and the absence of the same from the Mg(2+) ions.
Publisher: Springer Science and Business Media LLC
Date: 2000
Publisher: American Chemical Society (ACS)
Date: 31-03-2004
DOI: 10.1021/LA035870J
Abstract: We demonstrate herein the formation of a free-standing gold nanoparticle membrane and its use in the immobilization of the enzyme, pepsin. The nanogold membrane is synthesized by the spontaneous reduction of aqueous chloroaurate ions at the liquid-liquid interface by the bifunctional molecule bis(2-(4-aminophenoxy)ethyl) ether (DAEE) taken in chloroform. This process results in the formation of a robust, malleable free-standing nanogold membrane consisting of gold nanoparticles embedded in a polymeric background. Recognizing that gold nanoparticles are excellent candidates for immobilization of enzymes, we have immobilized pepsin on the nanogold membrane, leading to a new class of biocatalyst. A highlight of the new pepsin-nanogold biocatalyst is the ease with which separation from the reaction medium may be achieved. The catalytic activity of pepsin in the bioconjugate was comparable to that of the free enzyme in solution. The pepsin-nanogold membrane bioconjugate material exhibited excellent biocatalytic activity over 10 successive reuse cycles as well as enhanced pH, temperature, and temporal stability.
Publisher: Elsevier BV
Date: 06-2002
Publisher: AIP Publishing
Date: 12-11-2001
DOI: 10.1063/1.1414298
Abstract: Nanoparticles of silver and nickel were grown in thermally evaporated fatty acid (stearic acid) films by immersion of the film sequentially in solutions containing Ag+ ions and Ni2+ ions. Attractive electrostatic interaction between the metal cations and the carboxylate ions in the fatty acid film leads to entrapment of the cations in the film. Thereafter, the metal ions were reduced in situ to yield nanoparticles of Ag and Ni of ∼30 nm diameter within the fatty acid matrix. Thermal treatment of the stearic acid-(silver+nickel) nanocomposite films led to the formation of a Ni–Ag alloy at ∼100 °C. Prolonged heat treatment at this temperature resulted in the phase separation of the alloy and the reformation of in idual Ag and Ni nanoparticles.
Publisher: Elsevier BV
Date: 03-2005
DOI: 10.1016/J.JCIS.2004.09.018
Abstract: The phase transfer protocols in vogue for the oleic acid capped silver nanoparticles, viz., salt-induced precipitation and redispersion or phosphoric acid-induced method, are examined and compared thoroughly. A comprehensive evaluation with respect to the mechanistic aspects involved is made and the merits and demerits of the different procedures are delineated. It is found that the salt-induced precipitation and redispersion is more versatile in that the precipitate can actually be redispersed in both aqueous and organic media. However, in terms of mechanism both the routes seem to be very similar wherein the orientational change of oleic acid on the silver surface in the two different environments-organic and aqueous-plays a crucial role in the adaptability of the system to the different environments. Subsequently, this change of orientation of oleic acid on silver surface in aqueous and organic media has been utilized to phase transfer Ni-based nanoparticulate systems. The nascent oleic acid-capped Ni nanoparticles, which were synthesized by a foam-based protocol, were dispersible in water but not in nonpolar organic media such as cyclohexane or toluene. Then, just by coating a thin shell of silver on them we could achieve complete phase transfer of the Ni(core)Ag(shell) from aqueous to organic media following similar procedures used for oleic acid-capped silver nanoparticles. Here, the phase transfer seems to be facilitated by the orientational flexibility of oleic acid on the silver surface as opposed to other metal surfaces as evidenced from the infrared and thermogravimetric analyses of oleic acid-capped Ni and Ni(core)Ag(shell) nanoparticles. This orientation-assisted phase transfer method could be generalized and can be adapted to other systems where, if the nascent nanoparticles cannot be phase transferred as is, they can be coated by a silver shell and oleic acid making them suitable for dispersion in both aqueous and organic media.
Publisher: Royal Society of Chemistry (RSC)
Date: 2004
DOI: 10.1039/B308180J
Publisher: Wiley
Date: 29-11-2020
Abstract: Potassium metal batteries are considered as attractive alternatives beyond lithium-ion batteries. However, uncontrollable dendrite growth on the potassium metal anode has restrained their practical applications. A high-performance potassium anode achieved by confining potassium metal into a titanium-deficient nitrogen-containing MXene/carbon nanotube freestanding scaffold is reported. The high electronic transport and fast potassium diffusion in this scaffold enable reduced local current density and homogeneous ionic flux during plating/stripping processes. Furthermore, as verified by theoretical calculations and experimental investigations, such "potassium-philic" MXene sheets can induce the nucleation of potassium, and guide potassium to uniformly distribute in the scaffold upon cycling. Consequently, the as-developed potassium metal anodes exhibit a dendrite-free morphology with high Coulombic efficiency and long cycle life during plating/stripping processes. Such anodes also deliver significantly improved electrochemical performances in potassium-sulfur batteries compared with bare potassium metal anodes. This work can provide a new avenue for developing potassium metal-based batteries.
Publisher: Springer Science and Business Media LLC
Date: 09-2004
DOI: 10.1007/BF02708280
Publisher: American Chemical Society (ACS)
Date: 17-02-2005
DOI: 10.1021/BI048378N
Abstract: The folding of HIV-1 protease to its active form involves the coordination of structure formation and dimerization, which follows a hierarchy consisting of folding nuclei spanning from the active site, hinge region, and dimerization domain. However, the biochemical characteristics of the folding intermediates of this protein remain to be elucidated. In an experimental model, the denaturation of the tethered dimer of HIV-1 protease by guanidine hydrochloride revealed an alternative conformation resembling the molten-globule state. The molten-globule state binds to the molecular chaperone alpha-crystallin and prevents its aggregation however, the chaperone alone failed to reconstitute HIV-1 protease into its active form. Calcium ion assisted in the release of active enzyme from the chaperone complex. Alpha-crystallin, a member of the small heat-shock protein, assists proteins to fold correctly however, the underlying principle of signals responsible for chaperone-mediated protein folding remains enigmatic. X-ray photoelectron spectroscopy has been employed to provide the evidence of calcium binding to alpha-crystallin and to decipher the effect of calcium binding on the chaperone-mediated refolding of HIV-1 protease. On the basis of our spectroscopic data, we propose that calcium ions interact with the carboxyl groups of the surface-exposed acidic amino acids of alpha-crystallin bringing electrostatic interference, which plays a pivotal role in inducing conformational changes in the chaperone responsible for the release of the active enzyme.
Publisher: American Chemical Society (ACS)
Date: 06-02-2009
DOI: 10.1021/JP807542W
Publisher: Royal Society of Chemistry (RSC)
Date: 14-03-2003
DOI: 10.1039/B301314F
Publisher: AIP Publishing
Date: 15-01-1993
DOI: 10.1063/1.353335
Abstract: A Tougaard background deconvolution analysis of the x-ray photoelectron spectra of an a-Si1−xCx:H film deposited on a silicon substrate by the radio-frequency plasma-enhanced chemical vapor deposition method has been performed. The analysis indicates that carbon and silicon atoms inhabit an exponentially decreasing concentration profile from the surface with different characteristic attenuation lengths. Oxygen has also been incorporated in the film with a similar concentration profile. The differential inelastic scattering cross section for the deconvolution has been obtained from reflection electron energy-loss spectroscopy. This nondestructive depth profile analysis appears to be a powerful tool for determining the uniformity of deposition of such films.
Publisher: American Chemical Society (ACS)
Date: 19-08-2006
DOI: 10.1021/JA063011M
Abstract: The syntheses of inorganic materials by biological systems is characterized by processes that occur close to ambient temperatures, pressures, and neutral pH, as is exemplified by biosilicification and biomineralization processes in nature. Conversely, laboratory-based syntheses of oxide materials often require extremes of temperature and pressure. We have shown here the extracellular, room-temperature biosynthesis of 4-5 nm ternary oxide nanoparticles such as barium titanate (BT) using a fungus-mediated approach. The tetragonality as well as a lowered Curie transition temperature in sub-10 nm particles was established, and the ferroelectricity in these particles was shown using Kelvin probe microscopy.
Publisher: Royal Society of Chemistry (RSC)
Date: 2003
DOI: 10.1039/B302591H
Abstract: Anthracene anions bound to a liquid-liquid interface and charged by photochemically reduced Keggin ions when exposed to aqueous chloroaurate ions result in the formation of high concentration of thin, gold nanosheets at the interface.
Publisher: American Chemical Society (ACS)
Date: 06-01-2005
DOI: 10.1021/LA047707+
Abstract: A simple and efficient way of obtaining silver nanoparticles that are dispersible both in organic and in aqueous solvents using a single capping agent is described. The silver nanoparticles are initially prepared in water in the presence of aerosol OT [sodium bis(2-ethylhexyl)-sulfosuccinate, AOT]. Thereafter, transfer of the AOT-capped silver nanoparticles to an organic phase is induced by the addition of a small amount of orthophosphoric acid during shaking of the biphasic mixture. The AOT-stabilized silver nanoparticles could be separated out from the organic phase in the form of a powder. The hydrophobic nanoparticles thus prepared are stable and are readily resuspended in a variety of other polar (including water) and nonpolar solvents without further surface treatment. The hiphatic nature of the silver surface is brought about by a small orientational change in the AOT monolayer on the silver surface in response to the polarity of the solvent.
Publisher: Wiley
Date: 07-04-2006
DOI: 10.1021/BP0501423
Abstract: Biogenic gold nanotriangles and spherical silver nanoparticles were synthesized by a simple procedure using Aloe vera leaf extract as the reducing agent. This procedure offers control over the size of the gold nanotriangle and thereby a handle to tune their optical properties, particularly the position of the longitudinal surface plasmon resonance. The kinetics of gold nanotriangle formation was followed by UV-vis-NIR absorption spectroscopy and transmission electron microscopy (TEM). The effect of reducing agent concentration in the reaction mixture on the yield and size of the gold nanotriangles was studied using transmission electron microscopy. Monitoring the formation of gold nanotriangles as a function of time using TEM reveals that multiply twinned particles (MTPs) play an important role in the formation of gold nanotriangles. It is observed that the slow rate of the reaction along with the shape directing effect of the constituents of the extract are responsible for the formation of single crystalline gold nanotriangles. Reduction of silver ions by Aloe vera extract however, led to the formation of spherical silver nanoparticles of 15.2 nm +/- 4.2 nm size.
Publisher: Science China Press., Co. Ltd.
Date: 10-2014
Publisher: American Chemical Society (ACS)
Date: 06-09-2018
Abstract: Lithium-rich oxides have been regarded as one of the most competitive cathode materials for next-generation lithium-ion batteries due to their high theoretical specific capacity and high discharge voltage. However, they are still far from being commercialized due to low rate capability and poor cycling stability. In this study, we propose a heterostructured LiAlF
Publisher: American Chemical Society (ACS)
Date: 10-1997
DOI: 10.1021/JA971161E
Publisher: Royal Society of Chemistry (RSC)
Date: 2005
DOI: 10.1039/B501420B
Publisher: Springer Science and Business Media LLC
Date: 12-1997
DOI: 10.1007/BF01188937
Publisher: American Chemical Society (ACS)
Date: 16-07-2004
DOI: 10.1021/LA049258J
Abstract: We demonstrate that the amino acid tyrosine is an excellent reducing agent under alkaline conditions and may be used to reduce Ag+ ions to synthesize stable silver nanoparticles in water. The tyrosine-reduced silver nanoparticles may be separated out as a powder that is readily redispersible in water. The silver ion reduction at high pH occurs due to ionization of the phenolic group in tyrosine that is then capable of reducing Ag+ ions and is in turn converted to a semi-quinone structure. These silver nanoparticles can easily be transferred to chloroform containing the cationic surfactant octadecylamine by an electrostatic complexation process. The now hydrophobic silver nanoparticles may be spread on the surface of water and assembled into highly ordered, linear superstructures that could be transferred as multilayers onto suitable supports by the versatile Langmuir-Blodgett technique. Further, tyrosine molecules bound to the surface of Au nanoparticles through amine groups in the amino acid may be used to selectively reduce silver ions at high pH on the surface of the Au nanoparticles, thus leading to a simple strategy for realizing phase-pure Au core-Ag shell nanostructures.
Publisher: AIP Publishing
Date: 12-1991
DOI: 10.1063/1.349788
Abstract: In this paper the attenuation length measurements in lead arachidate [(C19H39COO)2Pb] Langmuir Blodgett films deposited on copper was reported on. A discrete layer model appropriate to the ordered structure of these built up films is applied to the measurements of the x-ray photoemission intensity variation with electron takeoff angle and attenuation lengths for Pb 4f7/2, O 1s and Cu 2p3/2 electrons (kinetic energy range 550–1350 eV) are determined. There is evidence for the dependence of the attenuation length on the dielectric properties of the film/substrate interface through a variation of the film thickness.
Publisher: American Scientific Publishers
Date: 12-2006
DOI: 10.1166/JNN.2006.615
Abstract: Development of simple and efficient protocol for the synthesis of Ni nanoparticles in aqueous media and their subsequent phase transfer to organic media is reported. The synthesis of nickel nanoparticles in aqueous medium is accomplished by reducing the nickel nitrate with sodium borohydride in presence of oleic acid. It results in the formation of nickel nanoparticles capped with oleic acid. The pristine oleic acid capped nickel nanoparticles were then phase transferred to nonpolar solvents such as toluene using stearic acid. The phase transfer was effective probably due to the space exchange between the oleic acid moiety and stearic acid molecules. The hydrophobized Ni thus obtained was organized at the air-water interface and it was observed that by controlling the pressure and concentration of hydrophobized Ni nanoparticles at air-water interface, linear ribbon like assemblies could be obtained. The organization process was followed by surface pressure-area isotherm measurement and Brewster Angle Microscopy.
Publisher: American Chemical Society (ACS)
Date: 08-11-2003
DOI: 10.1021/JA0374877
Abstract: The biosynthesis of CaCO3 by reaction of aqueous Ca2+ ions with a fungus, Fusarium sp., and an actinomycete, Rhodococcus sp. (both plant organisms), is described. In the case of the fungus, cruciform-shaped calcite crystals are obtained (SEM picture A) while the actinomycete yielded the unstable polymorph of CaCO3, vaterite (SEM picture B). Specific proteins secreted by the microorganisms are responsible for the morphology and crystallography control observed. A highlight of this approach is that the microorganisms also provide CO2 for reaction with the Ca2+ ions, making the crystals completely biogenic.
Publisher: American Chemical Society (ACS)
Date: 17-11-2001
DOI: 10.1021/LA0155101
Publisher: Wiley
Date: 11-2004
Publisher: Elsevier BV
Date: 06-2002
Publisher: American Scientific Publishers
Date: 12-2007
DOI: 10.1166/JNN.2007.891
Abstract: Development of synthesis methods for anisotropic metal nanoparticles is of considerable interest due to their remarkable optoelectronic properties. Various shapes ranging from rods to cubes to tetrapods and prisms may be obtained by chemical methods. Here we show that anisotropic gold nanoparticles can be synthesized biologically by the bacterium Actinobacter spp. when challenged with gold chloride in the presence of Bovine serum albumin (BSA). We also observed that synthesis of gold nanoparticles occur with simultaneous induction of the protease enzyme secreted by the bacterium in the presence of BSA. The presence of BSA helps to enhance the rate of gold nanoparticles biosynthesis and may also impart some shape control. Controlling simple experimental conditions like incubation temperature and presence or absence of oxygen have drastic effect on the reaction rate and the morphology of the particles. Various assay experiments show that the presence of enzyme protease can act as a reducing as well as shape directing agent.
Publisher: American Chemical Society (ACS)
Date: 23-02-2000
DOI: 10.1021/LA990948A
Publisher: Elsevier BV
Date: 1998
Publisher: Wiley
Date: 05-08-2003
Publisher: Royal Society of Chemistry (RSC)
Date: 2005
DOI: 10.1039/B502704G
Publisher: AIP Publishing
Date: 15-09-1993
DOI: 10.1063/1.466189
Abstract: Molecular packing in lead arachidate [(C19H39COO)2Pb] Langmuir Blodgett monolayer films transferred to glass substrates has been investigated using x-ray photoemission spectroscopy. It was observed that the degree of salt formation was a sensitive function of the subphase pH reaching a maximum at a pH of nearly 5.8. The loss features in the C 1s core level spectra of the films were clearly defined for films consisting of purely metal salt of arachidic acid while they became progressively diffused as the subphase pH was reduced. The blurring of the C 1s loss features has been explained as arising due to disorder introduced into the alkyl chains of lead arachidate molecules by the evaporation of acid molecules under ultrahigh vacuum. This leads to changes in the quasi one-dimensional electronic band structure in such molecular crystal films. A comparison is made with results obtained on cadmium arachidate and arachidic acid monolayer Langmuir Blodgett films. It is thus shown that molecular packing in Langmuir Blodgett films may be investigated using core level loss spectroscopy.
Publisher: Elsevier BV
Date: 1989
Publisher: Elsevier BV
Date: 11-2010
Publisher: Royal Society of Chemistry (RSC)
Date: 1997
DOI: 10.1039/A704355D
Publisher: Royal Society of Chemistry (RSC)
Date: 12-11-2002
DOI: 10.1039/B209050C
Abstract: A single step method for the synthesis of catalytically active, hydrophobic Pt nanoparticles by the spontaneous reduction of aqueous PtCl(6)2- ions by hexadecylaniline molecules at a liquid-liquid interface is described.
Publisher: Springer Science and Business Media LLC
Date: 11-1987
DOI: 10.1007/BF01133375
Publisher: American Chemical Society (ACS)
Date: 09-06-2005
DOI: 10.1021/JA0508469
Abstract: The synthesis of iron oxide nanoparticles of the predominantly magnetite phase by the reaction of aqueous iron complexes with the bacterium, Actinobacter spp., is described. This reaction occurs at room temperature and under aerobic conditions, resulting in the formation of superparamagnetic magnetite.
Publisher: IOP Publishing
Date: 14-01-1988
Publisher: Informa UK Limited
Date: 2005
Publisher: Elsevier
Date: 2003
Publisher: Wiley
Date: 2004
DOI: 10.1002/BIT.10856
Abstract: Gold nanoparticles are excellent biocompatible surfaces for the immobilization of enzymes. However, separation of the gold nanoparticle-enzyme bioconjugate material from the reaction medium is often difficult. In this study, we investigate the assembly of the gold nanoparticles on the surface of the amine-functionalized zeolite microspheres in the formation of zeolite-gold nanoparticle "core-shell" structures and, thereafter, the use of this structure in immobilization of fungal protease. The assembly of gold nanoparticles on the zeolite surface occurs through the amine groups present in 3-aminopropyltrimethoxysilane (3-APTS). The fungal proteases bound to the massive "core-shell" structures were easily separated from the reaction medium by mild centrifugation and exhibited excellent reuse characteristics. The biocatalytic activity of fungal protease in the bioconjugate was marginally enhanced relative to the free enzyme in solution. The bioconjugate material also showed significantly enhanced pH and temperature stability and a shift in the optimum temperature of operation.
Publisher: American Chemical Society (ACS)
Date: 11-07-2002
DOI: 10.1021/LA025802H
Publisher: American Chemical Society (ACS)
Date: 24-04-2001
DOI: 10.1021/JP0034877
Publisher: American Chemical Society (ACS)
Date: 26-10-2000
DOI: 10.1021/LA000753Z
Publisher: Elsevier BV
Date: 08-2002
Publisher: Royal Society of Chemistry (RSC)
Date: 2004
DOI: 10.1039/B401431F
Publisher: AIP Publishing
Date: 07-05-2001
DOI: 10.1063/1.1370993
Abstract: The assembly of nanoparticles in topologically predefined superstructures is an important problem in the area of nanoscale architecture. In this letter, we demonstrate the electrostatic assembly of lysine-capped colloidal gold particles on drop-coated DNA films. Electrostatic interaction between the positive charges on the gold nanoparticles and the negative charges on the phosphate groups of the DNA template molecules leads to the assembly of the gold nanoparticles in linear superstructures. The use of DNA as templates for the assembly of nanoparticles shows promise for extension to more complex geometries through rational design of the DNA base sequences as well as in the realization of nanowires by stringing together metal nanoparticles.
Publisher: American Chemical Society (ACS)
Date: 17-01-2003
DOI: 10.1021/LA026523X
Publisher: AIP Publishing
Date: 02-1988
DOI: 10.1063/1.340051
Abstract: We report the results of the investigation carried out on the aging and field effect of discontinuous copper films deposited on glass substrates held at around 125 K. Using the scheme adopted in our earlier investigations, it was found that even at this temperature there is considerable increase in resistance. However, the agglomeration rate is much less than for films deposited at room temperature. The I-V characteristics of the films revealed an irreversible change in resistance following removal of the field. On stabilization, heating of the films revealed a decrease in resistance with temperature followed by an irreversible resistance increase beyond a transition temperature which was less than room temperature.
Publisher: Royal Society of Chemistry (RSC)
Date: 2003
DOI: 10.1039/B303808B
Publisher: American Chemical Society (ACS)
Date: 02-1993
DOI: 10.1021/LA00026A036
Publisher: Elsevier BV
Date: 04-2003
Publisher: American Chemical Society (ACS)
Date: 14-04-2000
DOI: 10.1021/CM990439U
Publisher: American Chemical Society (ACS)
Date: 15-07-2005
DOI: 10.1021/LA051125Q
Abstract: Photoresponsive gold nanoparticle networks were prepared by functionalizing them with azobenzene derivatives. A network can be formed when a linker molecule constituting the azobenzene moiety suitably derivatized on either side with gold surface sensitive groups such as thiols and amines is added to the nanoparticle solution. It is shown that the interparticle spacing in the networks could be controlled by the reversible trans-cis isomerization of the azobenzene moiety induced by UV and visible light, respectively. The photoinduced variation in the interparticle spacings is inferred by the changes in the optical spectra of the gold nanoparticles which display a red or blue shift in the surface plasmon resonance peak depending on a decrease or increase in the interparticle spacing, respectively. Transmission electron microscopy images are in consonance with the evidence from the optical spectra.
Publisher: Elsevier BV
Date: 2010
Publisher: American Chemical Society (ACS)
Date: 27-08-2004
DOI: 10.1021/CM0352504
Publisher: American Chemical Society (ACS)
Date: 23-06-2007
DOI: 10.1021/JP067906X
Abstract: The binding strength of the carboxylic acid group (-COOH) with different alent metal ions displays considerable variation in arachidic acid (AA) thin films. It is considered that in AA thin films the metal ions straddle the hydrophilic regions of the stacked bilayers of AA molecules via formation of carboxylates. In this study first the uptake of different alent cations in films of AA is estimated by atomic absorption spectroscopy (AAS). Through the amount of cation uptake, it is found that the strength of binding of different cations varies as Ca2+>Co2+>Pb2+>Cd2+. Variation in the binding strength of different ions is also manifested in experiments where AA thin films are exposed to metal ion mixtures. The higher binding strength of AA with certain metal ions when exposed in idually, as well as the preference over the other metal ions when exposed to mixtures, reveal some interesting deviation from the expected behavior based on considerations of ionic radii. For ex le, Pb2+ is always found to bind to AA much more strongly than Cd2+ even though the latter has smaller ionic radius, indicating that other factors also play an important role in governing the binding strength trends apart from the effects of ionic radii. Then, to get a more meaningful knowledge regarding the binding capability, first-principles calculations based on density functional theory have been applied to study the interaction of different cations with the simplest carboxylic acid, acetic acid, that can result in formation of metal diacetates. Their electronic and molecular structures, cohesive energies, and stiffness of the local potential energy well at the cation (M) site are determined and attempts are made to understand the ersity in geometry and the properties of binding of different metal ions with -COOH group. We find that the calculated M-O bond energies depend sensitively on the chemistry of M atom and follow the experimentally observed trends quite accurately. The trends in M-O bond energies and hence the total M-acetate binding energy trends can actually be related to their molecular structures that fall into different categories: Ca and Cd have tetrahedral coordination Fe, Ni, and Co exhibit planar 4-fold coordination and Pb is off-centered from the planar structure (forming pyramidal structure) due to its stereochemically active lone pair of electrons.
Publisher: Elsevier BV
Date: 1994
Publisher: American Chemical Society (ACS)
Date: 11-11-2000
DOI: 10.1021/LA000886K
Publisher: IOP Publishing
Date: 18-06-2003
Start Date: 01-2007
End Date: 10-2008
Amount: $65,000.00
Funder: Australian Research Council
View Funded ActivityStart Date: 12-2020
End Date: 12-2025
Amount: $3,574,272.00
Funder: Australian Research Council
View Funded ActivityStart Date: 08-2023
End Date: 08-2029
Amount: $5,000,000.00
Funder: Australian Research Council
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