Antimicrobial Photodynamic Effect of Cross-Kingdom Microorganisms with Toluidine Blue O and Potassium Iodide

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.

Antimicrobial photodynamic therapy for the treatment of oral infections: A systematic review

“… 117 Potassium Iodide Potassium iodide significantly enhanced the efficacy of TB-mediated aPDT in eliminating S. mutans and C. albicans due to the synergistic effect of molecular iodine and H 2 O 2 . 58 Dual light Dual light therapy holds promise as a beneficial adjunctive homecare tool against peri -implantitis. Moreover, it offers a convenient and safe solution without any associated adverse effects.…”

“…conducted the antimicrobial efficacy, cytotoxicity, and mechanism of TB-mediated aPDT in combination with potassium iodide. 58 Their experiments revealed that KI acted to quench 1 O 2 signals, resulting in the oxidation of excess iodide ions and the formation of iodine and H 2 O 2 . These findings concluded that KI had the potential to enhance TB-mediated aPDT and effectively eliminate S. mutans and C. albicans due to the synergistic effect observed.…”

“…The absorption of TB solutions varies with concentration, allowing excitation in various modality using light sources from 600 to 660 nm. 58 Several studies have shown that TB is effective in the treatment of oral diseases. 59 , 60 , 61 For example, Vahabi et al.…”

Managing Corneal Infections: Out with the old, in with the new?

“…TBO is an acidophilic metachromatic dye that has high affinity for nucleic acids and polysaccharides. As a cost-effective chemical substrate, this dye has been studied for its potential photosensitizing effects to eliminate infectious agents [ 83 ] and has even been explored as a potential anticancer treatment [ 84 ]. TBO absorbs red light (peak absorption at 633 nm) and, upon excitation, undergoes a type II photochemical reaction generating singlet oxygen [ 85 ].…”

Potential Use of Brazilian Green Propolis Extracts as New Photosensitizers for Antimicrobial Photodynamic Therapy against Cariogenic Microorganisms

“…Several studies have demonstrated the efficacy of photodynamic therapy (PDT) in cariogenic bacteria [ 9 , 10 , 11 ], highlighting that it may help control dental caries [ 12 , 13 ]. PDT is a non-invasive therapy that requires specific light sources, the presence of oxygen, and a photosensitizing agent (PS) to cause cell death [ 14 ].…”