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Abstract：
Streptococcus mutans (S. mutans) and Candida albicans (C. albicans) are prominent microbes associated with rapid and aggressive caries. In the present study, we investigated the antimicrobial efficacy, cytotoxicity, and mechanism of toluidine blue O (TBO)-mediated antimicrobial photodynamic therapy (aPDT) and potassium iodide (KI). The dependence of KI concentration, TBO concentration and light dose on the antimicrobial effect of aPDT plus KI was determined. The cytotoxicity of TBO-mediated aPDT plus KI was analyzed by cell counting kit-8 (CCK-8) assay. A singlet oxygen (1O2) probe test, time-resolved 1O2 detection, and a 1O2 quencher experiment were performed to evaluate the role of 1O2 during aPDT plus KI. The generation of iodine and hydrogen peroxide (H2O2) were analyzed by an iodine starch test and Amplex red assay. The anti-biofilm effect of TBO-mediated aPDT plus KI was also evaluated by counting forming unit (CFU) assay. KI could potentiate TBO-mediated aPDT against S. mutans and C. albicans in planktonic and biofilm states, which was safe for human dental pulp cells. 1O2 measurement showed that KI could quench 1O2 signals, implicating that 1O2 may act as a principal mediator to oxidize excess iodide ions to form iodine and H2O2. KI could highly potentiate TBO-mediated aPDT in eradicating S. mutans and C. albicans due to the synergistic effect of molecular iodine and H2O2.
摘要：
变形链球菌(S.变形)和白色念珠菌(C.白色念珠菌）是与快速和侵袭性龋齿相关的突出微生物。在本研究中,我们调查了抗菌效果，细胞毒性，甲苯胺蓝O（TBO）介导的抗菌光动力疗法（aPDT）和碘化钾（KI）的作用机制。KI浓度的依赖性，测定了TBO浓度和光照剂量对aPDT加KI的抑菌效果。通过细胞计数试剂盒-8(CCK-8)测定分析TBO介导的aPDT加KI的细胞毒性。单线态氧(1O2)探针测试,时间分辨1O2检测，并进行了1O2猝灭剂实验以评估1O2在aPDT加KI过程中的作用。通过碘淀粉测试和Amplex红测定法分析了碘和过氧化氢（H2O2）的产生。还通过计数形成单位(CFU)测定评价了TBO介导的aPDT加KI的抗生物膜作用。KI可以增强TBO介导的aPDT对抗浮游和生物膜状态下的变形链球菌和白色念珠菌，这对人类牙髓细胞是安全的。1O2测量表明，KI可以抑制1O2信号，暗示1O2可以作为主要介质来氧化过量的碘离子以形成碘和H2O2。由于分子碘和H2O2的协同作用，KI可以高度增强TBO介导的aPDT根除变形链球菌和白色念珠菌。
