Cartilage tissue engineering PLLA scaffold with surface immobilized collagen and basic fibroblast growth factor.

A previously reported "grafting and coating" method (J. Biomed. Mater. Res. (Appl. Biomater.) 63 (2002) 838) was modified and used to introduce stable collagen layer and incorporate basic fibroblast growth factor (bFGF) on PLLA scaffold surface to prepare tissue engineering scaffold with improved biocompatibility. To make the modification of the 3-D porous PLLA scaffold possible, grafting of polymethacrylic acid (PMAA) onto the PLLA surface was initiated by the -OOH/Fe2+ system instead of the UV light used in the former method. Water soluble carbodimmide chemistry was applied to graft collagen onto the PLLA scaffold surface, followed by physical coating of the collagen solution with or without basic fibroblast growth factor (bFGF). Surface modification of 2-D PLLA membrane was also done for fundamental understanding of the modification. The -COOH density on/in the PMAA grafted PLLA membrane/scaffold was measured by colorimetric method and the collagen content on/in the collagen immobilized PLLA membrane/scaffold was measured by ninhydrin method. Chondrocyte culturing on the collagen immobilized PLLA surfaces showed significantly improved cell spreading and growth. Incorporation of fibroblast growth factors in the collagen layer further enhanced the cell growth. This convenient and effective method can be used to prepare bioactive scaffolds with extra cellular matrix (ECM)-mimic composition for tissue engineering.