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Background: This study aimed to examine the efficacy of methylene blue (MB) and toluidine blue O (TBO) photodynamic therapy (PDT) as adjuncts to root surface debridement (RSD). Methods: This split-mouth, randomized, controlled clinical trial included eighteen patients, and a total of 332 sites (control = 102, MB = 124 and TBO = 106) were examined. Two sessions of PDT were completed at baseline and two weeks after RSD. Clinical parameters of bleeding on probing (BOP), plaque index (PI), probing pocket depth (PPD), and clinical attachment level (CAL) were measured pre- and post-treatment. Results: PPD and BOP reductions in sites treated by RSD with adjunctive photosensitizers (MB and TBO) were significantly higher than in control sites. RSD with MB showed higher efficacy in improving moderately deep pockets (OR 3.350), while adjunctive TBO showed better results in treating deeper pockets (OR 4.643). Conclusions: Results suggested that adjunctive use of MB and TBO to RSD could significantly improve periodontal pocket closure and reduce signs of inflammation. In addition, TBO seems to be more efficient in treating deep periodontal pockets than MB, which is more effective in resolving shallower pockets.

In the current study, tannic acid-functionalized iron oxide nanoparticles have been synthesized using a cost-effective co-precipitation method and subsequently characterized using various instrumentation techniques such as Fourier transform infrared spectroscopy, X-ray diffractometer, field emission scanning electron microscopy, and thermal gravimetric analysis. Further, these surface-modified magnetite nanoparticles have been used for the adsorption of toluidine dye from an aqueous solution. The adsorption process was accompanied using batch procedure, and influences of several factors such as adsorbent dose, contact time, pH, temperature, and initial concentration of adsorbate were inspected concurrently. The maximum adsorption capacity of tannic acid-functionalized magnetite nanoparticles was found to be 50.68 mg/g. The adsorption process was observed to follow the Temkin isotherm model, whereas the kinetic study was well described by pseudo-second order. The thermodynamic study revealed the adsorption process to be endothermic and spontaneous in nature with a high degree of freedom between adsorbent and adsorbate. Therefore, the study indicated that the tannic acid-functionalized magnetite nanoparticles have promising adsorption capability and can be used as an excellent adsorbent for the removal of toluidine blue O dye from the aqueous solution. HIGHLIGHTS Tannic acid-tailored magnetite nanoparticles were employed as adsorbents for the removal of coloured pollutants from an aqueous solution.; Batch adsorption techniques were applied to scrutinize the adsorption behaviour of these magnetite nanoparticles.; The adsorption process obeys pseudo-second-order kinetics and the Langmuir model of isotherm.; The desorption study suggested the reusability of adsorbents.;

Background: This study aimed to examine the efficacy of methylene blue (MB) and toluidine blue O (TBO) photodynamic therapy (PDT) as adjuncts to root surface debridement (RSD). Methods: This split-mouth, randomized, controlled clinical trial included eighteen patients, and a total of 332 sites (control = 102, MB = 124 and TBO = 106) were examined. Two sessions of PDT were completed at baseline and two weeks after RSD. Clinical parameters of bleeding on probing (BOP), plaque index (PI), probing pocket depth (PPD), and clinical attachment level (CAL) were measured pre- and post-treatment. Results: PPD and BOP reductions in sites treated by RSD with adjunctive photosensitizers (MB and TBO) were significantly higher than in control sites. RSD with MB showed higher efficacy in improving moderately deep pockets (OR 3.350), while adjunctive TBO showed better results in treating deeper pockets (OR 4.643). Conclusions: Results suggested that adjunctive use of MB and TBO to RSD could significantly improve periodontal pocket closure and reduce signs of inflammation. In addition, TBO seems to be more efficient in treating deep periodontal pockets than MB, which is more effective in resolving shallower pockets. [ABSTRACT FROM AUTHOR]

We report on the formation of toluidine blue O (TBO) sulfoxide by a self‐sensitized photooxidation of TBO. Here, the photosulfoxidation process was studied by mass spectrometry (MS) and discussed in the context of photodemethylation processes which both contribute to TBO consumption over time. Analysis of solvent effects with D2O, H2O, and CH3CN along with product yields and MS fragmentation patterns provided mechanistic insight into TBO sulfoxide's formation. The formation of TBO sulfoxide is minor and detectable up to 12% after irradiation of 3 h. The photosulfoxidation process is dependent on oxygen wherein instead of a type II (singlet oxygen, 1O2) reaction, a type I reaction involving TBO to reach the TBO sulfoxide is consistent with the results. Density functional theory results point to the formation of the TBO sulfoxide by the oxidation of TBO via transiently formed peroxyl radical or thiadioxirane intermediates. We discover that the TBO photosulfoxidation arises competitively with TBO photodemethylation with the latter leading to formaldehyde formation. [ABSTRACT FROM AUTHOR]

Coronaviruses (CoVs) belong to the group of enveloped positive-sense single-strand RNA viruses and are causative agents of respiratory, gastro-intestinal, and central nervous systems diseases in many host species, i.e., birds, mammals, and humans. Beta-CoVs revealed a great potential to cross the barrier between species by causing three epidemics/pandemics among humans in the 21st century. Considering the urgent need for powerful antiviral agents for decontamination, prevention, and treatment of BCoV infections, we turned our attention to the possibility of photodynamic inactivation with photosensitizers in combination with light irradiation. In the present study, we evaluated, for the first time, the antiviral activity of toluidine blue O (TBO) against Beta-coronavirus 1 (BCoV) in comparison to methylene blue (MB). First, we determined the in vitro cytotoxicity of MB and TBO on the Madin–Darby bovine kidney (MDBK) cell line with ISO10993-5/Annex C. Thereafter, BCoV was propagated in MDBK cells, and the virus titer was measured with digital droplet PCR, TCID50 assay and plaque assay. The antiviral activity of non-toxic concentrations of TBO was estimated using the direct inactivation approach. All effects were calculated in MAPLE 15® mathematical software by developing programs for non-linear modeling and response surface analysis. The median inhibitory concentration (IC50) of TBO after 72 h of incubation in MDBK cells was 0.85 µM. The antiviral activity of TBO after the direct inactivation of BCoV (MOI = 1) was significantly stronger than that of MB. The median effective concentration (EC50) of TBO was 0.005 µM. The cytopathic effect decreased in a concentration-dependent manner, from 0.0025 to 0.01 µM, and disappeared fully at concentrations between 0.02 and 0.3 µM of TBO. The number of virus particles also decreased, depending on the concentration applied, as proven by ddPCR analysis. In conclusion, TBO exhibits significant potential for direct inactivation of BCoV in vitro, with a very high selectivity index, and should be subjected to further investigation, aiming at its application in veterinary and/or human medical practice. [ABSTRACT FROM AUTHOR]

In the present work, halloysite nanotubes modified with gold nanoparticles (AuNPs-HNT) are successfully prepared by wet chemical method for the catalytic degradation of phenothiazine dyes (azure B (AZB) and toluidine blue O (TBO)) and also cleaner reduction of 4-(4-nitrophenyl)morpholine (4NM) in the sodium borohydride (NaBH4) media. The catalyst is formulated by modifying the HNT support with a 0.964% metal loading using the HNT supports modified with 3-aminopropyl-trimethoxysilane (APTMS) coupling agent to facilitate the anchoring sites to trap the AuNPs and to prevent their agglomeration/aggregation. The AuNPs-HNT catalyst is investigated for structural and morphological characterization to get insights about the formation of the catalyst for the effective catalytic reduction of dyes and 4NM. The microscopic studies demonstrate that AuNPs (2.75 nm) are decorated on the outer surface of HNT. The as-prepared AuNPs-HNT catalyst demonstrates AZB and TBO dye degradation efficiency up to 96% in 10 and 11 min, respectively, and catalytic reduction of 4NM to 4-morpholinoaniline (MAN) is achieved up to 97% in 11 min, in the presence of NaBH4 without the formation of any by-products. The pseudo-first-order rate constant (K1) value of the AuNPs-HNT catalyst for AZB, TBO, and 4NM were calculated to be 0.0078, 0.0055, and 0.0066 s−1, respectively. Moreover, the synthesized catalyst shows an excellent reusability with stable catalytic reduction for 7 successive cycles for both the dyes and 4NM. A plausible mechanism for the catalytic dye degradation and reduction of 4NM by AuNPs-HNT catalyst is proposed as well. The obtained results clearly indicate the potential of AuNPs-HNT as an efficient catalyst for the removal of dye contaminants from the aquatic environments and cleaner reduction of 4NM to MAN, insinuating future pharmaceutical applications. [ABSTRACT FROM AUTHOR]

Antimicrobial Photodynamic Therapy (aPDT) is an emerging strategy against resistant pathogenic bacteria, a serious global health threat. We describe herein the efficient preparation of photosensitized cellulose nanocrystals (CNC) using trialkoxysilane linkers for covalent incorporation of anionic (Rose Bengal: RB) and cationic (Toluidine blue O: TBO) photosensitizers (PSs), along with a N -alkyl- d -gluconamide ligand to specifically target Escherichia coli , as model nanosystems for aPDT. The synthesized nanomaterials exhibited high PS loading, high singlet oxygen quantum yield comparable to the solution, and good stability in aqueous media with minimal PS release under physiological conditions. Experimental viability tests in bacteria demonstrated their capability for aPDT, mitigating the inherent cytotoxicity of both PSs under dark conditions while retaining high phototoxicity against E. coli bacteria. The presence of gluconamide further enhanced photoactivity, highlighting the importance of surface functionalization with a specific bacterial ligand for improved efficacy. The CNC-supported RB system exhibited sufficient fluorescence for tracking via fluorescence microscopy, making it suitable for theranostics, integrating bioimaging and aPDT. Overall, photosensitized CNCs hold great promise as nanocarriers for combating topical infections caused by Gram-negative bacteria, addressing the urgent need for novel therapeutic strategies in infectious disease management while also mitigating antimicrobial resistance. [Display omitted] [ABSTRACT FROM AUTHOR]

The surface sulfate groups of cotton-derived cellulose nanowhiskers (CNWs) were quantified using three different methods: conductometric titration, adsorption of toluidine blue O (TBO), and sulfur elemental analysis. The former two methods indicated comparable values, whereas the last method indicated a considerable overestimation of up to 1.4 times the sulfate content compared to the values obtained by titration. This overestimation may be due to the inaccessibility of the sulfates inside the CNWs to the titrant and TBO, and/or the presence of non-sulfate sulfur elements. In addition to the quantitativeness of the TBO adsorption method, the present results also demonstrate the desulfation efficiency under several different desulfation conditions, where the sulfate content decreased by only half after alkali-mediated desulfation even with 2 M NaOH, whereas quite effective desulfation (ca. 90% decrease) was achieved with dilute HCl (0.25 M). [ABSTRACT FROM AUTHOR]

Toluidine blue O (TBO) is a type I-type II photosensitizer that has shown good efficacy and selectivity in antimicrobial and anticancer photodynamic therapy applications. However, its complex photochemistry with multiple photoproducts hinders its application as a photosensitizer. We have previously described the mechanism for photooxidative demethylation of TBO which in acetonitrile yields two main products: demethylated-TBO (d-TBO) and double-demethylated-TBO (dd-TBO). In the current work, we describe the photophysical properties of these two photoproducts. In acetonitrile and phosphate buffer, demethylation induces an hypsochromic shift in the absorption and fluorescence emission maxima. Fluorescence quantum yields increase slightly for the demethylated photoproducts, in agreement with the lengthening of the fluorescence lifetimes. Triplet excited states lifetimes in the presence of oxygen decreased slightly upon demethylation. However, the singlet oxygen quantum yield increased significantly reaching unity for the dd-TBO photoproduct. These results are interpreted in terms of the competing pathways of TBO photochemistry. For TBO, demethylation is the main pathway for deactivation of the excited state, while for d-TBO, demethylation and singlet oxygen generation are significant. For dd-TBO, singlet oxygen generation is the main deactivation pathway. Overall, TBO demethylated photoproducts demonstrate good potential as candidates for photodynamic therapy applications., (© 2025 American Society for Photobiology.)

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. [ABSTRACT FROM AUTHOR]

Objective To investigate the bactericidal effect of toluidine blue O (TBO)-mediated photodynamic antimicrobial therapy (APDT) on multi-drug resistant Pseudomonas aeruginosa (P. aeruginosa). Methods Multi-drug resistant P. aeruginosa isolated from 1 patient with burn wounds was used as study subject, and so was the standard strain from ATCC (No. 27853). The study bacteria were treated with different concentrations of TBO (2.5, 5.0, 7.5 and 10.0 μmol/L) combined with different doses of light (10, 20, 30 and 40 J/cm2, Red light, wavelength of 635±5 nm). While the control bacteria were divided into blank control group, TBO group and light group. The bacterial survival rate was determined by colony counting. Morphological alterations of the bacteria were observed with laser confocal electron microscopy (CLSM), transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The effect of sub-lethal dose of APDT (2.5 μmol/L TBO, 10 J/cm2 lighting) on minimum inhibitory concentrations (MICs) of several antibiotics were detected, including piperacillin/tazobactam, ceftazidime, cefepime, imipenem and meropenem. The expression levels of drug-resistant genes related to the multi-drug resistant P. aeruginosa were detected using RT-qPCR before and after APDT. Results The antibacterial efficacy of APDT was improved with the increases of TBO concentrations and light dose (P < 0.05). After sub-lethal dose of APDT, the bacteria showed shrinkage, depression and perforation of bacterial cell wall by SEM, and fimbriae disappearance, cell wall discontinuity and decreased cytoplasmic electron density and nucleus mimics disorder by TEM. And the sub-lethal dose treatment resulted in enhanced sensitivity of the multi-drug resistant strain to above antibiotics, and down-regulation of efflux pump genes (P < 0.05). Conclusion TBO-mediated APDT exerts a bactericidal efficacy on multidrug-resistant P. aeruginosa. APDT could alter the expression of drug-resistant genes by attacking nucleoid DNA, and thereby improve the sensitivity of drug-resistant bacteria to antibiotics.

Amyloid precursor‐like protein‐2 (APLP2) and its C‐terminal fragments (CTFs) are expressed at high levels in pancreatic cancer cells and knockdown of APLP2 expression inhibits tumor growth. CTFs are released from APLP2 by beta‐secretase (BACE). In this study, our goal was to determine whether methylene blue (MethB) and toluidine blue O (TBO) could be used to slow down the growth and viability of pancreatic cancer cells (Hs 766T). We found that TBO and MethB decreased the growth and viability of Hs 766T cells in a dose‐ and time‐dependent manner compared to vehicle‐treated control, as demonstrated by MTT and trypan blue exclusion assays. Although TBO led to decreased expression of APLP2, MethB did not show any significant effect on APLP2. However, both MethB and TBO reduced BACE activity and the levels of APLP2 CTFs in Hs 766T cells. In conclusion, MethB and TBO may be valuable candidates for the treatment of pancreatic cancer by targeting APLP2 processing. [ABSTRACT FROM AUTHOR]

This work reports on a new TBO–Pluronic F–127 three-dimensional (3D) gel dosimeter for UV light dose distribution measurements. The optimal gel composition was found to be 60 µM Toluidine Blue O (TBO), which acts as a UV-sensitive compound; 5% w/w hydrogen peroxide (H2O2), which is necessary for initiation of TBO photodegradation and 25% w/w poly(ethylene oxide)-block-poly(propylene oxide)-block-poly(ethylene oxide) (Pluronic F–127), which forms a physical gel matrix. The dosimeter becomes discoloured when exposed to UV radiation and a discolouration is the more intense, the higher the absorbed dose is. The samples after irradiation with UVA, UVB and UVC radiation were measured using UV-Vis spectrophotometry to obtain the basic dose–response characteristic of the dosimeter, including dose sensitivity, linear and dynamic dose range, threshold dose, stability over time and dose–response for fractioned and non-fractioned doses. Additionally, the TBO–Pluronic F–127 gel dosimeter was investigated for spatial stability and the ability to measure the dose distribution of UV radiation. The results obtained indicate that the TBO–Pluronic F–127 dosimeter is a promising UV sensor and 2D/3D UV dosimeter. [ABSTRACT FROM AUTHOR]

Lactobacillus acidophilus (L. acidophilus) is one of the etiological agents for dental caries and dominant in the deep carious lesion. L. acidophilus has also been identified in persistent root canal infection and also related to the failure of endodontic treatment. Photodynamic therapy is a therapeutic process involving the combination of a nontoxic photosensitizer and a light source. The excited photosensitizer reacts with reactive oxygen species (ROS), which induce injury and death of the microorganism. This study aimed to prove the effect of irradiation time of photodynamic therapy to the number of L. acidophilus. Fortytwo Eppendorf tubes were treated with 0.5 ml L. acidophilus distributed into seven groups. Group 1 as the control group received no treatment. Groups 2, 3, 4, 5, 6 and 7 were treated with a combination of 0.5 ml toluidine blue O (TBO) as a photosensitizer and 630 nm photoactivated (Fotosan®) exposure time for 10, 20, 30, 40, 50 and 60 sec. Then, all were stored in an incubator of 37°C for 48 h. Later, the colony-forming unit (CFU) was counted for each group. There were significant differences in the number of L. acidophilus in CFU of the various irradiation times. The longer the photodynamic therapy irradiation was, the lesser the number of live L. acidophilus became. At 50 sec and 60 sec irradiation, none of the L. acidophilus was found alive. [ABSTRACT FROM AUTHOR]

The surface carboxyl and sulfate groups on cellulose nanowhiskers were quantified via the adsorption of toluidine blue O (TBO), a cationic dye. Here, simple and rapid protocols, such as mixing the nanowhisker suspensions with a dye solution, separating the supernatants via centrifugation, and determining the excess dye concentration via visible light absorbance techniques, were used to obtain reproducible results comparable with those obtained via titration. In addition to facilitating the discrete quantification of the sulfate and carboxyl groups, the TBO adsorption method enabled carboxyl quantification in the presence of mercapto groups, which was difficult to achieve via titration. The adsorption of TBO onto the carboxyl groups was completed within 30 min, enabling the rapid treatment of many samples within a short period. [ABSTRACT FROM AUTHOR]

Maryam Pourhajibagher,1–3 Roghayeh Ghorbanzadeh,4 Abbas Bahador1,3,5 1Department of Microbiology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran; 2Dental Implant Research Center, Dentistry Research Institute, Tehran University of Medical Sciences, Tehran, Iran; 3Dental Research Center, Dentistry Research Institute, Tehran University of Medical Sciences, Tehran, Iran; 4Private Practice, Tehran, Iran; 5Laser Research Center, Dentistry Research Institute, Tehran University of Medical Sciences, Tehran, Iran Introduction: Porphyromonas gingivalis, an important endodontic pathogen, may be exposed to sublethal doses of photo-activated disinfection (sPAD) during root canal therapy. Such an exposure can affect bacterial survival and virulence features. In this study, we evaluated the effect of sPAD-related oxidative stresses on the expression of oxidative stress response gene (oxyR) in P. gingivalis clinical isolates surviving in vitro photodynamic treatment. Materials and methods: To determine the sPAD, 16 clinical P. gingivalis isolates photosensitized with toluidine blue O (TBO), methylene blue (MB), and indocyanine green (ICG) were irradiated with specific wavelength and energy density of diode laser corresponding to the photosensitizers following bacterial viability measurements. The effects of sPAD on the expression ratio of oxyR of 16 clinical P. gingivalis isolates were then assessed using quantitative real-time PCR (qRT-PCR) assay. Results: Maximum values of sPAD against P. gingivalis were 6.25, 15.6, and 25 µg/mL at fluencies of 171.87, 15.6, and 93.75 J/cm2, respectively, for TBO-, ICG-, and MB-sPAD (P>0.05). ICG-, MB-, and TBO-sPAD could increase the oxyR gene expression of the clinical P. gingivalis isolates 12.3-, 5.6-, and 8.5-fold, respectively. ICG-sPAD increased the expression of oxyR gene in clinical isolates of P. gingivalis ~1.5- and 2-fold higher than TBO- and MB-sPAD, respectively. Conclusion: Our results showed that upregulation of oxyR during sPAD may lead to better survival and increased pathogenicity of P. gingivalis isolates. Therefore, selection of appropriate photo-activated disinfection dosage should be considered for the successful treatment of endodontic infection. Keywords: antimicrobial photodynamic therapy, indocyanine green, methylene blue, oxidative stress, Porphyromonas gingivalis, toluidine blue O, low-level laser therapy

A new L-phenylalanine dehydrogenase (PHD) and Toluidine Blue O (TBO) based amperometric biosensor for the determination of L-phenylalanine was reported in this study. An amperometric L-phenylalanine biosensor with immobilization of TBO (as a mediator,), PDH and nicotinamide adenine dinucleotide (NAD+) onto polypyrrole-polyvinylsulphonate (PPy-PVS) film was accomplished on the surface of a platinum electrode. Cross-linking with glutaraldehyde technique was used for immobilizing PDH on PPy-PVS film. Toluidine Blue O (TBO) was used as the mediator. The changes in the anodic current at −0.195 V vs Ag/AgCl produced by TBO was proportional to the L-phenylalanine concentration changes in the sample. The effects of substrate concentration, pH and temperature on the response of the L-phenylalanine biosensor were investigated. Optimum pH and temperature were found to be 7.0 and 60 °C, respectively. The linear working region of biosensor is ${5.0}\times {10}^{- {7}}$ - ${2.5}\times {10}^{- {5}}$ M (R2 = 0.9816). The detection limit of the biosensor was ${1.0}\times {10}^{- {8}}$ M and response time of the biosensor was 200 s. The storage stability and application stability of the biosensor were also studied. Several possible interfering substances’ effects on the phenylalanine biosensor were investigated. The developed biosensor was tested in determinations of content in a synthetic blood sample. [ABSTRACT FROM AUTHOR]

The present work intended to evaluate the applicability of photodynamic inactivation (PDI) of Xanthomonas citri subsp. citri with toluidine blue O (TBO), a commercial photosensitizer, as a strategy to control citrus canker. Assays were conducted with cell suspensions and biofilms, constructed either on polypropylene microtubes (in vitro assays) or on the surface of orange leaves (ex vivo assays), in the presence of TBO and under irradiation with artificial white light or natural sunlight. PDI assays using TBO alone caused a maximum 5·8 log10 reduction of X. citri viable cells in suspensions, and a much smaller inactivation (1·5 log10) in biofilms. However, concomitant use of KI potentiated the TBO photosensitization. Biofilms were inactivated down to the detection limit (>6 log10 reduction) with 5·0 µmol l−1 TBO + 10 mmol l−1 KI (in vitro) or 5·0 µmol l−1 TBO + 100 mmol l−1 KI (ex vivo) after artificial white light irradiation. Under natural sunlight, a reduction down to the detection limit of the Miles–Misra method was achieved with 50 µmol l−1 TBO and 100 mmol l−1 KI. PDI has potential to be applied in the control of citrus canker in field conditions although further studies are needed to show that there are no risks to plant physiology or fruit quality. Significance and Impact of the Study: Xanthomonas citri subsp. citri is a major cause of disease in citrus orchards. Because of the low efficacy and high environmental toxicity of copper‐based treatments, there is growing interest on more sustainable phytosanitary approaches. Photodynamic inactivation (PDI) is being successfully used to control infectious agents and literature reports indicate that it is effective against some fungi and bacteria attacking fruit crops. The results of the present work open the perspective of using a low‐cost photosensitizer and sunlight, as energy source, to control of the causative agent of citrus canker. [ABSTRACT FROM AUTHOR]

A new choline oxidase (ChO) and toluidine blue O (TBO) based amperometric choline biosensor was reported in this article. An amperometric choline biosensor with immobilization of TBO (as a mediator), ChO onto polypyrrole–polyvinylsulphonate (PPy–PVS) film was accomplished on the surface of a platinum electrode. ChO was immobilized on PPy–PVS film by cross-linking with glutaraldehyde (GA). TBO was used as the mediator. Choline is oxidized to betaine and hydrogen peroxide in an oxygenated environment by ChO. Mediator reduced by reaction with hydrogen peroxide. The amperometric response was based upon the electrocatalytic properties of TBO. Optimum pH and temperature values were 7.0 and 30 °C, respectively. There was linearity between 1.0 × 10−8 and 2.0 × 10−8 M (R2 = 0.9805). The detection limit of the biosensor was 1.0 × 10−9 M and response time of the biosensor was 200 s. The storage stability and reproducibility of the biosensor were also investigated. Interfering effect of several interferants such as ascorbic acid, uric acid, alanine, dopamine, paracetamol, cysteine, and glucose on the choline biosensor was examined. The developed biosensor was tested in determinations of content in a synthetic blood sample. [ABSTRACT FROM AUTHOR]

We developed a novel sectioning and staining method to make high contrast, high resolution sections of plant tissue for light microscopy. Specimens of teosinte (Zea mays L., ssp. mexicana) root tips were fixed and embedded in Technovit 7100™ plastic resin. Thin sections, 1−2.5 μm, were cut and mounted on glass slides. The sections were either treated with RNase or not, then stained with 0.1% toluidine blue O and observed through ∞/0 objective lenses. For light microscopy, the enzyme staining procedure increased resolution and contrast. High magnification ∞/0 objective lenses produced high quality images for digital photography without using a coverslip or immersion oil. Our slide preparation and microscopic analysis were less labor intensive and more rapid than previous methods and enabled rapid and precise alignment of serial transverse sections for both tracking cell lineages and tissue measurements. [ABSTRACT FROM AUTHOR]

Antibacterial photodynamic therapy (A-PDT) has been shown to kill oral bacteria in the planktonic culture, dental plaque, and biofilm. This study sought to assess the antimicrobial effect of A-PDT with toluidine blue O (TBO) and diode laser on salivary mutans streptococci in 5-6-year-olds with severe early childhood caries (SECC). This case-control study was conducted on 56 children with SECC divided into four groups, namely 0.1 mg/mL TBO, diode laser (633 nm, 20 mW, 6 J/cm2), combination of the two, and no intervention control group. A-PDT was performed on days 1 and 3. Salivary samples were collected before and after A-PDT on days 1 and 3, and 1 and 2 weeks after the second intervention (day 3). Samples were cultured on mitis salivarius agar, and after incubation, the colonies were counted. Data were subjected to repeated measures ANOVA, ANCOVA, and paired comparisons with least square difference and Tukey's test. Bacterial count significantly decreased on days 1 and 3, and 1 and 2 weeks after the second intervention. Bacterial count also decreased following the use of TBO and laser separately, but these reductions were not significant (P > 0.05). Within the limitations of this study, antimicrobial efficacy of TBO + laser was higher than that of diode laser or TBO alone. Durability of treatment increased with double-dose therapy. This modality may be used to decrease the colony count of salivary mutans streptococci in children with SECC. [ABSTRACT FROM AUTHOR]

Photodynamic therapy has always been an antibacterial tool for solving multi-drug resistant bacteria problem, but the side effects and the low efficiency due to the high aggregation and low solubility of photosensitizers limit its application. Due to the anti-inflammatory effect of caffeic acid, two novel photosensitizers (CA-1-TBO, CA-TBO) were synthesized by conjugating caffeic acid with toluidine blue O (TBO). The structures have been characterized by 1HNMR and high-resolution mass spectrometry. The UV–vis absorption, fluorescence spectra and the octanol-water partition coefficient of two photosensitizers were measured to evaluate their photophysical properties and hydrophilic/hydrophobic properties. Compared with parent TBO, the two modified photosensitizers have shown a higher quantum yield and kinetics constants of singlet oxygen, which has been supported by the simulation results of density functional theory. As drug-resistant representatives of gram-positive and gram-negative bacteria, respectively, S. aureus and P. aeruginosa have been used for in vitro antibacterial experiments. The sterilization efficiencies of the two modified photosensitizers far exceed that of parent TBO. The results of the octanol-water partition coefficient and fluorescence quantification showed that modified photosensitizers CA-1-TBO and CA-TBO could be more accumulated than parent TBO. Based on scanning electron microscopy images, protein gel electrophoresis, and the conductivity of the bacterial solution, the possible mechanism of improved antibacterial photodynamic efficiencies could be induced by membrane permeability due to the caffeic acid effect. The findings demonstrate the significant potential of natural phenolic compounds in the development of photosensitizer molecules with characteristics such as more efficient, biocompatible and less side effects. • Novel photosensitizers from caffeic acid and toluidine blue O have been prepared. • CA-1-TBO and CA-TBO can penetrate bacterial membranes. • CA-1-TBO and CA-TBO could accumulate efficiently into bacterial cells. • CA-1-TBO and CA-TBO showed the enhanced aPDT efficiency. • CA-1-TBO and CA-TBO could target intracellular proteins. [ABSTRACT FROM AUTHOR]

Fucoidan is a sulfated polysaccharide with promising pharmacological applications. Due to its medicinal properties, there is a demand for a separation technique that yields a high purification grade. Here, we present a novel purification tool for recovering fucoidan from the marine brown macroalgae Fucus vesiculosus. The developed method is based on amino‐derivatized Sepabeads® EC‐EA. The beads were modified with toluidine blue (TB), a thiazine derivative, to exploit the strong donor acceptor interactions between the cationic dye and the anionic polysaccharide. The adsorption kinetics and the binding capacity of the resin were analyzed. A Sips model was used to approximate the adsorption isotherm, resulting in a maximum capacity of 127.7 mg fucoidan per g adsorbent. Investigation of the effect of adsorption step's pH on purity and chemical structure was performed by TB and Fourier transform infra‐red spectroscopy assays. Results showed that adsorption at pH 1 and 6 had negligible effects on fucoidan's chemical structure. However, purity was actually improved by 1.55‐ and 1.69‐fold at pH 1 and 6, respectively, with an average yield of 5 g/100 g dried algae powder. In contrast, only a 1.46‐fold increment was observed in fucoidan purified by the traditional method at pH 2, with a yield of 7.5 g/100 g dried algae powder. Furthermore, fucoidan purified by this method at pH 6 complies with, or even exceeds the quality of the commercially available (≥95% pure) fucoidan (Sigma‐Aldrich®) with respect to molecular weight and sulfur content. Therefore, dye affinity chromatography provides more advantages than the classically used techniques for fucoidan purification.

Highlights • CUR and ICG mediated antimicrobial photodynamic therapy (aPDT) have considerable antibacterial effects against Enterococcus faecalis. • aPDT by CUR and ICG has more anti-biofilm formation activity against E. faecalis. • The antimicrobial activities of CUR mediated aPDT are higher than TBO and MB. Abstract Background Despite the high success rate of endodontic treatment, failure may occur in some cases. In this case, Enterococcus faecalis is the most common species in endodontic treatment failure and post-treatment apical periodontitis. Therefore, a new adjunctive strategy is needed for the prevention of endodontic infections due to E. faecalis. The aim of the present study was to compare the antimicrobial and anti-biofilm activities of different common photosensitizers (PSs) for use in antimicrobial photodynamic therapy (aPDT) against E. faecalis. Materials and methods E. faecalis strain ATCC 29212 was used as the tested strain and methylene blue (MB), toluidine blue O (TBO), indocyanine green (ICG), and curcumin (CUR) were used as PSs. Irradiation was carried out using diode laser and light emitting diode (LED) at wavelengths related to the above PSs. Then, antimicrobial and anti-biofilm activities were measured using the microbial viability assay and crystal violet test, respectively. Results aPDT with using the above PSs significantly decreased the CFU/mL count of E. faecalis compared to the control group (P < 0.05). The killing percentage of E. faecalis via PS mediated aPDT was 99.6%, 98.2%, 85.1%, and 65.0% for CUR, ICG, TBO, and MB, respectively. aPDT using the above PSs significantly decreased the biofilm formation ability of E. faecalis compared to the control group (P < 0.05). The biofilm reduction percentage of the PSs was 68.4%, 62.9%, 59.0%, and 47.6% for CUR, ICG, TBO, and MB, respectively. Conclusion CUR and ICG mediated aPDT exhibited considerably more antimicrobial activity than other PSs, while TBO and MB demonstrated weaker anti-biofilm effects against E. faecalis compared to other PSs. [ABSTRACT FROM AUTHOR]

Highlights • ICG, TBO, and MB can enhance aPDT against E. faecalis. • Choosing appropriate concentration of PS and irradiation time for laser is necessary to achieve to the best results. • ICG as a PS in aPDT showed higher efficacy in elimination of E. faecalis compared to TBO and MB. Abstract Background During antimicrobial photodynamic therapy (aPDT) in the treatment of endodontic intracanal infection, it is extremely likely that microorganisms would be exposed to sub-lethal doses of PDT (sPDT). Although sPDT would not result in microorganism death, it can considerably influence microbial virulence. This study evaluated the effect of sPDT on gene expression of Enterococci surface protein (esp) as a major virulence factor for biofilm formation in Enterococcus faecalis. Materials and Methods The lethal and sub-lethal potential of aPDT using indocyanine green (ICG), toluidine blue O (TBO), and methylene blue (MB), as the photosensitizers (PSs) and 660, 635, and 810 nm diode laser against E. faecalis was analyzed using colony-forming unit assays. Considering sub-lethal doses of PSs and photo-irradiation time of the diode laser, the expression of esp was evaluated through quantitative Real-time PCR (qRT-PCR). Results ICG at a concentration of 31.2–1000 μg/mL and both TBO and MB at 6.2–100 μg/mL significantly reduced E. faecalis growth. 660, 635, and 810 nm diode laser with energy density of 93.75–140.62, 137.5–206.25, and 31.25–62.5 J/cm2, reduced the bacterial count. ICG with a concentration of 15.6 μg/mL and irradiation time of 0.5 min, TBO with a concentration of 3.1 μg/mL and irradiation time of 3 min, and MB with a concentration of 3.1 μg/mL and irradiation time of 3 min were found as a sPDT dose against E. faecalis. The esp expression was significantly reduced at sub-lethal doses of ICG compared to TBO (2 fold) and MB (2.4 fold). Conclusion Although all tested PSs showed bacterial reduction, ICG may be considered as the best PS in treating endodontic infection due to its higher efficacy in reduction of esp expression which has a main role in biofilm formation of E. faecalis. [ABSTRACT FROM AUTHOR]

Background Several microbial species have been implicated in the pathogenesis of endodontic diseases that colonize the infected root canal system. Since the complete removal of endopathogenic agents is essential in endodontic infection therapy, photo-activated disinfection (PAD) is suggested as an alternative method to traditional antimicrobial therapy. Recent studies reported that the molecular methods with low sensitivity and high efficiency to identify fastidious anaerobic endopathogenic microbiota can be replaced by the cultivation-based approaches. This study aimed to validate the multiplex real-time PCR in order to identify six common microorganisms associated with the endodontic infections before and after the PAD. Materials and methods Microbial specimens from the root canals of 50 patients with primary and secondary endodontic infections were collected before PAD treatment using sterile paper points. Toluidine blue O (TBO)-mediated PAD was performed on the root canals, followed by resampling. The prePAD- and postPAD-treatment endodontic samples were transferred to a transport medium and six target microorganisms were then identified from the samples using the microbiological culture techniques and multiplex real-time PCR approach. Results Multiplex real-time PCR could represent the presence of all target microorganisms in 100% cases before and after the PAD. Before PAD, using the culture method, Enterococcus faecalis (100%) was found to be the most frequent, followed by Veillonella parvula (97.5%), Aggregatibacter actinomycetemcomitans (94.7%), Porphyromonas gingivalis (84.3%), Lactobacillus rhamnosus (84.3%), and Actinomyces naeslundii (66.6%); whereas, after PAD these microbial frequencies changed to 80%, 83.3%, 66.6%, 80%, 66.6%, and 33.3%, respectively. The sensitivity and negative predictive value of the multiplex real-time PCR were 100% before and after the PAD, whereas the highest and the lowest specificities were 100% and 82% before PAD, and 97% and 89% after PAD for E. faecalis and P. gingivalis , respectively. The highest (100%) and the lowest (66%) positive predictive values were for V. parvula and A. naeslundii before and after the PAD, respectively. Conclusion As observed from the results, multiplex real-time PCR demonstrated high sensitivity and specificity when compared to the culture technique. Therefore, it can prove to be a highly sensitive technique to detect the endodontic infections microflora. [ABSTRACT FROM AUTHOR]

Background It is essential to identify the root canal microbial diversity and count. This is due to the polymicrobial nature of the primary endodontic infection that is associated with the microbial diversity and increased resistance to the antimicrobial agents. Photo-activated disinfection (PAD), also known as antimicrobial photodynamic therapy, is a new promising non-antibiotic approach, studied to prevent microbial resistance and treatment failure. Materials and methods In this study, we investigated the effect of PAD on reduction of microbial diversity and count, related with primary endodontic infections. Microbial specimens were collected before PAD from patients infected with the primary endodontic infection. PAD with toluidine blue O (TBO), in combination with diode laser, was performed on infected root canals. Resampling was carried out on the root canal after PAD, and microorganisms were identified by classical microbiological tests using biochemical and analytical profile index (API ® 20A) assays and nucleic acid approaches. Results From the 36 subjects studied before TBO-PAD, 187 cultivable isolates from 14 different genera and 19 various microbial species were retrieved. Of the bacterial isolates, 45.4% were strict anaerobes including Veillonella parvula , Porphyromonas gingivalis, Propionibacterium acnes , Lactobacillus acidophilus, Campylobacter rectus , and Slackia exigua , in order of their frequency; 45.4% were facultative anaerobes; and 9.2% were microaerophilic bacteria ( Aggregatibacter actinomycetemcomitans ). This in vivo study revealed significant decrease in the microbial diversity and count of the infected root canal after TBO-PAD ( P  < 0.05); whereas P. gingivalis strains, the most resistance microorganisms, were recovered in 34% of the samples after TBO-mediated PAD ( P  > 0.05). Conclusions TBO-mediated PAD is an effective in exhibiting efficient antimicrobial activity due to the substantial reduction of the microbial diversity and count in the primary endodontic infections. [ABSTRACT FROM AUTHOR]

Recently, we have demonstrated that toluidine blue O (TBO), a phenothiazine dye, shows inhibitory effects on both cholinesterases and amyloid pathology in Alzheimer's disease (AD) cellular model. In the present study, we aimed to determine the effects of TBO (in a purity of 85%) on amyloid and tau pathologies in a triple transgenic mouse model of AD (3xTg-AD). Beginning at 7.5 (mild pathology) or 13 (severe pathology) months of age, 3xTg-AD mice were treated intraperitoneally with 4 mg/kg TBO or vehicle daily for 30 days. TBO treatment significantly reduced the levels of insoluble Aβ40 and Aβ42 in the hippocampi of mild and severe pathology groups compared to vehicle-treated counterparts. When the levels of full-length amyloid precursor protein (APP) and β-site APP-cleaving enzyme 1 (BACE1) were assessed in 3xTg-AD mice at late pathological stage, no significant changes were observed after TBO treatment. Similarly, TBO did not recover hyperphosphorylation of tau at residues Thr181 and Ser202/Thr205 significantly in soluble and insoluble hippocampal fractions of 3xTg-AD mice. Taken together, the current study is the first in vivo report, to our knowledge, demonstrating that TBO mitigates amyloid pathology in 3xTg-AD mice with no apparent change on tau phosphorylation. Overall, the preliminary data presented here support the possible use of TBO as a disease-modifying drug for AD treatment. [ABSTRACT FROM AUTHOR]

Background The infected root canal system harbors one of the highest accumulations of polymicrobial infections. Since the eradication of endopathogenic microbiota is a major goal in endodontic infection therapy, photo-activated disinfection (PAD) can be used as an alternative therapeutic method in endodontic treatment. Compared to cultivation-based approaches, molecular techniques are more reliable for identifying microbial agents associated with endodontic infections. The purpose of this study was to evaluate the ability of designed multiplex real-time PCR protocol for the rapid detection and quantification of six common microorganisms involved in endodontic infection before and after the PAD. Materials and methods Samples were taken from the root canals of 50 patients with primary and secondary/persistent endodontic infections using sterile paper points. PAD with toluidine blue O (TBO) plus diode laser was performed on root canals. Resampling was then performed, and the samples were transferred to transport medium. Then, six target microorganisms were detected using multiplex real-time PCR before and after the PAD. Results Veillonella parvula was found using multiplex real-time PCR to have the highest frequency among samples collected before the PAD (29.4%), followed by Porphyromonas gingivalis (23.1%), Aggregatibacter actinomycetemcomitans (13.6%), Actinomyces naeslundii (13.0%), Enterococcus faecalis (11.5%), and Lactobacillus rhamnosus (9.4%). After TBO-mediated PAD, P. gingivalis strains, the most resistance microorganisms, were recovered in 41.7% of the samples using molecular approach ( P >  0.05). Conclusion As the results shown, multiplex real-time PCR as an accurate detection approach with high-throughput and TBO-mediated PAD as an efficient antimicrobial strategy due to the significant reduction of the endopathogenic count can be used for detection and treatment of microbiota involved in infected root canals, respectively. [ABSTRACT FROM AUTHOR]

Background Photodynamic therapy has been studied as a method for inactivating bacterial growth. Workers have used planktonic bacterial as well as biofilm bacterial cultures to evaluate the potential of photodynamic therapy in inactivating bacteria. However, almost all the studies use a photosensitiser in aqueous solution, which could be detrimental to the efficiency of photodynamic therapy. Methods In this study, the photodynamic killing effect of toluidine blue O (TBO) has been investigated on Staphylococcal biofilms in-vitro. The sensitivity of the in-vitro biofilms to photodynamic killing action was compared using different formulations of TBO, different dosages of photosensitiser and different light irradiation strengths. Effect of TBO formulations on bacterial quorum sensing system was evaluated using a colorimetric assay. Finally, dual staining using hoechst and propidium iodide stains was carried out on the photodynamically treated biofilms to visualise and compare the effects of photodynamic therapy. Scanning electron microscope imagery was also carried out to evaluate the photodynamic killing effect on the in-vitro biofilms. Results The sensitivity of biofilms to the photodynamic killing effect increased proportionally with the photosensitiser dosage and the light irradiation duration. TBO encapsulated in microemulsion was more effective in killing the biofilm bacteria than only TBO in water. The combination of TBO in microemulsion with EDTA was another effective way of increasing the photodynamic killing effect on the bacterial biofilms. Effect of encapsulated TBO on the quorum sensing system of bacteria was greater than the effect of aqueous solution of TBO. The in-vitro Staphylococcal biofilms could thus be inhibited by the photodynamic effect, and TBO encapsulated in microemulsion was much more effective than only TBO in water. Conclusions The encapsulation of a photosensitiser is an effective way of increasing the likelihood of the complete and successful inactivation of the biofilm growth. The encapsulated photosensitiser achieves higher inactivation of the bacterial biofilm than that of the aqueous solution of a photosensitiser. [ABSTRACT FROM AUTHOR]

Porphyromonas gingivalis is a significant root canal pathogen capable of causing endodontic infections, which during their treatment may receive sub-lethal doses of photo-activated disinfection (sPAD). As sPAD can influence microbial virulence, this study was designed to evaluate the effect of sPAD on gene expression level of arginine A-specific cysteine proteinase (rgpA), as one of the underlying virulence factors involved in the development of endodontic infection via P. gingivalis strains. To find out the sPAD against 16 clinical isolates of PAD-resistant P. gingivalis that were isolated in vivo, we used toluidine blue O (TBO), methylene blue (MB), and indocyanine green (ICG) as the photosensitizers, which were excited with specific wavelength of light in vitro. Quantitative real-time PCR (qRT-PCR) was then applied to monitor gene expression of rgpA in P. gingivalis isolates to characterize its virulence agent and understand the effect of sPAD on its pathogenicity. Maximal sPAD that could not decrease the count of P. gingivalis isolates were 6.25, 15.6, and 25 μg/mL at fluencies of 171.87, 15.6, and 93.75 J/cm2 for TBO, ICG, and MB, respectively. ICG-sPAD could suppress the rgpA gene expression about 14-fold, while MB and TBO-mediated sPAD could cause the attenuation of rgpA expression about 4.9- and 11.6-fold, respectively. ICG-sPAD with the maximum ability to reduce rgpA gene expression compared with other photosensitizers can be an appropriate candidate for the treatment of endodontic infections. [ABSTRACT FROM AUTHOR]

The tear glucose analysis is an important alternative for the indirect, simple and less invasive monitoring of blood glucose levels. However, the high cost and complex manufacturing process of tear glucose analyzers combined with the need to exchange the sensor after each analysis in the disposable tests prevent widespread application of the tear in glucose monitoring. Here, we present the integration of a biosensor made by the electropolymerization of poly(toluidine blue O) (PTB) and glucose oxidase (GOx) with an electroanalytical microfluidic device of easy assembly based on cotton threads, low cost materials and measurements by microflow injection analysis (µFIA) through passive pumping for performing tear glucose analyses in a simple, rapid and inexpensive way. A high stability between the analyses (RSD = 2.54%) and among the different systems (RSD = 3.13%) was obtained for the determination of glucose, in addition to a wide linear range between 0.075 and 7.5 mmol L −1 and a limit of detection of 22.2 µmol L −1 . The proposed method was efficiently employed in the determination of tear glucose in non-diabetic volunteers, obtaining a close correlation with their blood glucose levels, simplifying and reducing the costs of the analyses, making the tear glucose monitoring more accessible for the population. [ABSTRACT FROM AUTHOR]

Background The endodontic disinfection therapy majorly aims to eradicate microbial pathogens. Photo-activated disinfection (PAD), also known as antimicrobial photodynamic therapy, is an alternative antimicrobial modality used to control the microorganisms causing endodontic infections. Notably, microorganisms may be exposed to sub-lethal doses of PAD (sPAD), influencing microbial virulence. The present study assessed the effects of sPAD on expression profiling of the gene associated with the biofilm formation being the most essential virulence factor in Porphyromonas gingivalis strain cells that survive the photodynamic reatment in vivo . Materialas and methods Sixteen clinical strains of PAD resistant P. gingivalis that were isolated in vivo, were further photosensitized in vitro with toluidine blue O (TBO), methylene blue (MB), and indocyanine green (ICG) as the photosensitizing agents, which were excited with specific wavelength of light based on the photosensitizer. After evaluating sPAD, its effects on the fimA gene expression were assessed using real-time quantitative reverse transcription PCR (qRT-PCR). Results In this study, maximum values of sPAD against P. gingivalis were 6.25 μg/mL TBO at a fluency of 171.87 J/cm 2 , 15.6 μg/mL ICG at fluency of 15.6 J/cm 2 , and 25 μg/mL MB at fluency of 93.75 J/cm 2 . MB-, TBO-, and ICG-sPAD could cause about 4.6-, 14.4-, and 17.3-fold suppression of fimA expression, respectively. P. gingivalis strains expressed less virulence in cells surviving PAD. Conclusions In conclusion, the gene expression profiling was reduced in the bacterial cells, wherein greater reduction was observed for ICG-sPAD than TBO- and MB-sPAD. [ABSTRACT FROM AUTHOR]

Photodynamic therapy (PDT) has been successfully employed in the treatment of oral cancer. Toluidine blue O (TBO) is a photosensitizer (PS) that has exhibited remarkable photocytotoxicity in a variety of tumour cells; however, its physicochemical properties, as well as the physicochemical properties of oral mucosa, prevent the drug from reaching the target site at a therapeutic concentration. The aim of this study was to evaluate the influence of Tween 80 ® (TW), which has shown potential as a penetration enhancer, on the mucosal retention of TBO for the PDT of oral cancer. 4% Chitosan-based mucoadhesive gels (CH gels) containing or not 5%TW were prepared (both containing 1%TBO), and their physicochemical properties (pH, rheology and mucoadhesion), TBO in vitro release profiles and TBO in vitro mucosal retention were evaluated. In vivo mucosal penetration studies of TBO followed by laser exposition were also carried out. The results showed that 4%CH gels containing 5%TW and 1%TBO have adequate mucoadhesive and rheological properties for oral mucosa use, although they present a slightly acid pH. TBO release studies showed that TW reduces TBO release, but it prolongs TBO release and increases TBO retention in the mucosa. In vivo studies showed that 4%CH gels containing 5%TW and 1%TBO cause an increase in the number of apoptotic cell, after laser exposition. In summary, 4%CH gels containing 5%TW may be a promising vehicle to optimize the penetration of TBO in oral mucosa and to improve the PDT response for the treatment of oral cancer. [ABSTRACT FROM AUTHOR]

Background Widespread methicillin resistant Staphylococcus aureus (MRSA) and absence of effective antimicrobial agents has led to limited therapeutic options for treating MRSA infection. We aimed to evaluate the effect of antimicrobial photodynamic therapy (aPDT) on the expression of novel identified methicillin resistance markers (NIMRMs) in S. aureus using complementary DNA-Amplified Fragment Length Polymorphism (cDNA-AFLP) approaches to address the therapeutic alternatives for MRSA infections. Materials and methods We used cDNA-AFLP to compare MRSA and methicillin susceptible S. aureus (MSSA) for identification of target genes implicated in methicillin resistance. To determine the sub-lethal aPDT (sPDT), MRSA and MSSA clinical isolates photosensitized with toluidine blue O (TBO), and then were irradiated with diode laser. After sPDT, the colony forming units/mL was quantified. Antimicrobial susceptibility against methicillin was assessed for cell-surviving aPDT. Effects of sPDT on the expression of NIMRMs were evaluated by real-time quantitative reverse transcription PCR. Results According to our results, serine hydrolase family protein (Shfp) encoding gene and a gene encoding a conserved hypothetical protein (Chp) were implicated in methicillin resistance in MRSA. sPDT reduced the minimum inhibitory concentrations of methicillin by 3-fold in MRSA. sPDT could lead to about 10- and 6.2- fold suppression of expression of the Chp and Shfp encoding genes, respectively. Conclusion sPDT would lead to reduction in resistance to methicillin of MRSA in surviving cells by suppressing the expression of the Shfp and Chp encoding genes associated with methicillin resistance. This may have potential implications of aPDT for the treatment of MRSA infections. [ABSTRACT FROM AUTHOR]

Photodynamic therapy with toluidine blue O (TBO) hydrogel exhibits antibacterial activity against Staphylococcus aureus and Escherichia coli in this paper. The response surface methodology is employed to optimize formulations for antibacterial activity. The optimal formulations are carbomer concentration of 3% (w/v), TBO concentration of 0.1 mg/mL and the quality ratio of NaOH and carbomer of 0.4 (w/w). Under the optimized formulations, the log-transformed of CFU mL − 1 on the Staphylococcus aureus and Escherichia coli are 0.84 and 1.26 (the log-transformed of CFU mL − 1 of negative control groups on the Staphylococcus aureus and Escherichia coli are 8.21 and 8.47), respectively. In comparison with photodynamic therapy with TBO aqueous solution, the proposed formulations provide a much stronger antibacterial activity against Staphylococcus aureus and Escherichia coli . TBO hydrogels are stable during 6 weeks at three different temperatures (4, 25 and 40 °C) with respect to no change of color, transparency, pH and viscosity. 50% and 68.26% of TBO are released from carbomer hydrogel after 4 h and 24 h, respectively. TBO hydrogel alone or light alone (630 nm) treatment is incapable of showing antibacterial activity against Staphylococcus aureus and Escherichia coli . Therefore, photodynamic therapy with the novel optimized TBO hydrogel formulations is a promising treatment strategy for periodontitis. [ABSTRACT FROM AUTHOR]

Background Secondary/persistent endodontic infection can be the outcome of failure of endodontic treatment. Photo-activated disinfection (PAD) can be a useful adjunct to mechanical and antimicrobial agents in eliminating endopathogenic microorganisms. In this study, we evaluated the effect of PAD on diversity and count of microbiota related to secondary/persistent endodontic infections. Materials and methods Root canal samples were taken using sterile paper points from the root canals of 14 patients with secondary/persistent endodontic infections after removing the root-canal filling materials. PAD was performed on teeth with toluidine blue O (TBO) in combination with diode laser. Then re-sampling was conducted from the canal root using sterile paper points and transferred to transport medium. The samples were plated and pure cultures of the target microorganisms were then isolated and identified by analytical profile index (API ® 20A) assays and 16S ribosomal RNA gene sequencing. Results Before TBO-PAD, a total of 31 cultivable isolates could be retrieved; 25.8% of the isolated species were obligate anaerobic or microphilics including Veillonella parvula , Porphyromonas gingivalis , Aggregatibacter actinomycetemcomitans , Propionibacterium acnes , and Lactobacillus acidophilus, and 74.2% of the isolated species were facultative anaerobic such as Enterococcus faecalis , Actinomyces naeslundii , L. rhamnosus, L. casei , Streptococcus sanguinis, S. mitis, and Candida albicans . According to this in vivo study, the diversity and count of microbiota in root canal-treated teeth were decreased after TBO-PAD, so that E. faecalis, V. parvula , and C. albicans were the microorganisms that recovered after PAD. Conclusion TBO-PAD is an effective approach that exhibited anti-microbial potential activity against microbiota involved in secondary/persistent endodontic infection. [ABSTRACT FROM AUTHOR]

Background Antimicrobial photodynamic therapy (aPDT) is a novel technique for reduction of pathogenic microorganisms in dentistry. The aim of this study was to evaluate the effects of aPDT on Streptococcus mutans reduction in children with severe early childhood caries. Methods Twenty-two children with severe early childhood caries aged 3–6 years were treated with toluoidine blue O (TBO) for 1 min and irradiated by a Light Emitting Diode (LED; FotoSan, CMS Dental, Denmark) with the exposure time of 150 s. Saliva samples were collected at baseline, 1 h and 7 days after treatment. S. mutans counts were determined using the Dentocult SM Strip mutans. Results The counts of S. mutans in saliva decreased significantly after 1 h ( P < 0.001). However, the difference in reduction of S. mutans counts in saliva was not significant between the baseline and 7 days after treatment ( P > 0.05). Conclusion aPDT seems to be efficient to reduce salivary S. mutans immediately after treatment in children with severe early childhood caries. However, further research is needed to evaluate different doses and frequency of irradiation in combination with restoring carious teeth to find more durable results. [ABSTRACT FROM AUTHOR]

A disposable microfluidic amperometric dual-sensor was developed for the detection of glycated hemoglobin (HbA 1C ) and total hemoglobin (Hb), separately, in a finger prick blood sample. The accurate level of total Hb was determined through the measurements of the cathodic currents of total Hb catalyzed by a toluidine blue O (TBO)-modified working electrode. Subsequently, after washing unbound Hb in the fluidic channel of dual sensor with PBS, the cathodic current by only HbA 1C captured on aptamer was monitored using another aptamer/TBO-modified working electrode in the channel. To modify the sensor probe, poly(2,2´:5´,5″-terthiophene-3´- p -benzoic acid) and a multi-wall carbon nanotube (MWCNT) composite layer (pTBA@MWCNT) was electropolymerized on a screen printed carbon electrode (SPCE), followed by immobilization of TBO for the total Hb probe and aptamer/TBO for the HbA 1C probe, respectively. The characterization of each sensor surface was performed using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), X-ray photoelectron spectroscopy (XPS), quartz crystal microbalance (QCM), field-emission scanning electron microscopy (FE-SEM), and transmission electron microscopy (TEM). The experimental conditions affecting the analytical signal were optimized in terms of the amount of TBO, pH, temperature, binding time, applied potential, and the content ratio of monomer and MWCNT. The dynamic ranges of Hb and HbA 1C were from 0.1 to 10 µM and from 0.006 to 0.74 µM, with detection limits of 82(±4.2) nM and 3.7(±0.8) nM, respectively. The reliability of the proposed microfluidic dual-sensor for a finger prick blood sample (1 µL) was evaluated in parallel with a conventional method (HPLC) for point-of-care analysis. [ABSTRACT FROM AUTHOR]

Treating skin and soft tissue infections of severe limb traumas can be challenging. Crucial concerns focus on inhibiting biofilm formation by antibiotic-resistant bacteria, and preventing scar formation by fibroblastic hyperproliferation. The local use of toluidine blue O (TBO)-mediated photodynamic therapy (PDT) may be a promising strategy for treating such lesions. The present study used Staphylococcus epidermidis (strain ATCC 35984) to assess the effects of TBO-PDT on bacterial adherence and biofilm formation, using confocal laser scanning microscopy (CLSM), tissue culture plating (TCP) and scanning electron microscopy (SEM). Primary human fibroblast cells were used to evaluate the cytotoxicity of TBO-PDT using the 3-(4,5-dimethylthiazol-2-yl) -2,5-diphenyltetrazolium bromide (MTT) assay and CLSM. Six different treatment groups were investigated: Medium only [tryptone soy broth (TSB) or Dulbecco's modified Eagle's medium (DMEM)]; red light control (light dose, 30 J/cm²); TBO group (50 mM TBO); TBO-PDT1 (TBO irradiated with 10 J/cm²); TBO-PDT2 (TBO irradiated with 20 J/cm²); and TBO-PDT3 (TBO irradiated with 30 J/cm²). The results of the S. epidermidis adhesion assay indicated that the TSB, light and TBO groups exhibited significant bacterial adherence, compared with the TBO-PDT groups. Analysis of biofilm formation revealed significant light dose-dependent differences between the TBO-PDT groups and the TSB, light, and TBO groups. Furthermore, SEM indicated fewer colony masses in the TBO-PDT groups compared with the control groups. The MTT assay for fibroblastic cell toxicity demonstrated ~1.1, 4.6, 14.5, 29.7 and 43.4% reduction in optical density for the light, TBO, TBO-PDT1, TBO-PDT2 and TBO-PDT3 groups, respectively, compared with the DMEM control group. There was no difference in toxicity between the light and control groups, however, there were significant differences among the TBO-PDT groups. Finally, alterations in fibroblast morphology and cell spreading were revealed by CLSM, following TBO-PDT treatment. TBO-PDT inhibited bacterial adhesion and biofilm formation, and exhibited significant cytotoxic effects on human fibroblasts. These results indicate that the local use of TBO-PDT in limb lesions may be a useful treatment method for inhibiting bacterial biofilm formation and fibroblastic hyperproliferation, which may prevent infectious hypertrophic scar formation. [ABSTRACT FROM AUTHOR]

• Indocyanine green-photodynamic therapy had the highest antimicrobial efficacy. • Photodynamic therapy with Indocyanine green was more effective than Toluidine blue. • Toluidine blue- photodynamic therapy didn't have an additional effect on NaOCL. Photodynamic therapy (PDT) is an antimicrobial approach that can be used as an adjunctive safe technique for root canal disinfection. In this study, we aimed to evaluate the antibacterial efficacy of PDT with indocyanine green and toluidine blue in combination with sodium hypochlorite (NaOCl) in compared with NaOCl alone against Enterococcus faecalis in infected root canals. Sixty five root canals of sound human premolars were collected. First, the teeth were sterilized, then 60 root canals were inoculated with the E. faecalis , and 5 samples served as negative control remained uncontaminated. The contaminated root canals were randomly assigned into 4 experimental groups (n =15): (1) NaOCl, (2) NaOCl+ PDT-1 (toluidine blue + 630nm LED), (3) NaOCl+ PDT-2 (indocyanine green + 808nm diode laser), and (4): positive control (no treatment). Then, the colony-forming units (CFU/mL) of E. faecalis were calculated in all the groups. Moreover, 5 samples from each group were examined under a scanning electron microscope. The data were analyzed by independent T-test and the Mann-Whitney U test at the significance level of 0.05. The CFU count was significantly lower in the indocyanine green-PDT group in comparison with other groups (p˂0.05). The mean of CFU in the positive control group was significantly higher than the other groups (p˂0.05). No significant difference was detected between NaOCl and toluidine blue –PDT group (p =1.00). Indocyanine green- PDT improved the antibacterial effects of NaOCl against E. faecalis , while toluidine blue – mediated PDT had no significant additional effect on NaOCl. [ABSTRACT FROM AUTHOR]