Synthesis, characterization and catalytic activity of gold nanoparticles biosynthesized with Rhizopus oryzae protein extract

Sujoy K. Das, Calum Dickinson, Fathima Lafir, Dermot F. Brougham, Enrico Marsili

Research output: Contribution to journalArticlepeer-review

210 Citations (Scopus)

Abstract

A simple one-pot green chemical method for the biosynthesis of gold nanoparticles (AuNPs) by reducing chloroauric acid (HAuCl4) with protein extract of Rhizopus oryzae to produce novel gold nano-bio-conjugates (AuNBC) is described. AuNBCs, having sizes ranging from 5 to 65 nm, were synthesized by altering the HAuCl4–protein extract ratio. The conjugates were characterized by spectroscopic, electron microscopic, light scattering and electrophoretic mobility measurements. It was found that the aqueous AuNBC suspensions exhibited excellent stability over a wide range of ionic strength, pH and temperature. The effect of pH and ionic strength indicated that stabilization is due to electrostatic repulsion arising from the negative charge of the conjugate proteins. The AuNBCs were stable at temperatures lower than the denaturation temperature of the fungal proteins. The catalytic activity of the as-synthesized AuNBCs was quantified by analysing the reduction of p-nitrophenol by borohydride. The conjugates exhibited interesting size and shape dependent catalytic activity, which was stronger than that observed for AuNPs prepared by conventional chemical methods. The catalytic activity was found to be sensitive to both the surface-area-to-volume ratio and the thickness of the protein coating on the NP.

Original languageEnglish
Pages (from-to)1322-1334
Number of pages13
JournalGreen Chemistry
Volume14
Issue number5
DOIs
Publication statusPublished - May 2012
Externally publishedYes

ASJC Scopus subject areas

  • Environmental Chemistry
  • Pollution

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