The Preparation Of Antibacterial Modified Eggshell Powder As Bone Graft Material

[Objective]This study is to prepare new bone graft material with modifying natural ovarian eggshell (ES) powder by physicochemical methods and coating zinc and detect physicochemical characteristics. Explore the feasibility of the preparation of anti-bacterial complex bone graft material.[Methods]Part 1:The preparation of anti-bacterial complex bone graft material.Discarded eggshell (ES) was collected and cleaned. After simple treatments, surface-modified natural ovarian ES powder was prepared by hydro-thermal method and microwave method respectively. Quantitative ovarian ES powder was immerged in Na2HPO4 solution (200ml,0.1 mol/L) for 5,8,12 and 24hours by hydrothermal method, then filtrated and dried. Quantitative ovarian ES powder was immerged in Na2HPO4 solution (200ml,0.1mol/L) for 20minutes and 60 minutes at medium power by microwave method, filtrated and dried. And then certain surface-modified natural ovarian ES powder respectively was coated with zinc for 30 minutes at medium power by micro-wave method, then filtrated and dried.Part 2:Physicochemical characteristics were detected.The physicochemical characteristics of surface-modified natural ovarian ES and surface-modified ovarian ES with coating zinc were analyzed by SEM,EDXA,XRD,FT-IR.Part 3:A preliminary pilot in rat.Three adult male Sprague-Dawley rats were used in this study. Cranial defect animal models were built. The 5-mm diameter cranial defect was created in the mid-portion of each parietal bone per rat. There were six defects totally divided into six groups.(group A:the defect was unfilled; group B:the defect was filled with ES powder; group C:the defect were filled with surface-modified ES powder for 60min by microwave method; group D:the defect was filled with Bio-OssTM; group E:the defect was filled with auto bone; group F:the defect was filled with surface-modified ES powder for 24h by hydrothermal method). The samples were harvested 8weeks postoperation. The undecalcified bone sections were observed with histological method.[Results]1. The surface-modified ES as bone graft material was prepared by hydrothermal method and microwave method, respectively. The antibacterial surface-modified ES as bone graft material was prepared with zinc coating by microwave method.2. SEM:Hydrothermally and microwave treated ES (5h,8h,12h and 24h) showed different surface morphology in the micron-scale such as ball-like, needle-like, or rod-like microstructure. Surface-modified ES kept original pore structure.3. EDXA:Phosphate of surface-modified ES increased dramatically. The longer, the more phosphate. It showed the new material existed. After coating zinc, EDXA showed zinc existed. It demonstrated surface-modified ES could be coated with zinc effectively by microwave method.4. XRD:Samples maintained their typical peaks of calcite, but they showed gradual reduction in calcite peaks and increased formation of CHA peaks after hydrothermal and microwave reaction respectively. After coating treated ES with zinc, the sample showed zinc peaks.5. FTIR:After hydrothermal or microwave treatment, phosphate bands appeared at 473,566,606, and 1034 cm-1 in the FTIR.6. Histological observations:group A:New bone formation was confined to areas close to the defect margin and the height of defect was almost unchanged. Group B,C and D:The new bone formation was surrounding graft particles or between graft particles, and all of areas of defects were filled by new bone. In group C graft material had a high biodegradability and more new bone formation compared to group B.In group C more obvious calcified new bone existed compared to group D. The rat of group E and F was dead 10 days postoperation, so the histological results couldn't be observed.[Conclusions]1. Surface-modified ES as osteoconductive bone graft material could be considered. It can repair limited bone defects. Due to lots of advantages such as nature> safety,obtain-easy,low-price,good biocompatibility and so on, it would have profound development.2. Physicochemical characteristics analysis showed ES own pore structure as bone.3. Surface-modified ES was coated with zinc by microwave. Physicochemical characteristics were stable. The antibacterial and osteoconductive effectiveness should be tested in advance.4. The histological observations of the preliminary pilot in rats showed new bone formation and mineralization. It provided experimental basis for further research on the quantitative index and mechanism of new bone formation.