Photosensitizer Riboflavin Research Articles

Caries affected Dentin biomodification using Bromelain, Riboflavin photosensitizer via UVA, and Chitosan Nanoparticles on shear bond strength and microleakage scores: A SEM evaluation.

Assessment of the impact of different dentin bio-modifiers i.e., Bromelain, Riboflavin photosensitizer (RFP/Ultraviolet-A), and Chitosan nanoparticles (CHNPs) on the shear bond strength (SBS) and microleakage of composite bonded to acid etched carious affected dentin (CAD). Sixty-four human molars in which carious lesions extend till the middle third of the dentin were included. The infected dentin was removed and CAD was exposed. All specimens were categorized into four groups based on the application of dentin bio-modifier (n=16) Group 1 (No dentin modifier), Group 2 (Bromelain), Group 3 (RFP/UVA), and Group 4 (CHNPs). Dental adhesive application and composite buildup were performed. A dye penetration test was used to assess marginal leakage. Resin CAD interface assessment was performed using SEM. For SBS and failure pattern analysis, a universal testing machine and stereomicroscope were used respectively. One-way ANOVA followed by Bonferroni's posthoc test was employed to analyze the differences among various groups (p ≤ 0.05) RESULTS: The lowest microleakage (13.27 ± 0.10) and highest SBS (11.64 ± 0.16 MPa) were observed in Group 2 (Bromelain). However, the maximum values of marginal leakage (37.21 ± 0.21) and minimum SBS (7.34 ± 0.07 MPa) were detected in Group 1 samples. The length of resin tags in the Group 2 specimens (Bromelain) was found to be the highest (102.11 ± 5.12μm). However, Group 1 (No modifier) exhibited the lowest resin tag length (50.45 ± 2.37 μm). Caries-affected dentin modified with Bromelain resulted in satisfactory SBS with minimal microleakage scores. Chitosan nanoparticles and RFP/Ultraviolet-A also presented better outcomes in terms of microleakage and SBS than the control.

One-step green synthesis of platinum mesoporous nanoparticles by riboflavin for light activated antitumoral therapy

Photodynamic therapy (PDT) has been established as one of the most promising novel cancer therapies with fewer side-effects and enhanced efficacy compared to the currently available conventional treatments. However, its application has been hindered by the limitations that photosensitizers (PS) have. The combination of PS with metallic nanoparticles like platinum nanoparticles (PtNPs), can help to overcome these intrinsic drawbacks. In this work, the combination of PtNPs and the natural photosensitizer riboflavin (RF) is proposed. PtNPs are synthesized using RF (Pt@RF) as reducing and stabilizing agent in a one-step method, obtaining nanoparticles with mesoporous structure for UV triggered PDT. In view of possible future UV irradiation treatments, the degradation products of RF, ribitol (RB) and lumichrome (LC), this last being a photosensitizing byproduct, are also employed for the synthesis of porous PtNPs, obtaining Pt@LC and Pt@RB. When administered in vitro to lung cancer cells, all the samples elicit a strong decrease of cell viability and a decrease of intracellular ATP levels. The antitumoral effect of both Pt@RF and Pt@LC is triggered by UV-A irradiation. This antitumoral activity is caused by the induction of oxidative stress, shown in our study by the decrease in intracellular glutathione and increased expression of antioxidant enzymes.

Antimicrobial photodynamic effect of the photosensitizer riboflavin, alone and in combination with colistin, against pandrug-resistant Pseudomonas aeruginosa clinical isolates

IntroductionDevelopment of multi-, extensively-, and pandrug-resistant (MDR, XDR, and PDR) strains of Pseudomonas aeruginosa remains a major problem in medical care. The present study evaluated the effect of antimicrobial photodynamic therapy (aPDT) as a monotherapy and in combination with colistin against P. aeruginosa isolates. MethodsTwo P. aeruginosa isolates recovered from patients with respiratory tract infections were examined in this study. Minimum inhibitory concentration (MIC) of colistin was determined by the colistin broth disk elution (CBDE) and the reference broth microdilution (rBMD) methods. aPDT was performed using the photosensitizer (Ps) riboflavin at several concentrations and a light-emitting diode (LED) emitting blue light for different irradiation times with or without colistin at 1/2 × MIC concentration. ResultsBoth PA1 and PA2 isolates were identified as colistin-resistant P. aeruginosa with a MIC ≥4 μg/mL by the CBDE and MICs of 512 μg/mL and 256 μg/mL, respectively, by the rBMD. In aPDT, neither riboflavin nor LED light alone had antibacterial effects. The values of colony forming units per milliliter (CFU/mL) in both isolates were significantly reduced by LED + Ps treatments in a time-dependent manner (LED irradiation time) and dose-dependent manner (Ps concentration). In comparison with control, treatment with Ps (50 μM) + LED (120 s) and Ps (100 μM) + LED (120 s) resulted in 0.27 log10 CFU/mL and 0.43 log10 CFU/mL reductions in PA1, and 0.28 log10 CFU/mL and 0.34 log10 CFU/mL reductions in PA2, respectively, (P < 0.01). The best results were obtained after the combination of aPDT followed by colistin, which increased bacterial reduction, resulting in a 0.41−0.7 log10 CFU/mL reduction for PA1 and 0.35−0.83 log10 CFU/mL reduction for PA2 (P = 0.001). ConclusionsThis study suggests the potential implications of aPDT in combination with antibiotics, such as colistin for treatment of difficult-to-treat P. aeruginosa infections.

Photoinactivation of the bacteriophage PhiX174 by UVA radiation and visible light in SM buffer and DMEM-F12

ObjectiveIt has been observed that viruses can be inactivated by UVA radiation and visible light. The aim of this study is to investigate whether a medium that contains a photosensitizer might have an influence on viral reduction under irradiation by UVA, violet or blue light. Test virus is the bacteriophage PhiX174 in the photosensitizer-free SM buffer and DMEM-F12, which contains the known photosensitizer riboflavin.ResultsThe determined PhiX174 D90 doses in SM buffer and DMEM were 36.8 J/cm² and 13.6 J/cm² at 366 nm, 153.6 J/cm² and 129.1 J/cm² at 408 nm and 4988 J/cm² and 2477.1 J/cm² at 455 nm, respectively. It can be concluded that the medium has a large influence on the results. This might be caused by the photosensitizer riboflavin in DMEM-F12. As riboflavin is a key component in many cell culture media, irradiation experiments with viruses in cell culture media should be avoided if the investigation of intrinsical photoinactivation properties of viruses is aimed for.

Riboflavin-Vancomycin Conjugate Enables Simultaneous Antibiotic Photo-Release and Photodynamic Killing against Resistant Gram-Positive Pathogens.

Decades of antibiotic misuse have led to alarming levels of antimicrobial resistance, and the development of alternative diagnostic and therapeutic strategies to delineate and treat infections is a global priority. In particular, the nosocomial, multidrug-resistant "ESKAPE" pathogens such as Gram-positive methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus spp (VRE) urgently require alternative treatments. Here, we developed light-activated molecules based on the conjugation of the FDA-approved photosensitizer riboflavin to the Gram-positive specific ligand vancomycin to enable targeted antimicrobial photodynamic therapy. The riboflavin-vancomycin conjugate proved to be a potent and versatile antibacterial agent, enabling the rapid, light-mediated, killing of MRSA and VRE with no significant off-target effects. The attachment of riboflavin on vancomycin also led to an increase in antibiotic activity against S. aureus and VRE. Simultaneously, we evidenced for the first time that the flavin subunit undergoes an efficient photoinduced bond cleavage reaction to release vancomycin, thereby acting as a photoremovable protecting group with potential applications in drug delivery.

The Effect of Different Output Powers of Blue Diode Laser along with Curcumin and Riboflavin against Streptococcus mutans around Orthodontic Brackets: An In Vitro Study.

The aim of the present study was to determine the effects of antimicrobial photodynamic therapy (aPDT) using the blue diode laser (BDL) with different output powers and the photosensitizers riboflavin and curcumin on reducing the number of Streptococcus mutans around orthodontic brackets. A total of 36 orthodontic brackets were contaminated with S. mutans and randomly assigned to 12 groups as follows: control, riboflavin alone, riboflavin + BDL with an output power of 200, 300, 400, or 500 mW, and curcumin alone, curcumin + BDL with an output power of 200, 300, 400, or 500 mW, and 0.2% chlorhexidine (CHX-positive control). Orthodontic brackets were irradiated with a BDL (wavelength 445 nm) at a power density of 0.4-1.0 W/cm2 for 30 s. All orthodontic brackets were examined under a stereomicroscope at 10× magnification. Mean colony-forming units (CFUs)/mL were measured before and after treatment. A one-way analysis of variance with Tukey's post hoc test was performed to compare CFU/mL between groups. CHX and curcumin plus BDL with an output power of 500 mW had the highest reduction in S. mutans colony numbers (p < 0.001). The curcumin groups were more effective than the riboflavin groups. Riboflavin alone and riboflavin + BDL with an output power of 200 mW showed no significant difference from the control group (p = 0.99 and 0.74, respectively). Our results suggest that aPDT using curcumin as a photosensitizer plus BDL with an output power of 500 mW and a power density of 1.0 W/cm2 at a wavelength of 445 nm can effectively reduce colonies of S. mutans around stainless steel brackets.

Efficacy of Riboflavin Activated by PDT, Sapindus macrossi when Used as Final Irrigant on Microleakage, Sealer Penetration, Extrusion Bond Strength, and Martens Hardness Sealed with Bioactive Cement

Aim To compare the effects of riboflavin photosensitizer (RFP) Sapindus Macrossi (SM) on extrusion bond strength (EBS), Marten's hardness (MH), microleakage, and sealer penetration of bioactive cement. Materials and Methods Inclusion/exclusion criteria selected samples. All samples were opened, and the working length was established using pro taper for canal completion and steady irrigation with 2.25% NaOCl. Four randomly chosen groups. EDTA, RFP final irrigant, SM, and saline were the groups. Obturated samples were vertically put in 1% methylene blue dye and cut in half lengthwise for a stereomicroscope. SEM investigated dentinal tubule SP. Mean, standard deviation, and one-way ANOVA measured microleakage, EBS, and MH. Results Final watering procedures did not affect samples. Final irrigant SM increased sealer penetration. Radicular dentin irrigated with 2.25% NaOCl+ SM had the highest EBS in the cervical region. Group 2: 2.25% NaOCl+ RFP had the lowest MH while Group 1: SM had the highest. Conclusion Sapindus mukorossi, often known as soapberry or reetha, could replace current watering methods when used with a bioactive sealant.

The Impact of Riboflavin, Nd: YAG Laser, and Ceramic Primer Pretreatment on Surface Roughness, Bond Failure, and Adhesive Strength of Resin Composite to Lithium Disilicate Ceramics: A Scanning Electron Microscopy (SEM) Analysis

Aim: Adhesive bond integrity and surface roughness (Ra) of LDS ceramics following the application of various surface treatments. Material and Method: Forty disks of LDS ceramics were prepared and randomly distributed into different groups based on the method of pretreatment. Group 1: HF (hydrofluoric acid) + S (Silane), Group 2: RFP (riboflavin photosensitizer) S, Group 3: SECP (selfetch ceramic primer and Group 4: Nd: YAG laser. Following conditing LDS ceramic was assessed for Ra and Scanning electron micrographs. All LDS ceramics were bonded and the strength of the resin-ceramic interface was tested using a universal testing machine. The debonded samples were examined under a stereomicroscope. The failure modes were categorized as cohesive, admixed, and adhesive interfaces. Ra and bond integrity values were tested using, two-way ANOVA, and Tukey post hoc tests. (p = 0.05). Results: The highest Ra and bond values were exhibited by samples pretreated using HF + S. Nevertheless, group 2 (RFP + S) demonstrated the lowest bond integrity (12.37 ± 1.98 MPa). No significant differences in the bond integrity outcomes between group 1, group 3 (SECP), and group 4 (Nd: YAG laser + S) (p &gt; 0.05). Conclusion: Nd: YAG and SECP have the potential to be used as an LDS ceramic conditioner alternative to HFA for adequate bond scores.

Pretreatment of Root Dentin Using Photon-Induced Photoacoustic Streaming, Photodynamic Therapy, and Riboflavin with EDTA as a Final Irrigant to Improve Bond Integrity of Glass Fiber Post.

Objective: To evaluate the outcome of post space disinfection using Er,Cr:YSGG laser (ECYL), riboflavin photosensitizer (RFP), and photon-induced photoacoustic streaming (PIPS) along with ethylene diamine tetra acetic acid (EDTA) as final irrigant on the bond values of glass fiber post (GFP) to the canal wall. Materials and methods: Forty human mandibular premolars were subjected to root canal treatment after decoronation till the cementoenamel junction. Post space was prepared using a Gates-Glidden drill leaving 4 mm of gutta perch at the apical third of the root section. Random allocation of samples was performed into four groups based on the post space disinfection (n = 10 each): Group 1: 1% RFP and 17% EDTA, group 2: 5.25% sodium hypochlorite (NaOCl) and 17% EDTA (control), group 3: PIPS and 17% EDTA, and group 4: ECYL and 17% EDTA. GFP was luted using Rely X Unicem. A universal testing machine and stereomicroscope were used to assess the push-out bond strength (PBS) and failure mode, respectively. Analysis of variance determined the PBS amid different experimental groups at three root levels. Multiple group comparison using means of tested groups was identified using post hoc Tukey. Results: The coronal third of group 2 (5.25% NaOCl +17% EDTA) demonstrated the highest PBS (8.83 ± 0.11 MPa). However, the lowest bond integrity (4.15 ± 0.52 MPa) was displayed in an apical third of group 1 (RFP +17% EDTA). The intergroup comparison revealed that 5.25% NaOCl +17% EDTA at all three levels demonstrated comparable outcomes of PBS with PIPS +17% EDTA and ECYL +17% EDTA specimens (p > 0.05). However, riboflavin +17% EDTA demonstrated the lowest bond strength (p < 0.05). Conclusions: Er,Cr: YSGG and PIPS in combination with 17% EDTA demonstrated comparable outcomes of bond score with those of conventional gold standard irrigation regime 5.25% NaOCl.

Effectiveness of Morinda citrofolia, Sapindus mukorossi, and curcumin used in curry spice, to the radicular canal irrigant in improving bond integrity of glass fiber post

AimEvaluation of the push-out bond strength (PBS) of glass fiber reinforced post (GFRP) bonded to root dentin after canal disinfection using food-based root canal irrigants i.e., Curcumin photosensitizer (CP), Riboflavin photosensitizer (RFP), Morinda ctrifolia juice (MCJ) and Sapindus mukorossi (SM) along with MTAD as a final irrigant. Material methodsFifty human single-rooted premolar teeth were decoronated. Endodontic preparation was performed along with 2.25% sodium hypochlorite NaOCl solution followed by EDTA solution. Canals were dried and obturated followed by post-space preparation by removing GP. Specimens were allocated into five groups based on different food-based disinfection regimes (n = 10). Group 1: 2.25% NaOCl + MTAD (Control), Group 2: 6% MCJ + MTAD, Group 3: SM + MTAD, Group 4: CP + MTAD and Group 5: RFP + MTAD. All GFRP were bonded to radicular dentin. Root sectioning was performed followed by PBS and failure analysis using a universal testing machine (UTM) and stereomicroscope respectively. The data were analyzed using a one-way analysis of variance (ANOVA) test and the Post Hoc Tukey HSD test (p = 0.05). ResultsSamples disinfected with(MCJ+MTAD) at coronal third demonstrated maximum PBS (9.41 ± 0.51 MPa). However, the apical third of group 5 (RFP + MTAD) exhibited the minimum values (4.06 ± 0.23 MPa). Intergroup comparison analysis unveiled that group 2 (MCJ +MTAD) and group 3 (SM+MTAD) displayed comparable outcomes of PBS at all three-thirds. Similarly, samples in group 1 (2.25% NaOCl + MTAD), group 4 (CP + MTAD), and group 5 (RFP + MTAD) exhibited comparable PBS. ConclusionFruit-based irrigants Morinda citrifolia and Sapindus mukorossi have the potential to be used as root canal irrigants with a positive influence on bond strength.

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.

Riboflavin (Vitamin B2), Turmeric (Curcumin) Photosensitizers Mediated Photodynamic Therapy, and Er, Cr: YSGG on Microleakage of Class V Cavities Restored by Resin-Modified Glass-Ionomer Cement

Purpose: The present study aimed to assess the effect of RF and CP intervened PDT and Er, Cr: YSGG laser on microleakage in class V RMGIC restorations in permanent teeth. Materials and Methods: In-vitro eighty standardized class V cavities (4×4×2) were prepared in extracted permanent molars based on ICDAS II (International Caries Detection and Assessment System II) caries severity code 0. All samples were arbitrarily alienated into four groups: Group 1, PDT mediated riboflavin photosensitizer (RF) [concentration of 150 μg/mL]; Group 2, PDT with curcumin photosensitizer (CP) [concentration of 100 μg/mL]; Group 3, Er, Cr: YSGG laser application; Group 4, control group: rinsed and dried dentin. Cavities were restored with conventional RMGIC. The specimens were immersed in 0.5% Fuchsine solution for 24 hrs. and sectioned. Microleakage scores were assessed under a microscope. Intergroup and intragroup comparisons were made at enamel and cementum margin respectively. Data were analyzed by non-parametric Kruskal-Wallis test and Wilcoxon tests at the level of significance deemed p &lt; 0.05. Results: Riboflavin and curcuminmediated PDT would produce a superior reduction (95% viz 90%) of microleakage as compared to Er, Cr: YSGG laser (85%), and no control groups. Cu-PDT observed the highest amount of microleakage with the least amount of microleakage in the control group. Conclusion: Riboflavin and curcumin photosensitizers mediated PDT and Er, Cr: YSGG laser has the potential to be utilized in class V cavities before RMGIC restorations at enamel margins without adversely affecting the marginal integrity.

Noncarious cervical lesion pretreated using antimicrobial photodynamic therapy and diode laser in reducing dentin hypersensitivity bonded to different restorative material: Valuation of bond values and invitro dye leakage

AimThe present study aimed to appraise the effect of Diode laser (DL), riboflavin, and curcumin on the bond strength of adhesive restorative material and the effects of pretreatment on microleakage scores. Material and MethodsNinety caries-free human permanent premolars were obtained and disinfected. All specimens were mounted till CEJ. To provide standardization, a 2 × 2 mm flat non-carious cervical lesion (NCCL) dentin surface was exposed. This was followed by dentin surface roughening/cervical groove preparation with a round bur. After tooth surface preparation, ninety specimens were divided arbitrarily into three groups. Group 1: NCCL exposed to DL; group 2: NCCL pretreated with riboflavin photosensitizer (RFP) and group 3 pretreated with curcumin photosensitizer (CP). All the three groups were further divided into two subgroups A1, A2, B1, B2, C1, and C2 based on the restorative material used (n = 15). Subgroup A1, B1, and C1 were restored with composite resin (CR). Subgroup A2, B2, and C2 were restored with RMGIC. Ten samples from each subgroup were evaluated for shear bond strength (SBS) testing under a universal testing machine (UTM). Five from each subgroup were evaluated for microleakage assessment. Bond strength and microleakage analysis were performed using analysis of variance (ANOVA) with a Post-hoc test (Tukey's post hoc test) at a significance level (p = 0.05). ResultsThe group A1, DL-CR shows the highest SBS (16.41± 0.4 MPa). However, CP-RMGIC groups demonstrated the lowest bond integrity. RFP-CR and the DL-CR group displayed comparable outcomes of SBS (p>0.05). The highest microleakage was observed with CP-RMGIC. The least microleakage was displayed by DL-CR. ConclusionNoncarious cervical lesions pretreated with diode laser and riboflavin photosensitizer showed better shear bond strength and reduced microleakage when bonded to composite resin than non-carious cervical lesions pretreated with curcumin.

Assessment of push-out bond strength of post-surface pretreatment before salinization using hydrogen peroxide, aluminum trioxide, and natural photosensitizers to radicular dentin

ObjectiveThe study aimed to evaluate the effect of different post surface pretreatment methods i.e., 24% hydrogen peroxide (H2O2), riboflavin photosensitizer (RFP), curcumin photosensitizer (CP) and aluminum oxide (Al2O3), and silane only on the bond values of glass fiber post to resin cement Materials and MethodsFifty single-rooted human teeth were obtained and crowns were sectioned coronally to the cementoenamel junction (CEJ). Protaper universal file system was used for canal cleaning and shaping followed by obturation. Post space was prepared and all the posts were then randomly divided into five groups depending on the surface pretreatment used (n = 10). Group 1: 24% H2O2 + silane, Group 2: RFP + silane, Group 3: CP + silane, Group 4: Al2O3 + silane, Group 5: silane only. Post-surface treatment was followed by post-placement using a self-etch dual-cure cement Panavia F 2.0. Acrylic blocks were used to hold the specimens perpendicularly and all the samples were sectioned by slow-speed saw into coronal, middle, and apical third. The universal testing machine determines pushout bond strength and failure mode was analyzed by stereomicroscope. One-way analysis of variance (ANOVA) and Tukey multiple comparison tests were used to analyze data. ResultThe coronal section of group 4 (Al2O3 + silane) displayed the highest PBS (8.23±0.14 MPa). Whereas, an apical third of group 2 (RFP + silane) exhibited the lowest PBS (2.02±0.12 MPa). PBS values in samples in group 1 surface treated with 24% H2O2 + silane displayed comparable outcomes to samples in group 4 at all three levels (p>0.05). Samples in group 2 (RFP + silane) group 3 (CP + silane) and group 5 (Silane Only) demonstrated comparable PBS (p>0.05). ConclusionGlass fiber reinforced post-surface pretreatment method using hydrogen peroxide and aluminum trioxide along with silane improves push-out bond strength at all three levels (coronal, middle, and apical). The use of a silane coupling agent on glass fiber posts alone does not improve bond values. The practice of photosensitizer on post-surface needs to be investigated further.

Influence of methylene blue, Riboflavin, and indocyanine green on the bond strength of caries affected dentin when bonded to resin-modified glass ionomer cement

AimThe present study aimed to assess the influence of methylene blue (MBP), Riboflavin, and indocyanine green (ICG) on the bond strength of caries affected dentin (CAD) when bonded to resin-modified glass ionomer cement (RMGIC). Materials and MethodsHuman third molars with caries lesions were isolated and collected scrutinized based on ICDAS criteria. The teeth were cleaned using a periodontal scaler and disinfected. All samples were positioned in polyvinyl up to the cementoenamel junction. The samples were randomly distributed into five groups based on the pretreatment regime. Samples in group 1, were pretreated with MBP; group 2, polyacrylic acid (PAA) group 3, ICG, group 4, Riboflavin photosensitizer, and group 5, 37% phosphoric acid (PA). All samples were bonded with RMGIC. 10 samples were subjected to the universal testing machine for shear bond strength (SBS) testing. Five samples from each group were placed in fuchsine dye for the microleakage assessment. Comparison of means and standard deviations (SD) of SBS and microleakage in investigated groups was performed using analysis of variance (ANOVA) and Tukey's post hoc test at a significance level (p = 0.05) ResultsThe highest micro shear bond values were observed in group 2 (CAD conditioned with PAA) (14.26±1.67 MPa). Whereas, the lowest bond values were found in group 1 (treated with MBP) (8.82±1.08 MPa). CAD conditioned with different photosensitizers i.e., MBP, ICG, and Riboflavin before bonding to RMGIC displayed comparable bond values (8.82±1.08 MPa), (9.47±0.21 MPa), and (11.23±0.47 MPa) respectively (p>0.05). Samples conditioned with 37% PA showed significantly higher microleakage scores compared to other surface-treated groups (p<0.05). ConclusionCaries-affected dentin conditioned with polyacrylic acid demonstrated low microleakage and high bond strength.

Inactivation of Opportunistic Pathogens Acinetobacter baumannii and Stenotrophomonas maltophilia by Antimicrobial Photodynamic Therapy.

Acinetobacter baumannii and Stenotrophomonas maltophilia are opportunistic pathogens causing hospital infections with limited treatment options due to bacterial multidrug resistance. Here, we report that antimicrobial photodynamic therapy (aPDT) based on the natural photosensitizers riboflavin and chlorophyllin inactivates A. baumannii and S. maltophilia. The riboflavin and chlorophyllin photostability experiments assessed the photomodifications of photosensitizers under the conditions subsequently used to inactivate A. baumannii and S. maltophilia. A. baumannii planktonic cells were more sensitive to riboflavin-aPDT, while biofilm bacteria were more efficiently inactivated by chlorophyllin-aPDT. S. maltophilia planktonic and biofilm cells were more susceptible to chlorophyllin-aPDT compared to riboflavin-aPDT. The results suggest that riboflavin- and chlorophyllin-aPDT can be considered as a potential antimicrobial treatment for A. baumannii and S. maltophilia inactivation.

Radicular canal disinfection using photon-induced photoacoustic streaming and riboflavin photosensitizer to silver diamine fluoride and diode laser bonded to fiber post: An assessment of extrusion bond strength

AimThe present study aimed to estimate and compare the effectiveness of different innovative canal cleansing approaches photon induced photoacoustic streaming (PIPS) Riboflavin Photosensitizer (RF), Diode Laser, and silver diamine fluoride (SDF) on push out bond strength (PBS) of fiber post cemented to radicular dentin Material and methodsForty extracted premolars were disinfected and decoronated up to the cement-o-enamel junction. Canals of all specimens were cleaned and shaped utilizing a reciprocating system. Post space was created by employing peso-reamers and samples were randomized into four groups based on methods of disinfection (n = 10). Group 1 (PIPS), group 2 (Diode Laser), group 3 (RP), and group 4 (SDF) canal disinfection. Fiber posts were cemented via Self etch resin cement (SERC) in a radicular dentin post space area and root was segmented at three levels (coronal, middle and apical). PBS analysis was performed, and a stereomicroscope was used to assess the failure mode. The means and standard deviations of PBS among studied groups were measured using one-way analysis of variance (ANOVA) after exposure. The means of bonding strength were compared by Tukey multiple comparison tests (p > 0.05). ResultsRF had the highest PBS at all three root levels, coronal (8.31 ± 0.64 MPa), middle (8.13 ± 0.11 MPa) and apical (5.68 ± 0.54 MPa) while group 4 SDF samples showed lowest PBS at all root portions, coronal (6.14 ± 0.78 MPa), middle (5.18 ± 0.15 MPa) and apical (3.15 ± 0.19 MPa), respectively. Intergroup comparison unveiled comparable PBS at all three root levels for group 1 (PIPS) and group 3 RF (p > 0.05). Intragroup comparison displayed a significant decline in PBS values from coronal, middle to the apical direction in all studied groups ConclusionDisinfection of radicular dentin with Riboflavin Photosensitizer and photon-induced photoacoustic streaming bonded to fiber post have the greatest PBS at all three levels cervical, middle and apical.

Collateral Damage Occurs When Using Photosensitizer Probes to Detect or Modulate Nucleic Acid Modifications.

Nucleic acids are chemically modified to fine-tune their properties for biological function. Chemical tools for selective tagging of base modifications enables new approaches; the photosensitizers riboflavin and anthraquinone were previously proposed to oxidize N6 -methyladenine (m6 A) or 5-methylcytosine (5mdC) selectively. Herein, riboflavin, anthraquinone, or Rose Bengal were allowed to react with the canonical nucleosides dA, dC, dG, and dT, and the modified bases 5mdC, m6 A, 8-oxoguanine (dOG), and 8-oxoadenine (dOA) to rank their reactivities. The nucleoside studies reveal that dOG is the most reactive and that the native nucleoside dG is higher or similar in reactivity to 5mdC or m6 A; competition in both single- and double-stranded DNA of dG vs. 5mdC or 6mdA for oxidant confirmed that dG is favorably oxidized. Thus, photosensitizers are promiscuous nucleic acid oxidants with poor chemoselectivity that will negatively impact attempts at targeted oxidation of modified nucleotides in cells.

Collateral Damage Occurs When Using Photosensitizer Probes to Detect or Modulate Nucleic Acid Modifications

AbstractNucleic acids are chemically modified to fine‐tune their properties for biological function. Chemical tools for selective tagging of base modifications enables new approaches; the photosensitizers riboflavin and anthraquinone were previously proposed to oxidize N6‐methyladenine (m6A) or 5‐methylcytosine (5mdC) selectively. Herein, riboflavin, anthraquinone, or Rose Bengal were allowed to react with the canonical nucleosides dA, dC, dG, and dT, and the modified bases 5mdC, m6A, 8‐oxoguanine (dOG), and 8‐oxoadenine (dOA) to rank their reactivities. The nucleoside studies reveal that dOG is the most reactive and that the native nucleoside dG is higher or similar in reactivity to 5mdC or m6A; competition in both single‐ and double‐stranded DNA of dG vs. 5mdC or 6mdA for oxidant confirmed that dG is favorably oxidized. Thus, photosensitizers are promiscuous nucleic acid oxidants with poor chemoselectivity that will negatively impact attempts at targeted oxidation of modified nucleotides in cells.

Экспериментальное обоснование кросслинкинга склеры

Purpose. To substantiate the efficacy and safety of scleral collagen cross-linking with riboflavin and ultraviolet radiation. Material and methods. The study was conducted on cadaver porcine eyes and rabbit eyes. Results. It has been experimentally proven that crosslinking with riboflavin / ultraviolet A leads to an increase in the biomechanical strength of the scleral tissue, changing its structure and leading to an increase in the packing density of collagen fibers and an increase in the diameter of collagen fibrils, which confirms the formation of additional cross-links between scleral macromolecules. The absence of any pathological changes in the fibers of the fibrous membrane of the eye was established. The permeability of scleral tissue for ultraviolet radiation of the A range was determined. Based on the data obtained, a formula was proposed for calculating the threshold value of the intensity of ultraviolet radiation during the SCXL procedure. Using the methods of light microscopy, electroretinography and optical coherence tomography, it was revealed that SCXL with riboflavin / ultraviolet A under the studied parameters is safe for the structures of the eye (cornea, retina and optic nerve). A gentle technology for photopolymerization of the sclera with the use of the “UFalink S” device has been developed, the advantage of which is the ability to carry out ultraviolet irradiation in hard-to-reach areas of the eyeball. At the same time, an effective increase in the biomechanical strength characteristics of the scleral tissue was proved and the absence of a damaging effect on the structures of the eye was demonstrated. Conclusion. A clinical study of the scleral crosslinking procedure with riboflavin / ultraviolet A with the proposed parameters: irradiance of 3 mW / cm², irradiation time 30 minutes and preliminary saturation of the sclera with 0.1% aqueous solution of riboflavin for 20 minutes, which in experiments have shown their effectiveness and safety, is recommended. During the procedure, it is recommended to use a water-based photosensitizer riboflavin, without the addition of dextran, which leads to dehydration of the sclera and an increase in its permeability to ultraviolet light, which increases the risk of damage to the inner layers of the eye. Key words: scleral crosslinking, ultraviolet A, riboflavin, experiment, myopia.