Classification of DLC films for cell proliferation based on optical constants

Abstract

Nine types of diamond-like carbon (DLC) films were prepared on 316L stainless steel by physical vapor deposition and chemical vapor deposition under different plasma processing conditions. The refractive index and extinction coefficient of the DLC films were evaluated with a spectroscopic ellipsometer. The DLC samples were classified into 4 types of films: a-C, a-C:H, polymer-like, and graphite-like types. In addition, the surface functions of the DLC films were analyzed by X-ray photoelectron spectroscopy and cell culture. DLC films on which high levels of cell proliferation were observed had relative high extinction coefficients and CO bond ratios. The extinction coefficient was related to cell proliferation on the DLC films and depended on the film structure and deposition methods. Using optical properties, such as the extinction coefficient, it is possible to distinguish various types of DLC films on which cells can be grown as a biointerface.