Construction Of Bacterial Cellulose-based Composite Materials And Their Applications In Artificial Valve And Cornea

At present,the study of artificial heart valves and cornea are the hotspots in the field of tissue engineering.The artificial heart valve replacement surgery is one of the most important means for the treatment of heart valve disease.However,the mechanical valves and biological valves used in above method often suffer from severe problem,such as thrombosis diseases and calcification.For the corneal disease with high morbidity,the corneal substitutes are often accompanied by calcium deposition affecting light transmittance,poor biocompatibility and lack of donors and other problems.Therefore,how to alleviate the easy calcification and thrombosis of valve materials,and improve the light transmittance and biocompatibility of corneal materials are the essential issues that need to be resolved in related fields.With very good biocompatibility,high chemical purity,excellent water resistance,good mechanical properties,three-dimensional network of hyperfine structure and the characteristics of its sources and cheap,bacterial cellulose(BC)has become a popular and a new type of biomedical material is widely used in the field of tissue engineering.At the same time,with the good anticalcification properties and high transparency,BC is also the potential materials which could be developed as artificial heart valves or cornea scaffold for tissue engineering.However,compared with the natural heart valves and corneas,the mechanical properties and water retention ability of BC need to be improved.Therefore,our work aims to construct the artificial heart valve materials with good mechanical properties,bionic anti-calcification and anticoagulation and the artificial corneal scaffold materials with high light transmittance,high water retention rate and excellent biocompatibility by preparing the BC-based composites.(1)In this work,bacterial cellulose / poly(vinylidene fluoride)(BC/PVDF)composites developed as potential biological valve materials have been prepared by the methods of liquid membrane interface culture and electrostatic spinning.The structures of BC/PVDF were characterized by scanning electron microscope(SEM),atomic force microscope(AFM),infrared spectroscopy(FT-IR),X-ray diffraction(XRD).The mechanical,chemical and biological properties of BC/PVDF were evaluated by the two-way tensile,cytotoxicity,blood compatibility,anticalcification experimentsin vivo and in vitro,respectively.The cardiac valve materials(BC/PVDF)was prepared by electrospinning and membrane liquid interface culture method.The SEM and AFM images show that the fiber of BC/PVDF composites consists of micro-fiber and nano-fiber.The tensile strength of BC/PVDF composites can reach 4.93 ± 0.15 MPa.BC/PVDF has a good capability of anticoagulant.Importantly,the anti-calcification performance in vitro is robust enough in the short term.The anti-calcification performance of BC/PVDF are better than those of bovine pericardium which are widely applied as the biological valve materials.With its good biomimetic structure,mechanical properties,anticalcification ability and blood compatibility,BC/PVDF composites are promising to used as the artificial heart valves.(2)Besides,the chondroitin sulfate / gelatin-bacterial cellulose(CS/GEL-BC)composites developed as potential biological valve materials have been prepared by crosslinking methods with the use of EDC/NHS.The structures of CS/GEL-BC were characterized by SEM,FT-IR and XRD.The mechanical properties,the light transmittance,water retention performance,biocompatibility of CS/GEL-BC have been studied.The experimental results are summarized as follows.CS/GEL-BC composites were prepared by EDC/NHS cross-linking.It was found that the light transmittance of CS/GEL-BC reached 90% at 700 nm which was higher than that of pure BC,and the water retention rate was also significantly improved compared with that of pure BC.The results of experiments related to the corneal epithelial cells showed that CS/GelBC composites had better biocompatibility compared with pure BC.In addition,CS/Gel-BC displayed facilitating effect for the spread and proliferation of corneal cells,and the cell adhesion.Therefore,CS/Gel-BC composites material is expected to be used for corneal repair and replacement of artificial corneal materials.To sum up,based on BC which through the electrospinning method combined with the membrane-liquid interface culture method,and the cross-linking method to construct artificial Heart valve materials and artificial cornea materials.The two materials have excellent properties,and both effectively solve some of the current problems in their respective fields.They are expected to change the easy calcification and blood coagulation of heart valve materials,and the long-term light transmittance of corneal materials is difficult to maintain,and the mechanical properties Poor,poor biocompatibility and other issues provide an important experimental basis for research in the field of artificial heart valves and artificial cornea.