| Tissue engineering is a new developing science and medical technology.It is a multidisciplinary science,which combines engineering and life science in the research of the structures,functions and growth of the tissue,in the research of biological substitutes,to restore the injured tissue and organs.In recent years,tissue engineering has large developing potential,as more researches have been done on natural biomaterials, novel materials and new technology.Some tissue engineering technologies have been applied into clinic to cure the patients.However, there are still lots of problems for scientists to solve.In this study,by the view of bionic,the concept of functionally gradient was applied into the research of scaffold materials in tissue engineering,to explore new methods to prepare tissue engineering scaffold materials.The mimic of porosity and grade structure was expected.Biosynthesized PHB and modified HAP(FHAP,HAP-HP,HAP-SR)were the main materials.Electrospinning method was used in preparing gradient electrospinning films.There are four parts in this paper, that is,the synthesize and modification of HAP,the preparation and property study of CGF PHB/FHAP,in vitro degradation study of CGF, the property study of PHB/HAP-HP and PHB/HAP-SR electrospinning films.Conclusions are as following:1.Chemical coprecipitation method was used to prepare HAP powder.The study showed that Ca/P mol ratio of the products was close to that of the reactants by coprecipitation method.The Ca/P mol ratio of the product HAP was close to 1.67 when the Ca/P mol ratio of the reactants was 1.67 at 60℃and PH was 10.2.Three distinct methods were used in chemical modification of HAR The research indicated that the crystallinity,crystalline size and chemical stability of FHAP were significantly improved.The crystallinity and crystalline size of heparin modified HAP(HAP-HP)were slightly decreased and the anticoagulant property was significantly improved.The crystalline size of stearic acid modified HAP(HAP-SR)was slightly increased.Its crystallinity and the dispersion in organic solvent were greatly increased.3.CGF PHB/FHAP75 was successfully prepared by using electrospinning method.Multi-fractal theory was firstly used to estimate the porosity of CGF.The study indicated that the mechanical and thermal properties could display a gradient change in the direction of thickness of the films by different FHAP content.By multi-fractal spectrum,the porosity and distribution of CGF could be well described.The cytotoxicity grade of CGF was 0-2,that is,it had good cellular compatibility.4.In phosphate buffer solution,the degradation behavior of PHB/FHAP electrospinning films(PHB/FHAP25,PHB/FHAP50,PHB/FHAP75,PHB/FHAP100)were studied.FHAP was HAP with different content of fluorine.The study indicated that the degradation rate of PHB/FHAP was gradually decreased with the increasing fluorine content in FHAP.That is,PHB/FHAP25>PHB/FHAP50> PHB/FHAP75>PHB/FHAP100.The degradation rate of gradient electrospinning films can be controlled by fluorine content in FHAP.5.PHB/HAP-HP electrospinning film was firstly prepared.The activated partial thromboplastin time(APTT)and prothrombin time(PT) were also observed.The results indicated that APTT and PT of PHB/HAP-HP electrospinning films were significantly prolonged, compared with that of PHB and PHB/HAP electrospinning films.In particular,the maximum value of APTT was above 500s.The anticoagulant property became better with the increasing extent of modification of HAP-HP。 6.PHB/HAP-SR electrospinning film was firstly prepared.The distribution of HAP-SR in the films and the cellular compatibility of PHB/HAP-SR electrospinning films were also observed.The results illustrated that the stearic acid modified HAP could be well distributed in PHB matrix.The interfacial compatibility of HAP and PHB was distinctly improved by stearic acid.The cytotoxicity grade of PHB/HAP-SR was 0-1,that is,it had good biocompatibility.
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