Immobilization of heparin on gelatin modified three-dimensional osteoconductive Ca-P/PHBV nanocomposite scaffolds

Abstract

In bone tissue engineering, an effective and sustained delivery of growth factors such as bFGF, VEGF and BMP-2 at the target site is of significant importance. Heparin, a sulfated polysaccharide, is known to have the binding affinity with a number of growth factors and thus capable of blocking their degradation and prolonging their release time. In this study, the surface modification of three dimensional Ca-P/PHBV scaffolds produced via selective laser sintering was achieved through physical entrapment of gelatin by using a miscible mixture of a solvent and a non-solvent for PHBV, with gelatin being dissolved in the mixture. The amount of gelatin entrapped on the surface of scaffold struts was determined quantitatively by bicinchoninic acid (BCA) kit assay. After surface modification, a hydrophilicity/hydrophobicity balance was obtained for the surface of scaffold struts. Heparin was subsequently surface immobilized through covalent conjugation onto gelatin-modified scaffolds. The amount of heparin conjugated to the scaffold surface was determined using the toluidine blue method. Ca-P/PHBV scaffolds with entrapped gelatin and immobilized heparin should have enhanced binding of growth factors and hence promote cell proliferation and bone tissue regeneration.