复合N-乙酰半胱氨酸丝素蛋白磷酸钙骨水泥的理化性能及细胞毒性

Physiochemical properties and cytotoxicity of silk fibroin based calcium phosphate cement incorporated with N-acetylcysteine

BACKGROUND: Calcium phosphate cements (CPCs) possess the bio-degradation and osteoconduction, and its final hydration product, hydroxyapatite, is the main inorganic constituent of bones. However, its poor mechanical property makes it unable to be used for repairing weight-bearing bone defects.OBJECTIVE: To develop a kind of bioactive bone cements with decent biomechanical property and biocompatibility.METHODS: 6% silk fibroin aqueous solutions containing different concentrations of N-acetylcysteine (0, 10 and 25 mmol/L) were prepared. Each cement sample was prepared by mixing the curing liquid and α-tricalcium phosphate powder with the ratio of 0.4 mL: 1 g; α-tricalcium phosphate powder mixed with ddH2O as control group. The compressive strength, setting time of the cements were measured. The crystal components of the cements were characterized using X-ray diffraction and the microstructure was observed using scanning electron microscope. MC3T3-E1 cells were seeded onto the material in each group, and cell morphology was observed under scanning electron microscope at 24 hours. MC3T3-E1 cells were cultured in the extract of each material, cell proliferation was detected at 1, 3, 5 and 7 days, and the lactate dehydrogenase level was detected at 1 and 3 days.RESULTS AND CONCLUSION: X-ray diffraction and scanning electron microscope showed that the final hydration products of α-tricalcium phosphate in all specimens were hydroxyapatite. When the concentration of N-acetylcysteine was 25 mmol/L, the compressive strength of the material reached (49.39±1.68) MPa, with the initial setting time of (21.77±1.07) minutes and the final setting time of (31.88±1.69) minutes. There was no significant difference in cell morphology among cements. These results suggest that the cement containing N-acetylcysteine exhibites good biocompatibility and high mechanical strength.