The Research On The Synthesis And Properties Of Polylactic Acid/bacterial Cellulose Composite Scaffolds

Bacterial cellulose(BC)has become a common biomaterial because of its high purity,high crystallinity,good mechanical properties,excellent biocompatibility and biodegradability.Its nanoscale fiber bundles interweave together to form a unique three-dimensional network structure.Polylactic acid(PLA)has good mechanical properties and excellent biocompatibility and biodegradability.Therefore,polylactic acid(PLA)has been widely applied in tissue engineering.A new type of scaffold,polylactic acid / bacterial cellulose composite scaffold(PLA/BC),was prepared by combining polylactic acid with bacterial cellulose,and its physicochemical properties and biological properties were characterized and evaluated.In this paper,BC was produced by fermentation of Kombucha using static culture method,and then purified and homogenized,finally,we obtain a bacterial cellulose film by pumping.The scanning electron microscope(SEM)shows that the BC film consists of a three-dimensional network of intertwined superfine fibers.The diameter of the fiber is about 20~60 nm,with a large number of pores on the surface,and the porosity of the fiber is 93.75%.The PLA /BC composite scaffold was successfully prepared by solution pouring and solvent removal.The two materials were successfully synthesized indicated by the result of FTIR and XRD.The tensile test showed that the fracture strength of the composite scaffold was higher than that of the pure BC film.The biocompatibility of the composite film was evaluated by cell cytotoxicity,adhesion and proliferation experiments.The cytotoxicity grade of the composite film was 1,which accords with the application conditions of tissue engineering.The Schwann cells(SCs)were planted on the PLA/BC-0 composite film,and the cells adhered successfully after 24 hours and entered the logarithmic growth period in the co-cultured 3~5 days,and the cell proliferation was achieved.The 3D printing method not only realizes the combination of the two materials,but also controls the size and shape of the PLA layer accurately by controlling the process parameters in the 3D printing process,thus exploring the optimal layer structure required for cell adhesion and proliferation.In this paper,the influence of the topological structure of circular hole and stripe surface on the growth behavior of cells was characterized.SCs cells can adhere successfully on the surface of 3D printed composite films,and their proliferation rate on the surface of regular round-shaped and stripe-like structures is larger than that on smooth and flat surfaces.The microscale pore structure can promote the proliferation process.The results of cytotoxicity experiments showed that the 3D printed PLA/BC composite film had no cytotoxicity and even had a certain degree of promotion of proliferation(the cell survival rate was greater than 100%).Erythrocyte fixation and platelet adhesion experiments demonstrate that the 3D printed composite films possess the excellent blood compatibility.Further degradation studies showed that several materials appeared loose structure after one week of implantation,and structural defects began three weeks later.In vitro degradation results showed that the degradation rate of BC film after 6 weeks in simulated body fluid was 14.38%,while the degradation rate of PLA/BC composite membrane reached 18.75%,and all had biodegradability.