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Rose bengal has been used in the diagnosis of ophthalmic disorders and liver function, and has been studied for the treatment of solid tumor cancers. To date, the antibacterial activity of rose bengal has been sporadically reported; however, these data have been generated with a commercial grade of rose bengal, which contains major uncontrolled impurities generated by the manufacturing process (80–95% dye content). A high-purity form of rose bengal formulation (HP-RBf, >99.5% dye content) kills a battery of Gram-positive bacteria, including drug-resistant strains at low concentrations (0.01–3.13 μg/mL) under fluorescent, LED, and natural light in a few minutes. Significantly, HP-RBf effectively eradicates Gram-positive bacterial biofilms. The frequency that Gram-positive bacteria spontaneously developed resistance to HP-RB is extremely low (less than 1 × 10−13). Toxicity data obtained through our research programs indicate that HP-RB is feasible as an anti-infective drug for the treatment of skin and soft tissue infections (SSTIs) involving multidrug-resistant (MDR) microbial invasion of the skin, and for eradicating biofilms. This article summarizes the antibacterial activity of pharmaceutical-grade rose bengal, HP-RB, against Gram-positive bacteria, its cytotoxicity against skin cells under illumination conditions, and mechanistic insights into rose bengal’s bactericidal activity under dark conditions.

Photodynamic therapy (PDT) is a promising cancer treatment. However, the efficacy of photosensitizers such as rose bengal (RB) is often limited by poor delivery. Dendrimer-based nanocarriers can enhance PDT efficacy in vitro, but their in vivo safety profile remains largely uncharacterized. This study aimed to assess the systemic safety of three different dendrimer-based RB delivery systems in a healthy mouse model. BALB/c mice were randomly divided into eight groups and received weekly intraperitoneal injections of either PBS (control), free RB, or one of three carriers (phosphorus dendrimer 1cat, dendrimersome DG2, PPI G3 dendrimer) with or without RB. Body weight was monitored weekly. Blood and urine samples were collected over four weeks for comprehensive biochemical and microscopic analysis, assessing markers for liver, kidney, and muscle function. No significant changes in body weight were observed across any of the groups. Analysis of blood biochemical parameters (including ALT, AST, urea, creatinine, and LDH) and urine profiles revealed no statistically significant differences between any treatment group and the PBS control group over the four-week study period. The observed minor fluctuations in some parameters were not dose- or time-dependent and remained within normal physiological ranges. The three tested nanocarrier systems - phosphorus dendrimer 1cat, dendrimersome DG2, and PPI G3 dendrimer - and their respective rose bengal formulations are well tolerated and do not induce systemic toxicity in BALB/c mice at the tested concentrations. These findings support their safety for in vivo applications and provide a basis for future efficacy studies in tumor-bearing animal models.

Adsorptive removal of rose bengal (RB) from contaminated water samples was approached using pineapple leaves (PAL). Three adsorbents were utilized for that purpose; raw pineapple leaves (RPAL) and the thermally activated bio-waste leaves at 250 and 500 °C. Two measures were executed to evaluate the functionality of exploited biomasses; percentage removal (%R) and adsorption capacity (qe). Face-centered central composite design (FCCCD) was conducted to experiment the influence of variables on the %R. Dose of PAL as adsorbent (AD), concentration of RB (DC), pH and contact time (CT), were the inspected factors. Existence of functional groups and formation of activated carbon was instigated employing Fourier-transform infrared (FT-IR) and Raman spectroscopies. Scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX) analyses were used to explore surface features. Thermal behavior of adsorbents was studied using thermogravimetric analysis (TGA). The surface area and other surface structural properties were established using the Brunauer Emmett-Teller (BET) analysis. An amount of 92.53% of RB could be removed with an adsorption capacity of 58.8 mg/g using a combination of pH 5.00 ± 0.20, RPAL dose of 0.05 mg/50 mL, and 10-ppm RB for 180 min. Equilibrium studies divulge a favorable adsorption that follows the Freundlich isotherm. Pseudo-second-order model explains the observed adsorption kinetics.

Dental diseases, including conditions affecting oral structures, have become more common due to unhealthy lifestyle choices. Traditional antibiotic treatments face challenges related to the development of antibiotic resistance in bacteria. Photodynamic antibacterial chemotherapy is emerging as a promising alternative using photosensitizers to generate reactive oxygen species upon exposure to light. This article examines the photosensitizer Rose Bengal (RB) immobilized in hyaluronic acid (HA) for prolonged antibacterial action. The RB-HA conjugate demonstrated a molar ratio of approximately three RB residues to each of the ten units of HA. RB-HA exhibited a high singlet oxygen quantum yield (ΔΦ = 0.90), suggesting its efficacy in photodynamic treatment. A photostability analysis revealed slower photobleaching of RB-HA, which is essential for prolonged application. Under visible light and ultrasonic treatment, RB-HA exhibited effective antibacterial activity against Gram-positive S. aureus and Gram-negative E. coli bacteria for at least 80 days. The gradual release of RB ensured sustained bactericidal concentration. The study establishes RB-HA as a promising candidate for antimicrobial photodynamic and sonodynamic therapy in dental and other medical fields, providing enhanced stability and prolonged antibacterial efficacy.

The global spread of bacterial resistance to antibiotics promotes a search for alternative approaches to eradication of pathogenic bacteria. One alternative is using photosensitizers for inhibition of Gram-positive and Gram-negative bacteria under illumination. Due to low penetration of visible light into tissues, applications of photosensitizers are currently limited to treatment of superficial local infections. Excitation of photosensitizers in the dark can be applied to overcome this problem. In the present work, dark antibacterial activity of the photosensitizer Rose Bengal alone and in combination with antibiotics was studied. The minimum inhibitory concentrations (MIC) value of Rose Bengal against S. aureus dropped in the presence of sub-MIC concentrations of ciprofloxacin, levofloxacin, methicillin, and gentamicin. Free Rose Bengal at sub-MIC concentrations can be excited in the dark by ultrasound at 38 kHz. Rose Bengal immobilized onto silicon showed good antibacterial activity in the dark under ultrasonic activation, probably because of Rose Bengal leaching from the polymer during the treatment. Exposure of bacteria to Rose Bengal in the dark under irradiation by electromagnetic radio frequency waves in the 9 to 12 GHz range caused a decrease in the bacterial concentration, presumably due to resonant absorption of electromagnetic energy, its transformation into heat and subsequent excitation of Rose Bengal.

The search for new formulations for photodynamic therapy is intended to improve the outcome of skin cancer treatment using significantly reduced doses of photosensitizer, thereby avoiding side effects. The incorporation of photosensitizers into nanoassemblies is a versatile way to increase the efficiency and specificity of drug delivery into target cells. Herein, we report the loading of rose bengal into vesicle-like constructs of amphiphilic triazine-carbosilane dendrons (dendrimersomes) as well as biophysical and in vitro characterization of this novel nanosystem. Using established protocol and analytical and spectroscopy techniques we were able to synthesized dendrons with strictly designed properties. Engaging biophysical methods (hydrodynamic diameter and zeta potential measurements, analysis of spectral properties, transmission electron microscopy) we confirmed assembling of our nanosystem. A set of in vitro techniques was used for determination ROS generation, (ABDA and H DCFDA probes), cell viability (MTT assay) and cellular uptake (flow cytometry and confocal microscopy). Encapsulation of rose bengal inside dendrimersomes enhances cellular uptake, intracellular ROS production and concequently, the phototoxicity of this photosensitizer. Triazine-carbosilane dendrimersomes show high capacity as drug carriers for anticancer photodynamic therapy.

Due to rising antibiotic resistance, it is necessary to develop alternative ways to combat pathogenic bacteria. One alternative is photodynamic antibacterial chemotherapy (PACT). This work presents the conjugation of the photosensitizer Rose Bengal (RB) to lectins to improve its efficacy against Gram-positive and Gram-negative bacteria. Two lectins, concanavalin A (ConA) and wheat germ agglutinin (WGA), were covalently linked to RB. Spectroscopic and chromatographic data confirmed successful conjugation. Microscopic examination demonstrated that both lectins agglutinate cells of Gram-positive S. aureus, including clinical multidrug-resistant MRSA strains, and Gram-negative E. coli, P. aeruginosa, and S. paratyphi B, although ConA showed a more pronounced reaction. Photodynamic assays showed that ConA-RB achieved complete eradication of S. aureus at significantly lower concentrations and light doses than free RB or WGA-RB. ConA-RB also exhibited higher efficacy against Gram-negative bacteria compared to free RB at lower concentrations and shorter illumination periods. WGA-RB was less effective, showing preferential activity against S. aureus. Our findings suggest that lectin–RB conjugates offer a promising approach for selective antibacterial treatment under illumination.

This study systematically evaluated the efficiency of rose bengal and methylene blue as photosensitizers against the immature aquatic stages of Anopheles pharoensis . Genetic identification using the COI partial sequence confirmed the species, and the obtained sequence was submitted to GenBank (Accession No. PQ346929). Both photosensitizers exhibited 100% mortality in larvae I within 24 h at their highest concentrations, demonstrating strong biocidal activity. LC 50 values for rose bengal increased from 1.50 ppm (24 h) and 1.34 ppm (48 h) in larvae I to 3.83 ppm (24 h) and 3.12 ppm (48 h) in pupae. Similarly, methylene blue showed LC 50 values rising from 1.14 ppm (24 h) and 0.90 ppm (48 h) in larvae I to 2.91 ppm (24 h) and 2.51 ppm (48 h) in pupae, indicating stage-dependent susceptibility. Enzymatic responses revealed a progressive increase in acetylcholinesterase (AChE) and glutathione S-transferase (GST) activity in the developmental stage, suggesting a physiological adaptation to the photosensitizers. Molecular docking against the AChE protein (PDB ID: 6xyu) confirmed insecticidal bioactivity, with methylene blue exhibiting superior binding affinity, aligning with the in-vitro larvicidal results. Furthermore, a Complex GAPI assessment confirmed the environmental sustainability of both photosensitizers, supporting their potential as eco-friendly alternatives for mosquito control. The use of Complex GAPI in assessing the environmental sustainability of photosensitizers in mosquito control represents a novel approach in the field of integrated pest management. This advancement not only aligns with the principles of green chemistry but also addresses the growing need for sustainable alternatives to traditional chemical insecticides. These findings highlight the feasibility of utilizing light-activated photosensitizers for sustainable vector management.

Background Micro-photodynamic therapy (MWPDT) combines photo-dynamic (PDT) and microwave-dynamic (MWDT) therapies with sensitizers, offers new avenues for cancer treatment. Despite the fact that novel sensitizers for MWPDT have been successfully synthesized, only a few are being employed effectively. The low tumor-targeting specificity, inability to transport sensitizer's deeper intratumorally, and deteriorating tumor microenvironment all restrict their anti-tumor efficacy. The current work was done aiming at microwave assisted drug delivery of titanium dioxide / rose Bengal conjugated chitosan nanoparticles (TiO 2 /RB@CSNP) for micro- photo-dynamic skin cancer (SKCA) treatment in vitro and in vivo as activated cancer treatment up-to-date modality. Materials and methods The study was conducted in vitro on human SKCA cells (A-375) and the study protocol application groups in vivo on Swiss albino mice treated with 7,12-dimethylbenz[a]anthracene (DMBA)/croton oil only and were not received any treatment for inducing SKCA, and only after SKCA induction the study treatment protocol began, treatment was daily with TiO 2 /RB@CSNP as MWPDT sensitizer with or without exposure to laser (IRL) or microwave (MW) or a combination of them for 3 min for two weeks. Results Revealed that CSNP can be employed as effective TiO 2 /RB delivery system that directly targets SKCA cells. Additionally TiO 2 /RB@CSNP is a promising MWPS for and when combined with MWPDT can be very effective in treatment of SKCA-A-375 in vitro (cell viability decreased in a dose-dependent basis, the cell cycle progression in G0/G1 was slowed down, and cell death was induced as evidenced by an increase in the population of Pre-G cells, an increase in early and late apoptosis and necrosis, and an increase in autophagic cell death) and DMBA/croton oil SKCA-induce mice in vivo (induced antiproliferative genes (caspase 3,9, p53, Bax, TNFalpha), suppressed antiapoptotic and antiangiogenic genes (Bcl2,VEGF respectively) effectively reducing the tumors growth and leading to cancer cell death as well as decreased oxidative stress (MDA), and ameliorated enzymatic and non-enzymatic antioxidants (SOD, GR, GPx, GST, CAT, GSH, TAC) as well as renal (urea, creatinine) and hepatic (ALT, AST) functions. This process could be attributed to MWPDT; microwave and/or photo-chemical TiO 2 /RB activation mechanism and antioxidant potential of non activated TiO 2 /RB as well. Conclusion The results indicate that TiO 2 /RB@CSNP has great promise as an innovative, effective delivery system for selective localized treatment of skin cancer that is activated by MWPDT.

Nonspecific targeting, large doses and phototoxicity severely hamper the clinical effect of photodynamic therapy (PDT). In this work, superparamagnetic Fe O mesoporous silica nanoparticles grafted by pH-responsive block polymer polyethylene glycol- -poly(aspartic acid) (PEG- -PAsp) were fabricated to load the model photosensitizer rose bengal (RB) in the aim of enhancing the efficiency of PDT. Compared to free RB, the nanocomposites (polyethylene glycol- -polyaspartate-modified rose bengal-loaded magnetic mesoporous silica [RB-MMSNs]) could greatly enhance the cellular uptake due to their effective endocytosis by mouse melanoma B16 cell and exhibited higher induced apoptosis although with little dark toxicity. RB-MMSNs had little dark toxicity and even much could be facilitated by magnetic field in vitro. RB-MMSNs demonstrated 10 times induced apoptosis efficiency than that of free RB at the same RB concentration, both by cell counting kit-8 (CCK-8) result and apoptosis detection. Furthermore, RB-MMSNs-mediated PDT in vivo on tumor-bearing mice showed steady physical targeting of RB-MMSNs to the tumor site; tumor volumes were significantly reduced in the magnetic field with green light irradiation. More importantly, the survival time of tumor-bearing mice treated with RB-MMSNs was much prolonged. Henceforth, polyethylene glycol- -polyaspartate-modified magnetic mesoporous silica (MMSNs) probably have great potential in clinical cancer photodynamic treatment because of their effective and low-toxic performance as photosensitizers' vesicles.