Study On The Performance Of PHBV/PCL Blends And Its Preparation For Tissue Engineering Scaffold

Acting as templates for cell adhesion and growth, scaffolds play an important role in construct of tissue engineering. Thus, scaffold biomaterials should meet a series of physical, chemical and mechanical need such as surface and degradation characteristics, blood and cell compatibilities etc. PHBV is microbially produced materials with many excellent properties such as biodegradability , biocompatibility , non-toxicity etc. And PCL also have those excellent properties. But due to its high crystallinity and large spherulite, PHBV shows high brittleness and strong hydrophobic property. At the same time, its processing scope is rather narrow. PCL has important application in the field of biomedical engineering and tissue engineering. But it also has disadvantage. For example, its strength is too lower to be used effectively in tissue engineering. So, it is very necessary to further improve its intensity. In addition, the bone binding ability of the PHBV/PCL blend will be improved, because the PCL have better bone binding ability.In this paper, poly (hydroxybutyrate-co-hydroxyvalerate) (PHBV) and poly (ε-caprolactone) (PCL) were blended by co-solution casting method and co-melt spinning method. The properties of PHBV/PCL blends were investigated. Such as crystallization , miscibility , biodegradability, mechanical property, etc. At the same time, three dimensional scaffolds were prepared by fiber bonding method and Solvent Casting /Particulate Leaching method. The result indicated that there is immiscibility for PHBV and PCL blends. Crystallization of PHBV and PCL was studied and analyzed by Avrami equation using two-step crystallization in the PHBV/PCL blends. The crystallization rate of PHBV at 70℃decreased with the increase of PCL in the blends, while the crystallization mechanism did not change. In the case of the isothermal crystallization of PCL at 40℃, the crystallization rate increased with the addition of PHBV, and the crystallization mechanism changed, too. And the Crystallinity of the PHBV/PCL blends is less than the pure PHBV and pure PCL. The processing ability was improved after adding PCL, which is due to decrease of the melting temperature and the crystallinity. With the tenacity and elongation increased much , PHBV/PCL blends mechanism property was improved, especially when the PHBV content 40%. After water absorption and contact angle tested and analyzed, the results indicated that the surface and interior structure were changed. Hydrophilic property is improved, especially when PHBV content 40%. The degradation behavior of PHBV/PCL blends was investigated in the phosphate solution and lipase phosphate solution by weight loss and SEM, etc. The results indicated that the degradation rate increased twice than before with the addition of lipase. Scaffolds fabricated via SC/PL could be applied in tissue engineering of cartilage with porosity higher than 90% and appropriate pore size. The porosity of scaffolds obtained from fiber bonding method could reach 70% with pore size between 70-300μm. Scaffolds fabricated from two methods hold good hydrophilic, which was favorable for cell adhesion and generation.PHBV/PCL owning excellent biological and physical properties should be an attracting prospect as scaffold biomaterial. For scaffold fabrication, improving of traditional methods and new attempted melt bonding process both were feasible to obtain high performance in microstructures which were controllable for different applications.