Influence of N atomic percentages on cell attachment for CN<Subscript>x</Subscript> coatings

Carbon film is an excellent candidate for use as a biocompatible coating due to its excellent properties. However, considerable attention has just been focused on the biocompatibility of diamond-like carbon (DLC) in recent years. It is difficult to find reports on the investigations of the biocompatibility of CN_x so far. It is well known that CN_x has similar structural characteristics as that of DLC. Its excellent mechanical and tribological properties are comparable to that of DLC. In addition, it is probable that the presence of nitrogen leads to a positive effect on biocompatibility. So, this work focusses on cell attachment of CN_x coating and the relation between nitrogen atomic percentage and cell attachment. CN_x coatings were prepared using magnetron sputtering under two N₂ partial pressures for the evaluation of relation between nitrogen atomic percentage and cell attachment. Cell culture tests using human endothelial cells and mouse fibroblasts were performed. Both coatings resulted in no adverse effects on the cells in culture. Compared with CN_x (x = 0.088), CN_x (x = 0.149) film provided a better surface for normal cellular attachment, spreading and proliferation without apparent impairment of cell physiology. At the same time, the coatings exhibited excellent tribological and corrosion performance. XPS and AES analyses showed that higher nitrogen atomic percentage might lead to a positive effect on the cell attachment.     

βPreparation and Dielectric Properties of Nonstoichiometric β-SiC Powder by Combustion Synthesis

The nonstoichiometric β-SiC powders were synthesized via combustion reaction of Si and C system in a 0.1 MPa nitrogen atmosphere, using Teflon as the chemical activator. The prepared powders were invistigated by XRD and Raman spectra. The results indicates that the cell parameters of all the prepared β-SiC powder are smaller than the standard value of β-SiC because of generation of CSi defects. The complex permittivity of prepared products was carried out in the frequency range of 8.2−12.4 GHz. It shows that the dielectric property of prepared β-SiC powder decrease with increasing PTFE content. The effect of CSi defects on dielectric property of -SiC powder has been discussed.