Research On The Effect Of Ni-Ti Alloy Modified By Quaternary Ammonium Salt Of Chitosan Coatings On The Bioactivity Of Osteoblasts

Objective: 1)To explore the effects of different concentrations of quaternary ammonium salt of chitosan and sodium alginate on the proliferation of osteoblasts;2)To evaluate the effect of nickel-titanium alloy on the activity of alkaline phosphatase of osteoblasts which modified by the coating of quaternary ammonium salt of chitosan.Methods: Different concentrations of chitosan quaternary ammonium salt solution and sodium alginate solution were made by using isometric dilution method and co-cultured with mouse osteoblasts.The cytotoxicity of different concentrations of chitosan quaternary ammonium salt solution and sodium alginate solution for osteoblasts was detected by CCK-8 kit at the set time point.The quaternary ammonium salt of chitosan and sodium alginate were introduced into the surface of Ni-Ti alloy by layer-by-layer self-assembly method and the surface morphology of Ni-Ti alloy was observed by scanning electron microscope.Hydrophilic angle test was used to evaluate the histocompatibility of Ni-Ti alloy after coating modification.The coated Ni-Ti alloy and unmodified Ni-Ti alloy were co-cultured with osteoblasts,and the changes of alkaline phosphatase activity of osteoblasts were evaluated by AKP alkaline phosphatase kit at the set time point.Results: There were statistical differences in OD values among different concentration groups of chitosan quaternary ammonium salt and sodium alginate(P<0.05).In different concentration groups of chitosan quaternary ammonium salt,the OD value of 2mg/ml quaternary ammonium salt group was significantly lower than that of other concentration groups and blank control group.Compared with blank control group,the OD value between different concentration groups of sodiumalginate were similar.The OD values of chitosan quaternary ammonium salt(2mg/ml)group,sodium alginate(2mg/ml)group,mixed group(2mg/ml quaternary ammonium salt + 2mg/ml sodium alginate solution)and control group were statistically different(P <0.05).After 24 hours,the change trend of OD value of each group was consistent with time,but the OD value of chitosan quaternary ammonium salt group was significantly lower than that of other concentration groups and blank control group.Scanning electron microscope images showed that the holes etched by concentrated sulfuric acid and hydrogen peroxide solution on the surface of Ni-Ti alloy were gradually filled,which was significantly different from that of Ni-Ti alloy without any treatment.The hydrophilic angle of Ni-Ti alloy decreased after being modified by quaternary ammonium salt coating of chitosan,and the alkaline phosphatase activity of osteoblasts co-cultured with quaternary ammonium salt coating of chitosan was higher than that of other groups.Conclusion: chitosan quaternary ammonium salt(degree of substitution 26%)solution of 2mg/ml has cytotoxicity to osteoblasts,while sodium alginate solution has opposed resluts.Sodium alginate solution of 2mg/ml combined with chitosan quaternary ammonium salt of 2mg/ml can significantly reduce the latter cytotoxicity.The histocompatibility and osteogenic activity of Ni-Ti alloy are effectively improved by the modification chitosan quaternary ammonium salt coating with the method of layer-by-layer self-assembly.