Fabrication and characterization of PCL/CaCO3 electrospun composite membrane for bone repair

Abstract

Tissue engineering offers a promising approach to repair bone defects, of which a scaffold is an indispensable component. An ideal scaffold should mimic the organic and inorganic compositions of bone. Here, CaCO₃/casein microspheres were encapsulated in PCL composite membranes using co-solvent electrospinning to mimic the hierarchical structure and composition of bone ECM. As PCL lacks functional groups to support cell adhesion, gelatin was grafted onto membranes. To find the optimum composition, CaCO₃/casein microspheres were entrapped at five different concentrations. Various analytical techniques, including FTIR, XRD, SEM and EDS, were applied to characterize the particles and membranes. The CaCO₃/casein microparticles were spheres of ~1 μm, mainly in vaterite form. The amount of casein was 23.9 ± 1% determined by BCA assay and its presence stabilized CaCO₃ in vaterite. After surface modification, the hydrophilicity of membranes was improved while the membrane morphology was not significantly changed; on the membranes, both gelatin and CaCO₃/casein microspheres were evenly distributed. Due to the presence of vaterite, the biomineralization property of a composite membrane was significantly enhanced. Furthermore, we compared HMSC proliferation on composite membranes with FDA staining and MTT assay. After cells were cultured in osteogenic medium, differentiation potential was investigated by analyzing gene expressions of RUNX2, COL-I and ALP, and monitoring ALP activity. Presence of CaCO₃/casein microspheres enhanced cell proliferation and differentiation, especially sample P-20 which demonstrated better potential to be used in bone tissue engineering than others.