Circular dichroism and UV-Vis absorption spectroscopic monitoring of production of chiral silver nanoparticles templated by guanosine 5′-monophosphate

Abstract

Herein we report the chemical reduction of silver ions incorporated into chiral supramolecular nanostructures by NaBH₄ in buffered (basic) and unbuffered conditions. In situself-assembly of guanosine 5′-monophosphate (5′-GMP) templated by Ag(I) and generation of silver nanoparticles (NPs) were continuously monitored by CD and UV-Vis spectroscopy measurements. 5′-GMP has been identified as an efficient chiral organic ligand to complex silver ions into a hierarchical helical nanostructure and is a useful capping agent for stabilizing silver NPs with a size diameter lower than 20 nm. The observation of opposite signed bands in the CD spectra of Ag(I)/5′-GMP complexes at different pH has suggested the existence of opposite-handed supramolecular helical structures depending on pH. Both helical supramolecular structures induce chirality in the silver NPs during their growth of the same handedness as shown by the CD signals in the plasmon resonance band.