Catalytic and SERS activities of tryptophan-EDTA capped silver nanoparticles

This report describes the synthesis of silver nanoparticles (AgNPs) by in situ reduction of silver nitrate with designed ethylenediaminetetraacetic acid-tryptophan bioconjugates. Conjugation of EDTA was chosen to augment water solubility of resulting conjugate, which in turn facilitates synthesis of AgNPs in aqueous medium. Various spectroscopic and microscopy techniques were employed to characterize the EDTA-tryptophan capped AgNPs. The nanoparticles show excellent catalytic activity towards reduction of p-nitrophenol to p-aminophenol with a rate constant of 16.43×10^-2 min^-1. In addition, as-synthesized AgNPs show high SERS activity, which was used for low concentration detection of biomolecules.