Characteristic of silicon doped diamond like carbon thin films on surface properties and human serum albumin adsorption

• Diamond like carbon modified with silicon
• Both DLC and Si-DLC synthesised and characterised
• Adsorption study using human serum albumin
• Investigation of protein conformation via Raman and AFM spectroscopes
• Significant change in the surface behaviour after adsorption of HSA
• The adsorbed amount of protein increases with increasing of silicon content DLC.

Diamond-like carbon (DLC) coatings are useful for creating biocompatible surfaces for medical implants. DLC and silicon doped DLC have been synthesised using plasma enhanced chemical vapour deposition (PECVD). The effects of surface morphology on the interaction of human serum albumin (HSA) with doped and undoped DLC films have been investigated using a range of surface analysis techniques using Raman spectroscopy and atomic force microscopy (AFM). Raman spectra of doped DLC show that silicon doped DLC reduces the growth range of the ID/IG ratio, with a significant red-shift of the G peak position. Following exposure to protein, for undoped DLC the peaks at 1664 cm− 1 and around 1241 cm− 1 can be attributed to amide I and III, respectively, with an increase in the surface morphology of the surfaces giving some indication of the protein structure on the surfaces. Results indicate that HSA exhibit the majority of β-sheet during the adsorption on the surfaces. The results showed that the silicon incorporation DLC tends to increase of surface roughness and the adsorbed level of HSA is higher with higher levels of silicon doping of the DLC. Therefore, doping DLC may provide a method of controlling the adsorption of protein.