Study of Human Serum Albumin Adsorption and Conformational Change on DLC and Silicon Doped DLC Using XPS and FTIR Spectroscopy

摘要

Diamond-like carbon (DLC) coatings are extremely useful for creating biocompatible surfaces on medical implants. DLC and silicon doped DLC synthesised on silicon wafer substrate by using plasma enhanced chemical vapour deposition (PECVD). The effects of surface morphology on the interaction of HSA with doped and undoped DLC films have been investigated. The chemical composition of the surface before and after adsorption was analysed using X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR). Results showed that silicon incorporation DLC tends to increase of sp3/sp2 hybridization ratio by decreasing sp2 hybridized carbon bonding configurations. Following exposure to solutions containing (0.250 μg/ml) HSA, the results indicated that significant changes in the C, N and O levels on the surfaces with reducing of the Si2p band at 100 eV. From FTIR spectrum, the peaks occur the following functional groups were assigned as amide I and II groups at 1650 cm-1 and 1580 cm-1. Both XPS and FTIR spectroscopy confirm that HSA was bound onto the surfaces of the DLC and Si-DLC films via interaction of ionized carboxyl groups and the amino group did not play a significant role in the adsorption of protein. These results from peak intensity show that an adsorbed layer of HSA is higher at high level (19%) silicon doping. Therefore doping of DLC may provide an approach to controlling the protein adsorption.