ORCID Profile
0000-0002-9991-8123
Current Organisation
Western Sydney University
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Research Topics
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.
Top 5 Research Topics
ANZSRC Field of Research (FoR)
Synthesis Of Macromolecules | Macromolecular and Materials Chemistry | Polymerisation Mechanisms | Characterisation Of Macromolecules
ANZSRC Socio-Economic Objective (SEO)
Other cereals | Chemical sciences | Polymeric materials (e.g. paints) |
Related Links
Publications
Structural modifications of cellulose samples after dissolution into various solvent systems
Publisher: Springer Science and Business Media LLC
Date: 10-2016
DOI: 10.1007/S00216-016-9958-1
Abstract: This work deals with the modifications resulting from the dissolution of four commercial cellulosic s les, with different crystallinity rates and degrees of polymerization (DPs), in four solvent systems, known and used to dissolve cellulose. The dissolution conditions were optimized for the 16 various systems and followed by turbidity measurements. After regeneration, the s les were analyzed by thermal gravimetric analysis (TGA), scanning electron microscopy (SEM), and X-ray diffractometry (XRD) to study their modification. Viscosimetry measurements were used to evaluate the potential decrease of the DP after dissolution. The observed structural modifications established that, for low DP, all the solvent systems were efficient in dissolving the cellulose without altering the DP, except BMIM [Cl], which provoked a decrease of up to 40 % and a decrease of around 20 % of the degradation temperature (onset temperature, T
Separation and Characterization of Synthetic Polyelectrolytes and Polysaccharides with Capillary Electrophoresis
Publisher: Hindawi Limited
Date: 14-09-2014
DOI: 10.1155/2014/798503
Abstract: The development of macromolecular engineering and the need for renewable and sustainable polymer sources make polymeric materials progressively more sophisticated but also increasingly complex to characterize. Size-exclusion chromatography (SEC or GPC) has a monopoly in the separation and characterization of polymers, but it faces a number of proven, though regularly ignored, limitations for the characterization of a number of complex s les such as polyelectrolytes and polysaccharides. Free solution capillary electrophoresis (CE), or capillary zone electrophoresis, allows usually more robust separations than SEC due to the absence of a stationary phase. It is, for ex le, not necessary to filter the s les for analysis with CE. CE is mostly limited to polymers that are charged or can be charged, but in the case of polyelectrolytes it has similarities with liquid chromatography in the critical conditions: it does not separate a charged homopolymer by molar mass. It can thus characterize the topology of a branched polymer, such as poly(acrylic acid), or the purity or composition of copolymers, either natural ones such as pectin, chitosan, and gellan gum or synthetic ones.
Understanding and improving direct UV detection of monosaccharides and disaccharides in free solution capillary electrophoresis
Publisher: Elsevier BV
Date: 2014
DOI: 10.1016/J.ACA.2013.12.001
Abstract: Direct UV detection of carbohydrates in free solution capillary electrophoresis at 270 nm is made possible by a photo-oxidation reaction. Glucose, rhamnose and xylose were shown to have unique UV absorption spectra hypothesizing different UV absorbing intermediates for their respective photo-oxidation. NMR spectroscopy of the photo-oxidation end products proved they consisted of carboxylates and not malondialdehyde as previously theorized and that oxygen thus plays a key role in the photo-oxidation pathway. Adding the photo-initiator Irgacure(®) 2959 in the background electrolyte increased sensitivity by 40% at an optimum concentration of 1×10(-4) mM and 1×10(-8) mM for conventional 50 μm i.d. capillaries and for the corresponding extended light path capillaries, respectively.
Assessment of starch branching and lamellar structure in rice flours
Publisher: Elsevier BV
Date: 07-2021
Simple and robust determination of monosaccharides in plant fibers in complex mixtures by capillary electrophoresis and high performance liquid chromatography
Publisher: Elsevier BV
Date: 05-2013
DOI: 10.1016/J.CHROMA.2013.03.041
Abstract: Carbohydrates partially liberated by acid hydrolysis of plant fiber can be separated by hydrophilic interaction liquid chromatography (HILIC), ligand-exchange liquid chromatography or other forms of LC with ion-exchange columns. However, the robust hydrogen-exchange columns show co-elution of galactose, xylose and mannose. Free solution capillary electrophoresis (CE) can be used without derivatization at pH 12.6 and was found to provide a higher resolution of galactose and xylose than common LC with no s le pre-treatment required, other than dilution, within 26min. CE was able to provide resolution higher than 0.79 for all separated carbohydrates, and the RSDs of determined concentrations lower than 10% for concentrations above 1.3gL(-1). A quantitative comparison between CE and HPLC revealed that up to 22% more carbohydrates are quantified with CE. Direct UV detection in CE of mono- and disaccharides is unexpectedly possible at 270nm. NMR analysis shows that alkaline degradation is too slow to explain this detection. This CE detection sensitivity is increased by the electric field and our CE and NMR analyses are consistent with a photo-oxidation process.
Mechanistic investigation of a starch-branching enzyme using hydrodynamic volume SEC analysis
Publisher: American Chemical Society (ACS)
Date: 23-02-2008
DOI: 10.1021/BM701213P
Abstract: Two linear alpha-(1,4)-D-glucans substrates, of degrees of polymerization DP approximately 150 and 6000, were exposed to maize starch-branching enzyme IIa (mSBEIIa) in vitro. The resulting branched alpha-glucans and their constituent chains (obtained by debranching) were analyzed by nuclear magnetic resonance (NMR) and size-exclusion chromatography (SEC). SEC data for the debranched species are presented as chain-length distributions, while those for branched species are presented as hydrodynamic volume distributions (HVDs), which is the most meaningful way to present such data (because SEC separates by size, not molar mass, and a s le of branched polymers with the same size can have a range of molar masses). A rigorous interpretation of the HVDs of the substrate and its branched product show that at least part of the branching is an interchain transfer mechanism in both the short- and long-chain substrate cases. A bimodal HVD of the in vitro branched alpha-glucan derived from the short-chain substrate was observed, and it is postulated that the ergence of the two populations is due to very small chains being unable to undergo branching. In the case of the in vitro branching of the long-chain substrate, the formation of maltohexaose during the reaction and the presence of a monomodal HVD were observed, suggesting a distinct mode of action of mSBEIIa on this substrate. Quantification of the branching level by NMR showed the branched glucans from both substrates had substantial amounts of branching (2.1-4.5%), ascribed to the intrinsic nature of the action of mSBEIIa on the two substrates. It is postulated that differences in the degrees of substrate association affect the pattern of branching catalyzed by the enzyme, and a putative active site structure is proposed based on the appearance of maltohexaose. The molar mass distribution of the constituent chains of the in vitro branched alpha-glucans obtained by isoamylase treatment reveals the transfer of chains of specific size and supports the supposition given in the literature that mSBEIIa is responsible for short-chain branching in amylopectin. It is suggested that hydrodynamic volume SEC analysis should be used as a tool for the mechanistic investigation of SBEs, allowing SEC data of in vitro branched alpha-glucans to be both comparable and quantitative.
Advanced spectroscopy, microscopy, diffraction and thermal analysis of polyamide adhesives and prediction of their functional properties with solid-state NMR spectroscopy
Publisher: Royal Society of Chemistry (RSC)
Date: 2021
DOI: 10.1039/D0PY01348J
Abstract: Advanced spectroscopy, microscopy, diffraction and thermal analysis reveal heterogeneity and dynamics in polyamide industrial adhesives solid-state NMR spectroscopy enable the prediction of their functional properties.
Size-exclusion chromatography (SEC) of branched polymers and polysaccharides
Publisher: Springer Science and Business Media LLC
Date: 22-10-2011
Separation of poly(acrylic acid) salts according to topology using capillary electrophoresis in the critical conditions
Publisher: Springer Science and Business Media LLC
Date: 04-06-2013
DOI: 10.1007/S00216-013-7059-Y
Abstract: Branching was detected in polyacrylates synthesised through radical polymerization via solution-state NMR, while inconsistencies have been reported for the determination of the molar mass of hydrophilic polyacrylates using aqueous-phase and organic-phase size-exclusion chromatography. In this work, poly(sodium acrylate)s, PNaAs, of various topologies were separated for the first time using free-solution capillary electrophoresis (CE). Free-solution CE does not separate the PNaAs by their molar mass, similarly to separations by liquid chromatography in the critical conditions, rather by different topologies (linear, star branched, and hyperbranched). The electrophoretic mobility of PNaAs increases as the degree of branching decreases. Separation is shown to be not only by the topology but also by the end groups as expected for a separation in the critical conditions: replacing a relatively bulky nitroxide end group with hydrogen atom yielded a higher electrophoretic mobility. This novel method, capillary electrophoresis in the critical conditions enabled, for the first time, the separation of hydrophilic polyacrylates according to their topology (branching) and their chain ends. This will allow meaningful and accurate characterization of their branched topologies as well as molar masses and progress in for advanced applications such as drug delivery or flocculation.
Interplay between Structure and Dynamics in Chitosan Films Investigated with Solid-State NMR, Dynamic Mechanical Analysis, and X-ray Diffraction
Publisher: American Chemical Society (ACS)
Date: 23-03-2011
DOI: 10.1021/BM200193U
Versatility of the dipolar filter selection: From 1H nuclear spin diffusion experiment to the measurement of nuclear Overhauser effect in homopolymer melts
Publisher: Elsevier BV
Date: 09-2005
DOI: 10.1016/J.SSNMR.2005.07.006
Abstract: Dipolar filters select 1H magnetization according to local dipolar dephasing, which corresponds to site mobility in systems with heterogeneous molecular mobility. Combined with a conventional exchange experiment, it is usually applied to polymeric s les exhibiting structures on the nanometer length scale associated with a strong dynamic contrast. There, the resulting 1H nuclear spin diffusion experiment yields the size of the structure. When the same experiment is applied to homopolymer melts exhibiting a weak dynamic contrast and dynamic heterogeneities on significant shorter length scales, the recorded magnetization decay is in agreement with decays expected from a heterogeneous nanostructure. However, dipolar filters actually can also select mobile parts of the repeat unit, e.g. the end of the alkyl side chains and the subsequent magnetization transfer then can occur via cross relaxation due to non coherent zero-quantum transitions (nuclear Overhauser effect, NOE). The difficulties of distinguishing these two cases are examined and it is demonstrated that NOE experiments exploiting magnetization selection via the dipolar filter allow quantifying the local dynamics of the side chains. This opens new possibilities for measurements of local dynamics in non isotopically labeled homopolymer melts.
Reducing the Degree of Branching in Polyacrylates via Midchain Radical Patching: A Quantitative Melt-State NMR Study
Publisher: American Chemical Society (ACS)
Date: 11-06-2010
DOI: 10.1021/MA100991C
Chain Dynamics in Poly(n-alkyl acrylates) by Solid-State NMR, Dielectric, and Mechanical Spectroscopies
Publisher: American Chemical Society (ACS)
Date: 24-07-2007
DOI: 10.1021/MA0706531
Mechanistic insights into the formation of polyion complex aggregates from cationic thermoresponsive diblock copolymers
Publisher: Elsevier BV
Date: 05-2021
Kinetics of In Vitro Digestion of Starches Monitored by Time-Resolved H-1 Nuclear Magnetic Resonance
Publisher: American Chemical Society (ACS)
Date: 09-03-2009
DOI: 10.1021/BM8014413
Abstract: A (1)H NMR method is presented that monitors the initial and later stages of in vitro enzymatic digestion of starch suspensions. It allows, for the first time to our knowledge, the accurate analysis of the initial 5% of the extent of hydrolysis. This is significant because rapidly digested starch produces glucose that determines the blood glucose concentration immediately after ingestion of food. The two key hydrolytic enzymes, alpha-amylase and amyloglucosidase, showed clear systematic deviation from Michaelis-Menten kinetics as the starch or wheat flour substrate that was used changed its character during the reaction. Estimates of Michaelis-Menten parameters for amyloglucosidase and alpha-amylase were successfully found by analyzing two stages of digestion separately. The Michaelis-Menten constants for purified starch were (6.4 +/- 0.8) and (1.1 +/- 0.3) g dL(-1) (% w/v), respectively and the maximum velocities of glucose release by amyloglucosidase, and short oligoglucosides and glucose by alpha-amylase were (1.9 +/- 0.4) x 10(-2) and (1.6 +/- 0.2) x 10(-2) mmol L(-1) s(-1) for the first stage of digestion, and (9.0 +/- 1.0) x 10(-3) and (4.7 +/- 1.4) x 10(-3) mmol L(-1) s(-1) for the second stage, giving a ratio of the two V(max) values of 2.1 and 3.4, respectively.
Starch-graft-(synthetic copolymer) latexes initiated with Ce4+ and stabilized by amylopectin
Publisher: Wiley
Date: 06-08-2007
DOI: 10.1002/POLA.22189
Investigation of Chain Dynamics in Poly(n‐alkyl methacrylate)s by Solid‐State NMR: Comparison with Poly(n‐alkyl acrylate)s
Publisher: Wiley
Date: 15-10-2008
Molecular weight and tacticity of oligoacrylates by capillary electrophoresis-mass spectrometry
Publisher: CSIRO Publishing
Date: 2010
DOI: 10.1071/CH10088
Abstract: Oligo(acrylic acid) efficiently stabilizes polymeric particles, especially particles produced by reversible addition–fragmentation chain transfer (RAFT) (as hydrophilic block of an hiphilic copolymer). Capillary electrophoresis (CE) has a far higher resolution power to separate these oligomers than the commonly used size exclusion chromatography. Coupling CE to electrospray ionization mass spectrometric detection unravels the separation mechanism. CE separates these oligomers, not only according to their degree of polymerization, but also according to their tacticity, in agreement with NMR analysis. Such analysis will provide insight into the role of these oligomers as stabilizers in emulsion polymerization, and into the mechanism of the RAFT polymerization with respect to degree of polymerization and tacticity.
Grafting of oligosaccharides onto synthetic polymer colloids
Publisher: American Chemical Society (ACS)
Date: 12-05-2007
DOI: 10.1021/BM061119O
Abstract: A new method to form colloidally stable oligosaccharide-grafted synthetic polymer particles has been developed. The oligosaccharides, of weight-average degree of polymerization approximately 38, were obtained by enzymatic debranching of amylopectin. Through the use of a cerium(IV)-based redox initiation process, oligosaccharide chains are grafted onto a synthetic polymer colloid comprising electrostatically stabilized poly(methyl methacrylate) or polystyrene latex particles swollen with methyl methacrylate monomer. Ce(IV) creates a radical species on these oligosaccharides, which then propagates, initially with aqueous-phase monomer, then with the methyl methacrylate monomer inside the particles. Ultracentrifugation, NMR, and total starch analyses together prove that the grafting process has occurred, with at least 7.7 wt % starch grafted and a grafting efficiency of 33%. The surfactant used in latex preparation was removed by dialysis, resulting in particles colloidally stabilized with only linear starch as a steric stabilizer. The debranched starch that comprises these oligosaccharides is found to be a remarkably effective colloidal stabilizer, albeit at low electrolyte concentration, stabilizing particles with very sparse surface coverage.
Correlation between Acidity and Catalytic Performance of Mesoporous Zirconium Oxophosphate in Phenylglyoxal Conversion
Publisher: American Chemical Society (ACS)
Date: 31-03-2019
Insight into Three‐Coordinate Aluminum Species on Ethanol‐to‐Olefin Conversion over ZSM‐5 Zeolites
Publisher: Wiley
Date: 30-10-2019
Abstract: Commercial bioethanol can be readily converted into ethylene by a dehydration process using solid acids, such as Brønsted acidic H-ZSM-5 zeolites, and thus, it is an ideal candidate to replace petroleum and coal for the sustainable production of ethylene. Now, strong Lewis acidic extra-framework three-coordinate Al
Towards a less biased dissolution of chitosan
Publisher: Elsevier BV
Date: 09-2016
DOI: 10.1016/J.ACA.2016.06.021
Abstract: The dissolution of polysaccharides is notoriously challenging, especially when one needs a "true" solution. Factors influencing chitosan's solubility include composition, also known as degree of acetylation (DA). The dissolution of chitosan was investigated by visual observation, size-exclusion chromatography (SEC), pressure mobilization (PM), free-solution capillary electrophoresis (CE) and real-time solution-state NMR spectroscopy. Aqueous HCl dissolves around 15% more chitosan than the commonly used aqueous acetic acid (AcOH), however aggregates were detected in SEC suggesting incomplete dissolution. Significant deacetylation of chitosan over the period needed for dissolution at high temperature was observed by NMR spectroscopy in DCl by about 20% of the initial DA value. Accurate DA determination by NMR spectroscopy may thus be possible only in the solid state (with a precision within 1% on the DA % scale above a DA of 10%). Overall a compromise between maximum solubilization and minimum degradation is required in attempting to obtain a "true" solution of chitosan. The completeness of the dissolution may be more influenced by the average DA than by molar mass.
Assessment of the Branching Quantification in Poly(acrylic acid): Is It as Easy as It Seems?
Publisher: American Chemical Society (ACS)
Date: 10-11-2017
SEC Analysis of Poly(Acrylic Acid) and Poly(Methacrylic Acid)
Publisher: Wiley
Date: 27-10-2014
Quantification of sugars in breakfast cereals using capillary electrophoresis
Publisher: Elsevier BV
Date: 05-2015
DOI: 10.1016/J.CARRES.2015.03.008
Abstract: About 80% of the Australian population consumes breakfast cereal (BC) at least five days a week. With high prevalence rates of obesity and other diet-related diseases, improved methods for monitoring sugar levels in breakfast cereals would be useful in nutrition research. The heterogeneity of the complex matrix of BCs can make carbohydrate analysis challenging or necessitate tedious s le preparation leading to potential sugar loss or starch degradation into sugars. A recently established, simple and robust free solution capillary electrophoresis (CE) method was used in a new application to 13 BCs (in Australia) and compared with several established methods for quantification of carbohydrates. Carbohydrates identified in BCs by CE included sucrose, maltose, glucose and fructose. The CE method is simple requiring no s le preparation or derivatization and carbohydrates are detected by direct UV detection. CE was shown to be a more robust and accurate method for measuring carbohydrates than Fehling method, DNS (3,5-dinitrosalicylic acid) assay and HPLC (high performance liquid chromatography).
Characterization of oligo(acrylic acid)s and their block co-oligomers
Publisher: Elsevier BV
Date: 11-2018
DOI: 10.1016/J.ACA.2018.05.030
Abstract: Oligo(acrylic acid), oligoAA are important species currently used industrially in the stabilization of paints and also for the production of self-assembled polymer structures which have been shown to have useful applications in analytical separation methods and potentially in drug delivery systems. To properly tailor the synthesis of oligoAA, and its block co-oligomers synthesized by Reversible-Addition Fragmentation chain Transfer (RAFT) polymerization to applications, detailed knowledge about the chemical structure is needed. Commonly used techniques such as Size Exclusion Chromatography (SEC) and Electrospray Ionization-Mass Spectrometry (ESI-MS) suffer from poor resolution and non-quantitative distributions, respectively. In this work free solution Capillary Electrophoresis (CE) has been thoroughly investigated as an alternative, allowing for the separation of oligoAA by molar mass and the RAFT agent end group. The method was then extended to block co-oligomers of acrylic acid and styrene. Peak capacities up to 426 were observed for these 1D CE separations, 10 times greater than what has been achieved for Liquid Chromatography (LC) of oligostyrenes. To provide a comprehensive insight into the chemical structure of these materials
Synthesis and Characterization of Synthetic Polymer Colloids Colloidally Stabilized by Cationized Starch Oligomers
Publisher: Wiley
Date: 24-02-2009
DOI: 10.1002/POLA.23287
Abstract: A method is developed for anchoring enzymatically degraded cationized starch as electrosteric stabilizers onto synthetic latices, using cerium(IV) to create free‐radical grafting sites on the starch. Direct anchoring of debranched starch onto a poly(methyl methacrylate) seed latex yields a latex stabilized by well‐defined oligosaccharides. Using α‐amylase to randomly cleave starch to form (1→4)‐α‐glucans, and a comonomer, N ‐isopropyl acrylamide (NIPAM), whose corresponding polymer exhibits a lower critical solution temperature (LCST), creates a means to synthesize block (or graft) oligomers of oligosaccharide and synthetic polymer, which are water soluble at room temperature. Above 30 °C, they become hiphilic and form self‐emulsifying nanoparticles (sometimes termed “frozen micelles”) from which a synthetic latex is grown after addition of methyl methacrylate, the collapsed NIPAM‐containing entities functioning as a type of in situ seed. This synthesis of stable synthetic latex particles is shown to have a high grafting efficiency. The starch fragments were characterized by 1 H solution‐state NMR before grafting, and 13 C solid‐state cross‐polarization magic‐angle spinning (CP‐MAS) NMR was used to characterize the starch oligomers actually grafted on the final latex. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1836–1852, 2009
Detection and quantification of branching in polyacrylates by size-exclusion chromatography (SEC) and melt-state 13C NMR spectroscopy
Publisher: Elsevier BV
Date: 05-2009
A new NMR method for directly monitoring and quantifying the dissolution kinetics of starch in DMSO
Publisher: Elsevier BV
Date: 12-2007
DOI: 10.1016/J.CARRES.2007.08.010
Abstract: The kinetics of dissolution of starch is needed for (i) understanding digestive processes (ii) providing data that could correlate with higher levels of starch structure (iii) improving techniques for starch characterization in solution. A novel method is presented here to directly monitor these dissolution kinetics by time-resolved (1)H solution-state nuclear magnetic resonance (NMR) studies were carried out in deuterated dimethyl sulfoxide (DMSO-d(6)). By assuming pseudo-first-order kinetics with respect to starch concentration, the data for various starch s les yield values of the apparent rate coefficients for the rate of appearance of completely dissolved anhydroglucose units, results which have not been obtained hitherto. The presence of a limited amount of water in DMSO had a drastic effect on dissolution kinetics (slowing it down at high temperatures), indicating multiple pathways for the dissolution mechanism. Dynamic light scattering (DLS) appears to be more limited than the NMR method to monitor the kinetics of dissolution. The newly developed NMR method can be extended to other solvents and polysaccharides.
Glucose conversion to 5-hydroxymethylfurfural on zirconia: Tuning surface sites by calcination temperatures
Publisher: Elsevier BV
Date: 07-2020
Theory of multiple-detection size-exclusion chromatography of complex branched polymers
Publisher: Wiley
Date: 16-01-2007
Supramolecular organization of protonated aminosilicones in water
Publisher: Elsevier BV
Date: 10-2013
DOI: 10.1016/J.JCIS.2013.07.010
Abstract: This study deals with the ionically-driven self-assembly of oligomeric aminosilicones, judiciously protonated with a variety of organic acids. Depending on the length of the silicone and the strength of the associated acids, (inverse) water-in-silicone emulsions, small nanoparticles, or catanionic vesicles were prepared and characterized by conventional (TEM) or original (DIC optical microscopy, DOSY NMR) techniques. For chains longer than about 40 units, a specific PEG-based sulfonic acid was synthesized and used to generate a supramolecular block-like copolymer and ensure fast and efficient emulsification. In all instances, a simple impulse such as pH increase triggered phase separation of the colloidal objects.
Starch-graft-copolymer latexes initiated and stabilized by ozonolyzed amylopectin
Publisher: Wiley
Date: 11-09-2006
DOI: 10.1002/POLA.21703
Characterization of gellan gum by capillary electrophoresis
Publisher: CSIRO Publishing
Date: 2012
DOI: 10.1071/CH12211
Abstract: Gellan gums were characterised for the first time using free-solution capillary electrophoresis (CE) or CE under critical conditions (CE-CC). CE-CC is a fast method that separates the polysaccharide. Gellan gums are shown to be heterogeneous in terms of their electrophoretic mobility at 55°C revealing: oligomer peak(s), broad peaks of polymers with a random coil conformation with different degrees of acylation (composition), aggregates, and polymers with double-helix conformation. CE-CC is complementary with the rheological analysis also performed in this work. Sonication of gellan gums is shown to decrease the viscosity of gellan gum mainly by breaking up aggregates. The effect of sonication is stronger on the high-acyl gellan gum since the latter has a far higher tendency to aggregate.
High-resolution separation of oligo(acrylic acid) by capillary zone electrophoresis
Publisher: Wiley
Date: 19-12-2006
Cellular Response to Linear and Branched Poly(acrylic acid)
Publisher: Wiley
Date: 10-08-2015
Abstract: Poly(acrylic acid-co-sodium acrylate) (PNaA) is a pH-responsive polymer with potential in anticancer drug delivery. The cytotoxicity and intracellular effects of 3-arm star, hyperbranched and linear PNaA were investigated with L1210 progenitor leukemia cells and L6 myoblast cells. Free solution capillary electrophoresis demonstrated interactions of PNaA with serum proteins. In a 72 h MTT assay most PNaAs exhibited a IC50 between 7 and 14 mmol L(-1), showing that precipitation may be a sufficient purification for PNaA dilute solutions. Dialyzed 3-arm star and hyperbranched PNaA caused an increase in L6 cell viability, challenging the suitability of MTT as cytotoxicity assay for PNaA. Fluorescent confocal microscopy revealed merging of cellular lipids after exposure to PNaA, likely caused by serum starvation.
Accessing Quantitative Degrees of Functionalization on Solid Substrates via Solid-State NMR Spectroscopy
Publisher: American Chemical Society (ACS)
Date: 16-03-2010
DOI: 10.1021/MA100149P
Extended Mechanistic Description of Particle Growth in Electrosterically Stabilized Emulsion Polymerization Systems
Publisher: American Chemical Society (ACS)
Date: 31-05-2007
DOI: 10.1021/MA070837F
Assessment of the extent of starch dissolution in dimethyl sulfoxide by 1H NMR spectroscopy
Publisher: Wiley
Date: 13-05-2009
Abstract: Complete dissolution is needed for the separation, characterization, or homogeneous labeling of whole starch molecules. A method is presented to quantify the extent of starch dissolution in DMSO for the first time it is validated on a commercial rice starch. It is used directly on starch dispersions containing possible undissolved or co-dissolved species. High-amylose maize starches, known to be digested slowly in vivo, only quantitatively dissolve in the presence of high concentrations of an H-bond disrupter, LiBr, although they form clear dispersions at low LiBr concentrations. Starch quantitatively dissolves from waxy rice flours non-starch components partially co-dissolve but do not interfere with the dissolution quantification.
Degree of branching in poly(acrylic acid) prepared by controlled and conventional radical polymerization
Publisher: Royal Society of Chemistry (RSC)
Date: 2019
DOI: 10.1039/C8PY01762J
Abstract: Poly(acrylic acid)s, PAAs and poly(sodium acrylate)s, PNaAs were characterized in detail.
Cellulose consolidation under high-pressure and high-temperature uniaxial compression
Publisher: Springer Science and Business Media LLC
Date: 28-01-2019
Viscosimetric detection in size-exclusion chromatography (SEC/GPC): The Goldwasser method and beyond
Publisher: Wiley
Date: 22-10-2010
Abstract: Size-exclusion chromatography (SEC or GPC) is the most widely used separation method to characterize polymers. The high level of complexity of most polymeric materials necessitates the use of not only concentration-sensitive detection but also structure-sensitive detection. Viscometry is usually used in conjunction with a concentration-sensitive detector and universal calibration to determine molecular weights of polymers. Goldwasser proposed to use a viscometer as a single detector to determine number-average molecular weights, M(n) (ACS Symposium Series, 521, 143). The method is particularly of interest when concentration-sensitive detection is not available, because the s le is isorefractive or not UV-absorbing, or because composition is not constant (copolymers). It has known very little applications so far. It actually does not only allow determining M(n), but also the number hydrodynamic volume distribution. This opens a wider range of applications for the Goldwasser method. Size-exclusion chromatography only yields inaccurate molecular weight distributions for some complex branched polymers. Hydrodynamic volume distributions have then a strong potential for comparative studies owing to their far higher accuracy. Our experimental tests highlight the fact that the method is highly sensitive to noise and careful optimization of the injection concentration is needed, but number distribution can be obtained as well as M(n).
Ethanol determination using pressure mobilization and free solution capillary electrophoresis by photo-oxidation assisted ultraviolet detection
Publisher: Elsevier BV
Date: 06-2014
DOI: 10.1016/J.CHROMA.2014.04.076
Abstract: Free solution capillary electrophoresis (CE) can separate and quantify carbohydrates using a simple direct UV detection based on a photo-oxidation reaction taking place in the detection window without any labeling. Ethanol interferes with this photo-oxidation reaction. We thus present the first detection and quantification of ethanol using either a simple pressure mobilization set-up or CE. Ethanol can be detected down to 34.9mgL(-1) and quantified in the range 117-1850mgL(-1) through the interference with photo-oxidization of 2gL(-1) sucrose. CE can thus separate and quantify both carbohydrates and ethanol, for ex le to monitor a lignocellulosic fermentation process. The method is not limited to ethanol and applies to alkyl amines and other alcohols and likely to most molecules possessing the ability to react with free radicals assuming they can be sufficiently separated from each other.
Purity of double hydrophilic block copolymers revealed by capillary electrophoresis in the critical conditions
Publisher: Elsevier BV
Date: 12-2014
DOI: 10.1016/J.CHROMA.2014.10.105
Abstract: Block copolymers enable combining properties of different polymers double hydrophilic block copolymers are innovative ex les. Size-exclusion chromatography (SEC or GPC) has a quasi-monopoly in separation-based characterization methods for polymers, including block copolymers. However, in terms of purity determination (unintended homopolymers present in the copolymers), SEC resolution proves insufficient except for the extreme compositions for which the second block is much larger than the first one. The free solution capillary electrophoresis (capillary zone electrophoresis) technique does not separate charged homopolymers by their molar mass and we thus named the corresponding method capillary electrophoresis in the critical condition (CE-CC). CE-CC provides a means to assess the purity of poly(acrylic acid-b-acrylamide) - P(AA-b-AM) - copolymers, as well as of the more challenging cationic poly(acrylamido-N-propyltrimethylammonium chloride-b-N-isopropylacrylamide)-P(APTAC-b-NIPAM). In addition it can identify that a block copolymer has been produced. It is to be noted that P(APTAC-b-NIPAM) block copolymers cannot be eluted in SEC due to their exceptional ability to adsorb onto surfaces, while some information is obtained from CE-CC. Both possible parent homopolymers can be detected and their quantity estimated in a single injection by CE-CC. In both cases, one of the parent homopolymers is neutral and comes with the electro-osmotic flow. If the electro-osmotic flow is weak (conditions used for the cationic copolymer) then pressure assisted CE-CC is used to detect this homopolymer.
Controlled/living radical polymerization of isoprene and butadiene in emulsion
Publisher: Elsevier BV
Date: 11-2009
Separation of complex branched polymers by size-exclusion chromatography probed with multiple detection
Publisher: Elsevier BV
Date: 05-2008
DOI: 10.1016/J.CHROMA.2008.03.031
Abstract: Size-exclusion chromatography (SEC) separates polymers by hydrodynamic volume (the universal calibration principle). Molecular weights can be determined using viscometry (relying on universal calibration) and light scattering (independent of universal calibration). In the case of complex branched polyacrylates with tetrahydrofuran as eluent, universal calibration is valid, although the separation in term of molecular weight is incomplete: a given elution slice contains a range of molecular weights, described in terms of a 'local polydispersity'. The local polydispersity index decreases when the number of branches per chain increases and complete separation is reached for highly branched chains.
Biohybrid cellulose fibers: Toward paper materials with wet strength properties
Publisher: Elsevier BV
Date: 08-2018
DOI: 10.1016/J.CARBPOL.2018.04.009
Abstract: Herein, we report on the preparation of novel cellulose-PEG biohybrid papers with wet strength properties. The biohybrid paper sheets are obtained using a two-step procedure where ω- or α, ω-azide functionalized PEG chains are anchored onto alkyne-functionalized wood fibers through CuAAC ligation in mild and aqueous conditions. The incorporation of the PEG grafts mostly occurs at the periphery of the cellulose fibers and degrees of substitution up to 0.028 are obtained. The presence of PEG grafts significantly increases the tensile, burst and tear strength properties in the wet state, the reinforcement being more pronounced for fibers grafted with α,ω-azide PEG. This reinforcement is consistent with a relatively sparse hetero-crosslink reaction creating inter-fiber covalent bonds and forming a cellulose network within the cell wall.
Functionalization of microspheres with malonates using Michael Addition as a pathway to create a drug delivery system for platinum drugs for the treatment of liver cancer
Publisher: Elsevier BV
Date: 12-2011
The Comparative Effect of Particle Size and Support Acidity on Hydrogenation of Aromatic Ketones
Publisher: Wiley
Date: 04-09-2019
Water vapour transmission in butadiene-MMA-methacrylic acid latex films
Publisher: Elsevier BV
Date: 02-2008
Synthesis by nitroxide-mediated aqueous dispersion polymerization, characterization, and physical core-crosslinking of pH- and thermoresponsive dynamic diblock copolymer micelles
Publisher: Royal Society of Chemistry (RSC)
Date: 2012
DOI: 10.1039/C2PY20084H
Engineering the Distinct Structure Interface of Subnano-alumina Domains on Silica for Acidic Amorphous Silica–Alumina toward Biorefining
Publisher: American Chemical Society (ACS)
Date: 19-02-2021
Poly(ethylene glycol) functionalization of monolithic poly(divinyl benzene) for improved miniaturized solid phase extraction of protein-rich samples
Publisher: Springer Science and Business Media LLC
Date: 11-01-2017
DOI: 10.1007/S00216-016-0164-Y
Abstract: Non-specific protein adsorption on hydrophobic solid phase extraction (SPE) adsorbents can reduce the efficacy of purification. To improve s le clean-up, poly( inyl benzene) (PDVB) monoliths grafted with hydrophilic polyethylene glycol methacrylate (PEGMA) were developed. Residual vinyl groups (RVGs) of the PDVB were employed as anchor points for PEGMA grafting. Two PEGMA monomers, M
Investigation of photochemical reactions of saccharides during direct ultraviolet absorbance detection in capillary electrophoresis
Publisher: Elsevier BV
Date: 04-2015
DOI: 10.1016/J.CHROMA.2015.02.030
Abstract: Direct UV detection of saccharides in capillary electrophoresis is possible due to a base-catalyzed conversion into UV absorbing substances initiated by the light of the UV detector l . In the present study the compounds formed during this reaction were investigated with capillary electrophoresis using an additional UV l for online irradiation at a certain distance before the detector resulting in a separation of the conversion products. It was found that for all investigated saccharides (glucose, ribose and sucrose) the major portion of the UV absorption in direct UV detection resulted from one and the same substance. By CE-UV, CE-MS as well as HPLC-MS measurements this substance was demonstrated to be malondialdehyde, present as its conjugate base malonenolate under alkaline conditions. Additional experiments revealed that the conversion reaction is highly sensitive to the residence time under the UV light as malondialdehyde can further degrade into non-UV absorbing products. NMR measurements showed that under alkaline conditions this degradation proceeds slowly even without UV irradiation.
Toward a full characterization of native starch: Separation and detection by size-exclusion chromatography
Publisher: Elsevier BV
Date: 09-2008
DOI: 10.1016/J.CHROMA.2008.07.090
Abstract: The structure of starch molecules is relevant to nutrition and industrial applications. Size-exclusion chromatography (SEC, also known as GPC) of native starch generally suffers non-satisfactory repeatability and reproducibility of the dissolution and separation. This work combines two polar organic solvents: dimethylsulfoxide for complete dissolution and dimethylacetamide to limit shear degradation. The separation is as repeatable as that of polystyrene standards performing dissolution and separation at 80 degrees C. Successful covalent-labeling on the glucose unit is claimed to be published here for the first time in non-degradative conditions and allows the use of UV detector with significantly higher sensitivity than with a refractometer.
Related Organisations
Related Funding Activities
Linkage Projects - Grant ID: LP0883881
Start Date: 2008
End Date: 12-2010
Amount: $420,000.00
Funder: Australian Research Council
View Funded Activity