Covalent attachment of cell-adhesive, (Arg-Gly-Asp)-containing peptides to titanium surfaces

A three-step reaction procedure was applied to introduce RGD-containing peptides on the titanium surface. Water-vapor-plasma-pretreated titanium surfaces were first silanized with (3-aminopropyl)-triethoxysilane, resulting in a multilayer film of poly(3-aminopropyl)siloxane. In a second reaction step, the free primary amino groups were linked to one of the three hetero-cross-linkers: N-succinimidyl-6-maleimidylhexanoate, N-succinimidyl-3-maleimidylpropionate, and N-succinimidyl trans-4-(maleimidylmethyl)cyclohexane-1-carboxylate. Onto the resulting terminal-maleimide surface, two model, cell-adhesive peptides, H-Gly-Arg-Gly-Asp-Ser-Pro-Cys-OH and H-Arg-Gly-Asp-Cys-OH were immobilized through covalent addition of the cysteine thiol (-SH) group. X-ray photoelectron spectroscopy, infrared reflection absorption spectroscopy, and radiolabeling techniques were applied to characterize the surfaces. From independent quantitative analysis, an approximate coverage of 0.2 similar to 0.4 peptides/nm(2) was calculated.