Composite membranes of native silk fibroin powder and biomedical polyurethane for controlled release of heparin

Native silk fibroin powder (NSFP) carrying heparin was blended with biomedical polyurethane (BPU) to fabricate novel composite membranes for the controlled release of heparin. The NSFP/BPU composite membranes exhibited excellent hydrophilicity, water vapour permeability, and water absorption. The release of heparin from the composite membranes was evaluated by immersing the membranes in phosphate-buffered saline at 37 °C. The release of heparin from the composite membrane could be controlled by adjusting the blend ratios of NSFP and BPU, the amount of heparin in the membrane, and the membrane thickness. The bioactivity of heparin released from the composite membrane (NSFP/BPU 30/70, thickness 110 µm, length 2 cm, width 0.5 cm) with different amounts of heparin was evaluated by immersing the novel release system (composite membranes) in 0.5 mL of platelet-poor plasma for 1 h at 37 °C. The thrombin time, activated partial thromboplastin time, and prothrombin time were measured, the three parameters all exceeding the measurement limit of the clot detection instrument. The results suggest that heparin has excellent bioactivity, and the novel heparin release system can improve the blood compatibility of BPU.