Preparation And Properties Of Abalone Shell/Calcium Sulfate Injectable Bone Cement

The abalone shell is a shell with precise micro-nano structure composed of more than 95%of inorganic calcium carbonate crystals and less than 5%of organic protein-based polymers.Based on the characteristics of the sea in Fujian Province,this paper studied the development of the discarded abalone shell of Fujian Lianjiang in terms of the water-soluble organic matrix and inorganic minerals.The main research and conclusions as follows:1.Firstly,the composition and structure of the abalone shell was analyzed,then water soluble organic matrix in the nacre layer of the abalone shell was extracted by water extraction.The cytotoxicity,activity and cell differentiation ability of organic matrix were explored by co-culture with the skull cells.It is found that the abalone shell is mainly composed of stable and dense calcite as outer layer and inner one with layer by layer self-assembled metastable aragonite.The organic protein active molecules mainly exist between the layered aragonite sheets in the nacre layer;The cell experiment showed that the water-soluble organic matter has good biocompatibility and inducing osteoblast differentiation ability.2.The injectable abalone shell/calcium sulfate bone cement powders were prepared using abalone shell powder and calcium sulfate dihydrate in the crystallizer salt solution by hydrothermal and condensation reflux oil bath heating method,which were hydrated to form three-dimensional bone cement scaffolds with controllable shapes.The safety and potential for bone formation of the composites were evaluated by testing the solidification behavior,mechanical properties,the mineralization,degradability in vitro,biocompatibility and an animal skull defect model.Research shows that:(1)Condensation reflux oil bath method:After recrystallization reaction of abalone shell and calcium sulfate dihydrate,calcium sulfate hemihydrate(CSH)bone cement powder coated with abalone shell powder can be obtained.When the content of abalone shell was within 20%(AS/20CS),the injectable(0.5-13.5min)time,the compressive strength(up to 5MPa)and the highest compressive strength of composite bone cements was increased with the addition of abalone shell;In vitro mineralization and degradation experiments showed that the addition of abalone shells effectively reduced the pH decline during mineralization,provided a microenvironment for phosphate formation,and significantly slowed the rate of bone cement degradation.This indicated that the abalone shell,as a present system stabilizer,optimized the overall physical and chemical properties of the composite.(2)Reactor hydrothermal method:The hexagonal columnar calcium sulfate hemihydrate obtained by the hydrothermal method is uniformly mixed with the active abalone shell powder,and the water-solidified composite cement having a dense interlaced network structure can be obtained.The addition of abalone shell adjusted the injectable time(1.5-10.5min)to achieve operational requirements at the solidification performance,and alleviated the brittleness of the composites by interweaving adhesion and improved the resistance to collapse;Bone cements facilitated mineralization by relieving acidification and an open ion exchange environment.Considering comprehensively,when the abalone shell content was 12%(AS-12),which was the optimal component of the system,the balanced package of calcium sulfate hemihydrate can be achieved.In vitro cell experiments showed that the composite bone cements had good biocompatibility and excellent inducing cell proliferation and differentiation ablity.The animal research showed that AS/12CS,AS/20CS and AS-12 bone cement have the ability to induce osteogenic gene expression and promote new bone formation.The ingenious combination of abalone shell and calcium sulfate provided a new way for natural resources development and distribution while relieving environmental pressure,and it is expected to become a substituted material in the field of bone repair.