<title>Characterization of fibroblasts and proteins on thin films</title>

Abstract

The ability of biomaterial surfaces to regulate cell behavior requires control over surface chemistry and microstructure. One of the greatest challenges with silicon biomedical microdevices is to improve biocompatibility, which may be achieved by modifying the exposed silicon surface with thin or adsorbed films. In this study, films of silicon nitride, doped polysilicon, undoped polysilicon, as well as RGD peptide adsorbed surfaces were incubated with fibroblasts for a period of four days. Results demonstrate that RGD adsorbed surfaces encourage the greatest cell proliferation, followed by undoped polysilicon and unmodified (control) surfaces. Protein adsorption studies using fibrinogen and albumin, two proteins implicated in cellular adhesion and surface activity, reveal greatest protein adsorption on low stress silicon nitride surfaces, followed by undoped polysilicon and unmodified surfaces. This finding may compliment the differential cellular binding found on modified and unmodified silicon surfaces. The thickness of adsorbed albumin and fibrinogen was measured by ellipsometry and compared to contact angle measurements of non-adsorbed surfaces. Moreover, silicon surfaces coupled with a synthetic RGD peptide, as characterized with XPS and atomic force microscopy, display enhanced cell proliferation and bioactivity. Understanding the biological response to thin films will allow us to design more appropriate interfaces for implantable diagnostic and therapeutic silicon-based microdevices.