Biological Evaluation Of Polyurethanes With Different Hard Segment Contents

In recent years,polycarbonate polyurethane（PCU）is generally became the new direction of polymer medical material studies because of its good mechanical properties,hydrolyzing resistance and promising biocompatibility.The PCU elastomer films that had three different contents of hard segment（20%PCU-1、25%PCU-2 and 30%PCU-3）,was synthesized by hard segment which contained H₁₂MDI and BDO as chain extender,and soft segment（PCDL）through solution prepolymer method.It was confirmed by ATR-FTIR analysis that the synthetic materials had the structure of polycarbonate polyurethane.Surface wettability and SEM were utilized to characterize the hydrophobic property and smooth surface structure of the synthetic PCU films.In order to find out the connection between different hard segment contents and biocompatibility,a series of primary biological assessments were used to analyze the synthesized PCU elastomers films.The mechanical properties and SEM photos of synthetic PCU films after subcutaneous implant showed that those films contained three different contents of hard segment generally had good biostability and no hug changes was observed in the SEM pictures of surface structure and the table of mechanical analysis of PCU films.The comparison among the three kinds of PCU materials indicated thatbiostability of synthetic materials became better following the increase of contents of hard segment.We observed inflammatory reaction from stained paraffin embedded sections of the rat tissue after PCU-1 implant.The blood compatibility of PCU medical materials is a vital part of the biocompatibility.Hemolysis rate of all synthetic materials is under 5%.CBB（Coomassie brilliant blue）standard curve method was used to evaluate protein absorption on the surface of PCU films;the number of platelet adhering was calculated after PCU incubating with PRP（platelet rich plasma）;dynamic clotting time was utilized to access the active degree of clotting factor.The outcome showed that the number of platelet adhering to PCU-2 was less than other groups,and the time to blood coagulation was longer.In conclusion,PCU-2 may have better anti-coagulation properties.Cytotoxicity was evaluated by MTT method.All the three kinds of PCU films had 1 degree of cell toxicity,and made no difference to cellular morphology.To sum up,through our research,25%content of hard segment have greater potential to apply to medical materials one day.