02686nas a2200193   4500008004100000022001400041245018200055210006900237260011000306300001400416490000600430520181900436100002302255700002302278700002302301700002502324700001902349856012402368       2013                        eng d  a2040-336400aIn situ synthesis and surface functionalization of gold nanoparticles with curcumin and their antioxidant properties: an experimental and density functional theory investigation0 aIn situ synthesis and surface functionalization of gold nanopart  aTHOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLANDbROYAL SOC CHEMISTRYcDEC  a1882-18930 v53 a<p>Curcumin ((1E,6E)-1,7-bis(4-hydroxy-3-methoxyphenyl)-1,6-heptadiene-3,5-dione) is an active component of turmeric; it is responsible for its characteristic yellow color and therapeutic potential, but its poor bioavailability remains a major challenge. In order to improve the bioavailability of curcumin, various approaches have been used. One of the possible approaches to increase the bioavailability of curcumin is its conjugation on the surface of metal nanoparticles. Therefore, in the present study, we report the binding of curcumin on the surface of gold nanoparticles (AuNPs). The AuNPs were synthesized by the direct reduction of HAuCl4 using curcumin in the aqueous phase, without the use of any other reducing agents. We found that curcumin acts both as a reducing and capping agent, stabilizing the gold sol for many months. Moreover, these curcumin-capped AuNPs also show good antioxidant activity which was confirmed by the DPPH (2,2-diphenyl-l-picrylhydrazyl) radical test. Thus, the surface functionalization of AuNPs with curcumin may pave a new way of using the curcuminoids towards possible drug delivery and therapeutics. Apart from the experimental study, a detailed quantum chemical calculation using density functional theory (DFT) has been performed, in order to investigate the formation of a complex of curcumin with Au3+ ions in different possible conformational isomeric forms. Our theoretical calculations indicate the evidence of electron transfer from curcumin into the Au center and essentially indicate that as a consequence of complexation, Au3+ ions are reduced to Au-0. Our theoretical results also propose that it is the breakage of intramolecular H-bonding that probably leads to the increased availability of curcumin in the presence of gold ions and water molecules.</p>1 aSingh, Dheeraj, K.1 aJagannathan, Ramya1 aKhandelwal, Puneet1 aAbraham, Priya, Mary1 aPoddar, Pankaj  uhttps://library.ncl.res.in/content/situ-synthesis-and-surface-functionalization-gold-nanoparticles-curcumin-and-their-001642nas a2200277   4500008004100000022001400041245015700055210006900212260010600281300001000387490000800397520061100405653002101016653001401037653001301051653001801064653001401082653001501096100002101111700002301132700001801155700002001173700001901193700002201212856013001234       2013                        eng d  a1386-142500aStudy of hydration of sarcosine, formation of its zwitterion and their different oligomers in aqueous media: a Raman spectroscopic and theoretical study0 aStudy of hydration of sarcosine formation of its zwitterion and   aTHE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLANDbPERGAMON-ELSEVIER SCIENCE LTDcDEC  a74-830 v1163 a<p>{Raman spectra of the biologically important molecule sarcosine (SAR) (C3H7NO2) were studied experimentally in aqueous solution at different concentrations. These spectra were also calculated theoretically using density functional theory (DFT) at the B3LYP/6-31 1++G(d,p) level. Further, all the observed normal modes were assigned through potential energy distribution (PED). Geometry optimization of SAR produced its three conformers with slightly different energies. The lowest energy conformer of SAR was selected for a systematic solvation study wherein different numbers of water molecules (nW</p>10aDFT calculations10aHydration10aOligomer10aRaman spectra10aSarcosine10aZwitterion1 aSharma, Poornima1 aSingh, Dheeraj, K.1 aGupta, Vineet1 aAsthana, B., P.1 aMishra, P., C.1 aSingh, Ranjan, K.  uhttps://library.ncl.res.in/content/study-hydration-sarcosine-formation-its-zwitterion-and-their-different-oligomers-aqueous-001877nas a2200181   4500008004100000022001400041245018800055210006900243260007700312300001200389490000700401520107600408100002301484700002301507700001701530700001901547856012901566       2014                        eng d  a2192-650600aModulation of reaction kinetics for the tuneable synthesis of gold nanoparticles and quantum clusters: application of gold quantum clusters as ``turn-off'' sensing probe for Sn4+ ions0 aModulation of reaction kinetics for the tuneable synthesis of go  aBOSCHSTRASSE 12, D-69469 WEINHEIM, GERMANYbWILEY-V C H VERLAG GMBHcJAN  a134-1420 v793 a<p>The syntheses of gold nanoparticles (Au NPs) and gold quantum clusters (Au QCs) that employ cefadroxil (CFX; an antibiotic) as both reducing and capping agents are reported. The HAuCl4/CFX concentration, temperature, and pH are crucial factors in the modulation of the nucleation and growth kinetics of the reaction, and consequently, in guiding the size and morphology of as-synthesized Au NPs. Interesting results are observed if the reaction is performed under different pH conditions. TEM analysis of the Au NPs synthesized at pH 6 shows an average particle size of approximately 2 nm along with a relatively smaller population of bigger NPs (up to 6 nm). The Au QCs were isolated by high-speed centrifugation and showed fluorescence at lambda approximate to 460 nm. Furthermore, the as-synthesized Au QCs were applied as sensor for Sn4+ ions on the basis of an aggregation-induced fluorescence quenching mechanism. These Au QCs offer acceptable sensitivity, high selectivity, and a limit of detection of approximately 10 mm for the determination of Sn4+ ions.</p>1 aKhandelwal, Puneet1 aSingh, Dheeraj, K.1 aSadhu, Subha1 aPoddar, Pankaj  uhttps://library.ncl.res.in/content/modulation-reaction-kinetics-tuneable-synthesis-gold-nanoparticles-and-quantum-clusters-002942nas a2200181   4500008004100000022001400041245018100055210006900236260011000305300001600415490000600431520211200437100002302549700002302572700001702595700001902612856012902631       2015                        eng d  a2040-336400aStudy of the nucleation and growth of antibiotic labeled Au NPs and blue luminescent Au-8 quantum clusters for Hg2+ ion sensing, cellular imaging and antibacterial applications0 aStudy of the nucleation and growth of antibiotic labeled Au NPs   aTHOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLANDbROYAL SOC CHEMISTRYcOCT  a19985-200020 v73 a<p>Herein, we report a detailed experimental study supported by DFT calculations to understand the mechanism behind the synthesis of cefradine (CFD - an antibiotic) labeled gold nanoparticles (Au NPs) by employing CFD as both a mild reducing and capping agent. The analysis of the effect of growth conditions reveals that a higher concentration of HAuCl4 results in the formation of an increasing fraction of anisotropic structures, higher temperature leads to the formation of quasi-spherical particles instead of anisotropic ones, and larger pH leads to the formation of much smaller particles. The cyclic voltammetry (CV) results show that when the pH of the reaction medium increases from 4 to 6, the reduction potential of CFD increases which leads to the synthesis of nanoparticles (in a pH 4 reaction) to quantum clusters (in a pH 6 reaction). The MALDI-TOF mass spectrometry results of supernatant of the pH 6 reaction indicate the formation of [Au-8(CFD)(2)S-6] QCs which show fluorescence at ca. 432 nm with a Stokes shift of ca. 95 nm. The blue luminescence from Au-8 QCs was applied for sensing of Hg2+ ions on the basis of an aggregation-induced fluorescence quenching mechanism and offers good selectivity and a high sensitivity with a limit of detection ca. 2 nM which is lower than the detection requirement of 10 nM by the U.S. EPA and 30 nM by WHO for drinking water. We have also applied the sensing probe to detect Hg2+ ions in bacterial samples. Further, we have investigated the antibacterial property of as-synthesized Au NPs using MIC, growth curve and cell survival assay. The results show that Au NPs could reduce the cell survival very efficiently rather than the cell growth in comparison to the antibiotic itself. The scanning electron microscopy study shows the degradation and blebbing of the bacterial cell wall upon exposure with Au NPs which was further supported by fluorescence microscopy results. These Au NPs did not show reactive oxygen species generation. We believe that the bacterial cytotoxicity is due to the direct contact of the Au NPs with bacterial cells.</p>1 aKhandelwal, Puneet1 aSingh, Dheeraj, K.1 aSadhu, Subha1 aPoddar, Pankaj  uhttps://library.ncl.res.in/content/study-nucleation-and-growth-antibiotic-labeled-au-nps-and-blue-luminescent-au-8-quantum-002387nas a2200253   4500008004100000022001400041245013900055210006900194260000900263300001400272490000600286520150800292653001801800653001501818653002101833653002101854653002201875653002601897653002601923100002301949700002301972700001901995856011902014       2019                        eng d  a2365-654900aAdvances in the experimental and theoretical understandings of antibiotic conjugated gold nanoparticles for antibacterial applications0 aAdvances in the experimental and theoretical understandings of a  cJUN   a6719-67380 v43 a<p>The worldwide bacterial resistance to a wide range of antibiotics originates a global health concern and calls for the development of new antibacterial agents. Over the recent years, nanomaterials-based agents have been proven to be useful for the effective antibacterial applications. Notably, the gold nanoparticles (AuNPs) draw particular attention due to their biological inertness and easy surface functionalization. It is now established that the antibiotic functionalization on the AuNPs surfaces increases the antibacterial efficacy even towards the antibiotic-resistant bacterial cells. Moreover, the antibacterial efficacy can be further enhanced by photothermal therapy using antibiotic conjugated AuNPs. In this review article, we have reviewed the advances in the development of the synthesis methods of antibiotic conjugated AuNPs and gold nanoclusters, and their antibacterial efficacy. We have also discussed the developments in the theoretical understandings behind the interaction of antibiotic molecules with gold surface and its relation to the antibacterial activity. We believe that few parameters including the selection of antibiotic molecules, the method of its attachment to AuNPs, the purification of antibiotic conjugated AuNPs, and the quantification of conjugated antibiotic are crucial and needs to be properly addressed. Moreover, there are many other future directions discussed, for using antibiotic conjugated AuNPs more effectively for antibacterial therapy.</p>
10aAntibacterial10aantibiotic10aDFT calculations10agold nanocluster10aGold nanoparticle10amulti-drug resistance10aphoto-thermal therapy1 aKhandelwal, Puneet1 aSingh, Dheeraj, K.1 aPoddar, Pankaj  uhttps://library.ncl.res.in/content/advances-experimental-and-theoretical-understandings-antibiotic-conjugated-gold