Antibacterial Properties Of Copper-containing Stainless Steel Against Oral Streptococcus Mutans And Streptococcus Sanguis

Objective:To study the antibacterial effect of 304 copper-containing antibacterial stainless steel?SS?on biofilms of Streptococcus mutans?S.mutans?,Streptococcus sanguis?S.sanguinis?and mixed bacteria,and to evaluate its biocompatibility and corrosion resistance.Methods:1.Metal powder injection molding?MIM?technology was used to prepare 304copper-containing stainless steel.The experimental group divided 304-Cu SS into two groups based on the difference in copper content,respectively 304-2.62Cu SS and304-4.33Cu SS.The control group was 304 SS.2.Evaluate the antibacterial performance of the material after co-cultivation with S.mutans,S.sanguinis and their mixed bacteria by plate counting method for 24h.Observe the bacterial adhesion and biofilm formation on the sample surface with scanning electron microscope?SEM?.The biofilm activity on the surface of the sample was observed by 4',6-diamidino-2-phenylindole?DAPI?staining method;the bacteriostatic performance of 304-Cu SS was evaluated by the inhibition zone method;and the effect of 304-Cu SS against bacterial biofilm metabolism was evaluated by the tetrazolium salt?XTT?method.3.After the metal extract was co-cultured with NIH3T3 mouse embryonic fibroblasts for 1,3,and 5 days,the cytotoxicity of the material was evaluated by the CCK-8 method;after the metal extract was co-cultured with NIH3T3 cells for 48 h,flow cytometry Cytometer Annexin V.FITC/PI double staining was used to observe the apoptosis.4.Evaluate the corrosion resistance of 304-Cu SS in artificial saliva by electrochemical test.Results:1.304-4.33Cu SS has obvious antibacterial property against S.mutans,S.sanguinis and mixed bacteria,with the antibacterial rates of 99.9%.It can inhibit the adhesion and formation of single and double bacteria biofilms on the surface,and can inhibit metabolic activity of bacteria and effectively kill surface bacteria.304-4.33Cu SS has no significant difference in direct bactericidal property against S.mutans,S.sanguinis and mixed bacteria?P>0.05?,and the bacteriostatic property against S.mutans is significantly stronger than that of S.sanguinis,the diameters of inhibition zone are21.7mm and 14.3mm,respectively,and it has no obviously dissolve antibacterial property against mixed bacteria,the diameter of inhibition zone is 0mm.304-2.62Cu SS and control group 304 SS had no obvious antibacterial property.2.The results of CCK-8showed that after co-culture of 304-Cu SS and NIH3T3 cells for 1,3,5 days,the cytotoxicity grades of 304-2.62Cu SS and 304-4.33Cu SS were both Grade 1,and the304 SS and blank control group were both Grade 0,no cytotoxicity.After co-culture of304-Cu SS and NIH3T3 cells for 48 hours,the apoptosis rates of 304 SS,304-2.62Cu SS,and 304-4.33Cu SS were 15.5%,16.7%,and 25.0%,respectively,and the apoptosis rate increased in turn.3.Electrochemical results showed that the pitting potentials(E_pit)values of 304 SS,304-2.62 Cu SS,and 304-4.33Cu SS were 392 mV,345 mV,and 301mV,respectively,which decreased in turn.The corrosion current density(i_corr)values were 0.23?A/cm²,0.44?A/cm² and 1.25?A/cm²,respectively,which increased in order,and the corrosion resistance decreased in order.Conclusions:1.304-4.33Cu SS has obvious antibacterial property against S.mutans,S.sanguinis and mixed bacteria,and 304-2.62Cu SS has no obvious antibacterial property.2.Both 304-2.62Cu SS and 304-4.33Cu SS have good biosecurity.3.The addition of copper reduces the corrosion resistance of copper-containing stainless steel.