Peptide assisted synthesis and functionalization of gold nanoparticles and their adsorption by chitosan particles in aqueous dispersion

A Nimrodh Ananth, S Umapathy, G Ghosh, Tharmarajan Ramprasath and M A Jothi Rajan

Abstract

We have reported a novel method of synthesis of gold nanoparticles (GNPs), using two different peptides, e.g. glutathione (GSH) and glycyl-glycine (GG), as reducing agents. The formation of GNPs was observed with the development of the surface plasmon resonance (SPR) peak in UV-visible spectrum. The nanoparticles phase has been investigated using powder x-ray diffraction (XRD) method and has been seen to be single phase. The as-synthesized GNPs were not fully covered by the used peptides as seen by the thermogravimetry analysis (TGA), and therefore, trisodium citrate (TSC) has been used further as a 'filler' agent for GNPs to become well dispersible in aqueous medium. The Fourier transform infrared (FTIR) spectroscopy method has confirmed the presence of peptides and TSC coatings on the nanoparticles' surface. In comparison, the GNPs formed using GG have been observed to be more stable than those formed using GSH. The nanoparticle size was measured using XRD, dynamic light scattering (DLS) and transmission electron microscopy (TEM). These dispersions were further used to investigate the interaction between the GNPs and chitosan (CS) microparticles. The effects of this interaction were studied using UV-visible spectroscopy, DLS and FTIR. XRD and TEM showed that GNPs were uptaken by CS microparticles.