Bionic Preparation And Characterization Of Apatite/Polymer Composites

The method of using biomimetic mineralized polymer as organic template has been extensively studied.Silk fibroin is widely used in bone tissue engineering because of its unique biological and mechanical properties.Polyurethanes have the potential to be used in bone repair materials because of their good mechanical properties.The aim of this paper is to discuss the factors affecting bionic mineralization when silk fibroin and polyurethane are used as organic template.This paper mainly concentrate on the following three aspects:(1)In the second chapter,the silk fibroin membrane was prepared by electrospinning,and the content of ?-sheet structure was increased by ethanol treatment.The fibroin membrane was then placed in a pre-calcified solution containing different concentrations of glutamic acid and then bionic mineralized in 1.5 SBF for 24 h to prepare the biomimetic material.The structures of the composites were characterized by FT-IR,SEM and XRD.The changes of the structure of the silk fibroin,the morphologies of the fibrous membranes and the crystallization of the composites were investigated by FT-IR,SEM and XRD.The effect of glutamate on the mineralization results was discussed.The results showed that with the increase of glutamate in the precalcification solution,the porous structure of the composites was more dense and uniform,but the morphology of the fibers was destroyed.Through the testing of ICP,it was found that the calcium and phosphorus ratio of the inorganic matter on the composite surface showed an increasing trend with the increase of glutamic acid.(2)In the third chapter,silk fibroin was modified by blending with carboxymethyl chitosan and blend membrane was prepared.Then the blend membrane was cross-linked by glutaraldehyde steam.Finally,the blend membrane/apatite composite was prepared by biomimetic minerialization.Blend membranes and composites were characterized by Fourier Transform infrared spectroscopy(FT-IR),X-ray diffraction(XRD),scanning electron microscope(SEM),and Inductive Coupled Plasma Emission Spectrometer(ICP).The results showed that as carboxymethyl chitosan/fibroin protein ratio increased,the content of carboxyl group on the surface of template increased and the inorganic composite surface precipitation more pronounced.And the deposition of inorganic first increased and then decreased with the increase of glutaraldehyde cross-link time.Additionally,with biomimetic minerialization time increased,inorganic deposits increased and the composition changed.Furthermore,a similar inorganic calcium salt was formed on the composite surface and they had a different ratio of calcium to phosphorus.The FTIR and ICP analysis showed that the content of HA was higher,and the ratio of calcium to phosphorus was about 1.6.The alkali treatment and mineralization stages of the two membranes were characterized by FT-IR,XRD,SEM and EDS.The results showed that the apatite deposition on the surface of the blend films was more than pure silk films,and the Ca/P of the apatite increased with the increase of the alkali treatment time.(3)In chapter 4,a series of non-ionic polyurethanes with different DMPA contents were synthesized,and then the biomaterials were prepared by bionic mineralization.In addition,the polyurethane prepared by adding Ca2+ in high speed agitation was prepared.The effects of precalcification temperature on biomimetic mineralization were also discussed in the paper.The composites were characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM)and energy dispersive spectroscopy(EDS).The results showed that with the increase of carboxyl groups in the polyurethane,the apatite deposition on the polyurethane surface increased.When the carboxyl content exceed 1.5%,the polyurethane film dissolved in the bionic solution;with the increase of Ca2+,the deposition of apatite on the surface of the material increased and the crystallization condition became better.The pre-calcination temperature had an effect on the biomimetic mineralization process.With the increase of precalcification temperature,the deposition of inorganic material on the surface of the material increased and the crystallization was better.