Papers by Author: Wei Shi

Abstract: Based on the unique redox property of electrically conductive polymers, Ca²⁺ was incorporated into polypyrrole (PPy) film that previously doped with polyelectrolyte heparin. Then the apatite-forming ability of the Ca²⁺-doped PPy was examined by a biomimetic method using stimulated body fluid (SBF), which has ion concentration nearly equal to those of human blood plasma. It was found that the Ca²⁺-doped PPy successfully formed bonelike apatite deposition on its surface after soaking in SBF for only 3 days, whereas the similar apatite deposition was formed on Ca²⁺-free PPy after soaking in SBF for 7 days. These indicated that the entrapment of Ca²⁺ into PPy could accelerate the formation of apatite deposition and the Ca²⁺-doped PPy was possessed of enhanced bioactivity. It is expected that the Ca²⁺-doped PPy would be a useful bioactive coating material of metallic medical devices or tissue engineering scaffolds to promote the bone tissue regeneration.

Abstract: Ca2+-containing porous gelatin-siloxane hybrids were prepared using sol-gel process, post-gelation soaking, and freeze-drying. The porosity and pore size of the hybrids could be well controlled by the freezing temperature and the pH value of the soaking solution. The pore characteristics were related to the structure change during the soaking treatment. A bone-like apatite layer was able to form in the Ca2+-containing porous gelatin-siloxane hybrids upon soaking in a stimulated body fluid. The porous gelatin-siloxane hybrids could release gentamicin sulfate which is an antibiotic drug in bone chemotherapy. Thus, those hybrid materials are proposed to find application as novel bioactive and biodegradable scaffolds in bone tissue engineering.

Abstract: An asymmetric polysulfone membrane with reactive group of –OH was obtained by hydrolyzing the chloromethylated polysulfone membrane, and the albumin molecules were immobilized into the membrane with a crosslinking reagent of 1,4-butanediol diglycidyl ether. The albumin-fixed membrane was used to remove lipophilic toxins, bilirubin, from the bilirubin-albumin solution. The experiment results showed that the transfer rate of bilirubin was clearly enhanced after fixing albumin into the hydroxylated polysulfone membranes. The clearance of bilirubin was 49.3%. In addition, the effect of membrane thickness on the removal of bilirubin is discussed.