Study of Lysine and Asparagine as Capping Agent for Gold Nanoparticles

Abstract

Abstract The wide application of gold nanoparticles has attracted much attention to the development of research in gold nanoparticles. In this study, the gold nanoparticles were prepared by chemical reduction method using potassium tetrachloroaurate as the gold source and sodium borohydride as reducer agent. The formation of gold nanoparticles was confirmed by surface plasmon spectra in ultraviolet-visible spectroscopy at wavelength 507 nm. The capping process of gold nanoparticles was studied using two different charges of amino acids. The asparagine had used as uncharge amino acid and lysine as a positive charge amino acid. The redshift in surface plasmon spectra showed the aggregation of the gold nanoparticles after being capped with amino acids that indicates the surface modification. The amine and carboxylate group was present on the gold nanoparticle surface after being capped with amino acids. The zeta potential results indicate the lysine capped gold nanoparticles have slightly higher stability than the asparagine capped gold nanoparticles. These stability and surface modification of gold nanoparticles are expected to increase their utilization on biological and medical applications.