Physiochemical properties and cytotoxicity of silk fibroin based calcium phosphate cement incorporated with N-acetylcysteine / 中国组织工程研究

ABSTRACT

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 andα-tricalcium phosphate powder with the ratio of 0.4 mL1 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 cel s were seeded onto the material in each group, and cel morphology was observed under scanning electron microscope at 24 hours. MC3T3-E1 cel s were cultured in the extract of each material, cel 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 ofα-tricalcium phosphate in al 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 cel morphology among cements. These results suggest that the cement containing N-acetylcysteine exhibites good biocompatibility and high mechanical strength.