ORCID Profile
0000-0003-4118-5737
Current Organisation
Australian National University
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Publisher: Royal Society of Chemistry (RSC)
Date: 2016
DOI: 10.1039/C6RA13160C
Abstract: A series of amino acid appended cholic acid–azobenzene dyads have been synthesized and studied for their phase selective gelation behavior, which was further explored for water purification and oil spill remediation.
Publisher: Royal Society of Chemistry (RSC)
Date: 2012
DOI: 10.1039/C2RA21705H
Publisher: Royal Society of Chemistry (RSC)
Date: 2014
DOI: 10.1039/C3TB21835J
Publisher: Elsevier BV
Date: 2015
DOI: 10.1016/J.CARBPOL.2014.08.021
Abstract: In this work we report novel chitosan-carbon dots nanocomposite hydrogel films. A new green source "tea" was used as precursor for carbon dots (CDs). The electrostatic interaction of positive charge on chitosan and negative charge on CDs prepared from tea was used for the successful preparation of a stable and robust chitosan-carbon dots nanocomposite hydrogel film. The hydrogel films were characterized by UV-visible spectroscopy, X-ray diffraction (XRD), Fourier transformed infra-red spectroscopy (FTIR), scanning electron microscope (SEM), fluorescent microscopy, thermogravimetric analysis (TGA) and contact angle analysis. It was observed that chitosan-carbon dots hydrogel films are soft but tough with superior UV-visible blocking, swelling, thermal and mechanical properties in comparison to chitosan hydrogel film. Moreover chitosan-carbon dots films are more water repellent (hydrophobic) as indicated by their high contact angle values. Thus, fabrication of such green soft but tough biocompatible chitosan-carbon dots nanocomposite hydrogel films offers tremendous bio-medical and industrial applications.
Publisher: Elsevier BV
Date: 02-2019
Publisher: American Chemical Society (ACS)
Date: 24-07-2017
Publisher: Cold Spring Harbor Laboratory
Date: 02-06-2022
DOI: 10.1101/2022.06.02.494465
Abstract: The utility of CRISPR in plants has remained limited by the dual difficulties of delivering the molecular machinery to target cells and the use of somatic cell techniques that require tissue culture-based de novo organogenesis. We developed 5-10 nm isodiametric polyplex nanoassemblies, comprising poly [2-(dimethylamino)ethylmethacrylate] PDMAEMA (PD) polycationic linear homopolymers and CRISPR/Cas9 ribonucleoproteins (RNPs), that enable endocytosis-driven RNP uptake into pollen grains. Pollen from wheat plants (genotype Gladius+Sr50), homozygous for monogenic Sr50 -mediated resistance to stem rust ( Puccinia graminis f. sp. tritici -Pgt), were incubated with RNP/PD nanoassemblies targeting the dominant, Sr50 rust resistance gene. The treated pollen grains were then used to fertilize Gladius+Sr50 florets and the resulting M1 plants were tested for loss of Sr50 function via rust resistance screens. The identification of fully susceptible M1 seedlings indicated that the Sr50 RNPs acted on both alleles, indicating they were transferred via the treated pollen to the zygote. The ability to readily deliver CRISPR RNPs to reproductive cells via biodegradable, polymeric nanocomplexes has significant implications for the efficiency of gene editing in plants.
Publisher: Hindawi Limited
Date: 2013
DOI: 10.1155/2013/529159
Abstract: We have successfully demonstrated the use of capped carbon dot systems, namely, CDs/ β -cd, CDs/LMH, and CDs/Suc, as fluorescent sensors for the detection of hemin. The capped carbon dot systems showed quenching of PL intensity in the presence of hemin. The minimum detection limit was determined to be ~1 μ M. The PL response with free Fe(II) and Fe(III) was also studied. It was observed that PL quenching of capped carbon dot systems in the presence of hemin is dependent on the number of –OH groups in the capping agent. The order of quenching towards hemin was determined to be CDs/ β -cd CDs/LMH = CDs/Suc CDs. A possible mechanism to account for the observation is also discussed in the paper.
Publisher: MDPI AG
Date: 25-08-2022
Abstract: The use of biotechnology for the genetic improvement of wheat (Triticum aestivum L.) has been h ered by its recalcitrance to standard transformation and regeneration protocols. Male gametes present a potentially useful option for introducing gene edits via clustered regularly interspaced short palindromic repeats (CRISPR). However, the utility of male gametes for introducing genetic improvements would be dependent on the retention of viability after treatment to introduce the CRISPR components. We have studied wheat pollen morphology and its viability in a range of germination media to identify conditions that optimize the viability of in vitro hydrated pollen. The size, shape, and aperture from seven different wheat genotypes were compared using scanning electron microscope (SEM). The SEM results revealed that the pollen of all of the wheat genotypes examined in this study were monoporate however, a significant variation in the size of the mature pollen grains was observed. The hydrated pollen of the wheat genotypes remained viable for up to five hours at 20 ± 2 °C. Of all of the germination media tested, the medium containing 5% sucrose, 10% PEG4000, 100 mg/L boric acid, 200 mg/L calcium nitrate, 100 mg/L potassium nitrate, and 100 mg/L magnesium sulphate at pH 6.5 achieved the highest percentage of pollen germination after 5 h of hydration. Impedance Flow Cytometry (IFC) provided similar results to the in vitro germination study. This work elucidates important factors that can form the basis for a pollen-based non-genetically modified system for gene editing in wheat.
Publisher: American Chemical Society (ACS)
Date: 06-12-2016
Abstract: In this work, we report a smart stimuli-responsive drug delivery system (DDS) that can release drug depending upon the amount of pathogen (MRSA) present in the target. A greater amount of MRSA in the system will lead to more release of drug and vice versa. Carbon-dot-coated novel alginate beads (CA-CD) exhibiting superior stability was successfully used as smart drug delivery vehicle. Garlic extract (GE), which contains allicin, was taken as model drug system to demonstrate the phenomena. It was observed that GE loading was 19 and 78% with CA and CA-CD, respectively. CA-CD-GE shows pH-dependent controlled drug release, which results in increased therapeutic efficiency. CA-CD-GE is not only stimuli responsive but also a controlled drug release system as it releases drug according to the pathogen concentration (MRSA). All the three factors viz. drug release, MRSA concentration and pH of the medium are interdependent as when the cell ides, it produces secondary metabolites that lead to the decrease in pH of the medium. The drop in the pH value triggers drug release from the beads. And the effect of the drug is reflected by the MRSA cell death. Hence, we demonstrate a smart stimuli responsive DDS. However, such DDS will be useful in cases where increased amount of pathogen in the system will lead to reduction in pH.
Publisher: Elsevier BV
Date: 03-2015
DOI: 10.1016/J.CARBPOL.2014.09.083
Abstract: In this work we have designed a novel system based on carbon dots prepared from chitosan gel capped with β-cyclodextrin and calix[4]arene-25,26,27,28-tetrol for sensitive and selective detection of fluoride ions in aqueous media. Fluorescent carbon dots prepared from chitosan gel when capped with β-cyclodextrin and calix[4]arene-25,26,27,28-tetrol results in quenching of its fluorescence intensity. Introduction of F(-) ions to carbon dots capped with β-cyclodextrin and calix[4]arene-25,26,27,28-tetrol system results in enhancement and restoration of fluorescence intensity leading to detection of F(-) ion. Minimum detection limit was determined to be ∼6.6 μM. The detection is selective as with other halide ions i.e. Cl(-), Br(-) and I(-) and hydroxyl ion (OH(-)), there is observed decrease of fluorescence intensity. A possible mechanism to justify the observation is also discussed in the paper.
Publisher: American Scientific Publishers
Date: 06-2014
Abstract: In this work storage of silver nanoparticles (Ag NPs) in chitosan gel and its subsequent release for catalytic reduction processes is investigated. The generation of small sized metal nanoparticles which acts as catalyst is prerequisite to progress of a catalytic reaction. We show that Ag NPs extracted from chitosan gel are less than 5 nm so very effective in catalysis. Chitosan-Ag nanocomposite gels were prepared from two different approaches. The first approach involves in-situ incorporation of Ag nanoparticles into the reaction mixture while preparing the chitosan hydrogel and termed as chitosan-Ag-in-situ (CH-Ag-I) nanocomposite gel. And, in second approach already prepared chitosan hydrogel was placed in Ag NPs solutions, resulting in adsorption of Ag NPs and thus forming chitosan-Ag-ex-situ (CH-Ag-E) nanocomposite gel. The prepared gels were characterized by UV-Visible spectroscopy, Fourier transformed infra-red spectroscopy (FTIR), Thermogravimetric analysis (TGA) and Scanning electron microscopy (SEM). Swelling studies showed that the CH-Ag-E exhibits efficient water absorption property compared to that of CH-Ag-I. In addition to efficient swelling properties the CH-Ag-E can also act as store house of Ag NPs that can be used to catalyze the reduction of 4-Nitrophenol (4-NP) to 4-Aminophenol (4-AP) as Ag NPs of this composite can be easily extracted just by treating with sodium borohydride which is not possible in case of CH-Ag-I. The rate of the reaction increases upto 10 fold when CH-Ag-E nanocomposite gel is used as catalyst in comparison to CH-Ag-I. The reduction reaction catalyzed by such Ag NPs follow zero order kinetics and dependent on the size of the Ag NPs loaded in the gel (CH-Ag-E) as well as on the amount of the gel used. We found that smaller is the size of the loaded Ag NPs in CH-Ag-E, more effective it is in catalyzing the reduction reaction. The CH-Ag-E gel also showed reusability with efficient catalysis.
Publisher: Royal Society of Chemistry (RSC)
Date: 2015
DOI: 10.1039/C5RA19567E
Abstract: A non-conventional fragmentation of supported gold nanoparticles@agarose film by thiols through a prompt electron transfer is demonstrated. The film also shows catalysis of p -nitrophenol reduction in only ∼20 to 30 s.
Publisher: American Chemical Society (ACS)
Date: 29-01-2015
DOI: 10.1021/AM506558D
Abstract: A robust solid sensing platform for an on-site operational and accurate detection of heavy metal is still a challenge. We introduce chitosan based carbon dots rooted agarose hydrogel film as a hybrid solid sensing platform for detection of heavy metal ions. The fabrication of the solid sensing platform is centered on simple electrostatic interaction between the NH3+ group present in the carbon dots and the OH- groups present in agarose. Simply on dipping the hydrogel film strip into the heavy metal ion solution, in particular Cr6+, Cu2+, Fe3+, Pb2+, Mn2+, the strip displays a color change, viz., Cr6+→yellow, Cu2+→blue, Fe3+→brown, Pb2+→white, Mn2+→tan brown. The optical detection limit of the respective metal ion is found to be 1 pM for Cr6+, 0.5 μM for Cu2+, and 0.5 nM for Fe3+, Pb2+, and Mn2+ by studying the changes in UV-visible reflectance spectrum of the hydrogel film. Moreover, the hydrogel film finds applicability as an efficient filtration membrane for separation of these quintet heavy metal ions. The strategic fundamental feature of this sensing platform is the successful capability of chitosan to form colored chelates with transition metals. This proficient hybrid hydrogel solid sensing platform is thus the most suitable to employ as an on-site operational, portable, cheap colorimetric-optical detector of heavy metal ion with potential skill in their separation. Details of the possible mechanistic insight into the colorimetric detection and ion separation are also discussed.
Publisher: Springer Nature Singapore
Date: 2022
No related grants have been discovered for NEELAM GOGOI.