Photobiomodulation for melasma treatment: Integrative review and state of the art.

PURPOSE: Photobiomodulation therapy (PBM) is a versatile technique for treating skin diseases. Melasma, a chronic hyperpigmentation condition, has recently been associated with vascular features and dermal photoaging and poses significant management challenges. We review the recent literature on melasma etiology and the evidence supporting PBM as a therapeutic modality for melasma treatment. METHODS: We conducted a comprehensive literature search in three different databases from May to August 2023, focusing on studies published in the past 10 years. The inclusion criteria comprised full-text studies investigating low-power lasers and/or light-emitting diodes (LEDs) in in vitro or in vivo models, as well as clinical trials. We excluded studies discussing alternative melasma therapies or lacking experimental data. We identified additional studies by searching the reference lists of the selected articles. RESULTS: We identified nine relevant studies. Clinical studies, in agreement with in vitro experiments and animal models, suggest that PBM effectively reduces melasma-associated hyperpigmentation. Specific wavelengths (red: 630 nm; amber: 585 and 590 nm; infrared: 830 and 850 nm) at radiant exposures between 1 and 20 J/cm2 exert modulatory effects on tyrosinase activity, gene expression, and protein synthesis of melanocytic pathway components, and thus significantly reduce the melanin content. Additionally, PBM is effective in improving the dermal structure and reducing erythema and neovascularization, features recently identified as pathological components of melasma. CONCLUSION: PBM emerges as a promising, contemporary, and non-invasive procedure for treating melasma. Beyond its role in inhibiting melanogenesis, PBM shows potential in reducing erythema and vascularization and improving dermal conditions. However, robust and well-designed clinical trials are needed to determine optimal light parameters and to evaluate the effects of PBM on melasma thoroughly.

The influence of growth medium on the photodynamic susceptibility of Aggregatibacter actinomycetemcomitans to antimicrobial blue light.

The aim of this study was to investigate whether antimicrobial blue light (aBL) can cause the death of Aggregatibacter actinomycetemcomitans (A.a) and to determine the influence of different culture media, specifically brain heart infusion and blood agar, on bacterial survival fraction. An LED emitting at 403 ± 15 nm, with a radiant power of 1W, irradiance of 588.2 mW/cm2, and an irradiation time of 0 min, 1 min, 5 min, 10 min, 30 min, and 60 min, was used. The plates were incubated in microaerophilic conditions at 37 °C for 48 h, and the colony-forming units were counted. The photosensitizers were investigated using spectroscopy and fluorescence microscopy. There was no significant difference between the culture media (p > 0.05). However, a statistical reduction in both media was observed at 30 min (1058 J/cm2) (p < 0.05). The findings of this study suggest that aBL has the potential to kill bacteria regardless of the culture media used. Light therapy could be a promising and cost-effective strategy for preventing periodontal disease when used in combination with mechanical plaque control.

Can the use of photobiomodulation for localized fat reduction induce changes in lipid profile? A critical integrative review.

The objective of this study is to clarify whether PBM for measures reduction can cause significant changes in the lipid profile. This is an integrative review and only original articles, both in vivo and clinical trials, that were published between 2010 and 2022 were selected. The article references were also analyzed to identify additional studies. A total of 15 articles were critically analyzed. The wavelength used ranged from 532 nm (green) to 956 nm (near infrared), and many authors failed to describe dosimetric parameters properly, as well as other important characteristics for the reproducibility of those found. Although it is not fully clear about the PBM interference level on the lipid profile, in general, there was no significant difference in lipid parameters when PBM was used alone, and when associated with techniques that promote beta-oxidation, there was an improvement in these biochemical variables. PBM use for localized fat reduction do not affect lipid serum levels. Clinical trials using standardized parameters are crucial to obtain more reliable results.

Effects of photobiomodulation on cellular viability and cancer stem cell phenotype in oral squamous cell carcinoma.

Oral squamous cell carcinoma (OSCC) is the most common head and neck malignancy; it has been shown that cancer stem cells (CSC) are present in OSCC and associated with tumor growth, invasion, metastasis, and therapeutic resistance. Photobiomodulation (PBM) is an alternative tool for oncologic treatment adverse effects such as oral mucositis (OM); however, controversy exists regarding the undesirable effects of PBM on tumor or CSC. This study aimed to evaluate in vitro, the effects of PBM, with the same dosimetric parameters as those used in the clinic for OM prevention and treatment, on OSCC cellular viability, as well as PBM's effect on CSC properties and its phenotype. OSCC cell lines were submitted to single or daily PBM with 3 J/cm2 and 6 J/cm2 and then the cellular viability was evaluated by MTT, NRU (neutral red uptake), and CVS (crystal violet staining). The CSC populations were evaluated by clonogenic formation assay, flow cytometry, and RT-qPCR. The single PBM with the 3 J/cm2 group was associated with increased cellular viability. Daily PBM with 3 J/cm2 and 6 J/cm2 was associated with a significant decrease in cellular viability. Additionally, daily PBM was not able to promote CSC self-renewal or the CD44high/ESAlow and CD44high/ESAhigh cellular phenotypes. Moreover, a decrease in the number of spheres and in the expression of the CSC related gene BMI1 was observed after daily PBM with 6 J/cm2. Daily PBM with 3 J/cm2 and 6 J/cm2 showed an inhibitory effect on cellular viability and was not able to promote the CSC self-renewal or phenotype.

Effect of Blue Light on Acne Vulgaris: A Systematic Review.

Acne is a dermatosis that affects almost 90% of the adolescent population worldwide and its treatment is performed with retinoids, antimicrobials, acids, and topical or systemic antibiotics. Side effects such as skin irritation in addition to microbial resistance to antibiotics are the main side effects found. Phototherapy with blue light is being used as an alternative treatment. Our objective was to analyze the use of blue light to treat inflammatory acne. We conducted a systematic literature review, following the recommendation PRISMA (Preferred Reporting Items for Systematic Reviews and MetaAnalyses), including in the sample randomized clinical trial studies that compared blue light with another intervention as control. The research was carried out in the PUBMED and WEB of SCIENCE databases and the methodological quality of the studies evaluated were made by the Cochrane Collaboration Bias Risk Scale. After the exclusion of duplicates, the titles and abstracts of 81 articles were evaluated, and 50 articles were selected for full reading, including in the review at the end 8 articles. Studies have shown significant improvements in the overall picture of acne. It is concluded that despite the great potential in its use in the treatment of acne, there is a need for more detailed trials on the effect of blue light on the treatment of inflammatory acne.

Can Photons Pass through Primary Coatings Used to Treat Cutaneous Wounds?

OBJECTIVE: To determine the transmittance spectrum of primary dressings commonly used in the treatment of cutaneous wounds to verify if there is a real need to remove them during photobiomodulation. METHODS: Spectroscopic analysis was performed on 17 dressings using a spectrophotometer (USB 2000+; OceanOptics, Delray Beach, Florida). A piece of each dressing was inserted into a quartz cuvette; the reflection from the slide walls was corrected for using a 0.9% saline solution to completely fill the cuvette (baseline). The transmittance of each dressing was measured between 350 and 950 nm, and a transmittance table was created based on the main wavelengths used in photobiomodulation. RESULTS: Six dressings (Supriderme, Membracel, Cuticell Contact, UrgoTul, Tegaderm, and Opsite Flexigrid) have a transmittance greater than 50% in most of the spectral range and therefore may remain on wounds during irradiation. CONCLUSIONS: It may not always be necessary to remove a primary dressing when lasers or LED lights are used to treat wounds. It is the authors' hope that the results of this article will increase the effectiveness of both photobiomodulation and primary dressings and reduce patient discomfort as well as the cost of primary dressings via a reduction in unnecessary dressing changes.

The effects of photodynamic therapy with blue light and papain-based gel associated with Urucum, on collagen and fibroblasts: a spectroscopic and cytotoxicity analysis.

Papacarie Duo™ is clinically used and has proven effectiveness; however, it is necessary to improve its antimicrobial action. The combined treatment of Papacarie Duo™ with Urucum (Bixa Orellana) could create a potential tool for dental caries treatment; its extract obtained from the seeds' pericarp contains a water-soluble primary pigment (cis-bixin) with smaller amounts of other carotenoids. The dicarboxylic acid salts of cis-norbixin and trans-norbixin occur in heated alkaline solutions. To analyze the absorption spectra and cytotoxicity (with human dermal fibroblasts) in different concentrations of Urucum, associated or not with Papacarie Duo™, we performed this in vitro study. The effects of pure Urucum, Papacarie Duo™, and PapaUrucum™ on the microstructure of collagen were also analyzed. The application of papain-based gel with Urucum did not present cytotoxicity, its exhibit UV absorption spectrum peak around 460 ± 20 nm. Also, it showed that the compound used did not alter the chemical structure of collagen. Consequently, this product could be used as a chemomechanical method to remove dentin caries as well as being a potential product for antimicrobial photodynamic therapy (aPDT) application.

Controlling methylene blue aggregation: a more efficient alternative to treat Candida albicans infections using photodynamic therapy.

Methylene Blue (MB) has been widely used in antimicrobial Photodynamic Therapy (aPDT), however, the mechanisms of action (Type I or Type II) are defined by its state of aggregation. In this sense, the identification of the relationships between aggregation, the mechanisms of action and the effectiveness against microorganisms, as well as the establishment of the means and the formulations that may favor the most effective mechanisms, are essential. Thus, the objective of this study was to assess the in vitro aPDT efficacies against Candida albicans, by using MB in vehicles which may influence the aggregation and present an oral formulation (OF) containing MB, to be used in clinical aPDT procedures. The efficacy of MB at 20 mg L-1 was tested in a range of vehicles (water, physiological solution - NaCl 0.9%, phosphate saline buffer - PBS, sodium dodecyl sulfate 0.25% - SDS and urea 1 mol L-1) in a C. albicans planktonic culture, when using 4.68 J cm-2 of 640 ± 12 nm LED for the irradiations, as well as 5 minutes of pre-irradiation time, together with measuring the UFC mL-1. Based upon these analyses, an OF containing MB in the most effective vehicle was tested in the biofilms, as a proposal for clinical applications. When comparing some of the vehicles, sodium dodecyl sulfate was the only one that enhanced an MB aPDT efficacy in a planktonic C. albicans culture. This OF was tested in the biofilms and 50 mg L-1 MB was necessary, in order to achieve some reduction in the cell viabilities after the various treatments. The light dosimetries still need further adaptations, in order for this formulation to be used in clinical applications. The present research has indicated that the development of this formulation for the control of MB aggregations may result in more effective clinical protocols.

A reliable protocol for colorimetric determination of iron oxide nanoparticle uptake by cells.

Size, shape, and surface properties of superparamagnetic iron oxide nanoparticles (SPIONs) can influence their interaction with biological systems, particularly the incorporation by tumor cells and consequently the biological activity and efficiency in biomedical applications. Several strategies have been used to evaluate cellular uptake of SPIONs. While qualitative methods are generally based on microscopy techniques, quantitative assays are carried out by techniques such as inductively coupled plasma-mass spectrometry and flow cytometry. However, inexpensive colorimetric methods based on equipments commonly found in chemistry and biochemistry laboratories are preferred for routine measurements. Nevertheless, colorimetric assays must be used judiciously, particularly when nanoparticles are involved, since their interaction with biological constituents tends to lead to quite underestimated results. Thus, herein described is a colorimetric protocol using 2,2'-bipyridine as chromogenic ligand, where each step was optimized and validated by total reflection X-ray fluorescence spectroscopy, realizing a highly reproducible and reliable method for determination of iron content in cells incubated with SPIONs. The limit of blank and limit of detection were determined to be as low as 0.076 and 0.143 µg Fe/mL, using sample volumes as small as 190 µL and a number of cells as low as 2.0 × 105. Furthermore, three different types of surface-functionalized nanoparticles were incorporated in cells and evaluated through this protocol, enabling to monitor the additive effect of o-phosphorylethanolamine (PEA) and folic acid (FA) conjugation on iron oxide nanoparticles (SPION-PEA and SPION-PEA/FA), that enhanced the uptake by HeLa cells, respectively, by four and ten times when compared to SPIONs conjugated with nonbioactive molecules. Graphical abstract Colorimetric determination of superparamagnetic iron oxide nanoparticles (SPIONs) incorporated by cells.

Therapeutic comparison between treatments for Vulvar Lichen Sclerosus: study protocol of a randomized prospective and controlled trial.

BACKGROUND: Vulvar lichen sclerosus (VLS) is a lymphocyte-mediated disease of unknown etiology that can cause intense itching as well stenosis, hindering the evacuation and urination. It can also limit the sex life due to severe local pruritus, pain and dyspareunia (pain during sexual intercourse). The standard treatment for this disease is the use of topical corticosteroids to reduce the clinical symptoms and to try to increase disease-free intervals. Photodynamic therapy (PDT), a treatment that associates a light radiation with a photosensitizing agent and photobiomodulation (PBM) are therapies that can promote effective immunomodulatory responses at the application site by means of photophysical and photochemical phenomena from the molecular to the systemic level, which promote their use in chronic dermatoses. The aim is to compare the effects of PDT, PBM, and topical corticosteroid in VLS evaluating clinical, histological, immunohistochemical and spectroscopic responses. METHODS: The study is prospective, randomized and controlled, in a population of 60 women with histological diagnoses of VLS. There will be 3 treatments groups: PDT, PBM and topical corticosteroid (control group), where will be allocated by randomization 20 patients in each one. The clinical course will be monitored by measuring local temperature, itching, atrophy, and the area of the lesion. Histologically, the slides will be classified and will have the ordering of collagen fibers quantified. Immunohistochemical analysis will be done using the markers IFN-γ, TGF-ß, CD4, CD8, IL-1, p53 and Ki-67. Finally, the spectroscopic evaluation will be done by reflectance. Descriptive and inferential statistical analyses will be conducted to compare the groups and make associations between different responses. The study is an open-label for patients with active symptomatic disease with a period of 1 year follow-up to determine the rate of recurrence in each groups. DISCUSSION: The immunological effects of PDT and PBM are described by several authors in inflammatory skin diseases, stimulating the production and organization of the associated collagen. Thus, it is reasonable to determine the efficacy and safety of these new treatments in VLS, in comparison to the control group, analyzing the recurrence time, the impact on the optical properties of the skin, and the benefit to patients. TRIAL REGISTRATION: ClinicalTrials.gov: NCT02416531 .

Photodynamic Efficiency: From Molecular Photochemistry to Cell Death.

Photodynamic therapy (PDT) is a clinical modality used to treat cancer and infectious diseases. The main agent is the photosensitizer (PS), which is excited by light and converted to a triplet excited state. This latter species leads to the formation of singlet oxygen and radicals that oxidize biomolecules. The main motivation for this review is to suggest alternatives for achieving high-efficiency PDT protocols, by taking advantage of knowledge on the chemical and biological processes taking place during and after photosensitization. We defend that in order to obtain specific mechanisms of cell death and maximize PDT efficiency, PSes should oxidize specific molecular targets. We consider the role of subcellular localization, how PS photochemistry and photophysics can change according to its nanoenvironment, and how can all these trigger specific cell death mechanisms. We propose that in order to develop PSes that will cause a breakthrough enhancement in the efficiency of PDT, researchers should first consider tissue and intracellular localization, instead of trying to maximize singlet oxygen quantum yields in in vitro tests. In addition to this, we also indicate many open questions and challenges remaining in this field, hoping to encourage future research.

Marked improvement in photoinduced cell death by a new tris-heteroleptic complex with dual action: singlet oxygen sensitization and ligand dissociation.

The new tris-heteroleptic complex [Ru(bpy)(dppn)(CH3CN)2](2+) (3, bpy = 2,2'-bipyridine, dppn = benzo[i]dipyrido[3,2-a;2',3'-c]phenazine) was synthesized and characterized in an effort to generate a molecule capable of both singlet oxygen ((1)O2) production and ligand exchange upon irradiation. Such dual reactivity has the potential to be useful for increasing the efficacy of photochemotherapy drugs by acting via two different mechanisms simultaneously. The photochemical properties and photoinduced cytotoxicity of 3 were compared to those of [Ru(bpy)2(dppn)](2+) (1) and [Ru(bpy)2(CH3CN)2](2+) (2), since 1 sensitizes the production of (1)O2 and 2 undergoes ligand exchange of the monodentate CH3CN ligands with solvent when irradiated. The quantum yield of (1)O2 production was measured to be 0.72(2) for 3 in methanol, which is slightly lower than that of 1, Φ = 0.88(2), in the same solvent (λirr = 460 nm). Complex 3 also undergoes photoinduced ligand exchange when irradiated in H2O (λirr = 400 nm), but with a low quantum efficiency (<1%). These results are explained by the presence of the low-lying ligand-centered (3)ππ* excited state of 3 localized on the dppn ligand, thus decreasing the relative population of the higher energy (3)dd state; the latter is associated with ligand dissociation. Cytotoxicity data with HeLa cells reveal that complex 3 exhibits a greater photocytotoxicity index, 1110, than does either 1 and 2, indicating that the dual-action complex is more photoactive toward cells in spite of its low ligand exchange quantum yield.

Lipid oxidation induces structural changes in biomimetic membranes.

Oxidation can intimately influence and structurally compromise the levels of biological self-assembly embodied by intracellular and plasma membranes. Lipid peroxidation, a natural metabolic outcome of life with oxygen under light, is also a salient oxidation reaction in photomedicine treatments. However, the effect of peroxidation on the fate of lipid membranes remains elusive. Here we use a new photosensitizer that anchors and disperses in the membrane to achieve spatial control of the oxidizing species. We find, surprisingly, that the integrity of unsaturated unilamellar vesicles is preserved even for fully oxidized membranes. Membrane survival allows for the quantification of the transformations of the peroxidized bilayers, providing key physical and chemical information to understand the effect of lipid oxidation on protein insertion and on other mechanisms of cell function. We anticipate that spatially controlled oxidation will emerge as a new powerful strategy for tuning and evaluating lipid membranes in biomimetic media under oxidative stress.

Photobiomodulation in the treatment of palmar-plantar erythrodysesthesia: a randomised controlled clinical study protocol.

INTRODUCTION: Hand-foot syndrome, also known as palmar-plantar erythrodysesthesia (PPE), is a complication caused by chemotherapy. Clinically, it manifests as erythema and oedema on the palms of the hands and feet, dry and scaly skin, accompanied by a sensation of tightness and pain. Extreme cases have blisters and ulcerations that may require hospitalisation and/or pause in cancer treatment. It can also be accompanied by paraesthesia. Considering the characteristics, photobiomodulation (PBM) may reduce the PPE effects. The objective of this protocol will be to evaluate the efficacy of PBM in reducing PPE induced by capecitabine and 5-fluorouracil chemotherapy. METHODS AND ANALYSIS: This will be a randomised controlled, double-blind, double-centre clinical trial (Centro Asistencial del Sindicato Médico del Uruguay and Instituto Nacional del Cáncer from Uruguay). The sample population (40 individuals) will be divided into two groups: group 1 will receive moisturising cream plus PBM treatment and group 2 moisturising cream plus PBM sham treatment, at the ratio of 1:1. PBM will be performed at 630 nm two times per week in palmoplantar areas of the hands and feet (4 J/cm2), for 4 weeks. The PPE degree and the data referring to the chemotherapy treatment plan will be measured, prior to the start of treatment in the middle and at the end of it. Quality of life questionnaires will be applied at the beginning of the trial and at the end of treatment. The data will be analysed based on the intention-to-treat analysis and α<0.05 will be considered statistically significant. ETHICS AND DISSEMINATION: The protocol was approved by the Research Ethics Committee of Universidad Católica del Uruguay (220316b), of Centro Asistencial del Sindicato Médico del Uruguay (221989) and of Instituto Nacional del Cáncer (2023-04). The recruitment has already started (March 2023). PROTOCOL VERSION: V.2, 27 October 2023. TRIAL REGISTRATION NUMBER: ClinicalTrials.gov Registry (NCT05337423).

Combining red photobiomodulation therapy with polydioxanone threads for wrinkle reduction in the glabella region: A randomized, controlled, double-blind clinical trial.

The combination of polydioxanone (PDO) threads with other technologies has garnered significant interest for rejuvenation purposes. Photobiomodulation (PBM) has the potential to improve patient comfort and recovery after minimally invasive rejuvenation protocols and also contribute to the overall efficacy of these procedures, fostering an integrative approach to cutaneous rejuvenation. The objective os this work was to investigate concurrent application of PDO threads and red LED PBM on glabellar static wrinkles, in a parallel randomized sham-controlled trial. Forty individuals with Glogau aging classification levels 3 and 4, static glabellar wrinkles, and no significant comorbidities received PDO threads applied along glabellar line. Effective PBM group received 1.35 J and 630 nm red LED light punctually along threads, twice weekly for nine sessions over 30 days. The outcome measures were swelling assessment, dermal thickness and PDO thread degradation via linear ultrasound. No swelling was detected 24 h post-PDO thread application, hindering PBM effect assessment. PDO threads induced dermal thickening; no added effect with PBM. No significant difference in thread hydrolysis between groups, though some ultrasound records inconclusive on thread presence. The absence of swelling may stem from various factors, including the timing of post-procedure swelling assessment, operator proficiency in thread application, and procedural characteristics. No evidence supports the notion that PBM augments dermal thickening, however other light parameters should be studied. Insufficient data to demonstrate PBM's effectiveness in controlling post-procedure swelling. Combination of PBM with PDO thread application doesn't enhance dermal thickening, nor accelerate thread degradation at the parameters used here.

Amber photobiomodulation versus tranexamic acid for the treatment of melasma: protocol for a double-blind, randomised controlled trial.

INTRODUCTION: Photobiomodulation (PBM) has been suggested as an alternative treatment for melasma. In vitro studies have shown PBM with amber light inhibits the tyrosinase enzyme, induces autophagy and reduces the melanin content, but randomised controlled clinical trials are still needed. This study aims to evaluate the efficacy of amber PBM (590 nm) in the treatment of melasma compared with liposomal tranexamic acid. METHODS AND ANALYSIS: This study is a controlled, randomised, double-blind, non-inferiority trial. This study will be performed in two centres (Universidade Nove de Julho Facility, Campus Vergueiro, and Galache Odontology Clinic, São Caetano do Sul, both in São Paulo State, Brazil). The sample (54 participants) will be divided into two groups in a 1:1 ratio; one group will receive active PBM and a placebo cosmetic and the other will receive sham PBM and liposomal tranexamic acid. Women presenting facial melasma, aged 35-50 years, with skin phototypes II-IV, will be eligible for inclusion. Women who use oral contraceptives, intrauterine devices, hormone replacement or photosensitive drugs, those with autoimmune disease and those who have undergone facial treatments in the last 3 months will be excluded from the study. The participants will receive PBM weekly for 12 weeks and will use the cosmetic two times per day at home during this period. The severity of melasma will be evaluated through the Melasma Area and Severity Index (MASI) as the primary outcome; pigmentation of the epidermis evaluated by corneomelametry, the photographic records, the global diagnosis of the face and the quality-of-life questionnaire (Brazilian Portuguese version of the Melasma Quality of Life Questionnaire) will assessed as secondary outcomes. All assessments will be made before starting the study (week 0), mid-study at 6 weeks and at the completion of treatment (week 12). MASI will also be evaluated during follow-up (weeks 16 and 20). The data will be analysed based on the intention-to-treat analysis using a generalised mixed model, and α <0.05 will be considered statistically significant. ETHICS AND DISSEMINATION: The protocol was approved by the Research Ethics Committee of Universidade Nove de Julho (5 332 384). All participants will fill out the patient informed consent form. The results obtained in this trial will be presented at conferences and submitted for publication. TRIAL REGISTRATION NUMBER: ClinicalTrials.gov Registry (NCT05326997).

The combination of methylene blue and sodium dodecyl sulfate enhances the antimicrobial photodynamic therapy of Candida albicans at lower light parameters.

BACKGROUND: The growth of resistant microorganisms has been a challenge for health systems. Antimicrobial Photodynamic Therapy (aPDT) has gained attention due to its effects on resistant strains. Recently, it was shown that the association of methylene blue (MB) and sodium dodecyl sulfate (SDS) are an effective strategy to increase the effect of aPDT; however, it is unknown which are the best light parameters (such as irradiance and radiant exposure, RE), to reach the most effective protocols. This work aimed to evaluate the light parameters, irradiance, and radiant exposure, in aPDT with MB when conveyed in water compared to MB associated with SDS. METHODS: Tests were carried out to quantify the colony-forming units (CFU) of ATCC 10,231 strain of Candida albicans when using MB in different media and with different light parameters: Control (water), SDS (0.25%), MB (20 mg/mL), and the MB/SDS at irradiances of 3.7; 11.2; 18.6, and 26.1 mW/cm2 and varied irradiation times to reach radiant exposures of 4.4; 17.8; 26.7, and 44 J/cm². RESULTS: The results showed that aPDT with MB/SDS had a higher antimicrobial effect than MB when conveyed in water. Furthermore, for the highest irradiance studied (26.1 mW/cm2), CFU decreases exponentially with increasing RE from 4.4 up to 44 J/cm2. Similarly, at a fixed RE, the higher the irradiance used, the higher the antimicrobial effect was observed, except for the lowest RE studied (4.4 J/cm2). CONCLUSIONS: aPDT with MB/SDS had a greater antimicrobial action at the lower light parameters when compared to MB conveyed in water. The authors suggest the use of RE above 18 J/cm2 and irradiance above 26 mW/cm2 since at the mentioned parameters the increase in its value caused a greater antimicrobial effect.

Enhancing antimicrobial photodynamic therapy with phenothiazinium dyes and sodium dodecyl sulfate against Candida albicans at various growth stages.

BACKGROUND: The eradication of C. albicans is difficult due to the organization of the yeast in biofilms. Photodynamic therapy (PDT) has been proposed as an alternative to antifungals. Phenothiazinium dyes, e.g. methylene blue (MB), have been proposed as photosensitizing agents (PS), and their association with sodium dodecyl sulfate (SDS) has recently been shown to improve the effectiveness of PDT in planktonic culture. In this sense, the objective of this work was to evaluate the effect of PDT with phenothiazinium dyes associated to SDS in biofilms at the different stages of growth. METHODS: Experiments were carried out to evaluate the effects of PDT on biofilm formation and on established biofilms of C. albicans ATCC 10231. Samples were exposed to PS 50 mg/L (MB, Azure A - AA, Azure B - AB and dimethyl methylene blue - DMMB) dissolved in water or 0.25% SDS, for 5 min in the dark. After irradiation at 660 nm, 37.3mW/cm2 for 27 min, 60.4J/cm2 colony forming units count assay (CFU/mL) was performed. One or two irradiations were applied. Statistical methods were used to assess effectiveness. RESULTS: PSs showed low toxicity in the dark. An application of PDT irradiation was not able to reduce the CFU/mL both in mature biofilms (24h) and in biofilms in the dispersion phase (48h), only in the adherence phase did PDT prevent the formation of biofilms. With two successive applications of PDT irradiation in the dispersion phase, PDT with MB, AA, and DMMB completely inactivated C. albicans. The similar was not observed with mature biofilms. CONCLUSIONS: Different stages of biofilm growth respond differently to PDT, with the greatest inhibitory effect found in the adhesion stage. Mature and dispersed biofilms are less susceptible to PDT. The use of two successive applications of PDT with PSs associated with SDS may be a useful approach to inactivate C. albicans biofilms.

Pericoronitis treatment with antimicrobial photodynamic therapy using a new formula of methylene blue: A case report.

Pericoronitis is a common disease that impacts the quality of life of individuals during the eruption of the third molars. Among the main clinical signs and symptoms reported were the presence of gingival operculum, pain, difficulty swallowing, and trismus with functional impairment. The present study shows a case report of pericoronitis treated with antimicrobial photodynamic therapy (aPDT), using a new oral formulation (INPI BR 1020170253902) of methylene blue. A female patient, 27 years old, presenting initial pericoronitis, had her pain, mouth opening, and swelling evaluated. She was submitted to a protocol of irrigation with sterile saline and photodynamic therapy using the new MB at 0.005% concentration and irradiation with low-intensity laser λ = 660 nm, 9 J per point, and radiant exposure of 318 J/cm2. The variables were evaluated on 4th day after aPDT. There was a 100% improvement in pain and an increase of 1,3 cm in mouth opening. There was no difference in the edema before and after aPDT using the new MB formula. Although the results are based on a single case report, suggest the hypothesis that aPDT using the new MB formula is an efficient therapy in the treatment of pain and trismus caused by the early stage of pericoronitis. Well-conducted randomized clinical trials are needed to compare this new formulation with conventional aPDT for further generalization of results.

Antimicrobial photodynamic therapy mediated by methylene blue in surfactant vehicle as adjuvant to periodontal treatment. Randomized, controlled, double-blind clinical trial.

BACKGROUND: Antimicrobial photodymanic therapy mediated by methylene blue has been investigated as an adjunctive to periodontal treatment but the dimerization of photosensitizer molecules reduces the phototoxic effects. Sodium dodecyl sulfate is a surfactant that may control this aggregation. The aim of this study was evaluated the photodynamic effect of methylene blue in sodium dodecyl sulfate in periodontitis. METHODS: 36 participants with periodontitis were selected and allocated randomly in two group for intervention and other two for control - all of them were treated with scaling and root planing before aPDT. Three periodontal evaluations were done: at the selection time, at the day of intervention and thirty-day after this. Pre-irradiation time was 1 min and 2 min for irradiation. Laser (Therapy XT, DMC, São Carlos, Brazil) with wavelength of 660 nm and 100 mW of power was used. Two photosensitizer solutions with 100 µM methylene blue was used, one of them was in water and other in 0,25% of sodium dodecyl sulfate. Two sites of each participant were selected for the experimental procedures. Microbiological evaluations were performed to quantify microorganisms before and immediately after intervention. Quantitative microbiological evaluation was the primary outcome; morphological aspects of bacterial colony, and clinical probing depth was the secondary one. RESULTS: There was no significant difference between the groups in both bacterial reduction and the clinical parameter evaluated. CONCLUSION: The effect of methylene blue in surfactant did not cause enough phototoxic effects that could promote reduction of periodontal pocket depth.