Relationship between Osteoblast Proliferation and the Surface Properties of Polymer-like Carbon Films Deposited at Different Ar/CH₄ Mixed-Gas Ratios in the Radio-Frequency Plasma CVD Process

In the deposition of polymer-like carbon (PLC) films on Si substrates via radio-frequency plasma CVD (RF-PCVD), the effect of the Ar/CH4 gas mixture ratio on the bio-interface of the PLC films remains unclear and the effectiveness of introducing Ar gas must be proven. In this study, five types of PLC films are prepared on Si substrates via RF-PCVD with an Ar/CH4 gas mixture. The effects of the Ar/CH4 gas ratio on the structure, surface properties, and osteoblast proliferation of the PLC films are investigated. The PLC film structure is graphitized as the hydrogen content in the PLC film decreases with the increasing Ar gas ratio. Based on in vitro cell culture tests, a PLC film with a higher Ar gas ratio promotes the osteoblast proliferative potential after 72 h compared with a PLC film with a relatively low Ar gas ratio. Moreover, the surface roughness and hydrophilicity of the PLC film increase with the Ar gas ratio. Accordingly, we demonstrate the effectiveness of Ar gas incorporation into the RF-PCVD process to promote the biological responsiveness of PLC films. PLC coatings are expected to be widely applied for surface modification to improve the mechanical characteristics and biological responses of orthopedic implant devices.