Surface engineering of PHBV by covalent collagen immobilization to improve cell compatibility

Covalent immobilization of collagen onto poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) film was achieved to improve its cell compatibility. Amide groups photografted on PHBV films were initially converted into amine groups through Hofmann degradation and collagen was then chemically bonded to amine groups, consequently forming the amide, amine, and collagen-modified PHBV. The structures of these modified PHBV films were confirmed by ATR-FTIR, XPS, and SEM analyses. Compared with that of PHBV film, surface wettability of the modified PHBV films enhanced remarkably. In particular, water contact angle of the collagen-modified PHBV film decreased from 65.0 degrees to 2.1 degrees within 130 s. Sheep chondrocytes cultured on PHBV and modified PHBV films were evaluated by cell adhesion test, MTT assay, and morphological observation under SEM. Results showed that the collagen-modified PHBV film had better cell adhesion and proliferation than other modified PHBV films and PHBV film. Chondrocytes on the collagen-modified PHBV film adhered through filopodia, spread by cytoplasmic webbing, and formed cells layer earlier than other modified ones, indicating that the collagen-modified PHBV is a promising biomaterial for cartilage tissue engineering.