Cytotoxicity of Silane Coupling Agents with Hydrophobic Groups

Abstract

Purpose: We developed novel silane coupling agents with hydrophobic groups to improve the water resistance of the coupling layer, and reported that these compounds showed no significant decrease compared with 3-methacryloylxytrimethoxysilane (3-MPS) alone in tensile bond strength after long-term water storage. The aim of this study was to investigate the cytotoxicity of the silane coupling agents nonafluorohexyltrimethoxysilane (4F) and 3- (4-methacryloyloxyphenyl) propyltrimethoxysilane (p-MBS). Methods: Glass plates were modified with 50 mmol/l solutions of 3-MPS, 4F and p-MBS, and then sterilized with ethylene oxide gas. The modified glass plates were immersed in cell culture medium (MO5) for 24 hours at 37℃ in a 5% CO₂ atmosphere to measure the toxicity of the extraction. The extracted medium (100%) was diluted with the MO5 into ten different concentrations (0.5-50%). Chinese Hamster fibroblast (V79) suspension (0.5 ml: 100 cells/ml) was seeded on a 24-well cell culture plate and pre-incubated for 6 hours at 37℃ in a 5% CO₂ atmosphere. After the pre-incubation, 0.5 ml of each concentration of the silane extracts was poured onto the cell culture. After cultivation for 6 days, the cells were stained with 0.1% methylene blue solution and colonies of more than 50 cells were counted. The cytotoxicity of the silane coupling agents was evaluated according to the 50% inhibitory concentration (IC₅₀). Results: The IC₅₀ values of 3-MPS, 4F, and p-MBS were all over 100%. Conclusion: These results suggest that silane coupling agents with hydrophobic groups are not cytotoxic.