Methylene Blue Photosensitizer Research Articles

Effect of Polymer Infiltered Ceramic Surface Treatment Using Photoactivated Low-Level Laser Therapy, CO2 Laser, and Aluminum Oxide on Surface Roughness, Shear Bond Strength, and Color Change: An In vitro SEM EDX Analysis

Contemporary surface conditioners (Sandblasting (SB), Self-etching ceramic primer (SECP), low-level laser therapy (LLLT) in conjunction with methylene blue photosensitizer (MBPS), Carbon dioxide (CO2) laser on the color change (ΔE), surface roughness (Ra) and bond strength of hybrid ceramic (HC) to resin cement. Hundred discs were prepared from HC which were surface treated (n = 15) Group 1: HFA(S), Group 2: SB, Group 3: SECP, Group 4: LLLT (MBPS), Group 5: CO2 laser. After surface conditioning, five samples from each group underwent ΔE and Ra analysis using a spectrophotometer and Profilometer respectively. Fifty specimens were applied with dual-cure resin luting cement. Specimens were thermocycled and underwent SBS and failure mode analysis using UTM and stereomicroscope. The mean and standard deviation (SD) of ΔE, Ra, and SBS were calculated using ANOVA. Intergroup comparisons were made using post hoc Tukey multiple comparisons. A maximum score of ΔE was observed in Group 5 samples (CO2 laser+HC). The minimum value of ΔE was displayed by Group 3 (SECP+HC) specimens. Group 2 (SB+HC) treated specimens that exhibited the highest Ra scores and SBS. Sandblasting and carbon dioxide laser-treated samples presented satisfactory outcomes of surface roughness and bond strength. However, Sandblasting and carbon dioxide laser groups presented significant changes in the color of the specimens.

Successful Intentional Replantation of a Severely Compromised Tooth Using 3 Types of Phototherapy: A Case Report.

Background: Intentional replantation (IR) is an emerging and cost-effective last-resort treatment for persistent apical periodontitis. Adjunctive phototherapy for IR aims to improve the management of challenging cases by enhancing disinfection, stimulating healing and promoting regeneration. Objective: We report a novel phototherapy-assisted IR protocol conducted on a compromised lateral incisor with an extensive periapical infection (Ø > 10 mm) in a 68-year-old diabetic male. Methods: The IR protocol involved pre- and postoperative photobiomodulation (660 nm, 0.2 J/cm2, 60 sec/site), antimicrobial photodynamic therapy of the root surface (660 nm, 0.6 J/cm2, 30 sec, methylene blue photosensitizer), and Er:YAG root and socket debridement (2940 nm, 21 J/cm2, 30 sec). The total time from extraction to replantation was 14 min 35 sec. Results: The tooth at 3.5-year follow-up remained clinically functional with radiographic resolution of the infection indicating a successful reimplantation. Conclusions: This case report demonstrated that an adjunctive phototherapy IR protocol can effectively treat a compromised tooth with extensive periapical infection.

Reduction of microorganisms in carious dentin by photodynamic therapy mediated by potassium iodide added to methylene blue and red laser

ObjectiveTo evaluate the effect of the association of potassium iodide to antimicrobial photodynamic therapy on human carious dentin produced with a microcosm biofilm model. MethodsA microcosm biofilm model was used to generate a caries lesion on human dentin. Pooled human saliva diluted with glycerol was used as an inoculum on specimens immersed on McBain artificial saliva enriched with 1 % sucrose (24 h at 37 °C in 5 % CO2). After refreshing culture media for 7 days, the dentin specimens were divided in 5 groups (3 specimens per group, in triplicate; n = 9): C (NaCl 0.9 %), CX (2 % chlorhexidine), PKI (0.01 % methylene blue photosensitizer+50 mM KI), L (laser at 15 J, 180 s, 22.7 J/cm2), and PKIL (methylene blue + KI + Laser). After the treatments, dentin was collected, and a 10-fold serial dilution was performed. The number of total microorganisms, total lactobacilli, total streptococci, and Streptococcus mutans was analyzed by microbial counts (CFU/mL). After normality and homoscedasticity analysis, the Welch's ANOVA and Dunnett's tests were used for CFU. All tests used a 5 % significance level. ResultsCX and PKIL groups showed significant bacterial decontamination of dentin, compared to group C (p < 0.05) reaching reductions up to 3.8 log10 for CX for all microorganisms’ groups and PKIL showed 0.93, 1.30, 1.45, and 1.22 log10 for total microorganisms, total lactobacilli, total streptococci, and S. mutans, respectively. ConclusionaPDT mediated by the association of KI and methylene blue with red laser reduced the viability of microorganisms from carious dentin and could be a promising option for cavity decontamination.

K+ Ions Crosslinked Kappa-Carrageenan/Methylene Blue Composite Film. Part-1: Synthesis, Characterization and Application as Controlled Release Device for Photodynamic Therapy Application

K+ ions crosslinked (KC/MB) Methylene blue photosensitizer loaded composite film is prepared for photodynamic therapy (PDT) application as Photosensitizer released by composite film can conveniently be controlled by using different quantities of K+ ions and this application is based on dynamic interaction between light with suitable wavelength, photosensitizer and molecular oxygen, promoting the death of the target tissue or bacterial cells. In this work, the Methylene Blue (MB) loaded Carrageenan polymeric film was prepared by the method of direct addition of MB into pre-polymerization solution of Carrageenan (KC). This composite film and plain KC film were characterized by FTIR, XRD and SEM analysis. The characteristic peaks of MB photosensitizer were obtained in FTIR spectrum of composite film. The composite film KC/MB shows prominence of amorphous nature may be due to MB is present in very small quantity. The SEM analysis reveals that the composite film (KC/MB) having much more smooth surface texture throughout the film. Finally, the result of effect of variation in degree of crosslinking on amount of MB release is, as the amount of K+ ions used to crosslink the film increases, MB release decreases.

The impact of methylene blue photosensitizer, aPDT and a calcium hydroxide-based paste on the physicochemical and mechanical characteristics of root canal dentin and the bonding interface of fiberglass posts

PurposeTo investigate the influence of methylene blue (MB)-mediated antimicrobial photodynamic therapy (aPDT) and calcium hydroxide (CH) medication on the mechanical characteristics, degree of conversion (DC), quantification, and volume of gaps at the adhesive interface of glass fiber posts (GFPs) luted to distinct thirds of root canal dentin. Additionally, the microhardness (MH), elastic modulus (Eit), morphology, and chemical structure of the intraradicular dentin were assessed. Materials and methods6 experimental groups were formed by sorting 102 bovine incisors. Canals receiving deionized water irrigation as a negative control; canals receiving deionized water irrigation and filled with CH as a positive control; groups treated with CH + MB at 50 and 100 mg/L without irradiation; and groups treated with CH + MB at 50 and 100 mg/L irradiated by red laser for 60 s (660 nm; 100 mW; 6.5 J; 72 J/cm2). MH, Eit, and DC properties were evaluated for both the resin cement layer and root dentin substrate (n = 8). Volume and quantification of gaps at the bonding interface (n = 6), and dentin morphology and chemical content were investigated (n = 3). Data were analyzed using a repeated-measures 2-way ANOVA followed by Tukey post hoc analysis (α = 0.05). ResultsThe distinct intraradicular thirds and treatment with MB-mediated aPDT, whether activated or not, in combination with CH, had a significant impact on the mechanical characteristics of the root dentin. This effect was also observed in the MH, Eit, DC, quantification, and volume of gaps at the luting interface (P < .05). In general, a higher concentration of MB, whether activated by a red laser or not, led to lower values in the mechanical properties of the root dentin, as well as in MH, Eit, and DC at the adhesive interface (P < .05). Additionally, these groups exhibited higher values for quantification and volume of gaps at the luting substrate (P < .05). Scanning electron micrographs and energy dispersive X-ray spectra showed qualitative similarity among all groups, except for the negative experimental control group. ConclusionsMB-mediated aPDT at 50 mg/L, in combination with CH, demonstrated favorable physico-chemical and mechanical characteristics in intraradicular dentin, along with satisfactory mechanical features and the adhesive interface integrity for GFPs at all intraradicular depths. Clinical significanceMB-mediated aPDT at a concentration of 50 mg/L combined to CH medication represents a suitable choice for photosensitization in the context of intracanal disinfection following the biomechanical procedure and prior to luting of intraradicular restorations.

In vitro study: methylene blue-based antibacterial photodynamic inactivation of Pseudomonas aeruginosa

Pseudomonas aeruginosa is one of the most antibiotic-resistant and opportunistic pathogens in immunocompromised and debilitated patients. It is considered the cause of most severe skin infections and is frequently found in hospital burn units. Due to its high antibiotic resistance, eliminating P. aeruginosa from skin infections is quite challenging. Therefore, this study aims to assess the novel in vitro antibacterial activity of methylene blue using a 635-nm diode laser to determine the effective power and energy densities for inhibition of P. aeruginosa. The strain was treated with various concentrations of methylene blue and 635-nm diode laser at powers of 300 mW/cm2 and 250 mW/cm2. The diode laser’s potency in the photo-destruction of methylene blue and its degradation through P. aeruginosa were also evaluated. Colony-forming unit (CFU)/ml, fluorescence spectroscopy, optical density, and confocal microscopy were used to measure the bacterial killing effect. As a result, the significant decrease of P. aeruginosa was 2.15-log10, 2.71-log10, and 3.48-log10 at 60, 75, and 90 J/cm2 after excitation of MB for 240, 300, and 360 s at a power of 250 mW/cm2, respectively. However, a maximum decrease in CFU was observed by 2.54-log10 at 72 J/cm2 and 4.32-log10 at 90 and 108 J/cm2 after 300 mW/cm2 of irradiation. Fluorescence images confirmed the elimination of bacteria and showed a high degree of photo-destruction compared to treatment with methylene blue and light alone. In conclusion, MB-induced aPDT demonstrated high efficacy, which could be a potential approach against drug-resistant pathogenic bacteria.Key points• Combination of methylene blue with 635-nm diode laser for antibacterial activity.• Methylene blue photosensitizer is employed as an alternative to antibiotics.• aPDT showed promising antibacterial activity against Pseudomonas aeruginosa.

Oral Health-Related Quality of Life among Complete Denture Stomatitis Patients Treated with Methylene-Blue-Mediated Photodynamic Therapy

Aim: The aim was to assess the effect of antimicrobial photodynamic therapy (a-PDT) on the oral health-related quality of life (OHRQoL) of denture stomatitis patients. Methods: Forty patients were randomly selected to participate. Candidal proliferation was confirmed by using a CHROMagar culture and Gram staining. The denture surface and palatal mucosa were sprayed with a methylene blue photosensitizer prior to the photobiomodulation application. Laser therapy was applied two times a week at 72 h intervals for a period of 8 weeks. The OHIP-EDENT questionnaire was used to analyze the improvement in the OHRQoL. A Wilcoxon test was used to perform the candidal colony-forming unit’s count and comparison. A t-test was applied to evaluate the OHRQoL responses. Results: The overall CFU/mL values were higher in the dentures of the patients compared to a palatal mucosa swab. For instance, the CFU count was reduced from 5.56 ± 2.15 (baseline) to 3.17 ± 2.77 CFU/mL on day 60 on the palates. Similarly, the a-PDT application on the intaglio surface of the denture showed a reduction from 38.83 ± 14.71 to 29.05 ± 15.52 CFU/mL. A significant difference (p &lt; 0.05) was found in function improvement as well as a reduction in physical pain, psychological discomfort, physical disability, and social interaction among the participants after photobiomodulation treatment. Conclusions: The OHRQoL was significantly improved in the DS patients. The Candida albicans abundance was radically reduced after the a-PDT application.

The Effect of UV-Vis Radiation on DNA Systems Containing the Photosensitizers Methylene Blue and Acridine Orange

As a vital biomolecule, DNA is known as a target of antineoplastic drugs for cancer therapy. These drugs can show different modes of interaction with DNA, with intercalation and groove binding being the most common types. The intercalation of anticancer drugs with DNA can lead to the disruption of its normal function, influencing cell proliferation. Methylene blue (MB) and acridine orange (AO) are examples of DNA-intercalating agents that have been studied for their application against some types of cancer, mainly for photodynamic therapy. In this work, the impact of light irradiation on these compounds in the absence and presence of DNA was analyzed by means of UV-vis spectroscopy. Bathochromic and hypochromic shifts were observed in the absorbance spectra, revealing the intercalation of the dyes with the DNA base pairs. Dyes with and without DNA present different profiles of photodegradation, whereby the dyes alone were more susceptible to degradation. This can be justified by the intercalation of the dyes on the DNA base pairs allowing the DNA molecule to partially hinder the molecules’ exposition and, therefore, reducing their degradation.

Dual-Responsive hollow mesoporous organosilicon nanocarriers for photodynamic therapy

Hypothesis: The nano-delivery platform, -SS-HMONs@MB@MnO2 nanoparticles (SMM NPs) loaded with methylene blue (MB) as photosensitizer have excellent photodynamic therapy (PDT) effect. The disulfide bond and MnO2 give the shell redox-responsive properties. SMM NPs consume glutathione (GSH) in tumor cells, reducing the scavenging of reactive oxygen species (ROS) by GSH and enhancing the PDT effect of MB.Experiments: The GSH dual-responsive nano-delivery platform, was designed and constructed by using disulfide-doped hollow mesoporous organosilicon nanoparticles (-SS-HMONs) as intermediate responsive layer, loaded with MB as photosensitizer and coated with MnO2 as shells. The MB photosensitizer release and GSH response were characterized. The PDT effect of nanoparticles was evaluated.Findings: The SMM NPs were uniform in size and well dispersed. The nanoparticles could react with GSH, leading to the decomposition of MnO2 shells and the breakage of disulfide bonds in -SS-HMONs, resulted in the release of MB photosensitizer. The cell experiment showed that SMM NPs had good ROS generating ability and PDT effect after being sucked by tumor cells, which could effectively kill tumor cells. However, in vivo experiments demonstrated that SMM NPs showed slight inhibition on tumor growth. The actual effect in animals was different from the effect in cells.

Antibacterial Effect of Three Kinds of Methylene Blue Photosensitizers Mediated Photodynamic Therapy on Streptococcus Mutans

In order to study the antibacterial effect of methylene blue (MB) photosensitizer-mediated photodynamic therapy (PDT) on Streptococcus mutans in aqueous solvent form, SDS solution form and their mixed form, the influence of MB-PDT on antibacterial effect of Streptococcus mutans in different dosage forms was analyzed. The number of colonies after and before photodynamic therapy mediated by MB-mediated photodynamic therapy was compared by in vitro viable bacterial colony counting method. Negative control group, light alone group, water dosage MB group, mixed dosage MB group, SDS dosage MB group, water dosage MB-PDT group, mixed dosage MB-PDT group and SDS dosage MB-PDT group were set up respectively the effect of different dosage forms of photosensitizers on the antibacterial effect of Streptococcus mutans was analyzed by counting and comparing in vitro for 24 hours. Through in vitro culture experiment, it was found that the number of colonies in water dosage form, mixed dosage form and SDS dosage form MB-PDT group was less than that in water dosage form, mixed dosage form and SDS dosage form MB. The proportion of viable bacteria in SDS MB group was significantly lower than that in water and mixed MB groups, and the antibacterial rate of SDS MB-PDT group was significantly higher than that in water and mixed MB-PDT group. These results indicated that MB-PDT could significantly inhibit the proliferation and growth of Streptococcus mutans. Among them, SDS MB-PDT group had more obvious antibacterial effect on Streptococcus mutans than water MB-PDT group and mixed MB-PDT group, but there was no significant difference in antibacterial effect between water MB-mediated PDT group and mixed MB-mediated PDT group.

Hybrid ceramic repair strength, surface roughness, and bond failure, using methylene blue-activated low-level laser therapy, Carbon dioxide, and Ti: Al2O3 laser

AimsTo evaluate the impact of various pretreatment regimes (LLLT, Ti-sapphire laser, CO2, and HFA-S) on hybrid ceramics, specifically focusing on their ability to enhance repair strength and minimize surface roughness (Ra). Material and methodsDiscs were made from hybrid ceramics and after disinfection were randomly divided into four groups based on different surface conditioning techniques. Each group consisted of 15 discs, resulting in a total sample size of 60. dics in group 1 was surface treated with Low-level laser therapy (LLLT) using methylene blue (MB), Discs in group 2 with Ti-sapphire laser, Discs in group 3 with CO2 laser, and discs in group 4 with HFA-S. Five samples from each group were assessed for Ra. The remaining 10 samples from each group underwent repair using a porcelain repair kit in adherence to the planned instructions. The bond strength of each sample in all groups was measured using a universal testing machine. Following the bond strength testing, the specimens from all study groups were analyzed to determine the mode of failure. To evaluate the data, a two-way analysis of variance (ANOVA) was used, followed by post hoc multiple comparisons. ResultsThe highest repair bond strength was observed in group 4 hybrid ceramics pretreated with HFA-S (19.05±0.79 MPa). The lowest repair bond scores were observed in group 1 hybrid ceramics preconditioned with LLLT in the presence of Photosensitizer (13.41±0.36 MPa). The highest Ra scores were exhibited in group 2 surface treated with Ti-sapphire laser (0.0515±0.16 µm) and the lowest Ra scores were observed in Group 4 HFA-S (0.0311±0.79 µm). Predominant bond failure among different investigated groups was cohesive. ConclusionThe current gold standard for hybrid ceramic conditioning is the use of hydrofluoric acid (HFA) combined with a silane coupling agent. Low-level laser therapy with methylene blue photosensitizer is not recommended for the treatment of hybrid ceramics.

Incorporation of Zirconium Oxide Nanoparticles in Adhesive Resin for Bonding of Brackets to Enamel Conditioned with Er,Cr:YSGG, Photodynamic Therapy, and Phosphoric Acid.

Objective: To evaluate the effect of enamel conditioning methods, that is, total-etch and rinse (TER), Er,Cr:YSGG (ECYL), and photodynamic therapy (PDT) on the shear bond strength (SBS) of orthodontic metallic brackets bonded using Zirconium oxide experimental adhesive (ZOEA). Methods: Sixty human incisor buccal surfaces were cleaned and allocated into three groups based on the method of enamel surface treatment, that is, TER using 37% phosphoric acid gel, methylene blue photosensitizer activated by PDT and ECYL (n = 20 each). Each group was further divided into two subgroups (n = 10) based on the type of adhesive, that is, ZOEA and experimental adhesive (EA). Metallic brackets were seated using composite resin. Samples were placed in a universal testing machine for SBS and failure mode using the ARI index. One-way analysis of variance and post hoc Tukey were used for multiple comparisons. ARI was presented in percentages in different investigated groups. Results: TER+ZOEA (17.16 ± 0.41 MPa) displayed the highest bond integrity. However, group PDT+EA (11.34 ± 0.25 MPa) demonstrated the lowest bond scores. The intergroup comparison revealed that the TER system displayed significantly higher SBS values than the PDT and ECYL groups (p < 0.05). The intragroup comparison revealed that enamel conditioned with TER and brackets bonded with ZOEA and EA displayed comparable bond integrity (p > 0.05). Conclusions: Enamel conditioned with TER bonded to a metallic bracket displayed better bond strength than PDT and ECYL. Zirconium oxide nanoparticles incorporated in adhesive have proved to be promising in improving the bond integrity of adhesive.

In vitro study on how photodynamic therapy and calcium hydroxide medication influence adhesive interface properties of glass-fiber posts to intraradicular dentin

PurposeThis in vitro study evaluated the influence of antimicrobial photodynamic therapy (aPDT), using methylene blue (MB) as photosensitizer (PS) and calcium hydroxide (CH) as intracanal medication on adhesive bond strength, sealing, and integrity of the luting interface of glass-fiber posts to different thirds of endodontically treated root canal dentin. Material and methods102 incisors were sorted into 6 groups: a negative control irrigated with deionized water; a positive control irrigated with deionized water and filled with CH; CH + MB 50 mg/L without laser radiation; CH + MB 100 mg/L without laser radiation; CH + MB 50 mg/L radiated by red laser; and CH + MB 100 mg/L radiated by red laser. Push-out bond strength (n = 8), adhesive interface sealing (n = 3), and volume and quantification of voids (n = 6) were assessed using a universal testing machine, confocal laser scanning microscope, and computerized microtomography, respectively. Scanning electron micrographs were obtained from representative samples to qualify the fracture patterns. Push-out bond strength and adhesive interface integrity data were subjected to 2-way ANOVA for repeated measures followed by Tukey’s test (α = 0.05). Adhesive interface sealing was evaluated by the inter-examiner Kappa test and submitted to Kruskal-Wallis and Dunns tests (α = 0.05). ResultsAssessing the apical region, the positive control and MB100WA + Ca(OH)2 groups showed lower adhesive bond strength compared to the MB100A + Ca(OH)2 group (P < 0.05). The cervical third showed higher bond strength than the apical third for the positive control, MB50WA + Ca(OH)2, MB100WA + Ca(OH)2, and MB50A + Ca(OH)2 groups (P < 0.05). A prevalence of mixed failure was observed in all experimental groups. There were no statistically significant differences in adhesive interface sealing for any of the parameters assessed (P > 0.05). MB100WA + Ca(OH)2 and MB100A + Ca(OH)2 groups promoted a higher volume and quantification of voids compared to the negative control group evaluating the cervical third (P < 0.05). In general, there were no differences in the quantification of voids comparing the intraradicular thirds (P > 0.05), differently to the volume of voids in which, in general, the cervical third promoted higher values compared to the middle and apical thirds (P < 0.05).Conclusion: aPDT with methylene blue PS at 50 mg/L associated with calcium hydroxide as intracanal medication demonstrated satisfactory bond strength, sealing, and integrity of the adhesive interface at any intraradicular depth.

Single-Excitation Triple-Emission Down-/Up-Conversion Nanoassemblies for Tumor Microenvironment-Enhanced Ratiometric NIR-II Fluorescence Imaging and Chemo-/Photodynamic Combination Therapy.

Tumor microenvironment-mediated ratiometric second near-infrared (NIR-II) fluorescence imaging and photodynamic therapy contribute to accurate diagnosis and highly efficient therapy of deep tumors. However, it is challenging to integrate these functions into one nanodrug due to the difficulty in preparing triple-emission nanoprobes. In this work, single-excitation triple-emission (wavelength at 660, 1060, and 1550 nm) down-/up-conversion nanoassemblies were prepared by conjugating dual-ligands-stabilized gold nanoclusters (cgAuNCs) into down-/up-conversion nanoparticles (D/UCNPs), which simultaneously realized ratiometric NIR-II fluorescence imaging and chemo-/photodynamic combination therapy toward tumors upon exposure to an 808 nm laser. The presence of dual ligands endowed cgAuNCs with an enhanced NIR-II fluorescence response to endogenous glutathione, allowing in situ ratiometric NIR-II fluorescence imaging of tumors using the prepared nanoassemblies. Additionally, the stabilizing ligand cyclodextrin of cgAuNCs facilitated the loading of the antitumor drug doxorubicin, and D/UCNPs could be modified with the photosensitizer methylene blue. Such a spatially separated functionalization method enabled chemo-/photodynamic combination therapy. This study provides new insights into the design of multifunctional nanoplatforms for tumor diagnosis and treatment.

Photodynamic Therapy in Non-Surgical Treatment of Periodontitis: A Systematic Review and Meta-Analysis

Aim: to evaluate the adjunctive effects of photodynamic therapy (aPDT) on nonsurgical mechanical treatment in patients with periodontitis. Materials and methods: The search strategy was conducted according to the PRISMA guidelines to answer research questions regarding the effectiveness of aPDT in association with non-surgical periodontal therapy. The mean values and standard deviations were collected by data extraction. A descriptive comparison between aPDT in association with periodontal treatment and periodontal treatment alone was performed, and meta-analyses of PPD were also performed. Both randomized controlled clinical trials (RCTs) and controlled clinical trials (CCTs) were included. Results: Out of 2059 records, 14 articles on adjunctive photodynamic therapy were included because they met the eligibility criteria. A comparison between the aPDT data and the control group showed improved PPD for photodynamic therapy (SMD −0.76, p = 0.003; I2 = 88%). Statistical analysis was then applied to the three PPD subgroups. The first group included studies that used indocyanine green in association with a wavelength of 810 nm (SMD −1.79, p &lt; 0.00001, I2 = 88%). The second group included studies that used phenothiazine chloride at a wavelength of 660 nm (SMD −0.03, p = 0.84, I2 = 0%). The last group included studies that used methylene blue photosensitizers treated with a wavelength 628–670 nm were included (SMD −0.13, p = 0.38; I2 = 0%). Conclusions: despite the limited number of RCTs and the great heterogeneity between them, it can be concluded that aPDT in association with nonsurgical periodontal treatment improved the clinical parameters at 3 months.

Amphiphilic di-cationic methylene blue for improving antibacterial photodynamic efficiency through high accumulation and low aggregation on bacterial cell surfaces.

The aggregation state of photosensitizers on the surface of bacterial cells is an important scientific problem for antibacterial photodynamic therapy (APDT). High accumulation and high photoactive state maintenance of photosensitizers are the prerequisite of high APDT efficiency. In this study, an amphiphilic di-cationic methylene blue photosensitizer (C12-MB) was synthesized through quaternization, and its structure, interface properties, photophysical properties and antibacterial photodynamic properties were studied. The results showed that C12-MB could reduce 4.27 log10 CFU and 4.8 log10 CFU for P. aeruginosa and S. aureus under irradiation of light at 660 nm, higher than the parent methylene blue. Through a spectroscopic study on photosensitizer adsorption over the bacterial surface, C12-MB can be accumulated with higher concentration, and the photo-active monomer content is 73% and 70% over P. aeruginosa and S. aureus, higher than those of methylene blue: 25% and 49%, respectively. The higher content of non-aggregated photo-active monomer could contribute to higher antibacterial photodynamic efficiency. For C12-MB adsorbed over bacterial surfaces, planar packing inhibition and electrostatic repulsion could contribute to lower C12-MB aggregation, which provides an useful reference for the structural design of high-efficiency photosensitizers.

Farklı Işığa Duyarlılaştırıcılar ile Uygulanan Foto Dinamik Terapinin Konvansiyonel İrrigasyon ile Karşılaştırılarak Dentin Sertliğine Etkisi

Objective: The aim of this study was to examine the effect of photodynamic therapy (PDT) using toluidine blue O (TBO), curcumin (CUR) and methylene blue (MB) photosensitizers on root canal dentin microhardness by comparing it with sodium hypochlorite (NaOCl) + ethylenediamine tetraacetic acid (EDTA).&#x0D; Materials and methods: The root canals of 100 human premolar teeth were shaped by the R25 file (Reciproc; VDW, Munich, Germany). The working length of the teeth was determined by using a #10 K-file, keeping it 1mm shorter than the tooth apex. The R25 file was used to prepare the root canals. After every three pecking motions, irrigation was performed and a total of 10 mm of distilled water was used. The specimens were randomly distributed according to the disinfection method; NaOCl+EDTA, PDT with TBO, PDT with CUR, PDT with MB and distilled water (DS) (n=20). Grooves were prepared on the buccal and lingual surfaces of the prepared teeth, parallel to the long axis of the tooth, without touching the root canals. The roots were divided into two parts by means of a cement spatula placed in these grooves. Root canal dentin microhardness was evaluated by the Vickers test method. Three measurements were made by applying 300 g of force for 15 seconds and the average was calculated. It was recorded as the Vickers hardness value. The data were analyzed by using the one-way ANOVA and Dunnett’s post hoc tests (α=0.05).&#x0D; Results: All photosensitizer groups showed significantly higher microhardness value than the groups of DS and NaOCl + EDTA (p0.05). &#x0D; Conclusions: PDT with CUR obtained the highest radicular dentin microhardness.

Natural and synthetic photosensitizers activated by photodynamic therapy on enamel reconditioning rebonded to metallic brackets: an in vitro study.

To evaluate the bond efficacy and failure rates of rebonded metallic brackets after enamel reconditioning with chemical 37% phosphoric acid (PA) and natural and synthetic photosensitizers activated by PDT. A total of 50 non-cavitated, and cautiously extracted human premolars were congregated after sample size calculation. The enamel exterior was etched, washed, dried for adhesive application, and cured. Metallic brackets were then oriented and adapted to enamel surface using composite. Later, brackets were debonded from the surface via a Weingart plier. Enamel was finished for ensuing surface reconditioning. Ultimately, specimens were randomly distributed into five groups (n=10). Enamel surface before rebonding was reconditioned with curcumin photosensitizer (CP), riboflavin photosensitizer (RP), rose bengal photosensitizer (RBP), methylene blue photosensitizer (MBP), and 37% PA (control) respectively. After following reconditioning protocol, brackets were rebonded to the enamel exterior employing a composite adhesive system. Then, specimens were subjected to the universal testing machine for analyzing shear bond strength (SBS), and bond failures were predicted using an ARI index. One-way ANOVA and Tukey multiple comparison tests were used for statistical analysis at a variance value of p < 0.05. Enamel reconditioned with 37% PA demonstrated the highest SBS for bracket rebonding, and the lowest SBS was presented by CP actuated by PDT. Enamel reconditioned with RP and RBP corroborated the analogous SBS outcome to 37% PA. Likewise, enamel surface treatment with MBP revealed a statistically significant result to CP for metallic bracket rebonding. The most prevalent failure scores anticipated among groups were 0 and 1 indicating an adhesive failure with the exemption of group 5 (control) that encountered more score 2 cohesive failure on debonding metallic brackets from enamel exterior. Rose bengal and riboflavin photosensitizers activated by photodynamic therapy with low ARI scores have the potential to be used as viable enamel reconditioning alternatives to 37% phosphoric acid for rebonding metallic brackets.

Use of photosensitizers activated by photodynamic therapy on the canal disinfection of radicular dentin bonded to Dimethacrylate-based glass fiber post: an assessment of pushout bond strength.

The present lab-based investigation aimed at evaluating the canal disinfectants using photodynamic therapy (PDT) using different photosensitizers, conventional NaOCl, a mixture of doxycycline, citric acid, and a detergent (MTAD) and their impact on the bond strength of glass fiber post to radicular dentin. Forty extracted human premolars were gathered and disinfected. The decoration was performed up to the cementoenamel junction. Using the crown down technique cleaning of the canal was done following rinse with distilled water. All canals were dried with paper points and obturated with gutta-percha. Post space was prepared using peso reamers and samples were randomly allocated into four groups following different disinfection regimes: Group 1 - Methylene blue photosensitizer (MBP) + MTAD; Group 2 - RBP (Rose Bengal photosensitizer) + MTAD; Group 3 - CP (curcumin photosensitizer) + MTAD and Group 4 - 2.25% NaOCl + MTAD (control). Following disinfection, the canals were dried and the post was placed and cemented within the canal. Samples were dissected at coronal, middle, and apical third and placed in a universal testing machine for push-out bond strength (PBS). Debonded surfaces were evaluated for failure modes. PBS was examined using a one-way analysis of variance (ANOVA). The means of PBS were compared using Tukey multiple comparison tests with a significance threshold of (p<0.05). Group 3 canals disinfected with CP and MTAD had the highest PBS at two levels: cervical (9.57±1.21 MPa), middle (6.37±0.79 MPa), and group 2 canal space disinfected by RBP and MTAD had the maximum PBS in apical portion (5.35±0.42 MPa). No significant difference at all root levels between group 2 (RBP + MTAD) and group 3 (p>0.05). Canal irrigation with group 1 (MBP + MTAD) and group 4 control (2.25% NaOCl + MTAD) exhibited comparable PBS at all three levels of the root. CP, MTAD, RBP and MTAD for canal disinfection and bonding of glass fiber post to radicular dentin demonstrated comparable bond values at all three root levels and can be recommended in clinical settings after further investigations.

Specific disruption of glutathione-defense system with activatable single molecule-assembled nanoprodrug for boosted photodynamic/chemotherapy eradication of drug-resistant tumors

Developing single molecule-assembled nanoprodrugs that can reverse the glutathione (GSH)–mediated drug resistance of tumors provides promising potentials for precision and effective cancer theranostics. Herein, we developed a novel single molecule-assembled nanoprodrug for effective photodynamic/chemotherapeutic eradication of drug-resistant tumors via the multistage GSH-depletion. The nanoprodrug MSSP-NP could be fancily fabricated by self-assembly of an amphiphilic activatable molecular MSSP, which is synthesized by covalently conjugating the photosensitizer methylene blue (MB) with a GSH-sensitive cisplatin prodrug via a tumor targeting thiolated polypeptide. Upon the nanoprodrug MSSP-NP systematic administrated, its photoactivities and pharmacological effects can be thoroughly switched on by intracellular GSH to produce the photosensitizer MB and chemotherapeutic drug cisplatin, along with the multi-step consumption of GSH, which could remarkably boost oxidative stress and reverse the drug resistance. As a result, the nanoprodrug could effectively disrupt the tumor GSH-defense system to afford high-efficiency photodynamic/chemotherapeutic inhibition of drug resistance tumors (96.4%) with minimum side effects.