Preparation And Characterization Of The OCS/PLLA Composite Film For Biomedical Materials

Aiming at drug-eluting coating material of coronary stents, the chitosan was acylated and mixed with PLLA to prepare the biodegradable composite coating material carring paclitaxel. The related properties were evaluated. The acylated chitosan was synthesized by acylation modification. Their chemical & crystal structure, solubility and film properties of obtained products were characterized. The experiment results showed that long alkyl chain had been modified in the side chain of chitosan, and its solubility had increased in common organic solvents. They still had film properties.The PLLA/OCS films were prepared by solvent evaporation method, and the chemical structure, phase structure, mechanical properties, hydrophobicity, degradation properties, and the biocompatibility of the films were studied in this work. The constituents of PLLA/OCS films were physically blended. When the concentration of OCS was 30%, composite film had certain compatibility. When it was higher than 40%, phase separation would appear. And chitosan weakened the crystallization ability of PLLA, reduced the mechanical property of composite film, and improved the hydrophilicity and degradation rate of the composite films. The results of hemolytic ratio and dynamic clotting time test indicated that the composite films satisfied the hemolytic ratio requirements for biomaterials, and possess the anticoagulation.The PLLA/OCS coating with the drug was prepared onto the stainless steel stent surface by ultrasonic atomization spray technology, and their chemical & crystal structure, mechanical properties, surface morphology and drug release properties were evaluated. Composite film and the paclitaxel were blended by physical interaction. With the increase of drug addition, the crystallization and mechanical performance of composite films declined.The drug eluting coatings on the stent suface were homogeneous and smooth and had good flexibility and bonding strength. Drug concentration and the coating thickness could influence the drug release behavior. The coating had excellent blood compatibility.