Research On Bacteriostasis Effect Of Multi-morphology Zinc Oxide On Streptococcus Mutans

Objective:Dental caries is the most common chronic infectious disease in the world Antibacterial materials with good biocompatibility can inhibit the accumulation of cariogenic bacteria and prevent the occurrence of caries.The objective of this experiment is to prepare ZnO with different morphological structures,and study their effect on the main cariogenic bacteria of dental caries-Streptococcus mutans(S.mutans)and its biofilm,and their biocompatibility,so as to provide a theoretical basis for the development of new dental antibacterial materials.Methods:1.The hydrothermal method under the atmospheric method is used to prepare rod-like ZnO,flower-like ZnO,and urchin-like ZnO.We used X-ray diffraction(XRD),scanning electron microscope(SEM),surface area and porosity analyzer to characterize their phase composition,crystal structure,morphology and BET specific surface area.2.The solid agar dilution method was used to determine the minimum inhibitory concentration(MIC)of multi-morphology ZnO.The multi-morphology ZnO with the concentration of MIC,3/4MIC,1/2MIC and 1/4MIC was selected for co-cultivation with S.mutans for 6 hours to compare the antibacterial ability of ZNO to S.mutans.The turbidimetric method was used to determine the influence of ZnO on the growth curve of S.mutans.The multi-morphology ZnO with a concentration of 1/2 MIC was selected for co-cultivation with S.mutans,and the OD600 value was determined and the growth curve was drawn.3.The MTT method was used to detect the effect of multi-morphology ZnO with concentrations of MIC,3/4MIC,1/2MIC and 1/4MIC on the formation of S.mutans biofilm after 24 hours.Then,the above-mentioned multi-morphology ZnO was applied to the formed S.mutans biofilm for 1 hour,and the damage to the S.mutans biofilm was tested.4.The MTT method was used to detect the cytotoxicity of multi-morphic ZnO with concentrations of MIC,3/4MIC,1/2MIC and 1/4MIC after direct contacted with human gingival fibroblast(HGF-1)for 24 hours.Results:1.The SEM image showed that the rod length of the rod-like ZnO was about 2.5μm and the rod diameter was about 0.8μm;the thickness of the flower-like ZnO layer was about 40nm;the needle length of urchin-like ZnO was about 4.5μm,and the tip size was about 50-100nm;ZnO NPs were agglomerated spherical particles with a particle size of about 30-40 nm.The specific surface areas of hexagonal rod-like ZnO,flower-like ZnO and urchin-like ZnO measured by BET method were 12.953m2/g,13.517m2/g and 9.140m2/g,respectively.XRD showed that they are all hexagonal wurtzite ZnO with complete crystals.2.The MIC values of rod-like ZnO,flower-like ZnO,urchin-like ZnO and ZnO NPs on S.mutans were 3.0mg/mL,0.8mg/mL,1.5mg/mL and 0.8mg/mL,respectively.At the concentration of MIC,3/4MIC,1/2MIC and 1/4MIC,the multi-morphology ZnO can significantly inhibit S.mutans at 6h(P<0.01),and the antibacterial effect is gradually enhanced in a dose-dependent manner.The effect of multi-morphology ZnO on the growth curve of S.mutans at 1/2MIC showed that multi-morphology ZnO can significantly inhibit the growth of S.mutans.Among them,ZnO NPs had a greater impact on the growth of S.mutans,followed by flower-like ZnO,rod-like ZnO,and urchin-shaped ZnO.3.At a concentration of MIC,3/4MIC,1/2MIC and 1/4MIC,the multi-morphology ZnO can inhibit the formation of S.mutans biofilm,and can destroy the formed S.mutans biofilm(P<0.01).At all the above concentrations,the inhibition of urchin-like ZnO on biofilm formation was relatively weak,lower than that of rod-like ZnO(P<0.05);flower-like ZnO had better destructive effects on biofilm,stronger than ZnO NPs(P<0.05).4.Within a certain range,the multi-morphology ZnO significantly reduced the relative proliferation rate of HGF-1 cells,and it gradually increased in a dose-dependent manner.The IC50 values of rod-like ZnO,flower-like ZnO,urchin-like ZnO and ZnO NPs were 21.40mg/L,24.94mg/L,45.58mg/L and 30.06mg/L,respectively.Conclusion:1.We have synthesized zinc oxide with various morphologies hydrothermal method,such as rod-like ZnO,flower-like ZnO and urchin-like ZnO.They had complete crystals,stable structure and high specific surface areas.2.Multi-morphology ZnO can inhibit the growth of S.mutans and the formation of S.mutans biofilms under both MIC and sub-MICs,and can destroy the formed S.mutans biofilms.Flower-like ZnO has shown the most excellent antibacterial activity,which is comparable to ZnO NPs.3.Multi-morphology ZnO showed dose-dependent cytotoxicity to HGF-1 cells.Among them,urchin-like ZnO had the lowest cytotoxicity to HGF-1 cells.