Multi-analytical approach to understand biomineralization of gold using rice bran: a novel and economical route

Abstract

Biomimetic fabrication of gold nanoparticles (AuNP) has received significant attention worldwide. However, most of the reports were unable to clearly indicate the responsible biomolecule involved in the production of AuNP. The present study aimed to address this challenge by critically identifying the active component of rice bran responsible for the biomineralization of gold. Fractionation of rice bran extract by HPLC and further characterization using LC-MS revealed that ferulic acid is the functional molecule responsible for the bioconversion of Au³⁺ to Au⁰. Real time monitoring of heat changes by isothermal titration calorimetry indicated biosynthesis of AuNP was exothermic in nature. Additionally, reaction between ferulic acid and HAuCl₄ for AuNP formation was observed to follow first order kinetics and finally various thermodynamic parameters were estimated by measuring residual ferulic acid concentration. Combinatorial observation of all these studies might lead the way to decipher the exact mechanism of nanoparticle biosynthesis.