New Polymethyl Methacrylate-containing Nanomagnesium Oxide Improves Resistance To C. Albicans

Part Ⅰ Inhibition of MgO NPs on the growth and biofilm formation of C.albicans Objective:The aim of this research was to study the effects of different concentrations of magnesium oxide nanoparticles(MgO NPs)on the growth and biofilm formation of Candida albicans.Methods:The minimum inhibitory concentration(MIC)of MgO NPs against C.albicans was determined by Colony count method.Crystal violet staining,the MTT assay and inverted fluorescence microscopy were employed to determine the effects of MgO NPs on C.albicans adhesion,Biofilm morphology,biofilm biomass,and metabolic activity.Results:1.MgO NPs were found to be circular-like structures with a size of 20-50 nm and tendencies towards agglomeration by TEM.SEM showed the surface morphology of MgoNPs,and the EDS spectrum results showed that there were no other impurity elements in MgoNPs except Mg and O.2.When the concentration of MgO NPs reached 0.391 mg/mL,the growth of planktonic cells was completely inhibited.3.Semi-quantitative crystal violet staining and MTT assays showed that MgO NPs significantly inhibited C.albicans biofilm formation and metabolic activity,and the difference was statistically significant(p<0.001).4.Inverted fluorescence microscopy showed that MgO NPs could inhibit the formation of C.albicans biofilm hyphae.5.Adhesion experiments showed that MgO NPs significantly inhibited the initial adhesion of C.albicans(p<0.001).Conclusion:This study demonstrates that MgO NPs can effectively inhibit the growth,initial adhesion and biofilm formation of C.albicans and is an antifungal candidate.Part Ⅱ Inhibition of MgO NPs on the growth and biofilm formation of C.albicans Objective:This study evaluated the effects of incorporation of MgO NPs into a denture base acrylic resin on the hydrophilicity,roughness and growth of C.albicans.Methods:MgO NPs-PMMA resins(2%,4%,6% and 8%)were prepared for determination of surface roughness and hydrophilicity.Then,the colony counting method was used to evaluate the antifungal effect of MgO NPs-PMMA resin on C.albicans.Results:1.The surface characterization of MgO NPs-PMMA resin was performed by SEM and EDS.MgO NPs were successfully embedded in PMMA resin.The EDS spectrum results showed that there was no Mg element in the control group.As the amount of MgoNPs added increased,the content of Mg and O in the EDS analysis increased.2.The wettability of the samples was evaluated by measuring the water contact angle on their surfaces(P < 0.001).The average value of the contact angles was observed to be the highest for the control group(73.56± 4.58)and lowest for the 8% MgO NPs-PMMA resin group(64.87 ± 1.78).With the increase in MgoNPs concentration,the contact angle showed a downward trend(P <0.001).3.The average roughness value of the surface of the 2% MgO NPs-PMMA resin(Ra: 12.210±3.494 nm)was not significantly different from that of the control group(Ra: 8.845±1.847 nm,p> 0.05),but there was a difference between the surface roughness value of the high concentration MgO NPs-PMMA resin and the control group(p <0.05).4.MgO NPs-PMMA resin base effectively inhibited the growth of C.albicans on the surface,and the number of colonies formed on the surface of the MgO NPs-PMMA resin was significantly different from that of the control group(P <0.001).Compared with the control group,the average antifungal rate of the 2% MgO NPs-PMMA resin base against C.albicans was 58.76%.with the increase in the dosage of MgO NPs,the antifungal rate also increased.When the amount of MgO NPs was 8%,the average antifungal rate of MgO NPs-PMMA resin base against C.albicans reached 93%.Conclusion:MgO NPs-PMMA resin exhibited antifungal activity and could inhibit the growth of C.albicans on its surface.