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Synthesis and capping of water-dispersed gold nanoparticles by an amino acid: bioconjugation and binding studies.

DIR@IMTECH: CSIR-Institute of Microbial Technology

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Title Synthesis and capping of water-dispersed gold nanoparticles by an amino acid: bioconjugation and binding studies.
 
Creator Wangoo, Nishima
Bhasin, K K
Mehta, S K
Suri, C Raman
 
Subject QR Microbiology
 
Description We report a novel strategy for the synthesis of aqueous stable, carboxylated gold nanoparticles (GNPs) by using glutamic acid as the reducing agent. The ratio of chloroaurate ions, AuCl(-)(4) to glutamic acid was optimized in the reaction medium to obtain monodispersed GNPs. Glutamic acid reduced gold nanoparticles were characterized by UV-visible, FTIR, dynamic light scattering and transmission electron microscopy, which demonstrated high stability in aqueous solution over a period of time indicating stabilization via surface-bound amino acid. Functionalized nanoparticles were conjugated with protein molecules through electrostatic attraction between the surface-terminated negatively charged carboxylate groups (COO(-)) of glutamic acid and the positively charged amino groups (NH(+)(3)) of the protein. The conjugation efficiency of the GNP:protein conjugates was confirmed qualitatively and quantitatively through gel electrophoresis and critical flocculation concentration analysis. The interaction between functionalized GNPs with protein molecules was investigated using fluorescence spectroscopy showing the fluorescence quenching of the tryptophan residues of protein molecules after conjugation. Circular dichroism (CD) studies of the conjugates confirmed that the protein undergoes a more flexible conformational state on the boundary surface of GNPs after conjugation. There was substantial conformational transition from alpha-helix to beta-sheet structure after conjugation of protein to GNPs.
 
Publisher Elsevier Science
 
Date 2008-07-15
 
Type Article
PeerReviewed
 
Format application/pdf
 
Identifier http://crdd.osdd.net/open/592/1/suri08.2.pdf
Wangoo, Nishima and Bhasin, K K and Mehta, S K and Suri, C Raman (2008) Synthesis and capping of water-dispersed gold nanoparticles by an amino acid: bioconjugation and binding studies. Journal of colloid and interface science, 323 (2). pp. 247-54. ISSN 0021-9797
 
Relation http://www.sciencedirect.com/science/article/pii/S0021979708004578
http://crdd.osdd.net/open/592/