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Photodynamic therapy (PDT) is a minimally invasive treatment showing promise against cancer and microbial infections. PDT targets tumor cells while sparing healthy tissue, reducing side effects. It induces immunogenic cell death, potentially stimulating antitumor immune responses and reducing cancer recurrence. In microbial treatment, PDT effectively combats bacteria, fungi and viruses. Combining PDT with chemotherapy, radiotherapy and immunotherapy enhances its efficacy. However, challenges such as tumor hypoxia, limited tissue penetration and phototoxicity necessitate ongoing research efforts to optimize PDT protocols and overcome limitations. Overall, PDT is versatile and continually advancing with refined protocols to improve its clinical utility against cancer and microbial infections., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Background: Novel combination of Toluidine Blue O (TBO) embedded silicone catheter with domestic/household LED bulb has a potential in clinical infection such as prevention of multi drug resistant catheter-associated urinary tract infections (CAUTIs) through photodynamic therapy., Material and Methods: Preliminarily, TBO was entrapped into silicone catheter by swell-encapsulation-shrink method. Further, in vitro study was carried out to check the antimicrobial photodynamic efficacy of TBO with domestic/household LED light. Antibiofilm activity was evaluated by scanning electron microscopy., Results: The results showed that these modified TBO embedded silicone catheters showed significant antimicrobial and antibiofilm activity against vancomycin resistant Staphylococcus aureus VRSA. Small piece (1 cm) of TBO-embedded silicone catheter (700 µM) showed 6 log 10 reduction in the viable count when exposed for only 5 min of domestic/household LED bulb, while 1 cm piece of 500 µM and 700 µM concentration of TBO-embedded catheter eradicated all bacterial load when exposed to 15 min of light. Segment of medical grade TBO-embedded silicone catheters were used to carry out investigation of reactive oxygen species generation mainly singlet oxygen that contributes to type II phototoxicity., Conclusion: These modified catheter provides cost effective, easy to manage and less time consuming therapy to eliminate CAUTIs., Competing Interests: Declaration of Competing Interest The authors declare no competing financial interest., (Copyright © 2023. Published by Elsevier B.V.)

Environmental pollution and various bacterial strains cause severe health problems. Thus a need exists to synthesize new materials and develop new techniques which can be used against these hazardous pathogens and components. In this research work, sustainable and effective Co/ZnO nanocomposites were prepared via a new hydrothermal technique and ammonia evaporation method. The synthesized nanomaterial was analytically characterized through various techniques such as X-ray diffraction (XRD), UV-vis spectroscopy, Scanning electron microscope (SEM), High transmission electron microscopy (HRTEM), Fourier transform infrared spectroscopy (FTIR), Energy-dispersive X-ray spectroscopy (EDX) and X-ray photoelectron spectroscopy (XPS). The as prepared nanocomposite was tested for photodegradation of methylene blue (MB). This test was performed both in visible light and in dark condition. The results demonstrate that the said material is more efficient in light compared to dark conditions and decomposed more than 80% MB dye only in 60 min. The synthesized nanomaterial Co/ZnO was also tested against highly drug resistant bacteria Escherichia coli and Staphylococcus aureus both in light and dark. Hence, the antibacterial assessment indicates the zone of inhibition in visible light of Co/ZnO counter with Escherichia coli is 15 (±0.2) and for Staphylococcus aureus is 18 (±0.4) mm and in dark for Escherichia coli is 11 (±0.6) and for Staphylococcus aureus is 14 (±0.1) mm. Moreover, the detail mechanism, reactive oxygen species production and bacterial surface damage were also observed. We demonstrate that Co/ZnO nanomaterial is stable, eco-friendly photocatalyst shows high strength against MB degradation and also shows strong inhibition effect against pathogens in visible light., (Copyright © 2022 Elsevier B.V. All rights reserved.)

The increase of microbial resistance poses threats to human health. Therefore, efficient treatment of microbial resistance is a global challenge.. During this study, the Ag/NiO nanocomposite was fabricated via simple and ecofriendly method, using Uncaria rhynchophylla extract as a reducing and capping agent to avoid the aggregation of as synthesized nanomaterials. Here, a range of characterization techniques were employed to characterize the sample which includes UV-vis spectroscopy, X-ray diffraction, FTIR spectroscopy, electron diffraction spectroscopy (EDX), scanning electron microscopy (SEM). Furthermore, the resultant nanocomposite demonstrated an efficient ability for the inhibition of both gram-positive and gram negative pathogenic multidrug resistant bacteria. Additionally, the Ag/NiO nanocomposite showed a durable antioxidant effect against DPPH that could still reach 63% at very low concentration, i.e. 0.5 mg/mL. Interestingly, the synthesized nanocomposite is efficient for the production of reactive oxygen species (ROS) and shows no hemolytic activity. Likewise, the Ag/NiO nanocomposite displayed excellent photocatalytic activity to degrade 85% methylene blue (MB) by 4 mg/25 mL and could be used for waste water treatment. It is believed that synthesized nanostructure with desirable morphology and preparation simplicity can be promising material for antimicrobial, antioxidant and catalytic applications., (Copyright © 2021 Elsevier B.V. All rights reserved.)

With increasing demand for the treatment of microbial resistance around the globe, it is necessary to develop metallic nanoparticles , ideally by the use of nontoxic medium i.e. plant constituents, that could arrest the microbial growth. For this reason, small and highly crystalline PdNPs were effectively synthesized by using Eryngium caeruleum leaf extract as both the reducing and capping agent. During the synthesis of PdNPs, the size and shape were made controlled by using different solvents i.e., ethanol, methanol and aqueous extract of Eryngium caeruleum. A series of physicochemical characterizations were applied to inquire the synthesis, crystal structure, particles size, and surface morphology of PdNPs. Furthermore, the PdNPs demonstrated excellent potential for the inactivation of gram-positive and gram-negative bacteria, where the methanol-PdNPs exhibited maximum growth inhibition zones against tested bacteria as compared to ethanol-PdNPs and aqueous-PdNPs. Besides, PdNPs showed better antioxidant activity to effectively scavenge 2, 2 diphenyl-1-picrylhydrazyl (DPPH). More importantly, the synthesized PdNPs are not only active for ROS generation but also show no hemolytic activity. We believe that this greener approach uncovered the useful and efficient applications of highly active PdNPs and their biocompatibility., (Copyright © 2021. Published by Elsevier B.V.)

Biofilm mediated infections have major clinical impact. Staphylococcus aureus is a pathogen that frequently causes biofilm forming infections, such as those associated with medical devices and persistent wounds. Microorganisms embedded in biofilm are impervious to antibiotics and other antimicrobial agents, thus they are difficult to eliminate. The upsurge of multi-drug resistant strains makes treating such illnesses even more difficult. Therefore, new strategies are required to combat such type of infections. In this work, we have proposed an alternative therapeutic option to eradicate preformed biofilm of vancomycin resistant Staphylococcus aureus (VRSA) and enhanced phagocytosis by neutrophils in fresh human blood using curcumin mediated antimicrobial photodynamic therapy (aPDT).At sub-MIC of curcumin, different anti-biofilm assays and microscopic examinations were performed, followed by 20 J/cm 2 of blue laser light irradiation which corresponds to 52 s only. The result showed significant disruption of VRSA biofilm. Moreover, when curcumin-aPDT treated VRSA biofilm was exposed to whole blood from healthy donors, it was nearly completely eradicated. The present study suggests that curcumin-aPDT enhanced phagocytosis may be a useful strategy for inactivating VRSA biofilms adhering to medical implant surfaces., (Copyright © 2021. Published by Elsevier B.V.)

The present study reports the synthesis of silver (Ag) decorated zinc oxide (ZnO) nanocomposite via green synthesis method by using Acacia arabica plant leaves extract as both reducing and capping agent. The results clearly indicate a uniform distribution of Ag nanoparticles (NPs) over ZnO surface. Various analytical and spectroscopic techniques were used for investigating the formation and morphology of as-synthesized Ag/ZnO nanocomposites. Emergence of SPR at 424 and 378 nm confirmed the synthesis of AgNPs and ZnO respectively. The confirmation of elemental composition and crystal structure of prepared nanomaterials (NMs) was carried out via EDX and XRD analysis. Results obtained from HRTEM and SEM analysis indicated small sized spherically shaped NMs. The as-synthesized was checked for its photocatalytic activity towards degradation of MB in the presence as well as absence of light irradiation. Results of degradation study revealed that Ag/ZnO exhibits remarkable photocatalytic activity in the presence of light whereby removing 90% of MB within 80 min. Moreover, the antibacterial activity of synthesized nanocomposite was examined in both visible light and dark conditions. The experiment showed that nanomaterial depicts enhanced antibacterial activity in light in comparison to dark. The results showed that the inhibition diameter of Ag/ZnO nanocomposite in light was found to be 18 (±0.2), 22 (±0.3) against E. coli and S. aureus respectively. The inhibition zone of the said nanomaterial against E. coli and S. aureus in dark was 11 (±0.3), 14 (±0.5) respectively. These results conclude that activity is delivered both in the presence of visible light and dark but efficiency of antibacterial activity is found to be more in visible light in comparison., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Nanotechnologyapplications in the field of biomedicine like drug delivery, cell labeling, and bacterial inhibition are growing . New nano-materials having less toxicity and excellent antibacterial activity attract research interest. In the current study, while taking advantage of green synthesis we have decorated zinc oxide on the surface of grephene oxide forming Zno@GO nanocomposite. The Transmission electron microscopy (TEM) study showed successfully synthesized trigonal small sizes ZnO on the surface of GO nanosheets. The as-synthesized ZnO@GO was used against MDR gram-negative pathogen E-coli (BL21 DE3) and showed excellent antibacterial activity killing about 95 % toxic bacteria within 5 h due to electrostatic interaction between cell membrane of E. coli (BL21 DE3) and ZnO@GO complex. Hence the nano composite subsequently penetrated into the cytoplasm by damaging the cell membrane of bacteria, as a result production of ROS into the cytoplasm led to imbalance of metabolic system in the cell. Moreover, the cell membrane damage of gram-negative bacteria verified through zeta potential and propidium iodide (PI) study. Thus, our study develops a way to solve the challenge of efficient design of a drug delivery system for dissolution enhancement according to the need for required drug release., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Water pollution and bacterial resistance are universal problems. Drugs and protocols have been employed to deal with involved microbes and pollutants but these customary chemicals have many limitations. It is essential to produce new methods and materials to deal with these deleterious microbes. In the present contribution, highly efficient and stable nanocomposite of platinum activated zinc oxide was synthesized by a new plant extract and surfactant assisted protocol. The cetylpyridinium chloride was applied as surfactant to obtain high dispersion of spherical ZnO. The platinum ions were reduced on the ZnO surface by the use of Rhazya stricta plant extract. The prepared nanomaterial was used for photoinactivation of multidrug resistant bacterium Escherichia coli (E. coli). The synthesized nanomaterial showed strong E. coli inhibition efficiency in the presence of light and the observed diameter of zone of inhibition was 21 ±0.4. The effect of light on the inhibition of E.coli was studied by measuring the activated oxygen radicals inside the bacterium cell. The surface morphology of E.coli before and after treatment with Pt/ZnO was studied by SEM. Such effect was not observed in dark. The toxicity of the synthesized nanomaterials was also studied through haemolytic activity and the result shows that the nanomaterial prepared by the said method has very low toxicity. The photocatalytic degradation of methylene blue (MB) was also investigated in the presence of the synthesized nanomaterials. Effect of different parameters such as concentration of Pt/ZnO, Irradiation time and dye concentrations were also studied. An incredible photocatalytic deprivation of MB (98 %) was observed for Pt/ZnO nanocomposite as compared to individual Pt (48%) and ZnO (71%) nanoparticles after 5 minutes of irradiations. Further research is required to investigate the applications of Pt/ZnO nanocomposite., (Copyright © 2021. Published by Elsevier B.V.)

Biofilm mediated infection caused by multi-drug resistant bacteria are difficult to treat since it protects the microorganisms by host defense system, making them resistant to antibiotics and other antimicrobial agents. Combating such type of nosocomial infection, especially in immunocompromised patients, is an urgent need and foremost challenge faced by clinicians. Therefore, antimicrobial photodynamic therapy (aPDT) has been intensely pursued as an alternative therapy for bacterial infections. aPDT leads to the generation of reactive oxygen species (ROS) that destroy bacterial cells in the presence of a photosensitizer, visible light and oxygen. Here, we elucidated a possibility of its clinical application by reducing the treatment time and exposing curcumin to 20 J/cm 2 of blue laser light, which corresponds to only 52 s to counteract vancomycin resistant Staphylococcus aureus (VRSA) both in vitro and in vivo. To understand the mechanism of action, the generation of total reactive oxygen species (ROS) was quantified by 2'-7'-dichlorofluorescein diacetate (DCFH-DA) and the type of phototoxicity was confirmed by fluorescence spectroscopic analysis. The data showed more production of singlet oxygen, indicating type-II phototoxicity. Different anti-biofilm assays (crystal violet and congo red assays) and microscopic studies were performed at sub-MIC concentration of curcumin followed by treatment with laser light against preformed biofilm of VRSA. The result showed significant reduction in the preformed biofilm formation. Finally, its therapeutic potential was validated in skin abrasion wistar rat model. The result showed significant inhibition of bacterial growth. Furthermore, immunomodulatory analysis with rat serum was performed. A significant reduction in expression of proinflammatory cytokines TNF-α and IL-6 were observed. Hence, we conclude that curcumin mediated aPDT with 20 J/cm 2 of blue laser treatment (for 52 s) could be used against multi-drug resistant bacterial infections and preformed biofilm formation as a potential therapeutic approach., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Green chemistry is a modern area of research which covers synthesis of nanomaterials through useful, environmentally, economically friendly techniques and their use in different fields. The synthesis involves the formation of bimetallic nanomaterials to enhance their synergistic relationship and achieve special modulated properties. That's why bimetallic nanomaterials are extremely important and gaining interest among researchers in the field of medicinal chemistry for the treatment of various diseases. In this particular study, bimetallic nanoparticles synthesis was done by reduction procedure using leaf extract of Olea cuspidata. The phytochemicals in leaf extract act as stabilizing and capping agent in reduction of precursor's salts. The characterization of green synthesized Ag@MgO nanocomposite was done through several analytical techniques such as ultraviolet-visible (UV-vis) spectroscopy, X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), Scanning electron microscope (SEM), High resolution transmission electron microscope (HRTEM) and Zeta potential. To explore the biological potential of synthesized nanocomposite, antibacterial activities against gram negative (Escherichia coli) bacteria and gram positive (Staphylococcus aureus) has been evaluated. The photocatalytic activity in contrary to methylene blue (MB) decomposition was seen efficiently. Moreover, the antioxidant nature of green synthesized Ag@MgO nanocomposite was analyzed by destabilizing and scavenging maximum percentage (93 %) of dangerous and harmful 2, 2-diphenyl-1-picrylhydrazyl (DPPH) free radical. The best and surprising results provided the information for the presence of essential and vital components in Olea Cuspidata in the form of organic acids (Citrus Acid) aids in stabilizing the entire structure with enhanced properties. Up to the best of our knowledge, the facts and results obtained regarding the structure of Ag@MgO nanocomposite clearly illustrates the uniqueness of green chemistry and also its role in future developing multifunctional nanoparticles in the field of nanobiotechnology., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Noble metal/metal oxide nanocomposites are pet and spellbound candidates in biomedical and catalytic fields because of their awestruck properties. This report put forward the facile and environmentally friendly fabrication of Ag/Fe 2 O 3 nanocomposite using the eqeous extract of Algaia Monozyga leaves. The Ag/ Fe 2 O 3 bimetallic nanocomposite was prepared using AgNO 3 , FeCl 3 (anhydrous) and plant leaves extract as a natural source for reduction and stabilization of this nanocomposite. We prepared a separate solution of Silver and Iron salts and upon addition of this solution to the plant extract, the conversion of colour to brown appears within 10 min at constant stirring at 350 rpm. To confirm the synthesis of nanocomposite, UV-vis spectroscopy, Scanning electron microscopy (SEM), EDX and X-ray diffraction spectroscopy were used. The as prepared nanocomposite was used for photocatalytic activity in degradation of Methylene Blue (MB) in the presence of light which shows effective photocatalytic activity. The antimicrobial activities were also determined for nanocomposite which were found to be efficient against human pathogenic multidrug resistant bacteria. The Ag/Fe 2 O 3 nanocomposite significantly preventing the growth of Staphylococcus aureus, E.coli QH4 and Pseudomonas putida with zones of inhibition 23 (±0.5), 21 (±0.4) and 19 (±0.4) mm, respectively.The eco-benignly synthesized Ag/Fe 2 O 3 nanocomposite could be a desired material for efficient remediation of toxic organic pollutants and microbes., (Copyright © 2020 Elsevier B.V. All rights reserved.)

In the current scenario, frontline antibiotics are losing effectiveness against multidrug-resistant (MDR) bacteria because of the single mode of action. The accumulation of mutations and spread of antibiotic resistance markers among the bacteria results into the severe threat to community health. Now, there is an urgent requirement for the development of an alternate and as well as multiple-targeted action of drugs to stop the spread of resistance in bacteria. Here, we showed an alternative nanoparticle based photodynamic therapy (PDT) targeting the bacterial efflux pumps and its cell wall. The dextran capped gold nanoparticles (GNP DEX ) were localized to the bacterial surface by nanoparticle attached Concanavalin-A (ConA), where GNP DEX attached methylene blue (MB) photosensitizer as an MB@GNP DEX -ConA formulation induced the killing of MDR Klebsiella pneumoniae clinical isolates in no time. The intervention of efflux pump inhibitor (EPI) further improved the MB@GNP DEX -ConA treatment modality and displayed the maximum bactericidal cytoplasmic phototoxicity. The CCCP EPI (carbonyl cyanide m-chlorophenylhydrazone) with the PDT increased the bacterial killing by>3 log10 as compared with or without EPI intervention. Further, the fractionated (two light treatment after long dark phase) PDT treatment modality decreased the bacterial biofilm growth up to ~90%. The microscopic as well as ROS fluorescent probes showed the singlet oxygen mediated cytotoxicity. The mode of interactions and genomic DNA photo-toxicity confirmed that EPI enhanced the killing mediated by singlet oxygen generation. The multi-targeted (Cell wall, DNA and efflux pump) modality of MB@GNP DEX -ConA in presence of EPI is an effective and alternative therapeutic approach against most potent Klebsiella MDR infections., (Copyright © 2020 Elsevier B.V. All rights reserved.)

In this work, principles and techniques of green chemistry were implemented which exploit environmentally and economically friendly methods using an accessible and non-toxic medium, that is water and ascorbic acid (Vit.C), which leads to the synthesis of silver/ copper oxide (Ag/CuO) nanocomposite. Vit.C was used to furnish the synthesis of excellent and controlled crystalline silver nanoparticles (AgNPs), copper oxide (CuO) and Ag/CuO nanocomposite. Moreover, the structures of all the synthesized nanomaterials were confirmed by wide range of characterization techniques which include UV-vis spectroscopy, FTIR, X-ray diffraction and Electron Diffraction Spectroscopy. However external and internal morphology of newly synthesized nanomaterials were examined by using Scanning Electron Microscopy and High resolution Transmission Electron Microscopy, respectively. The prepared nanomaterials were evaluated for catalytic decomposition of methyl orange (MO) in dark, visible light and UV light. The results showed that 20 %, 50 % and 90 % degradation of MO in 40 min was observed in dark, visible light and UV light, respectively. To further explore the biological potential of synthesized Ag/CuO nanocomposite, we also evaluated it for an inactivation of bacteria where Escherichia coli has 17(±0.5 mm) and Staphylococcus aureus has 20 (±0.6 mm) zone of inhibition in light. The results showed that reactive oxygen species (ROS) were produced in the presence of light and Ag/CuO. These ROS are the main source of inactivation of bacteria. The prepared nanomaterial has also good efficiency against DPPH stabilization. Further study is required to investigate the hidden applications of the as synthesized nanomaterials., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Objective: The objective of this study was to inhibit the Pseudomonas aeruginosa biofilm through curcumin-mediated antimicrobial photodynamic therapy (A-PDT)., Background: The mechanism behind A-PDT mediated photoinactivation depend upon reactive oxygen species (ROS) production, like singlet oxygen and free radicals., Methods: To evaluate the antibacterial efficacy of curcumin induced A-PDT on P. aeruginosa by colony forming unit (CFU) while antibiofilm action was determined by the use of crystal violet, XTT, congored binding assay and confocal laser scanning microscope (CLSM)., Results: We found that curcumin with 10 J/cm 2 of light reduces P. aeruginosa biofilm more efficiently than without light. Extracellular polymeric substances (EPS) production was also reduced by approx 94 % with 10 J/cm 2 of light dose. CLSM images showed that the thickness of biofilms were reduced from >30 μm to <5 μm after treatment with curcumin followed by 10 J/cm 2 of light irradiation. Curcumin showed better bacteriostatic activity than bactericidal activity. Singlet oxygen is primarily responsible for photodamage and cytotoxic reactions caused by curcumin-mediated APDT. Genes involved in quorum sensing (QS) pathway was also found to be inhibited after APDT. Curcumin with 5 J/cm 2 light inhibits QS genes and on increasing light dose i.e10 J/cm 2 , we found a drastic reduction in gene expression., Conclusion: We conclude that the curcumin mediated A-PDT inhibits biofilm formation ofP. aeruginosa through QS pathway by the action of singlet oxygen generation which in turn reduced EPS of the biofilm., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Photodynamic therapy (PDT) has been widely used in dermatology to treat different skin diseases. Here, we aim to compare the efficacy of single versus multiple fraction light illumination PDT for high grade lesions of cutaneous leishmaniasis (CL). In particular, 60 patients (104 CL lesions) were randomly divided into two groups; 30 patients (46 CL lesions) in group I were treated with methylaminolevulinate (MAL)-based PDT in three sessions, with a light dose of 90 J/cm 2 delivered in a single fraction in each session. The 30 patients (58 CL lesions) in group II received the same treatment, except the light dose in each session was delivered in three fractions. Patient assessment at nine months follow-up revealed complete response at 35 (76 %) for group I, compared to 53 (91.4 %) for group II. Moreover, partial response was observed in 11 (24 %) CL lesions for group I, as compared with 5 (8.6 %) CL lesions in group II. Pain and burning sensation in patients from group II was markedly less than patient from group I. In conclusion, fractionated illumination improves the treatment efficacy of PDT for high grade CL lesions., Competing Interests: Declaration of Competing Interest The authors declare no conflicts of interest., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Aim: The purpose of this study was to investigate how Enterococcus faecalis and Streptococcus mutans behave in mono and dual species biofilm after photodynamic treatment., Background: Antimicrobial photodynamic therapy (aPDT) leads to the generation of reactive oxygen species (ROS) that destroys bacterial cells in presence of a photosensitizer, visible light, and oxygen., Material and Methods: We have taken Enterococcus faecalis and Streptococcus mutans as monospecies culture and their dualspecies culture biofilm. Antibacterial effect was evaluated by colony forming unit while antibiofilm action by crystal violet and congored binding assays., Results: We found that dual species biofilm are more resistant than monospecies biofilm and S. mutans shows dominance over E. faecalis in dual species biofilm, it inhibited the growth of E. faecalis in dual species biofilm. Antibiofilm efficacy of TBO also validated that dualspecies show less inhibition than monospecies biofilm this may be due to different EPS constitution in dualspecies biofilm, hence less inhibition was observed in EPS production of dualspecies biofilm than monospecies biofilm. Reactive oxygen species and singlet oxygen yield was found to be light dose dependent and antimicrobial photodynamic efficiency is directly related to the ROS production., Conclusion: We conclude that dual species biofilm shows resistance over monospecies biofilm and S. mutans in dual species inhibits the growth of E. faecalis., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Background: Antimicrobial photodynamic therapy (APDT) is a process that generates reactive oxygen species (ROS) in presence of photosensitizer, visible light and oxygen which destroys the bacterial cells. We investigated the photoinactivation efficiency of phenothiazinium dyes and the effect of ROS generation on Gram positive and Gram negative bacterial cell as well as on biofilm., Material and Methods: Enterococcus faecalis and Klebsiella pneumonia were incubated with all the three phenothiazinium dyes and exposed to 630nm of light. After PDT, colony forming unit (CFU) were performed to estimate the cell survival fraction. Intracellular reactive oxygen species (ROS) was detected by DCFH-DA. Crystal violet (CV) assay and extracellular polysaccharides (EPS) reduction assay were performed to analyze antibiofilm effect. Confocal laser electron microscope (CLSM) scanning electron microscope (SEM) was performed to assess the disruption of biofilm., Results: 8log 10 reduction in bacterial count was observed in Enterococcus faecalis while 3log 10 in Klebsiella pneumoniae. CV and EPS reduction assay revealed that photodynamic inhibition was more pronounced in Enterococcus faecalis. In addition to this CLSM and SEM study showed an increase in cell permeability of propidium iodide and leakage of cellular constituents in treated preformed biofilm which reflects the antibiofilm action of photodynamic therapy., Conclusion: We conclude that Gram-positive bacteria (Enterococcus faecalis) are more susceptible to APDT due to increased level of ROS generation inside the cell, higher photosensitizer binding efficiency and DNA degradation. Phenothiazinium dyes are proved to be highly efficient against both planktonic and biofilm state of cells., (Copyright © 2017 Elsevier B.V. All rights reserved.)

The objective of this study was to evaluate the anti-biofilm efficacy of photodynamic therapy by conjugating a photosensitizer (TBO) with silver nanoparticles (AgNP). Streptococcus mutans was exposed to laser light (630 nm) for 70 s (9.1 J cm(-2)) in the presence of a toluidine blue O-silver nanoparticle conjugate (TBO-AgNP). The results showed a reduction in the viability of bacterial cells by 4 log10. The crystal violet assay, confocal laser scanning microscopy and scanning electron microscopy revealed that the TBO-AgNP conjugates inhibited biofilm formation, increased the uptake of propidium iodide and leakage of the cellular constituents, respectively. Fluorescence spectroscopic studies confirmed the generation of OH(•) as a major reactive oxygen species, indicating type I phototoxicity. Both the conjugates down-regulated the expression of biofilm related genes compared to TBO alone. Hence TBO-AgNP conjugates were found to be more phototoxic against S. mutans biofilm than TBO alone.

This article explores the novel gold nanoparticle-enhanced photodynamic therapy of methylene blue against recalcitrant pathogenic Candida albicans biofilm. Physiochemical (X-ray diffraction, ultraviolet-visible absorption, photon cross-correlation, FTIR, and fluorescence spectroscopy) and electron microscopy techniques were used to characterize gold nanoparticles as well as gold nanoparticle-methylene blue conjugate. A 38.2-J/cm(2) energy density of 660-nm diode laser was applied for activation of gold nanoparticle-methylene blue conjugate and methylene blue against C. albicans biofilm and cells. Antibiofilm assays, confocal laser scanning, and electron microscopy were used to investigate the effects of the conjugate. Physical characteristics of the gold nanoparticles (21 ± 2.5 nm and 0.2 mg/mL) and methylene blue (20 μg/mL) conjugation were confirmed by physicochemical and electron microscopy techniques. Antibiofilm assays and microscopic studies showed significant reduction of biofilm and adverse effect against Candida cells in the presence of conjugate. Fluorescence spectroscopic study confirmed type I photo toxicity against biofilm. Gold nanoparticle conjugate-mediated photodynamic therapy may be used against nosocomially acquired refractory Candida albicans biofilm.