Adsorption Reaction of L-Cysteine on Au Nanoparticle Prepared by Solution Plasma

tWe have investigated the L-cysteine adsorption reaction on the Au nanoparticles (NPs) prepared by means of the solution plasma method. The particle size of the Au NPs is estimated to be 2.4 1.0 nm as prepared. When the L-cysteine adds into the Au NPs colloidal solution, the solution color is quickly changed from red to dark blue. It is found that the adsorbates of L-cysteine thiolate, cystine and atomic sulfur exist on the Au NPs surface by sulfur K -edge NEXAFS. In addition, the Au NPs aggregate each other by the hydrogen bonding at carboxyl groups and produce the black colored precipitate. In this paper, we have revealed the adsorption behavior of the L-cysteine on the Au NPs by AFM, UV-vis, (-potential measurement and NEXAFS techniques.