Plasma Surface Treatment and Grafting of Nano-Gold Surface for Immobilization of Chitosan

Combination of biomaterials with nanotechnology has been applied to the immobilization of chitosan on nano-gold particles by plasma and grafting treatments. In this study, gold (Au) nanoparticles were first synthesized by chemical reduction method using mixing solution of HAuCl4.4H2O and sodium citrate or NaBH4. The synthesized gold nanoparticles were then reacted with 11- mercaptoundecanoic acid (MUA) containing thiol group to modify the surface of gold nanoparticle. The MUA-modified Au nanoparticles were subjected to O2 plasma pretreatment before the UV light grafting polymerization with N-Isopropylacrylamide (NIPAAm) on the plasma-treated Au nanoparticles to form a thermosensitive polymer on the surface. The functional groups on the grafted Au nanoparticles surface were combined with glutaraldehyde to immobilize biological molecules of chitosan. The results show that preparation of nano-Au particles using NaBH4 solution as reductant is better than using the sodium citrate solution. The preferable reaction temperature for the preparation using NaBH4 solution to produce nano-Au particles is 100°C. From the TEM observation the prepared Au nanoparticle was spherical-like and about 10~20 nm in size. The zeta potential measurement on the immobilized Au nanoparticles proves that chitosan was indeed immobilized on the Au nanoparticles surface.