Calcium Phosphate Mineralization In Cell Culture Environment And Its Effect On Cell Viability

Biomineralization is the process by which living organisms produce minerals, and it is an extremely widespread phenomenon. From the nano-world of rusty proteins and magnetic micro crystal in bacteria to the macroscopic structures of oyster shells, corals, ivory, bone and enamel, biology has evolved a new type of technology that brings together the synthesis and construction of hard and soft matter for the design of functionalized inorganic-organic materials. The mechanism of biominerals formation controlled by organic molecules in living organisms and the effect of these biomineralized materials on cells are the most interesting research filed in biomineralization.In the present work, we study the effect of organic molecules in culture media on calcium phosphate mineralization and the effect of the calcium phosphate formed in culture media on cells. The thesis is composed of five chapters:In chapter1, we introduce the basic knowledge of biomineralizaion including the kinds of biominerals, the calcium phosphate in biological tissues, the development of synthesis of calcium phosphate, the effect of organic molecules on the formation and crystallinity of calcium phosphate, the effect of size and crystallinity of calcium phosphate on cells and shellization of bare cells with polyelectrolytes or biominerals. Based on the above knowledge, the thoughts and views are summarized and the research proposals are introduced briefly at the end.In chapter2, we focus on the effect of fetal bovine serum (FBS) on the formation and crystallinity of calcium phosphate in cell culture media. Our results show that FBS is an effective biological regulator to prevent pathological calcification in biological fluids. The precipitation of large-sized HAP is greatly retarded by FBS and only the nanosized ACP can be resulted. In the presence of FBS, these nano-ACP particles can be well-dispersive against aggregation in the fluid and the phase transformation is suppressed. Our experiments suggest that FBS is an effective biological regulator to control the biomineralization process in biological fluids.In chapter3, the quantity effect of calcium phosphate nanoparticles (CaP-NPS) on MG-63cells is evaluated. The CaP-NPS with the same size and crystallinity in calcium and phosphate free culture media are synthesized in situ by adding calcium solution to phosphate solution. Our results demonstrate that cell viability is related to the quantity of CaP-NPS.240μg/mL CaP-NPS is a critical point for cell viability, exceeding which would cause severely cell death because it exceeded the limit of cell self-clarify or tolerant ability. This work provides an interesting view of the role of CaP-NPS which is an ideal biomedical material in future clinical application.In chapter4, shellization of mammalian cells with protein, polyelectrolyte, silica and calcium phosphate are studied. Our results demonstrate that all these materials could confer mammalian cells shells, but they also could damage cell membrane. The damage caused by soft materials like protein is slight and the cells could recover in a while, but the damage caused by minerals like silica and calcium phosphate is heavy and the cells lost their viability. The study on the shellization of mammalian cells should pay more attentions on the cell membrane integrity such as finding new materials which caused less damage on cells or improving the tolerance of cell membrane in future.In chapter5, the views and innovations of our studies have been systematically summarized. Some important but unsolved issues in the future studies are also suggested in this chapter.