In Situ Biomimetic Mineralization And Cellular Response Of Carbon Nanotubes/Chitosan Composite Microspheres

Natural bone tissue is a complex organic-inorganic composite material consisting of an organic phase composed natural polymer and a mineral phase of oriented hydroxyapatite crystals. In many studies, scholars usually directly mix natural polymer materials with nanometer hydroxyapatite powder or particles to prepare the composite materials. It shows that in the composite system n-HA powder or particles often exist in aggregation form, which is difficult to make chemical combination with organic matrix in nanometer. And n-HA powder are often wrapped in the organic matrix, it is difficult to play a role in bone regeneration. Therefore, we hope to construct n-HA coating on the surface of bone repair materials, which would effectively improve the cellular response biological activity.In this study, CS microspheres were prepared by emulsion cross-linking method. Then induce CNTs treated by mixed acids to increase reactive sites for mineralization. The results show that the more part CNTs were wrapped in microspheres and the other part CNTs relatively evenly distributed on the surface of microspheres.The CNTs/CS composite microspheres were immersed in saturated calcium phosphate solution by biomimetic mineralization. Nano-hydroxyapatite crystals were biomimetically formed on the surface of the composite microspheres with the slow rise of pH. The results show that the formation ability of the n-HA crystals on the CNTs/CS microspheres is significantly higher than pure CS microspheres. The average thickness of the mineralized layer is 1.70±0.52μm. The swelling ratio and water content of mineralized CNTs/CS microspheres were 0.84±0.25 and 55.0±3.6%, which exhibits better structure stability. Different types of microspheres were co-cultured with MG63 cells in vitro to determine their cytotoxicity and cellular compatibility by MTT and SEM. The results suggest that after culturing with MG63 cells for 4 days, we can found cells were adhesion and growth on the surface of the microspheres. For 7 days, the proliferation of cells cultured with mineralized CNTs/CS microspheres shows significant difference from the other microspheres. The mineralized CNTs/CS microspheres have the potential application in the repairment of anomalous bone defects and drug delivery system.