Effects of Rose Bengal‐ and Methylene Blue‐Mediated Potassium Iodide‐Potentiated Photodynamic Therapy on Enterococcus faecalis: A Comparative Study

Abstract

Background and Objectives: This study was performed to compare the use of methylene blue (MB) and rose bengal (RB) in antimicrobial photodynamic therapy (PDT) targeting Enterococcus faecalis (E. faecalis) bacteria in planktonic and biofilm forms with potassium iodide (KI) potentiation. Study Design/Materials and Methods: E. faecalis bacteria in planktonic form were exposed to antimicrobial PDT protocols activating MB and RB, with or without KI potentiation, following laser irradiation with different exposure times, 60 mW/cm 2 laser power, and different photosensitizer agent (PS)/potentiator concentrations to observe relationships among the variables. Two continuous-wave diode lasers were used for irradiation (red light: λ = 660 nm and green light: λ = 565 nm). The pre-irradiation time was 10 minutes. The vitality of E. faecalis biofilm was assessed by confocal laser scanning microscopy, and the morphology was determined by scanning electron microscopy. The effects on the proliferation of stem cells from the apical papilla (SCAPs) were analyzed by cell counting kit-8 assay. The staining effect of antimicrobial PDT on dentin slices was investigated. Statistical analysis using a one-way analysis of variance was done. Results: KI-potentiated RB and MB antimicrobial PDT both effectively eradicated E. faecalis bacteria in planktonic and biofilm forms. The minimum bactericidal concentrations of PSs (±100 mM KI) were obtained through PDT on planktonic E. faecalis, and the optimal light parameters were 60 mW/cm 2 , 6 J/cm 2 for 100 seconds. KI-potentiated PDT effectively strengthened the ability to inhibit E. faecalis biofilm with 86.50 ± 5.78% for MB (P = 0.0015 < 0.01) and 91.50 ± 1.75% for RB (P = 0.0418 < 0.05) of bactericidal rate, with less toxicity for SCAPs (P < 0.001) and less staining. KI could reduce the staining induced by antimicrobial PDT on dentin slices. Conclusion: A combination of KI and antimicrobial PDT may be a useful alternative to conventional disinfection methods in endodontic treatment. MB and RB antimicrobial PDT at much lower concentrations with KI could hopefully achieve disinfection effects comparable with those of 1.5% NaClO while causing few adverse effects on SCAPs. KI helps to avoid staining problems associated with high concentrations of photosensitizer agents. Lasers Surg. Med.

Poly(styrene-co-maleic acid) Micelle of Photosensitizers for Targeted Photodynamic Therapy, Exhibits Prolonged Singlet Oxygen Generating Capacity and Superior Intracellular Uptake

“…Along this line, in this study, we aimed to develop SMA micelles of rose bengal (RB) and methylene blue (MB) for tumor-targeted PDT. Both RB and MB are phenothiazine dyes and well-characterized PSs [ 27 ]. MB has already been approved and is being applied in the clinical treatment regimen of caries and periodontal diseases.…”

“…MB has already been approved and is being applied in the clinical treatment regimen of caries and periodontal diseases. For MB-based PDT, red light of 660 nm is applied as a light source for irradiation, which is close to the near-infrared window, and thus exhibits deep tissue penetration properties [ 27 ]. The potentials of RB as a PDT are relatively less explored.…”

Photodynamic sensitizers modulate cytoskeleton structural dynamics in neuronal cells

“…Photosensitizer such as chlorin 6 and photofrins showed anticancer activity against esophageal and lung carcinomas (Qiu, Kim, Penjweini, & Zhu, 2016;Srdanovi c et al, 2018). Whereas the dyes such as RB and TB were observed to have inhibitory efficiency against various microbial biofilms formation (Li, Yuan, Jia, Qin, & Wang, 2020;Parasuraman et al, 2019). The porphyrin photosensitizer ALA has been studied to have an inhibitory effect against papillomaviruses, leishmaniasis, and onychomycosis (Souza et al, 2017;Xie et al, 2019).…”

Photodynamic Inactivation of an Endodontic Bacteria Using Diode Laser and Indocyanine Green-Loaded Nanosphere

“…Golmohamadpour et al applied three types of metal-organic frameworks including ICG for aPDT/PACT, resulting in detection rates of living bacteria from 45.12% to 62.67% [41]. Furthermore, potassium iodide-potentiated PDT with MB and RB increased bactericidal effects to 86.50% and 91.50%, respectively, in a study by Li et al [42]. In this study, we used aPDT/PACT with ICG-Nano/c in an infected root canal model consisting of an E. faecalis monospecies biofilm in root canals.…”