Preparation Of A Biodegradable Guided Bone Regeneration Membrane For Skull Repair In Rats

Human bone is a kind of natural biological composite material,it is easy to cause bong tissue damage because of some innate or acquired factors.When the bone defect scope is beyond the self-healing ability,it needs to be repaired with bone graft.Synthetic biological tissue engineering materials with good biocompatibility can avoid the problem of autotransplantation and allotransplantation,like donor deficiency,immune rejection and Pathogen transfer,become a hotspot in the field of bone tissue repair and regeneration.Large bone defect is difficult to heal,one of the reasons is that neoformative connective tissue grows in to the bone defect rapidly and occupies the space,thus preventing the formation of new bone.Guided bone regeneration(GBR)technique solves this problem by implanting barrier material above the defect to block connective tissue.Based on the esterification crosslinking of acid and alcohol,we prepared a kind of biodegradable macromolecule elastic material with porous structure,and improved its surface properties by poly dopamine(PDA).We hope it can be used as a good guide bone membrane materials in bone tissue repair.In this study,succinic acid,glycerol and ethylene glycol were used as raw materials and crosslinked at high temperature to obtain polymer products(Poly(Glycerine-Ethylene glycol-Succinic acid),PGES).It was found that the mechanical properties and degradation rate can be adjusted by changing the reaction parameters such as time and temperature.Ideal guided bone regeneration membrane must have a certain porosity,which allows the transport of nutrients and metabolic waste.In this study,the porous structure of the material was obtained by particulate-leaching with sodium chloride as pore-making agent.In order to study the effect of pore size on the properties of the materials,three kinds of pore-making agents with different particle sizes were selected.Then we characterize it by SEM and measure its tensile properties and porosity.The results proved the that good pore connectivity of the porous membrane,and its tensile strength,elongation at break and elastic modulus decrease with the increase of pore diameter.To improve the surface properties,PDA coating was obtained by soaking the porous materials in dopamine tris-HCl buffer solution,and the effects of surface modification on hydrophilicity,biomineralization and biocompatibility properties were studied.It was found that the PDA coating can greatly improve the hydrophilicity and mineralization ability of the material in vitro,and was beneficial to cell adhesion.The animal experiment was carried out by implanting materials into rats with skull defect,then observed the repair condition after 12 weeks.The results of Micro-CT scan and section staining showed that the PDA-modified porous membrane could effectively promote the repair of bone defect.The above experimental results indicate that this material has great development potential in the application of BGRM in the field of bone tissue repair and regeneration.