Biochemical surface modification of Co-Cr-Mo.

Because of the limited mechanical properties of tissue substitutes formed by culturing cells on polymeric scaffolds, other approaches to tissue engineering must be explored for applications that require complete and immediate ability to bear weight, e.g. total joint replacements. Biochemical surface modification offers a way to partially regulate events at the bone-implant interface to obtain preferred tissue responses. Tresyl chloride, gamma-aminopropyltriethoxysilane (APS) and p-nitrophenyl chloroformate (p-NPC) immobilization schemes were used to couple a model enzyme, trypsin, on bulk samples of Co-Cr-Mo. For comparison, samples were simply adsorbed with protein. The three derivatization schemes resulted in different patterns and levels of activity. Tresyl chloride was not effective in immobilizing active enzyme on Co-Cr-Mo. Aqueous silanization with 12.5% APS resulted in optimal immobilized activity. Activity on samples derivatized with 0.65 mg p-NPC cm-2 was four to five times greater than that on samples simple adsorbed with enzyme or optimally derivatized with APS and was about eight times that on tresylated samples. This work demonstrates that, although different methods have different effectiveness, chemical derivatization can be used to alter the amount and/or stability of biomolecules immobilized on the surface of Co-Cr-Mo.