Preparation and Characterization of Gold Nanoparticles in Chitosan Suspension by One-Pot Chemical Reduction Method

Gold nanoparticles were synthesized in chitosan suspension by one-pot chemical reduction method without any chemical reducing reagent. In aqueous acidic medium, chitosan exhibits polycationic nature due to protonation of amine groups of each glucosamine repeating units. The adsorption of AuCl4- ions occurs on chitosan through electrostatic attraction and further reduction of Au3+ to Au0 proceeds through a three electron transfer mechanism by oxidation of protonated amine groups of chitosan chain. The change of color from dirty yellow to intense red indicates the formation of gold nanoparticles in chitosan suspension which acts as both reducing and stabilizing agent. Characterization techniques such as UV-VIS, FTIR, Zeta potential measurement, FESEM and TEM were carried out in order to examine the reduction and stabilization phenomena rendered by chitosan.