Investigation of the reduction and growth mechanisms of gold nanoparticles

Abstract

The presented project is aimed at investigating the synthesis and growth of gold nanoparticles under mildly (carboxylic acids) and strongly reducing (sodium borohydride) conditions and to study the effect of oligo-peptides as capping agents. A series of oligo-peptides were synthesized using solid phase peptide synthesis. The sulfur containing oligo-peptides were only soluble in acetic acid which was chosen as the reaction medium. As it is known that acetic acid can itself reduce gold ions to form nanoparticles, reduction using sodium borohydride and just acetic acid were used and compared. Furthermore, the effect of carboxylic acids in general on the formation of gold nanoparticles was investigated. Findings were compared to various proposed mechanisms from the literature. The change in pH, degradation and association of acids to the nanoparticles were investigated using a set of different characterization techniques.