Preparation of amide-amine bifunctionalized poly(3-hydroxybutyrate-co-3-hydroxyvalerate) films to improve chondrocyte adhesion.

Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) films were covalently functionalized with amide and amine domains, with the aim to improve chondrocyte adhesion. X-ray photoelectron spectroscopy spectra confirmed that amide and amine groups were present on the film surface. Scanning electron microscopy results showed that the amide-amine bifunctionalized PHBV films possessed a loose layer on the surface or formed pore structure. The crystallization properties were characterized by differential scanning calorimetry and wide-angle X-ray diffraction. The amide-amine bifunctionalized PHBV films had two endotherm peaks in the 60-80 degrees C and 130-170 degrees C regions, which suggested that imperfect PHBV crystals were formed owing to the penetration of the grafted amide-amine chains. Water-swelling percentage of the amide-amine bifunctionalized PHBV films increased with increasing polyacrylamide grafting percentage, especially the ability to hold water inside films. Sheep chondrocytes were cultured on the amide-amine bifunctionalized PHBV film and the PHBV film, respectively. Cell studies revealed that the bifunctionalized PHBV film was more favourable for chondrocytes adhesion than the PHBV film. These results suggest promising application of the amide-amine bifunctionalized PHBV film in cartilage tissue engineering.