Chiroptical study of plasmon-molecule interaction: the case of interaction of glutathione with silver nanocubes

Inorganic nanoparticle−chiral molecule coupling may produce chiroptical effects at the inorganic particles’ excitation wavelengths. In this work, we demonstrate that low concentrations of glutathione molecules adsorbed to cube-shaped silver nanoparticles lead to the appearance of new circular dichroism signals in the plasmon resonance absorption range. Moreover, for pH values of <4.5, the nanoparticle surface promotes reversible thiol group oxidation, leading to the formation of diglutathione and consequent reversible modification of both the molecular and plasmonic circular dichroism and absorption spectra. This study demonstrates the importance of chiroptical effects as probes of molecule−inorganic nanocrystal interaction.