Generation of biocompatible nanogold using H2O2-starch and their catalytic/antimicrobial activities

Biocompatible nanogold (AuNPs) have gained considerable attention for potential applications in nano-medicine due to their characteristic size dependent chemical, electronic and optical properties. Herein, energy saving and simple strategy was proposed for simultaneous preparation of nanogold suspension using starch polymer as bio-synthon and protective envelope for AuNPs, at room temperature H2O2 was used as enhancer for the reducibility and accessibility of starch by oxidative degradation of its macromolecules to more reducible fragments. While, the nucleation of nanoparticles was motivated by the action of alkali. The reducible fragments in solution were detected via measurements of reducing sugars content. Preparation of nanogold was investigated by absorbance spectra, transmission microscope and zetasizer instrument. Size of AuNPs was a function of reactants' concentration and the smallest sized AuNPs (11.74 nm) was produced by using 2 g/L starch, 1% H2O2 and 10 g/L NaOH, where, reducing sugars detected to be 0.46 g/L. The produced nanogold showed good catalytic activity in reduction of p-nitroaniline and accelerate the reduction percentage from 12.1% to 39.2% in 2 h. The prepared AuNPs displayed antibacterial efficacy towards different bacterial species and the MIC was evaluated to be 960 mu L/ mL against S. aureus.