Generation of a stable surface concentration of amino groups on silica coated onto titanium substrates by the plasma enhanced chemical vapour deposition method

This report describes the amino functionalisation of the surface of plasma enhanced chemically vapour deposited silica films (PECVD-SiO2), which were coated onto titanium substrates. Amino groups were linked to PECVD-SiO2 via 3-aminpropyl triethoxysilane (APTES). We showed that the APTES functionalised PECVD-SiO2 surfaces contained a high packing density of amino groups (67-92 NH2 groups per nm2), indicative of a multilayered and highly cross-linked APTES film. 65-66% of the original surface concentration of APTES was retained on the PECVD-SiO2 surface after incubation under physiological conditions, indicating that APTES films are relatively stable on PECVD-SiO2 in these environments. The stability of the amino groups obtained on PECVD-SiO2 in this study is much higher compared to other hydroxyl-bearing materials, such as titanium. Therefore, PECVD-SiO2 films may find use as functional biomaterial coatings and as intermediate adhesion layers in silanisation processes.