Cytocompatibility Assessment of Si, Plasma Enhanced Chemical Vapor Deposition-Formed SiO2 and Si3N4 Used for Neural Prosthesis: A Comparative Study

Abstract

SiO2 and Si3N4 layers to be used in the microfabrication of a neural probe were formed on Si substrate through plasma enhanced chemical vapor deposition (PECVD). To ensure their cytoconnpatibility, the surface properties and cytocompatibility of the PECVD-formed SiO2 and Si3N4 were investigated and compared. SEM images showed the SiO2 and Si3N4 layers consisted of nano-sized particles. In accordance with water contact angle measurement, the surface of both PECVD-formed SiO2 and Si3N4 layers were hydrophilic and there was no significant difference in wettability between them. A breast cancer cell line (MCF-7) was seeded on their surface to evaluate the cytocompatibility. After 3 days of cell culture, the adherent cells on PECVD-formed Si3N4 surface did not spread as well as those on Si or PECVD-formed SiO2, and the cells on the surface of PECVD-formed SiO2 and Si3N4 were significantly less than on Si. At day 7, however, there was no significant difference between them, in terms of cell morphology and number. Therefore, the PECVD-formed SiO2 and Si3N4 layers did not exhibit acute cytotoxicity and were as cytocompatible as tissue culture polystyrene.