Fabrication And Properities Of Polyurethane/Nano-bioactive Glass Composite Scaffold Materials

Tissue engineering scaffold material,with good biocompatibility,specific plasticity and three-dimensional porous structure,is an important aspect of the current bone tissue engineering research.Polyurethane(PU)can be applied to the biomedical materials field due to its good biocompatibility,molecular structure design designability and easy to processing molding;however,the lack of biological active group or cell signaling molecules limits its application scope.Bioactive glass,an important bone repair material,has good bioactivity,biocompatibility,high bone combination and bone inducing ability.PU/NBG composite porous scaffolds are expected to own good biocompatibility,mechanical properties and controllable degradation rate.A series of polyurethane prepolymers based on MDI as monomer,PCL and PEG as polyhydric alcohols,using DEG,MDEA or DMPA,as the chain-extender,were prepared.Then the polyurethane hydrogels were obtained from the prepolymers,using BPO as a cross-linking agent,by free radical polymerization.The PU hydrogels were characterized by FT-IR,SEM and DCS and their contace angles and swelling degree were measured.The influences of the types of chain-extenders and the ratio of polyols on the contact angle,swelling ratio,morphology and thermal behavior of the polyurethane hydrogels were investigated.The results showed that the PU hydrogels with different chain-extender were successfully synthesized.The MDI/PCL-PEG/DEG hydrogel was hydrophobic,and there were no small micropores on its surface;while the MDI/PCL-PEG/MDEA hydrogels had high hydrophilicity and a micropouous structure on their surface.With the increase of the content of PEG,the hydrophilicity improved and pore size increased.The preparation of the nanometer bioactive glass(NBG)adopts sol-gel technology with PEG-20000 as dispersant.The NBG was characterized by FT-IR,XRD and TEM.The results showed that the obtained NBG was amorphous and the size is about 100 nm.The porous PCL-PEG/MDI/DEG polyurethane scaffold materials were prepared by using water foaming craft.After foaming,the swelling degree of the polyurethane increased significantly,the pore structure was improved obviously and pore size increased.Using ultrasonic dispersing mixing method,a series of PU/NBG composite scaffold materials with different content of NBG were prepared.The PU/NBG scaffolds were characterized by using FT-IR and SEM.The influences of the content of NBG on the morphologies,porosities and swelling ratios were investigated.The results showed that the PU/NBG composite scaffolds had three-dimensional porous structure,the pore diameter is about 50-100?m,and with the increase of NBG content,the porosity increased.The PU scaffolds and PU/NBG composite scaffold materials were immersed into the PBS buffer solution respectively in order to study the vitro degradation.The water absorption,weight loss ratio,porosity and SEM of the PU and PU/NBG were studied and the changes of pH of the PBS buffer solution were also investigated.The results showed that the water absorption and weight loss ratio are increased and the pH of the PBS buffer solution is decreased.The weight loss ratio of the PU/NBG scaffold was higher than the PU scaffold materials all the time.The water absorption and porosity of the PU/NBG scaffolds were lower than PU during the 10 days;however,the water absorption and porosity of the PU/NBG were higher than that of the PU after 10 days.In addition,the changes of water absorption and porosity of all PU and PU/NBG scaffolds kept steady after 30 days.With the degradation of PU and PU/NBG,the pores increased and the structure became loose,and the PU/PBG scaffolds had more pores than the PU scaffolds.