ADSORPTION OF CHONDROITIN-4-SULFATE AND HEPARIN ONTO TITANIUM - EFFECT OF BOVINE SERUM-ALBUMIN

The adsorption of chondroitin-4-sulphate (C4S) and heparin onto titani um has been studied in the absence and presence of bovine serum albumi n (BSA). Isotherm data (0.02 M calcium acetate, pH 6.8) have shown tha t BSA in solution and BSA-coated titanium result in decreased adsorpti on for both C4S and heparin. For the BSA in solution data, C4S/heparin and BSA may compete for the same sites on the titanium surface via ca lcium ions, or alternatively in the case of heparin, complexes of hepa rin and BSA form in solution, leading to less binding due to steric ef fects. Evidence of an interaction between heparin and BSA in solution has been shown in this study, there being negligible interaction betwe en C4S and BSA. BSA adsorption from solution investigated in the prese nce of C4S/heparin decreases with increasing C4S/heparin solution conc entration. This may be due to a glycosaminoglycan (GAG) induced confor mational change of BSA from a compact to an extended structure. The de creased adsorption onto BSA-coated titanium may be due to masking of t he GAG binding sites, this effect being greater for C4S. Desorption of BSA from the pre-coated titanium in the presence of C4S and heparin i s <10% and <30% respectively, indicating that BSA is strongly bound to the titanium surface. (C) 1997 Elsevier Science Limited. All rights r eserved.