Electrostatic Self-Assemble Modified Electrospun Poly-L-Lactic Acid/Poly-Vinylpyrrolidone Composite Polymer and Its Potential Applications in Small-Diameter Artificial Blood Vessels

Abstract

Large (> 6 mm) artificial blood vessels have been successfully employed in clinic practice. However, small-diameter (< 6 mm) synthetic grafts have not been applied due to their hydrophobicity. In this study, poly-vinylpyrrolidone (PVP) was introduced into poly-L-lactic acid (PLLA) to prepare biodegradable small-diameter electrospun blood vessels which were further modified via electrostatic self-assembly (ESA). The characteristics of PLLA/PVP films were investigated by scanning electron microscopy (SEM), contact angle measurement and mechanical property testing. The cytocompatiblility and blood compatibility of the fiber films were further studied through vascular smooth muscle cells (VSMCs) proliferation and platelet adhesion, and the morphology of cells on films was viewed by laser scanning confocal microscopy (LSCM) and SEM. Next, the surface of ESA-modified electrospun fiber films was analyzed through SEM and photoelectron spectroscopy (XPS). The degradation characteristics of these films were investigated through SEM observation, weight loss, viscosity average molecular weight reduction, and pH change in the testing solutions as well. The films were also subcutaneously implanted in rabbits to analyze the biocompatibility. The results of these experiments showed that electrospun films with PVP possessed a good structure and improved hydrophilicity. The films assembled with chitosan/heparin by ESA were beneficial to VSMCs survival and had excellent blood compatibilities. The data indicated these films were biodegradable with good tissue compatibility. In conclusion, we successfully obtained biodegradable small-diameter blood vessels through electrospinning PLLA/PVP and modifying this blend's surface using ESA. The study provided a feasible method for making small-diameter synthetic blood vessels with improved hydrophilic and anticoagulant properties.