@article { ISI:000226424000029, title = {Epoxidation of styrene by anhydrous hydrogen peroxide over boehmite and alumina catalysts with continuous removal of the reaction water}, journal = {Journal of Molecular Catalysis A-Chemical}, volume = {227}, number = {1-2}, year = {2005}, month = {MAR}, pages = {217-222}, publisher = {ELSEVIER SCIENCE BV}, type = {Article}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

Boehmite and alumina (obtained from the boehmite by its calcination at different temperatures 300-900degreesC) are active and stable catalysts for the selective epoxidation of styrene by anhydrous H2O2 to styrene oxide with continuous removal of the reaction water. Influence of the catalyst (boehemite) calcination temperature, H2O2/styrene ratio and catalyst loading on the styrene conversion and selectivity for styrene oxide. phenyl acetaldehyde. benzaldehyde and benzoic acid in the epoxidation has been investigated. In the presence of water. the catalyst shows very poor activity and selectivity in the epoxidation. The catalyst also catalyses H2O2 decomposition and hence has optimum loading for obtaining high-styrene conversion in the epoxidation. (C) 2004 Elsevier B.V. All rights reserved.

}, keywords = {Alumina, anhydrous hydrogen peroxide, boehmite, Epoxidation of styrene, Styrene oxide}, issn = {1381-1169}, doi = {10.1016/j.molcata.2004.10.025}, author = {Choudhary, Vasant R. and Patil, N. S. and Chaudhari, Nitin K. and Bhargava, Suresh Kumar} } @article { ISI:000245961800014, title = {Reduction of oxygen by hydroxylammonium salt or hydroxylamine over supported Au nanoparticles for in situ generation of hydrogen peroxide in aqueous or non-aqueous medium}, journal = {Catalysis Communications}, volume = {8}, number = {5}, year = {2007}, month = {MAY}, pages = {811-816}, publisher = {ELSEVIER SCIENCE BV}, type = {Article}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

Reaction of O-2 with hydroxylamine or its salts over a number of supported gold catalysts containing An nanoparticles (at 10-70 degrees C) has been studied at atmospheric pressure for the in situ generation of H2O2 (required for organic oxidation reactions in the synthesis of fine/specialty chemicals) in aqueous (water) or non-aqueous medium. Hydrogen peroxide in high yields with harmless by-products (viz. water and nitrogen) can be generated in situ by the reduction Of O-2 by hydroxylammonium sulfate (or chloride) or hydroxylamine using the supported gold catalysts particularly Au/Gd2O3, Au/La2O3 and Au/MgO, in aqueous (water) or non-aqueous (viz. methanol) medium at close to ambient conditions. The reduction of O-2 by hydroxylammonium salt to H2O2, however, requires preneutralization of the salt by alkali; in the absence of the neutralization, only water is formed in the reaction. (c) 2006 Elsevier B.V. All rights reserved.

}, keywords = {Au Nanoparticles, Au/Gd2O3, Au/La2O3, Au/MgO, Hydrogen peroxide, hydroxylamine, hydroxylammonium salts, in situ H2O2 generation}, issn = {1566-7367}, doi = {10.1016/j.catcom.2006.08.041}, author = {Choudhary, Vasant R. and Jana, Prabhas and Bhargava, Suresh Kumar} } @article { ISI:000245736400045, title = {Zirconia enrichment in zircon sand by selective fungus-mediated bioleaching of silica}, journal = {Langmuir}, volume = {23}, number = {9}, year = {2007}, month = {APR}, pages = {4993-4998}, publisher = {AMER CHEMICAL SOC}, type = {Article}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, 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.

}, issn = {0743-7463}, doi = {10.1021/la062535x}, author = {Bansal, Vipul and Syed, Asad and Bhargava, Suresh Kumar and Ahmad, Absar and Sastry, Murali} } @article { ISI:000259412500020, title = {Direct H(2)-to-H(2)O(2) oxidation in aqueous acidic medium containing Br promoter over Pd/Al(2)O(3) and Pd/C catalysts thermally pretreated under different conditions}, journal = {Catalysis Letters}, volume = {125}, number = {3-4}, year = {2008}, month = {OCT}, pages = {296-301}, publisher = {SPRINGER}, type = {Article}, address = {233 SPRING ST, NEW YORK, NY 10013 USA}, abstract = {

Influence of thermal pretreatments (under N(2), air or H(2) gas atmosphere at 500 degrees C or 700 degrees C) has been investigated for the Pd/Al(2)O(3) and Pd/Carbon catalysts in terms of its effect on their Pd particle size and performance in the H(2)-to-H(2)O(2) oxidation and H(2)O(2) destruction (by decomposition and/or hydrogenation) reactions in aqueous acidic medium containing Br promoter. The influence on the net H(2)O(2) formation is found to depend strongly upon the catalyst support due to support-Pd cluster interactions. For both the catalysts, the thermal treatments (except in air) caused a large increase in their Pd particle size. The increase in Pd particle size caused an increase in the H(2)O(2) formation activity of Pd/Al(2)O(3) but a decrease in the H(2)O(2) formation activity of Pd/C.

}, keywords = {Hydrogen peroxide, oxidation of H(2) to H(2)O(2), Pd/Al(2)O(3), Pd/C}, issn = {1011-372X}, doi = {10.1007/s10562-008-9482-9}, author = {Choudhary, Vasant R. and Jana, Prabhas and Bhargava, Suresh Kumar} } @article { ISI:000271103500016, title = {Oxidation of benzyl alcohol to benzaldehyde by tert-butyl hydroperoxide over nanogold supported on TiO2 and other transition and rare-earth metal oxides}, journal = {Industrial \& Engineering Chemistry Research}, volume = {48}, number = {21}, year = {2009}, month = {NOV}, pages = {9471-9478}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {

Liquid-phase oxidation of benzyl alcohol to benzaldehyde by tertiary butyl hydroperoxide (at 95 degrees C) over nanogold supported oil TiO2 and other transition-metal oxides (viz, MnO2, Fe2O3, CoOx, NiO, CuO, ZnO, and ZrO2) or rare-earth oxides (viz, La2O3, Sm2O3, Eu2O3, and Yb2O3) by the homogeneous deposition-precipitation (HDP) method has been investigated. The Au/TiO2 catalyst, prepared using the HDP method, showed high activity and selectivity in the reaction. The ZrO2-Supported nanogold catalyst (HDP) also showed very good performance. The Au/TiO2 catalyst that was prepared using the deposition-precipitation (DP) method, however, showed poor catalytic activity, mostly because of its much-lower gold loading and/or lower Au3+/Au-0 ratio. Irrespective of the catalyst preparation method, the catalytic activity increased as the gold loading increased. The gold deposition method strongly influenced the amount of gold that was deposited on TiO2, the gold particle size distribution, and also the surface Au3+/Au-0 ratio; using the HDP method, the gold deposition was much larger, the gold particle size was smaller, the gold particle size distribution was much narrower, and the Au3+/Au-0 ratio was higher. Both the metallic and ionic gold species (Au-0 and Au3+) are present in the Au/TiO2 catalyst. However, the Au3+ species are mostly responsible for the high catalytic activity in the oxidation process.

}, issn = {0888-5885}, doi = {10.1021/ie801883d}, author = {Choudhary, Vasant R. and Dumbre, Deepa K. and Bhargava, Suresh Kumar} } @proceedings {43270, title = {Self{\textendash}assembled histidine acid phosphate nanocapsules as templates for multifunctional hollow platinum nanospheres in ionic liquid [BMIM][BF 4 ] for drug delivery}, year = {2012}, month = {JAN}, abstract = {

During the past few decades, the design and fabrication of nano drug delivery vehicle has received considerable attention for incorporating multi-functionality, emphasizing transportation of anticancer drugs to tumour sites. Protein-based nanoparticles hold significant promise in the development of anticancer drug delivery systems since they have remarkable superiority in biocompatibility, biodegradability and natural metabolism in physiologic systems. Ionic liquids (ILs) are a class of solvents that are composed solely of ions (ILs {\textendash} commonly referred as room temperature molten salts or room temperature ionic liquids). They have recently emerged as green solvents or green reaction media, because of their reported unique physico-chemical properties. We report for the first time the controlled self-assembly of Histidine Acid phosphatase (HAP) enzyme in the IL 1-butyl-3-methylimidazolium tetrafluoroborate [BMIM][BF 4 ], leading to the formation of HAP nanocapsules as template for synthesis of platinum nanospheres. These HAP nano-containers were loaded with an anticancer drug curcumin. We further demonstrated in vitro drug release and synergistic anticancer effect of these systems on three different cell lines viz. hepatocellular carcinoma (HepG2), breast cancer (MCF-7) and human acute monocytes (THP-1). The present work can extend our theoretical understanding on nano-bio interfacial molecular self assembly and will facilitate the motivated insights of inorganic/organic hybrid nano-materials/ nano-particles/ nano-objects and ionic liquids based multi functional drug delivery vehicles with synergistic combination chemotherapy for potential application in tumor targeting. INTRODUCTION During the past few decades, the design and fabrication of drug delivery vehicle has received considerable attention for incorporating multi-functionality emphasizing transportation of anticancer drugs to tumour sites. These nano drug delivery vehicles have many advantages including prolonged circulation time of the drugs (Duncan, 2003, Kiick, 2007) , improved drug targeting and solubility (Duncan, 2003, Kiick, 2007), higher payloads (Duncan, 2003) and controlled release of the therapeutics into the blood stream or the targeted tumour tissues (Uhrich et al. 1999, Duncan, 2003).

}, author = {Soni, Sarvesh Kumar and Sarkar, Sampa and Sarkar, Dhiman and Coloe, Peter J. and Bhargava, Suresh Kumar and Bansal, Vipul} } @article { ISI:000313024300028, title = {Thermally decomposed Cu-Fe-hydrotalcite. a novel highly active catalyst for o-arylation of naphthol and phenols by aryl halides}, journal = {Catalysis Communications}, volume = {29}, year = {2012}, month = {DEC}, pages = {132-136}, publisher = {ELSEVIER SCIENCE BV}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

A novel, efficient and environmentally benign method has been reported for the synthesis of diaryl ethers by the o-arylation of napthol or phenols with aryl halides in dimethylformamide (as a solvent) under reflux, using a novel heterogeneous catalyst (having redox properties), obtained from thermal decomposition of Cu-Fe at 600 degrees C in the absence of externally added base. The catalyst comprises Cu(II) and Fe(III) species (oxides and hydroxides), which are uniformly distributed during the catalyst formation. The catalyst can be easily separated from the reaction mixture, simply by filtration and reused several times without a significant loss of its activity. (C) 2012 Elsevier B.V. All rights reserved.

}, keywords = {Aryl halides, C-O cross coupling reaction, Cu-Fe-hydrotalcite, Naphthol, o-Arylation, Phenols}, issn = {1566-7367}, doi = {10.1016/j.catcom.2012.09.024}, author = {Choudhary, Vasant R. and Dumbre, Deepa K. and Yadav, P. N. and Bhargava, Suresh Kumar} } @article { ISI:000317558000024, title = {Epoxidation of styrene by t-butyl hydroperoxide over gold nanoparticles supported on Yb2O3: effect of gold deposition method, gold loading, and calcination temperature of the catalyst on its surface properties and catalytic performance}, journal = {Journal of Catalysis}, volume = {300}, year = {2013}, month = {APR}, pages = {217-224}, publisher = {ACADEMIC PRESS INC ELSEVIER SCIENCE}, address = {525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA}, abstract = {

Surface properties and epoxidation performance of Au/Yb2O3 catalyst are influenced by the method of gold deposition [viz. deposition-precipitation (DP), homogeneous deposition-precipitation (HDP) or impregnation], gold loading (0.9-6.6 wt\%), and the catalyst calcination temperature (400-900 degrees C)]. The catalyst showed the best epoxidation performance when it was prepared by the HDP method and calcined at 500 degrees C. The Au/Yb2O3 catalyst even after calcination at 900 degrees C showed good activity and epoxide selectivity. Both Au-0 and Au3+ surface species were found in the catalyst calcined at 800 degrees C, but only Au-0 species were observed at the lower calcination temperatures (\<600 degrees C). The selectivity for styrene oxide increased continuously with the reaction temperature (from 75 degrees C to 97 degrees C) and time (1-5 h), indicating that styrene oxide did not undergo secondary reactions under these conditions. (C) 2013 Elsevier Inc. All rights reserved.

}, keywords = {Au/Yb2O3 catalyst, Epoxidation of styrene, gold nanoparticles, Styrene oxide, tert-Butyl hydroperoxide}, issn = {0021-9517}, doi = {10.1016/j.jcat.2013.01.002}, author = {Choudhary, Vasant R. and Dumbre, Deepa K. and Patil, N. S. and Uphade, B. S. and Bhargava, Suresh Kumar} } @article { ISI:000318332300017, title = {Suzuki-Miyaura cross-coupling reaction between aryl halides and phenylboronic acids over gold nano-particles supported on MgO (or CaO) and other metal oxides}, journal = {Journal of Catalysis}, volume = {301}, year = {2013}, month = {MAY}, pages = {134-140}, publisher = {ACADEMIC PRESS INC ELSEVIER SCIENCE}, address = {525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA}, abstract = {

Gold nano-particles-supported alkaline earth metal oxides, particularly MgO or CaO, show high catalytic activity in the Suzuki-Miyaura cross-coupling reaction in the presence of K2CO3 and DMF (as a solvent). The catalytic activity is strongly influenced by the nature or type of metal oxide support (viz, alkaline earth oxide, Group IIIA metal oxide, transition metal oxide, or rare earth oxide actinide oxide). It is also strongly influenced by the nature of aryl halide (aryl iodide, bromide, chloride, or fluoride), amount of K2CO3 in the reaction mixture and catalyst calcination temperature. Influence of reaction parameters viz, temperature and time and different substituents in aryl halides and/or phenylboronic acids on the biphenyl product yield in the reaction over Au/MgO catalyst has also been investigated. The catalyst showed excellent reusability in the reaction. Moreover, it is ligand-free and also has much lower cost than the commonly used homogeneous and heterogeneous Pd catalysts. (C) 2013 Elsevier Inc. All rights reserved.

}, keywords = {Aryl halides, Au/MgO (or CaO) catalyst, Biphenyls, Gold nano-particles, phenylboronic acids, Suzuki-Miyaura coupling reaction}, issn = {0021-9517}, doi = {10.1016/j.jcat.2013.01.012}, author = {Dumbre, Deepa K. and Yadav, P. N. and Bhargava, Suresh Kumar and Choudhary, Vasant R.} } @article { ISI:000327915300016, title = {Calcium oxide supported gold nanoparticles as catalysts for the selective epoxidation of styrene by t-butyl hydroperoxide}, journal = {Journal of Colloid and Interface Science}, volume = {415}, year = {2014}, month = {FEB}, pages = {111-116}, publisher = {ACADEMIC PRESS INC ELSEVIER SCIENCE}, type = {Article}, address = {525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA}, abstract = {

Gold nanoparticles are deposited on basic CaO supports as catalysts for the selective conversion of styrene into styrene oxide. Synthetic methods, gold loading and calcination temperatures are varied to permit an understanding of their influence on gold nanoparticle size, the presence of cationic gold species and the nature of interaction between the gold nanoparticles and the CaO support. Based on these studies, optimal conditions are designed to make the Au/CaO catalyst efficient for the selective epoxidation of styrene. (C) 2013 Elsevier Inc. All rights reserved.

}, keywords = {Au/CaO, Epoxidation of styrene, gold nanoparticles, Homogenous deposition precipitation method, Styrene oxide}, issn = {0021-9797}, doi = {10.1016/j.jcis.2013.10.016}, author = {Dumbre, Deepa K. and Choudhary, Vasant R. and Patil, Nilesh S. and Uphade, Balu S. and Bhargava, Suresh Kumar} } @article { ISI:000336005600009, title = {Mesoporous, ligand free Cu-Fe solid catalyst mediated CS cross coupling of thiols with aryl halides}, journal = {Applied Catalysis A-General}, volume = {476}, year = {2014}, month = {APR}, pages = {54-60}, publisher = {ELSEVIER SCIENCE BV}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

Solid catalyst derived from Cu-Fe hydrotalcite was demonstrated to be a novel, ligandless, efficient and environmentally greener catalyst for the synthesis of diaryl sulfurs from the C-S cross coupling reaction of substituted thiols with different aryl halides. This catalyst has shown higher product yield in the presence of dimethylformamide (as a solvent) and K2CO3 (as a base) at 120 C. Influence of different solvents and bases on the product yield has also been investigated. The catalyst can be easily separated from the reaction mixture, simply by filtration and reused several times without a significant loss of its activity. The catalyst has been fully characterized for its surface and bulk properties and the mesoporous CuO:Fe2O3 phase was attributed for its catalytic activity towards S-arylation reactions. (C) 2014 Elsevier B.V. All rights reserved.

}, keywords = {C-S cross coupling, Cu-Fe-hydrotalcite, S-arylation}, issn = {0926-860X}, doi = {10.1016/j.apcata.2014.02.015}, author = {Dumbre, Deepa K. and Selvakannan, P. R. and Patil, S. K. and Choudhary, Vasant R. and Bhargava, Suresh Kumar} } @article { ISI:000359596600058, title = {Charge-switchable gold nanoparticles for enhanced enzymatic thermostability}, journal = {Physical Chemistry Chemical Physics}, volume = {17}, number = {33}, year = {2015}, month = {JUL}, pages = {21517-21524}, publisher = {ROYAL SOC CHEMISTRY}, address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND}, abstract = {

This study illustrates a facile strategy for efficient immobilization of enzymes on a metal nanoparticle surface. The strategy proposed here enables the enzymatic activity to be retained while increasing the enzyme thermostability. It is demonstrated that the use of a zwitterionic amino acid tyrosine as a reducing and capping agent to synthesise gold nanoparticles allows efficient immobilization of phytase enzyme through charge-switchable electrostatic interactions. The detailed kinetic and thermodynamic studies reveal that the proposed enzyme immobilization strategy improves the overall quality of phytase by reducing the activation energy required for substrate hydrolysis and broadening the temperature window in which immobilized enzyme is able to operate. The outcomes of this study indicate that the underlying zwitterionic nature of 20 natural amino acids along with significant variability in their isoelectric points and hydropathy indices as well the ability of some of the amino acids to reduce metal ions is likely to offer significant opportunities for tailoring nano-bio interfaces in a rational manner for a range of biological applications.

}, issn = {1463-9076}, doi = {10.1039/c5cp03021h}, author = {Shankar, Shiv and Soni, Sarvesh K. and Daima, Hemant K. and Selvakannan, P. R. and Khire, Jayant Malhar and Bhargava, Suresh Kumar and Bansal, Vipul} } @article { ISI:000358620100066, title = {Intrinsic therapeutic and biocatalytic roles of ionic liquid mediated self-assembled platinum-phytase nanospheres}, journal = {RSC Advances}, volume = {5}, number = {77}, year = {2015}, month = {JUL}, pages = {62871-62881}, publisher = {ROYAL SOC CHEMISTRY}, address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND}, abstract = {

We herein report the inherent antitumor efficiency of self-assembled phytase enzyme nanospheres and enhance their efficiency by decorating with platinum nanoparticles and with the anticancer drug curcumin. Firstly, controlled self-assembly of phytase enzyme in an Ionic Liquid 1-butyl-3-methylimidazolium tetrafluoroborate [Bmim][BF4], led to the formation of therapeutically active phytase nanospheres. These nanospheres were further decorated with platinum nanoparticles by adding the platinum ions to these spheres and the nanoparticles formation was mediated by the specific interaction between the histidine residue (in active site of phytase enzymes) and the platinum ions and subsequent reduction of the ions into nanoparticles. The enzyme spheres act as a functional soft template for the as-formed platinum nanoparticles. These Platinum decorated hybrid biomacromolecular phytase nanospheres were loaded with the anticancer drug curcumin and all the different kinds of nanospheres were subjected to in vitro cytotoxicity for their anticancer effect on three different kinds of cancer cell lines i.e. MCF-7, Hep-G2 and THP-1 derived human macrophages. We observed a gradual increase in the anticancer effect caused by only phytase nanospheres (25\%), platinum-phytase nanospheres (37\%), phytase-curcumin (78\%) and platinum-phytase-curcumin nanospheres (90\%) that establishes this protein based system as a robust combinatorial drug delivery vehicle. The platinum-phytase spheres also proved their usability as a highly efficient green and reusable biocatalytic system for phytate degradation. The present work facilitates our understanding of ionic liquid based synthesis for multifunctional protein based drug delivery vehicles incorporating combinatorial chemotherapy for potential application as biopharmaceutical agents for tumor treatment and bio-catalysis.

}, issn = {2046-2069}, doi = {10.1039/c5ra11273g}, author = {Soni, Sarvesh K. and Sarkar, Sampa and Selvakannan, P. R. and Sarkar, Dhiman and Bhargava, Suresh Kumar} } @article { ISI:000381165300025, title = {Studies of synergy between metal-support interfaces and selective hydrogenation of HMF to DMF in water}, journal = {Journal of Catalysis}, volume = {340}, year = {2016}, month = {AUG}, pages = {248-260}, publisher = {ACADEMIC PRESS INC ELSEVIER SCIENCE}, address = {525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA}, abstract = {

Metal-support interfaces play a very important role in heterogeneous catalysis. The interfacial interactions not only are responsible for stabilizing the necessary oxidation state to facilitate the reaction but also enhance the stability of the catalyst system. Nano dispersion of Ni on mesoporous nitrogen-rich carbon material has been achieved using two different synthesis methods. It was observed that nickel (0) gets stabilized by strong interfacial interaction with the nitrogen atoms of the support material, and the material was found to be very economic and efficient for the conversion of HMF to DMF in aqueous medium. The material shows \>= 99\% conversion to 5-(hydroxymethyl) furfural (HMF) within 6 h of reaction with 98.7\% DMF selectivity. A unique correlation between synthesis methods and particle sizes with catalytic performance has been observed for these newly developed materials. Furthermore, a DFT calculation has been performed to predict the reaction mechanism. (C) 2016 Elsevier Inc. All rights reserved.

}, keywords = {biofuels, Biomass, Hydrogenation, mesoporous carbon, Ni-CNx}, issn = {0021-9517}, doi = {10.1016/j.jcat.2016.05.012}, author = {Goyal, Reena and Sarkar, Bipul and Bag, Arijit and Siddiqui, Nazia and Dumbre, Deepa K. and Lucas, Nishita and Bhargava, Suresh Kumar and Bordoloi, Ankur} }