Surface modification of poly(propylene carbonate) by aminolysis and layer-by-layer assembly for enhanced cytocompatibility

Poly(propylene carbonate) (PPC) is a biodegradable polymer with desirable mechanical properties for bone and cartilage repair. However, the poor biocompatibility impedes its applications in tissue engineering. The aim of this study was to evaluate the effect of surface modification of PPC on the improvement of its cytocompatibility. The combination of aminolysis and layer-by-layer (LBL) assembly techniques was used to modify the PPC surface. The results of ATR–FTIR measurement demonstrated that PPC was aminolyzed by polyethylenimine (PEI) at specific reaction conditions and the degree of aminolyzation was quantitatively determined by ninhydrin method. Positively charged PEI and negatively charged gelatin were alternatively deposited on the aminolyzed PPC membranes at pH 7.4, which formed polyelectrolyte multilayers surface with gelatin as the outermost layer. The presence of amino groups on the aminolyzed PPC and gelatin on the multilayers had significant impact on enhancing the hydrophilicity of PPC. Fibroblast and primary human osteoblasts (HOBs) were used to assess the cytocompatibility of PPC. The deposition of PEI and gelatin bilayers on PPC remarkably promoted both fibroblast and HOBs cell attachment, spreading and growth. In particular, the osteogenic gene expression of HOBs cultured on the multilayers modified PPC was substantially increased. The aminolysis followed by LBL assembly is a convenient and cost effective technique for enhancing cell attachment and proliferation. The product has high potential for musculoskeletal tissue engineering applications due to its desirable mechanical strength and tunable cytocompatibility.