| Objective:To study the anti-Candida albicans（C.albicans）activity of AgBr-Nanoparticle（NP）@Cetyltrimethylammonium bromide（CTMAB）con-structed by quaternary ammonium salt,and further study its biocompatibility,and then add it to polymethyl methacrylate（PMMA）to study its anti-C.albicans biofilm adhesion effect,mechanical properties and in vitro cytotoxicity.Finally,the possibility of its application in the field of denture cleaning was explored,and the effect of inhibiting the adhesion of PMMA to C.albicans membrane,the residual toxicity and the color change of PMMA after immersion were tested.Methods:（1）Infraredradiation（IR）,Ultravioletrays-visible spectrophotometer（UV-Vis）,X ray diffraction（XRD）and Scanning electron microscope（SEM）were used to characterize the appearance and structure of AgBr-NP@CTMAB,and then agar plates containing 0,5,10,20 and 40μg/mL AgBr-NP@CTMAB solutions were made,and C.albicans ATCC90029 suspensions were inoculated on each plate.The inhibitory activity of different concentrations of AgBr-NP@CTMAB solution on C.albicans suspension was determined by agar plate culture method and Bioscreen automatic growth curve analyzer.Cell counting kit-8（CCK-8）method was used to detect the cytotoxicity of different concentrations（0,2,5,10,20μg/mL）of AgBr-NP@CTMAB solution to Human gingival fibroblast（HGF）and Human oral epithelial cell（HOEC）in vitro.（2）PMMA specimens（10.0 mm×10.0 mm×2.0mm）were prepared by customized metal moulds as blank control,and new specimens containing AgBr-NP@CTMAB were prepared according to different mass percentages of 0.25%,0.50%and1.00%.The surface roughness of each group of specimens was detected by surface roughness measuring instrument,and the microhardness was tested by digital vickers hardness tester.Then,after C.albicans biofilm was constructed in vitro,the antibacterial and long-term effect of PMMA specimens to C.albicans membrane were quantitatively compared by colony count,and the cytotoxicity of extract was detected by CCK-8method.（3）The routine PMMA specimens attached to C.albicans membrane for 24 h were randomly divided into three groups and immersed in 10,20μg/mL AgBr-NP@CTMAB solution and polident（positive control group）,respectively.The clearance rate of C.albicans membrane was quantitatively measured by OD600after immersion for 30 minute（min）and 8 hours（h）.Then the anti-C.albicans membrane effect of each group was qualitatively analyzed with SEM;the residual cytotoxicity of the extract was also detected by CCK-8 method;and the PMMA specimens of each group were soaked in fresh different soaking solution and artificial saliva circulation for one week,and the color of each group before and after immersion was observed by stereomicroscope.The single factor variance was used for analysis,and the test level wasα=0.05.Results:（1）IR,UV-Vis,XRD,SEM results showed that AgBr-NP@CTMAB nanoparticles had good hybridization and crystal phase.The results of agar plate showed that the antibacterial rates of 5,10,20 and 40μg/mL AgBr-NP@CTMAB were significantly different from those of the blank control group（P<0.05）.The results of growth curve showed that the growth of C.albicans was completely inhibited within 48h when the concentration of AgBr-NP@CTMAB solution was 10μg/mL or more.The results of cell relative proliferation rate showed that the cytotoxicity grade of 10μg/mL AgBr-NP@CTMAB solution to HGF and HOEC was as high as grade 3 and 4;（2）Compared with conventional specimens,the surface roughness of 0.25,0.50 and 1.00%AgBr-NP@CTMAB/PMMA samples had no significant difference（P>0.05）,and the microhardness increased with the increase of additive amount（P<0.05）,and not affect the polymerization.For the first time,it could inhibit the biofilm,but it decreased significantly after repeating use,and at the same time,it also had strong cytotoxicity.（3）The survival rates of C.albicans attached to PMMA by soaking in 10,20μg/mL AgBr-NP@CTMAB and polident solution for 30 min were 44.73±2.01%,76.00±4.18%and 79.44±4.05%,respectively.Soaking for 8 h reached 91.35±0.64%,92.57±0.61%and 92.73±0.67%,respectively.The results of cell relative proliferation rate showed that there was no obvious residual cytotoxicity.There was no obvious visual color change after soaking for one week.Conclusions:（1）AgBr-NP@CTMAB had good hybridization and crystal phase.AgBr-NP@CTMAB had good resistance to the proliferation of C.albicans plankton in vitro,but direct contact has strong cytotoxicity.（2）The new type of specimen incorporated by AgBr-NP@CTMAB into PMMA was unevenly distributed and has residual particles,which affects its appearance.Although the surface roughness had no obvious change,and enhance its hardness,and had the effect of anti-C.albicans biofilm,it had no long-term effect and strong cytotoxicity,so it was not suitable to be used as an additive for PMMA.（3）AgBr-NP@CTMAB can effectively remove C.albicans biofilm from PMMA without residual toxicity and not change its color,so it has the potential to be used as a denture cleaner. |
