@conference { ISI:000245886300024, title = {Novel method for the synthesis of siloxane nanowires and filaments using gold nanoparticle catalysts}, booktitle = {International Conference on Nanoscience and Technology}, series = {International Journal of Nanoscience Series}, volume = {4}, number = {5-6}, year = {2005}, note = {International Conference on Nanoscience and Technology, Calcutta, INDIA, DEC 17-20, 2003}, month = {DEC}, pages = {1007-1010}, publisher = {World Scientific Publ Co Pte Ltd, Po Box 128 Farrer Rd, Singapore 9128, Singapore}, organization = {World Scientific Publ Co Pte Ltd, Po Box 128 Farrer Rd, Singapore 9128, Singapore}, address = { Calcutta, India}, abstract = {

A unique polymerization reaction of alkylsilanes to siloxane nanowires, filaments and tubes in presence of gold nanoparticles and water is presented. The gold nanoparticles, which catalyze this reaction also work as templates restricting the shape of the resulting polymers into wires and tubes. High resolution transmission electron microscopy images clearly reveal the presence of gold nanoparticle at the tip of each wire supporting the template hypothesis. Elemental analyses by different methods confirm the stoichiometry to be C18H37SiO1.5, when the alkylsilane used was C18H37SiH3, thus proving that the alkyl group remains intact during the polymerization reaction.

}, keywords = {gold nanoparticles, Nanowires, siloxane polymers}, doi = {10.1142/S0219581X0500398X}, author = {Bhagavatula L. V. Prasad and Stoeva, S. and Sorensen, C. M. and Klabunde, Kenneth J. and Zaikovskii, V.}, editor = {Sanyal, M. K. and Raychaudhuri, A. K. and Chakravorty, D.} } @article { ISI:000252511300020, title = {Bacterial enzyme mediated biosynthesis of gold nanoparticles}, journal = {Journal of Nanoscience and Nanotechnology}, volume = {7}, number = {12}, year = {2007}, month = {DEC}, pages = {4369-4377}, publisher = {AMER SCIENTIFIC PUBLISHERS}, type = {Article}, address = {25650 NORTH LEWIS WAY, STEVENSON RANCH, CA 91381-1439 USA}, 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.

}, keywords = {Biosynthesis, bovine serum, gold nanoparticles}, issn = {1533-4880}, doi = {10.1166/jnn.2007.891}, author = {Bharde, Atul A. and Kulkarni, Aarohi and Rao, Mala and Prabhune, Asmita and Sastry, Murali} } @article { ISI:000268795100001, title = {Acute and subacute toxicity studies of chitosan reduced gold nanoparticles: a novel carrier for therapeutic agents}, journal = {Journal of Biomedical Nanotechnology}, volume = {5}, number = {3}, year = {2009}, month = {JUN}, pages = {233-239}, publisher = {AMER SCIENTIFIC PUBLISHERS}, address = {25650 NORTH LEWIS WAY, STEVENSON RANCH, CA 91381-1439 USA}, abstract = {

The objective of the present study was to evaluate the oral toxicity of chitosan reduced gold nanoparticles so as to demonstrate its applicability for drug delivery application. Acute oral toxicity studies in female rats documented no deaths or treatment related complications. The LD(50) value of gold nanoparticles was found to be greater than 2000 mg/kg. In case of sub-acute oral toxicity studies, gold nanoparticles were administered orally to male and female rats for a period of 28-days. At the end of study blood samples were collected for haematology and biochemical analysis. For histopathological analysis, organs of animals were weighed and processed for examination. All animals survived the duration of the study, with no significant changes in clinical signs, body weight, food consumption, hematological parameters, organ weights and histopathological findings. These studies establish that chitosan reduced gold nanoparticles produced no treatment related toxicity in rats following oral administration, thus can be exploited for potential therapeutic applications.

}, keywords = {Acute Toxicity, Chitosan, gold nanoparticles, Sub-Acute Toxicity, Wistar Rats}, issn = {1550-7033}, doi = {10.1166/jbn.2009.1027}, author = {Pokharkar, Varsha and Dhar, Sheetal and Bhumkar, Devika and Mali, Vishal and Bodhankar, Subhash L. and Bhagavatula L. V. Prasad} } @article { ISI:000272797200013, title = {Optical limiting properties of hydrophobic poly(etherimide) membranes embedded with isolated and aggregated gold nanostructures}, journal = {Colloids and Surfaces A-Physicochemical and Engineering Aspects}, volume = {352}, number = {1-3}, year = {2009}, month = {DEC}, pages = {79-83}, publisher = {ELSEVIER SCIENCE BV}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

A simple method to incorporate spherical or aggregated nanostructures of gold into hydrophobic poly(etherimide) membranes is demonstrated and their comparative nonlinear optical properties are investigated. When excited at 532 nm using laser pulses of 7 ns duration, a reduced transmission behaviour in both the cases, viz., polymers embedded with isolated nanoparticles and their aggregates is observed. This fits to a three-photon type nonlinear absorption process and is attributed to excited state absorption occurring in the nanostructures. Interestingly, the nonlinearity is more prominent in the aggregated nanostructures compared to the spherical nanostructures. These materials are potential candidates for optical limiting applications. (C) 2009 Elsevier B.V. All rights reserved.

}, keywords = {gold nanoparticles, Nanoparticle aggregation, Nonlinear optical properties, Optical limiting, Phase transfer, Polymer nanocomposites}, issn = {0927-7757}, doi = {10.1016/j.colsurfa.2009.10.002}, author = {D{\textquoteright}Britto, Virginia and Sandeep, C. S. Suchand and Philip, R. and Bhagavatula L. V. Prasad} } @article { ISI:000264897200052, title = {Shape and size selective separation of gold nanoclusters by competitive complexation with octadecylamine monolayers at the air-water interface}, journal = {Journal of Colloid and Interface Science}, volume = {333}, number = {1}, year = {2009}, month = {MAY}, pages = {380-388}, publisher = {ACADEMIC PRESS INC ELSEVIER SCIENCE}, address = {525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA}, 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. (c) 2009 Elsevier Inc. All rights reserved.

}, keywords = {Competitive complexation, gold nanoparticles, Langmuir-Blodgett technique, ODA monolayer}, issn = {0021-9797}, doi = {10.1016/j.jcis.2008.12.076}, author = {Pasricha, Renu and Singh, Amit and Sastry, Murali} } @article { ISI:000293587300003, title = {Biocompatible gellan gum-reduced gold nanoparticles: cellular uptake and subacute oral toxicity studies}, journal = {Journal of Applied Toxicology}, volume = {31}, number = {5}, year = {2011}, month = {JUL}, pages = {411-420}, publisher = {WILEY-BLACKWELL}, address = {COMMERCE PLACE, 350 MAIN ST, MALDEN 02148, MA USA}, abstract = {

Currently gold nanoparticles are being explored for drug delivery and other biomedical applications; therefore it is necessary to study the fate of such nanoparticles inside the body. The objective of the present study was to investigate the cellular uptake and toxicity of the gold nanoparticles synthesized using a microbial polysaccharide, gellan gum, as a capping and reducing agent. The cellular uptake of gold nanoparticles was studied on mouse embryonic fibroblast cells, NIH3T3 and human glioma cell line, LN-229. The cellular uptake study indicated that the gellan gum-reduced gold nanoparticles were located in cancer cells (LN-229) while no uptake was observed in normal mouse embryonic fibroblast cells (NIH3T3). The toxicity of the gold nanoparticles was evaluated by carrying out subacute 28 day oral toxicity studies in rats. Subacute administration of gum-reduced gold nanoparticles to the rats did not show any hematological or biochemical abnormalities. The weight and normal architecture of various organs did not change compared with control. The current findings, while establishing the specific uptake of nanoparticles into cancerous cells, also demonstrates that the gellan gum-reduced gold nanoparticles are devoid of toxicity in animals following oral administration. Copyright (c) 2010 John Wiley \& Sons, Ltd.

}, keywords = {cell lines, cellular uptake, Gellan gum, gold nanoparticles, subacute toxicity}, issn = {0260-437X}, doi = {10.1002/jat.1595}, author = {Dhar, Sheetal and Mali, Vishal and Bodhankar, Subhash L. and Shiras, Anjali and Bhagavatula L. V. Prasad and Pokharkar, Varsha} } @article { ISI:000288393700001, title = {Synthesis of gold nanoparticles by various leaf fractions of Semecarpus anacardium L. tree}, journal = {Trees-Structure and Function}, volume = {25}, number = {2}, year = {2011}, month = {APR}, pages = {145-151}, publisher = {SPRINGER HEIDELBERG}, address = {TIERGARTENSTRASSE 17, D-69121 HEIDELBERG, GERMANY}, abstract = {

Gold nanoparticles (NPs) were synthesized using Semecarpus anacardium leaf extracts in water and the green biomass. Extract prepared at ambient condition by crushing the leaves in deionized water is identified as {\textquoteleft}green extract{\textquoteright}, and that by boiling the leaf pieces as {\textquoteleft}boiled extract{\textquoteright}. The mass remaining after separating the {\textquoteleft}green extract{\textquoteright} is identified as {\textquoteleft}green biomass{\textquoteright}. These components triggered rapid reduction of Au(III) to Au (0) in HAuCl4 solution indicating the natural ability of the leaves of S. anacardium to synthesize NPs in ambient conditions. Green extract produced more NPs compared to the boiled extract suggesting denaturization of some of the useful factors due to boiling. NPs were quantified using UV and ICP-AES analysis. These were characterized using Transmission electron microscopy, Fourier transform infrared spectroscopy and X-ray diffraction. TEM images of the particles formed with green extract, boiled extract and green biomass showed that the particles were of different shapes and sizes.

}, keywords = {Biosynthesis, gold nanoparticles, Green extract, Semecarpus, TEM}, issn = {0931-1890}, doi = {10.1007/s00468-010-0493-y}, author = {Raju, D. and Mehta, Urmil J. and Hazra, Sulekha} } @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:000317836000016, title = {Extra- and intracellular gold nanoparticles synthesis using live peanut callus cells}, journal = {Current Nanoscience}, volume = {9}, number = {1}, year = {2013}, month = {FEB}, pages = {107-112}, publisher = {BENTHAM SCIENCE PUBL LTD}, address = {EXECUTIVE STE Y-2, PO BOX 7917, SAIF ZONE, 1200 BR SHARJAH, U ARAB EMIRATES}, abstract = {

An important challenge of considerable topical significance in nanotechnology is the development of eco-friendly experimental processes for the synthesis of nanomaterials in large quantities with variable sizes, shapes and chemical compositions. Green synthesis routes for the production of inorganic metal nanoparticles using whole cell of microorganisms and plant extracts are gaining tremendous popularity as these are non-toxic, cheap and occur at ambient conditions. The present work emphasizes on gold nanoparticles synthesis protocol using live plant callus cells. Peanut callus cells when incubated with HAuCl4 solution in ambient conditions reduced the precursor and lead to formation of well dispersed, water soluble extracellular and intracellular gold nanoparticles within 24 hours. The biosynthesis of gold nanoparticles was monitored by UV-visible spectroscopy (UV-Vis) and further characterized by X-ray diffraction analysis (XRD), Energy Dispersive Spectroscopy (EDS) and Selected Area Electron Diffraction (SAED). The particle size distribution shows that the average particle size is 50 nm for extra-and 31 nm for intracellular gold nanoparticles. The nanoparticles may be stabilized by proteins secreted by callus cells. The reduction process is believed to occur enzymatically, thus creating the possibility of a rational, plant cell-based method for the synthesis of nanoparticles over a wide range of chemical compositions.

}, keywords = {Biosynthesis, callus, gold nanoparticles, live cells, Peanut, TEM}, issn = {1573-4137}, author = {Raju, D. and Mehta, Urmil J. and Ahmad, Absar} } @article { ISI:000314381700030, title = {One-pot synthesis of gold nanoparticle/molybdenum cluster/graphene oxide nanocomposite and its photocatalytic activity}, journal = {Applied Catalysis B-Environmental}, volume = {130}, year = {2013}, month = {FEB}, pages = {270-276}, publisher = {ELSEVIER SCIENCE BV}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

The paper reports on a facile one-pot synthesis of a tri-component gold nanoparticle/molybdenum cluster/graphene oxide (AuNPs@Mo-GO) nanohybrid composite. The synthetic methodology consists on direct UV irradiation of an aqueous solution containing graphene oxide (GO), Na-2[Mo6Br8(N-3)(6)], HAuCl4 center dot 3H(2)O and isopropanol at room temperature in air using a UV fiber lamp. The composite material exhibits very high photocatalytic activity for the degradation of rhodamine B under visible light irradation. The resulting nanohybrid material was characterized using Raman spectroscopy, UV-vis spectrometry, transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). (c) 2012 Elsevier B.V. All rights reserved.

}, keywords = {gold nanoparticles, graphene oxide, Nanohybrid, Photodegradation, Rhodamine B, visible light, [Mo6Br8(N-3)(6)](2-)cluster}, issn = {0926-3373}, doi = {10.1016/j.apcatb.2012.11.017}, author = {Barras, Alexandre and Das, Manash R. and Devarapalli, Rami Reddy and Shelke, Manjusha V. and Cordier, Stephane and Szunerits, Sabine and Boukherroub, Rabah} } @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:000344448000007, title = {Development of bioconjugate from streptomyces tyrosinase and gold nanoparticles for rapid detection of phenol constituents}, journal = {Indian Journal of Experimental Biology}, volume = {52}, number = {11}, year = {2014}, month = {NOV}, pages = {1071-1081}, publisher = {NATL INST SCIENCE COMMUNICATION-NISCAIR}, type = {Article}, address = {DR K S KRISHNAN MARG, PUSA CAMPUS, NEW DELHI 110 012, INDIA}, abstract = {

Most of the phenol compounds are toxic and have been considered as hazardous pollutants. Several physicochemical and biological methods are available to detect and monitor the phenol pollutants in water and soil. In the present study, phenol constituents of winery, paper and plastic industrial effluents were successfully detected employing tyrosinase-gold nanoparticles bioconjugate. The synthesis of extracellular tyrosinase and gold nanoparticles was achieved by a single isolate of Streptomyces sp. DBZ-39. Enhanced production (369.41 IU) of tyrosinase was produced in submerged bioprocess employing response surface method with central composite design. Extracellular gold nanoparticles synthesized (12-18 nm) by Streptomyces sp. DBZ-39 were characterized with TEM, EDAX and FTIR analysis. A rapid detection (within 10 min) of phenol constituents from winery effluents was achieved by bioconjugate, when compared to tyrosinases and gold nanoparticles independently. Streptomyces tyrosinase could exhibit relatively a better performance than commercially available mushroom tyrosinase in the detection of phenol constituents. Winery effluent has shown much higher content (0.98 O.D) of phenol constituents than paper and plastic effluents based on the intensity of color and U.V absorption spectra.

}, keywords = {Bioconjugate, gold nanoparticles, Phenol detection, Streptomyces, Tyrosinase}, issn = {0019-5189}, author = {Zainab, Mazhari Bi Bi and Madhusudhan, D. N. and Raghavendra, H. and Dastager, Syed Gulam and Dayanand, Agsar} } @article { ISI:000333730900019, title = {Dilution does the trick: role of mixed solvent evaporation in controlling nanoparticle self-assembly}, journal = {Colloids and Surfaces A-Physicochemical and Engineering Aspects}, volume = {447}, year = {2014}, month = {APR}, pages = {142-147}, publisher = {ELSEVIER SCIENCE BV}, type = {Article}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

An easy and convenient way to prepare superlattices of amine capped gold nanoparticles is presented. It is clearly established that solvent evaporation significantly influences the nature of resulting superlattices and critically governs whether monolayer or multilayer superlattices are formed. More specifically, it is demonstrated that dilution of the nanoparticle dispersion with a similar solvent (but with different vapour pressure) is an expedient handle to control the nature of self-assembly. (C) 2014 Elsevier B.V. All rights reserved.

}, keywords = {Evaporation rate, gold nanoparticles, Nucleation, Self-assembly}, issn = {0927-7757}, doi = {10.1016/j.colsurfa.2014.01.070}, author = {Sahu, Puspanjali and Bhagavatula L. V. Prasad} } @article { ISI:000334440200001, title = {Functional silicon nanostructures derived from drying-mediated self-assembly of gold nanoparticles}, journal = {Journal of Nanoparticle Research}, volume = {16}, number = {5}, year = {2014}, month = {APR}, pages = {2372}, publisher = {SPRINGER}, address = {VAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDS}, abstract = {

Self-assembly of nanoparticles is an efficient technique where nanobuilding blocks spontaneously organize into ordered structures by thermodynamic and other constraints. We demonstrate that multifunctional Silicon (Si) nanostructures with unique morphologies like sheets, plates and flakes can be etched chemically by taking an advantage of natural self-assembly of gold nanoparticles (AuNPs) characterized with drying kinetics under external stimuli. We further demonstrated antireflection properties of the as-synthesized Si nanostructures.

}, keywords = {Antireflective material, gold nanoparticles, Metal-assisted chemical etching, Self-assembly, Si Nanostructures}, issn = {1388-0764}, doi = {10.1007/s11051-014-2372-8}, author = {Deshmukh, Ashvini B. and Devarapalli, Rami Reddy and Shelke, Manjusha V.} } @article { ISI:000330489500020, title = {In situ synthesized BSA capped gold nanoparticles: effective carrier of anticancer drug methotrexate to MCF-7 breast cancer cells}, journal = {Materials Science \& Engineering C-Materials For Biological Applications}, volume = {34}, year = {2014}, month = {JAN}, pages = {158-167}, publisher = {ELSEVIER SCIENCE BV}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

The proficiency of MTX loaded BSA capped gold nanoparticles (Au-BSA-MTX) in inhibiting the proliferation of breast cancer cells MCF-7 as compared to the free drug Methotrexate (MTX) is demonstrated based on MTT and Ki-67 proliferation assays. In addition, DNA ladder gel electrophoresis studies, flow cytometry and TUNEL assay confirmed the induction of apoptosis by MTX and Au-BSA-MTX in MCF-7 cells. Notably, Au-BSA-MTX: was found to have higher cytotoxicity on MCF-7 cells compared with an equivalent dose of free MTX. The enhanced activity is attributed to the preferential uptake of Au-BSA-MTX particles by MCF-7 cells due to the presence of BSA that acts as a source of nutrient and energy to the rapidly proliferating MCF-7 cells. Moreover, the targeting ability of the drug MTX to the over expressed folate receptors on MCF-7 cells also contributes to the enhanced uptake and activity. Taken together, these results unveil that Au-BSA-MTX could be more effective than free drug for cancer treatment. (C) 2013 Elsevier B.V. All rights reserved.

}, keywords = {Apoptosis, Bovine serum albumin, Cancer therapy, Cytotoxicity, Dual active agents, gold nanoparticles}, issn = {0928-4931}, doi = {10.1016/j.msec.2013.09.004}, author = {Murawala, Priyanka and Tirmale, Amruta and Shiras, Anjali and Bhagavatula L. V. Prasad} } @article { ISI:000352488300022, title = {Activity enhancement upon the incorporation of titanium: au@ti-sio2 core-shell nanocatalysts for the CO oxidation reaction}, journal = {ChemCatChem}, volume = {7}, number = {7}, year = {2015}, month = {APR}, pages = {1222-1230}, publisher = {WILEY-V C H VERLAG GMBH}, address = {BOSCHSTRASSE 12, D-69469 WEINHEIM, GERMANY}, abstract = {

The encapsulation of gold nanoparticles 8-12nm in size within a porous Ti-SiO2 shell to form a core-shell nanoarchitecture was investigated, and the catalytic activity of the resulting structure was probed. Detailed characterization of the synthesized materials shows that the core-shell morphology is lost beyond a certain amount of incorporated titanium, and results in normal gold-supported Ti-SiO2. The material has a high surface area (913m(2)g(-1)) and high porosity, both of which make it an excellent choice for catalytic applications. With the optimum amount of incorporated Ti, the core-shell catalyst shows excellent room-temperature CO oxidation activity over several cycles with retention of its morphology at higher temperatures.

}, keywords = {core-shell structures, gold nanoparticles, Oxidation, Ti-SiO2}, issn = {1867-3880}, doi = {10.1002/cctc.201402954}, author = {Sekhar, Anandakumari C. Sunil and Kottavarithottil Ziyad and Soni, Yogita and Vinod, Chathakudath P.} } @article { ISI:000345054100096, title = {Simple recovery of intracellular gold nanoparticles from peanut seedling roots}, journal = {Journal of Nanoscience and Nanotechnology}, volume = {15}, number = {2}, year = {2015}, month = {FEB}, pages = {1575-1581}, publisher = {AMER SCIENTIFIC PUBLISHERS}, address = {26650 THE OLD RD, STE 208, VALENCIA, CA 91381-0751 USA}, abstract = {

Fabrication of inorganic nanomaterials via a biological route witnesses the formation either extracellularly, intracellulary or both. Whereas extracellular formation of these nanomaterials is cherished owing to their easy and economical extraction and purification processes; the intracellular formation of nanomaterials, due to the lack of a proper recovery protocol has always been dreaded, as the extraction processes used so far were tedious, costly, time consuming and often resulting in very low recovery. The aim of the present study was to overcome the problems related with the extraction and recovery of intracellularly synthesized inorganic nanoparticles, and to devise a method to increasing the output, the shape, size, composition and dispersal of nanoparticles is not altered. Water proved to be much better system as it provided well dispersed, stable gold nanoparticles and higher recovery. This is the first report, where intracellular nanoparticles have been recovered using a very cost-effective and eco-friendly approach.

}, keywords = {gold nanoparticles, Peanut, Recovery, Sonication, Water}, issn = {1533-4880}, doi = {10.1166/jnn.2015.9046}, author = {Raju, D. and Mehta, Urmil J. and Ahmad, Absar} } @article { ISI:000380241600129, title = {Gold incorporated mesoporous silica thin film model surface as a robust SERS and catalytically active substrate}, journal = {Molecules}, volume = {21}, number = {5}, year = {2016}, month = {MAY}, pages = {667}, publisher = {MDPI AG}, address = {ST ALBAN-ANLAGE 66, CH-4052 BASEL, SWITZERLAND}, abstract = {

Ultra-small gold nanoparticles incorporated in mesoporous silica thin films with accessible pore channels perpendicular to the substrate are prepared by a modified sol-gel method. The simple and easy spin coating technique is applied here to make homogeneous thin films. The surface characterization using FESEM shows crack-free films with a perpendicular pore arrangement. The applicability of these thin films as catalysts as well as a robust SERS active substrate for model catalysis study is tested. Compared to bare silica film our gold incorporated silica, GSM-23F gave an enhancement factor of 10(3) for RhB with a laser source 633 nm. The reduction reaction of p-nitrophenol with sodium borohydride from our thin films shows a decrease in peak intensity corresponding to -NO2 group as time proceeds, confirming the catalytic activity. Such model surfaces can potentially bridge the material gap between a real catalytic system and surface science studies.

}, keywords = {gold nanoparticles, model catalysis, SERS, Thin films}, issn = {1420-3049}, doi = {10.3390/molecules21050667}, author = {Sekhar, Anandakumari Chandrasekharan Sunil and Vinod, Chathakudath Prabhakaran} } @article {43773, title = {Studies on the role of unsaturation in the fatty acid surfactant molecule on the thermal conductivity of magnetite nanofluids}, journal = {Journal of colloid and interface science }, volume = {506}, year = {2017}, month = {NOV}, chapter = {162-168}, abstract = {

To study the role of unsaturation in the surfactant molecule on the thermal conductivity of magnetite nanofluids, four different fatty acid (stearic, oleic, linoleic, and linolenic acids with different degree of unsaturation) coated magnetite nanoparticles of comparable size are prepared and dispersed in toluene. It is found that the nanofluid with the saturated fatty acid coated nanoparticles show larger viscosity than the fluid with the unsaturated fatty acid coated particles at all concentrations. Thermal conductivity studies show enhancement only above a critical concentration for all fluids. The critical concentration for thermal conductivity enhancement varies with the surfactant, possibly due to the difference in the degree of aggregation of the nanoparticles in the fluid, because of the difference in the conformation of the surfactant molecules on the nanoparticle{\textquoteright}s surface. The experimental thermal conductivity follows the Maxwell model at higher concentrations. From the overall studies, it is observed that the thermal conductivity of the fluids with aggregated or assembled nanoparticles shows slightly larger enhancement than that of the fluids with isolated particles. However, in the presence of a magnetic field, the fluids with isolated nanoparticles showed relatively larger enhancement, possibly due to the easy response of the isolated magnetite nanoparticles to the applied field. (C) 2017 Elsevier Inc. All rights reserved.

}, keywords = {Chains, Dynamics, Enhancement, Fields, Fluids, Forces, gold nanoparticles, Magnetic fluid; Nanofluid; Surfactant; Unsaturation; Conformation; Thermal conductivity; Viscosity, Self-assembled Monolayers}, issn = {0021-9797}, doi = {10.1016/j.jcis.2017.07.038}, author = {Lenin, Ramanujam and Joy, Pattayil Alias} } @article {48749, title = {Biosynthesis of gold nanoparticles by Penicillium rubens and catalytic detoxification of ochratoxin A and organic dye pollutants}, journal = {International Microbiology}, volume = {26}, year = {2023}, month = {NOV}, pages = {765-780}, type = {Article}, abstract = {

The environmental pollution caused by chemical dyes is a growing concern nowadays. Limitations of traditional methods opened the route for nanotechnology; owing to the versatile properties of nanomaterials, gold nanoparticles (AuNPs) became a potential strategy for different applications. In the present study, biosynthesis of gold nanoparticles (BioAuNPs) was carried out by reacting chloroauric acid (HAuCl4) with cell-free filtrate of Penicillium rubens sp. nov. NCIM 1937. The AuNPs were then characterized by UV-visible spectroscopy, HR-TEM, FTIR, and DLS analysis to further examine their efficacious biosynthesis and morphological properties including size, shape, and stability. The biogenic AuNPs are polydisperse in nature, with a mean size of 14.92 +/- 5 nm. These AuNPs exhibited promising antimicrobial activity against Escherichia coli NCIM-2065, Bacillus subtilis NCIM-2010, and Penicillium verrucosum MTCC 4935. In vitro quantitative HPLC results revealed that BioAuNPs significantly inhibited the biosynthesis of ochratoxin A (OTA). Microbial fuel cells (MFCs) are intriguing for power generation and wastewater treatment since they can directly transform chemical energy stored in organic matter to electricity by extracellular electron transfer (EET) via membrane proteins. AuNPs also showed excellent potential for dye degradation of organic pollutants, viz., methylene blue (MB), phenol red (PR), bromothymol blue (BTB), Congo red (CR), and 4-nitrophenol (4-NP). All dye removal efficiencies were estimated and fitted to pseudo-first-order processes using kinetic rate constants (Ka).The present study reveals a simple, original, and eco-friendly method for the synthesis of multifunctional biogenic AuNPs that could be effective in OTA detoxification in food products and organic pollutant removal during wastewater treatment for a sustainable environment.

}, keywords = {Catalytic organic dye degradation, gold nanoparticles, Ochratoxin A, Penicillium rubens, Penicillium verrucosum}, issn = {1139-6709}, doi = {10.1007/s10123-023-00341-5}, author = {Bhandari, Yogesh and Varma, Sanjana and Sawant, Amol and Beemagani, Sreelatha and Jaiswal, Neha and Chaudhari, Bhushan P. and Vamkudoth, Koteswara Rao} } @article {48806, title = {Transient response to perturbations in flow synthesis of citrate capped gold nanoparticles}, journal = {Biochemical Engineering Journal}, volume = {470}, year = {2023}, month = {AUG}, pages = {143890}, type = {Article}, abstract = {

This work reports the transient behavior of continuous flow synthesis of gold nanoparticles (Au NPs) when subjected to perturbations in operating conditions using controlled experiments. The intricacies are captured through a detailed mathematical model. Reversed Turkevich protocol was used for synthesis of Au NPs. The synthesis was first studied in batch mode to investigate the reaction kinetics and reproducibility of the process. The optimal set of operating conditions viz., residence time, flow rate, temperature was then used for flow synthesis in a 2 m, 1/16 \& DPRIME;Polytetrafluoroethylene (PTFE) reactor with micromixer. Reactor clogging was avoided by using segmented flow. Inline UV measurement was used for real time monitoring of the process. Transient experiments were performed by abruptly changing the operating conditions. A mathematical model was found to be accurate in predicting the transient behavior of the exit precursor concentration and the particle size for unsteady state synthesis. Even a small change in process variables for short duration was found to disturb the quality of Au NPs for a significantly longer duration. Of the three operating parameters, the effect of temperature variation was seen to have a prolonged effect where the system remained in unsteady state for long time.

}, keywords = {continuous flow synthesis, gold nanoparticles, Particle size, segmented flow, Unsteady behavior}, issn = {1385-8947}, doi = {10.1016/j.cej.2023.143890}, author = {Bari, Atul H. and Shukla, Neerja and Gavriilidis, Asterios and Kulkarni, Amol A.} }