Fabrication And Characterization Of Electrospun Peuu Elastomer And Gelatin Composites

The development of tissue engineering provide a new approach for artificial skin implantation,the biomimetic artificial tissue with superior properties is needed urgently for the clinical treatment.Biodegradable polyurethane possesses many strengths such as elastic,flexible structure design,tunable properties and processing easily,therefore it has great potential for applying in artificial skin area.However,only the synthetic polymer still cannot meet the actual requirements of artificial skin,and the blend between synthetic polymers and natural polymers is a good alternative for producing hybrid scaffolds with good comprehensive properties.In this study,we synthesized a biodegradable polyurethane elastomer by solution polymerization process.The PCL diol was used as the soft segment while HDI was a part of hard segment,and the chain extender was butanediamine,the FTIR result showed the existence of urethane group.GPC result suggested that the weight average molecular weight of PEUU was 155,000.The mechanical properties of PEUU showed that PEUU had excellent elastic properties.The PEUU elastomer was then blended with gelatin.The PEUU and gelatin with different mass ratio were fabricated with electrospinning.The prepared electrospun nanofiber was then crosslinked by glutaraldehyde for 24 hours.The result showed that the addition of gelatin decreased the mechanical properties of hybrid scaffold.The scaffold behaved excellent hydrophilia when the percentage of gelatin was 25%.With the increasing of gelatin's content,the crystallinity of the hybrid scaffold decreased.The existence of crosslinked structure decreased the crystallinity.The L929 cells were applied for MTT test.The MTT results and cell morphology results showed that scaffolds with PEUU content of 75%(PU75)had good biocompatibility.Therefore,PU75 nanofiber has relative excellent comprehensive properties.The ideal tissue engineering scaffold should provide bioactive substances to the wound,however the drug-loaded nanofiber always exist a burst release.To elongation the release time of drugs,a natural layered montmorillonite is used as a drug carrier.The layer gap of sodium montmorillonite(Na-MMT)is too small for drugs to enter,thus cetyltrimethyl ammonium bromide(CTAB)was used as an organic molecule for the organic modification of Na-MMT.The modified organic montmorillonite(CTAB-OMMT)was then intercalated by an antibacterial model drug amoxicillin(AMX)via intercalation process,the drug-loaded organic montmorillonite(AMX@CTAB-OMMT)was then acquired.The XRD result showed that the layer gap of Na-MMT,CTAB-OMMT and AMX@CTAB-OMMT powder were 1.501 nm,1.988 nm and 2.015 nm,separately.The layer gap results showed that both the intercalation process of CTAB into Na-MMT and AMX into CTAB-OMMT were achieved successfully.The TG result,FTIR result and TEM result also identify this process.To acquire the hybrid scaffold with the property of controlling the release rate of bioactive substances,the drug-loaded organic montmorillonite AMX@CTAB-OMMT was incorporated into PU75 nanofibers.The SEM result of the hybrid nanofiber suggested that there was no significant change after the incorporation of montmorillonite.The contact angle result showed that the hydrophilicity increased after the addition of montmorillonite.The mechanical properties increased significantly after the addition of montmorillonite.The MTT result showed that the addition of drug-loaded organic montmorillonite AMX@CTAB-OMMT did not inhabit the cell proliferation process.It could also be identified that the cell morphology on AMX@CTAB-OMMT and PU75 scaffold seemed good.To characterized the release properties of AMX,the physical mixture of AMX,CTAB-OMMT and PU75 nanofiber was set as one blank group while the blend of AMX and PU75 nanofiber was set as another blank group.The drug release result showed that the PU75 nanofiber with the drug-loaded organic montmorillonite AMX@CTAB-OMMT prepared from intercalation process underwent a sustained drug release process compared to the blank groups.The antibacterial experiment result also identified this conclusion.The result of allergic skin irritation experiment suggested that the drug-loaded montmorillonite and PU75 hybrid scaffold had no anaphylaxis on rat skin.Therefore,these data may provide experimental support for the further application of the hybrid scaffold in tissue engineering field.