The Study Of Fabrication And Properties Of Electrospun PLLA/Lecithin Nanofibrous Membranes

Scaffolds used in tissue engineering is an important part in regenerative medicine, which aims to regenerate and replace damaged organs or tissues. Currently a variety of fabrication methods of tissue engineering scaffolds have been developed, of which electrospin is an prevalent methord. Electrospin nanofibrous scaffolds have several advantages, such as high specific surface area, high porosity, which can mimic the architecture of natural extracellular matrix, therefore have gained more and more attention in the field of tissue engineering and regenerative medicine.PLLA, which has excellent biocompatibility, is widely used as tissue engineering scaffold material. As PLLA is highly hydrophobic and lacks of active groups, leading to poor biocompatibility, which limits its further applications in the field of tissue engineering scaffolds. In this study, we blended PLLA with lecithin(a kind of natural polymer extract) to change its surface properties, and successfully fabricated PLLA/Lec composite nanofibrous membranes with different content of lecithin(3, 5 and 7wt%). The morphology, chemical composition, thermodynamic properties, contact angle and degradation property of scaffold were characterized by SEM, ATR-FTIR, DSC, contact angle measurement and degradation experiment. The biocompatibility of samples was studied by cytological experiments. SEM micrographs show that PLLA/Lec sample still maintained the nanofibrous morphology. ATR-FTIR results confirmed the existence of PLLA and lecithin components. With the increase of lecithin, the contact angle decreased significantly, and the crystallinity of PLLA was also reduced. The composite membranes, with more appropriate hydrophilicity, promoted mBMSCs adhesion, spreading and proliferation. ALP activity of mBMSCs cells on composite samples have also improved. Among them, the composite membrane containing 5%wt lecithin has the best biocompatibility and osteogenic differentiation ability.In order to improve the surface properties of PLLA nanofibrous membranes, and promote its osteogenic differentiation ability, a layer of apatite mineral was deposited on the surface of PLLA and PLLA/Lec samples by biomimetic mineralization. The surface morphology, chemical composition, physical and chemical properties were characterized. Cell attachment, proliferation and osteogenic differentiation were used to characterize the cytocompatibility and differentiation property of mineralized nanofibrous membranes. Mineralization experiment results show that, after 48 hours mineralization, PLLA and PLLA/Lec membranes were completely covered by apatite mineral, and with different morphologies. ATR-FTIR and TG-DSC results confirmed the existence of apatite mineral. After biomineralization, contact angle decreased and the hydrophilicity was improved. Due to the apatite mineral layer on the surface of the nanofibrous scaffold, the protein adsorption decreased. Mineralized samples have better cell affinity ability, which can promote mBMSCs adhesion and spreading, and cells reach out more pseudopodias to interact with membranes. The cell proliferation and cell viability of the mineralized samples have significantly increased. In osteogenic differentiation tests, alkaline phosphatase were observed on all samples by alkaline phosphatase staining, and the ALP activity of mBNSCs cells on mineralized membranes have also been enhanced.