Sub-additive effects of photodynamic therapy combined with erlotinib for the treatment of epidermoid carcinoma: An in vitro study

BackgroundPhotodynamic therapy (PDT) is an antitumour treatment that employs the combination of a photosensitive compound, oxygen and visible light. To improve the antitumour activity of PDT, the present study used the strategy of combining PDT with erlotinib (ERL), a drug frequently used in the treatment of epidermoid carcinoma.MethodsAn MTT cell viability assay was used to evaluate the cytotoxicity of PDT combined with ERL on A431 epidermoid carcinoma cells in vitro. This study evaluated the cytotoxicity of the following treatments: red laser irradiation (660 nm) at different power densities (1.25–180 J/cm²), the photosensitizer methylene blue (MB) at concentrations of 0.39–100 μM, PDT (12.5 μM MB and laser power densities from 1.25 to 180 J/cm²), and PDT (12.5 μM MB and a laser density of 120 J/cm²) plus ERL (1 μM).ResultsThe laser power densities that were tested showed no cytotoxicity in A431 cells. MB showed a dose-dependent cytotoxicity. In PDT, an increase in the dose of light resulted in an increase in the cytotoxicity of MB. In addition, there was a sub-additive effect between PDT and ERL compared to the effect of each therapy alone.ConclusionsThe sub-additive effect between PDT and ERL suggests that their combination may be an important strategy in the treatment of epidermoid carcinoma.     

Photodynamic inactivation of Candida albicans by a tetracationic tentacle porphyrin and its analogue without intrinsic charges in presence of fluconazole

The photodynamic inactivation mediated by 5,10,15,20-tetrakis[4-(3-N,N-dimethylaminopropoxy)phenyl]porphyrin (TAPP) and 5,10,15,20-tetrakis[4-(3-N,N,N-trimethylaminepropoxy)phenyl]porphyrin (TAPP⁴⁺) were compared in Candida albicans cells. A strong binding affinity was found between these porphyrins and the yeast cells. Photosensitized inactivation of C. albicans increased with both photosensitizer concentration and irradiation time. After 30 min irradiation, a high photoinactivation (∼5 log) was found for C. albicans treated with 5 μM porphyrin. Also, the photoinactivation of yeast cells was still elevated after two washing steps. However, the photocytotoxicity decreases with an increase in the cell density from 10⁶ to 10⁸ cells/mL. The high photodynamic activity of these porphyrins was also established by growth delay experiments. This C. albicans strain was susceptible to fluconazole with a MIC of 1.0 μg/mL. The effect of photosensitization and the action of fluconazole were combined to eradicate C. albicans. After a PDI treatment with 1 μM porphyrin and 30 min irradiation, the value of MIC decreased to 0.25 μg/mL. In addition, a complete arrest in cell growth was found by combining both effects. TAPP was similarly effective to photoinactivate C. albicans than TAPP⁴⁺. This porphyrin without intrinsic positive charges contains basic amino groups, which can be protonated at physiological pH. Moreover, an enhancement in the antifungal action was found using both therapies because lower doses of the agents were required to achieve cell death.     

Antimicrobial photodynamic therapy on Streptococcus mutans is altered by glucose in the presence of methylene blue and red LED

BackgroundDental caries are a multifactorial disease that progressively produces tooth destruction as a result of bacterial colonization of enamel surface, especially Streptococcus mutans. The objective of this work was to investigate the role of glucose in antimicrobial photodynamic therapy (aPDT) on S. mutans.MethodsS. mutans ATCC 25175 were cultured on microaerophilia at 37 °C for 48 h, and we tested aPDT in the presence of 50 mM glucose. Bacterial suspension was used to investigate aPDT with 100 μM methylene blue (MB) under LED emitting radiation at ʎ = 660 nm and parameters as following (P = 473 mW; I = 166.8 mW/cm², and doses of 5, 10 and 20 J/cm²). A seventy-two hours biofilm was grown on 96 flat buttoned well-plate and irradiation was performed from 10 to 80 J/cm² at similar conditions.ResultsThere was no dark toxicity nor bacterial death regarding LED irradiation on suspension and on biofilm. Nevertheless, aPDT presented expressive bacterial inactivation following 1 and 2 min of irradiation on cell suspension. On the other hand, there was no inactivation in the presence of glucose under the same conditions. Biofilm was completely inactivated by MB-mediated aPDT after 6 min of irradiation. However, the presence of glucose delayed the complete inactivation of the biofilm.ConclusionThe presence of glucose in the suspension drastically delayed the effect of aPDT on S. mutans and this effect is more pronounced in bacterial suspension than on biofilm.     

Antimicrobial photodynamic effect of phenothiazinic photosensitizers in formulations with ethanol on Pseudomonas aeruginosa biofilms

Background dataMethylene blue (MB) and toluidine blue (TB) are recognized as safe photosensitizers (Ps) for use in humans. The clinical effectiveness of the antimicrobial photodynamic therapy with MB and TB needs to be optimized, and ethanol can increase their antimicrobial effect. Formulations of MB and TB containing ethanol were evaluated for their ability to produce singlet oxygen and their antibacterial effect on Pseudomonas aeruginosa biofilms.MethodsPhotoactivated formulations were prepared by diluting the Ps (250 μM) in buffered water (pH 5.6, sodium acetate/acetic acid), 10% ethanol (buffer: ethanol, 90:10), or 20% ethanol (buffer: ethanol, 80:20). Biofilms also were exposed to the buffer, 10% ethanol, or 20% ethanol without photoactivation. Untreated biofilm was considered the control group. The production of singlet oxygen in the formulations was measured based on the photo-oxidation of 1,3-diphenylisobenzofuran. The photo-oxidation and CFU (log₁₀) data were evaluated by two-way ANOVA and post-hoc Tukey’s tests.ResultsIn all the formulations, compared to TB, MB showed higher production of singlet oxygen. In the absence of photoactivation, neither the buffer nor the 10% ethanol solution showed any antimicrobial effect, while the 20% ethanol solution significantly reduced bacterial viability (P = 0.009). With photoactivation, only the formulations containing MB and both 10% and 20% ethanol solutions significantly reduced the viability of P. aeruginosa biofilms when compared with the control.ConclusionsMB formulations containing ethanol enhanced the antimicrobial effect of the photodynamic therapy against P. aeruginosa biofilms in vitro.     

Photodynamic therapy with high-power LED mediated by erythrosine eliminates Enterococcus faecalis in planktonic forms

BackgroundThe failure of endodontic treatment is linked to the presence of microorganisms, particularly Enterococcus faecalis, in the root canals. This study evaluated the effectiveness of photodynamic therapy (PDT) using erythrosine irradiated by a high-power curing light on a planktonic suspension culture of E. faecalis.MethodsBacterial suspensions of E. faecalis were adjusted and then mixed in a 1:1 proportion, in triplicate, in treatment groups by varying the length of irradiation time (120 and 240 s) and the molarity of the erythrosine (5 and 10 μM). In order to verify the post-treatment bactericidal effect, a count of the viable bacteria was performed (CFU mL⁻¹) and transformed into Log10 CFU. The one-way ANOVA with Tukey post-hoc test was applied to check for differences between the groups.ResultsThe bacteria were completely eradicated in the groups that used PDT with 5 μM 240 s, 10 μM 120 s and 10 μM 240 s (p ≪ 0.001). The effect of the PDT 5 μM 120 s group was significant (p ≪ 0.05) in comparison with the groups using only light or only erythrosine. Positive control (exposure to 2.5% NaClO for 120 and 240 s) completely eradicated E. faecalis. The negative control (PBS) did not alter the quantities of E. faecalis CFU with 9.605 Log10 CFU at 120 s and 9.621 Log10 CFU at 240 s.ConclusionPDT with erythrosine in a concentration of 10 μM and high-power LED is capable of totally eliminating E. faecalis in planktonic suspension.     

Dependence of damage within 10 min to myocardial cells by a photodynamic reaction with a high concentration of talaporfin sodium outside cells in vitro on parameters of laser irradiation

BackgroundTo investigate the immediate occurrence of irreparable severe damage to myocardial cells up to 10 min after a photodynamic reaction with a high concentration of photosensitizer outside cells, we measured the damage response time and the parameters that govern the response time via rat myocardial Ca²⁺ concentration. In our proposed method for catheter ablation of tachyarrhythmia by photodynamic reaction, there are two components to the electrical conduction block: an immediate electrical conduction block of several tens of seconds to several minutes, and a permanent electrical conduction block.MethodsRat myocardial intracellular Ca²⁺ concentration changes before, during and after the photodynamic reaction with a high concentration of photosensitizer outside myocardial cells were continuously observed using a Fluo-4 AM Ca²⁺ probe. Talaporfin sodium with 663-nm excitation was used to induce the photodynamic reaction. Talaporfin concentration was 10–30 μg/ml, radiant exposure was 10–40 J/cm², and irradiance was 30–290 mW/cm². We evaluated the response time of irreparable severe damage to myocardial cells, according to Ca²⁺ concentration.ResultsThe response time of the defined severe damage occurrence to myocardial cells ranged from 200 to 500 s. The response time decreased with increasing irradiance and photosensitizer concentration, but exhibited no significant change with total radiant exposure.ConclusionsWe found that severe myocardial cell damage caused by a photodynamic reaction with a high concentration of photosensitizer outside cells occurred within a few minutes, which might be useful for catheter ablation for tachyarrhythmia that needs immediate response during the ablation procedure.     

Comparative effect of photodynamic therapy on separated or mixed cultures of Streptococcus mutans and Streptococcus sanguinis

Antimicrobial photodynamic therapy (aPDT) has shown to exert a bactericidal effect against Streptococcus sanguinis and Streptococcus mutans. However, this efficacy has been reported for either type of bacteria separately. Bacterial suspensions of both strains, separately or together, were treated with concentrations of methylene blue (MB) and rose bengal (RB). Suspensions were irradiated with a light–emitting diode lamp (λ center at 625 nm for MB and λ center at 515 nm for RB) using a fluence of 18 J/cm². RB-aPDT at concentrations of 0.16–0.62 and 0.16–0.31 μg/mL, and MB-aPDT at concentrations of 0.62–1.25 and 0.31–1.25 μg/mL inhibited the growth of S. mutans and S. sanguinis respectively by 6 log₁₀. In suspensions of both strains together, the same 6 log₁₀ reduction in bacterial growth was achieved using the same concentrations of each photosensiziser.In conclusion, RB-aPDT and MB-aPDT appear to exert the same bactericidal effect against suspensions of S. sanguinis and S. mutans either for single strain treatment or for samples constituted by both bacteria mixed together. RB shows to be slightly more efficient than MB.     

Effect of different wavelengths and dyes on Candida albicans: In vivo study using Galleria mellonella as an experimental model

BackgroundStudies on photodynamic inactivation against microorganisms had a great development in recent years. The aim of this work was to test the application of different laser wavelengths with or without different photosensitizing dyes on Candida albicans cells in vitro and in photodynamic therapy protocols in vivo in larvae of Galleria mellonella.MethodsLaser application was realized on C. albicans cells suspended in saline solution or cultured on solid medium for the in vitro study, and in a model of G. mellonella candidal infection for the in vivo study. Three wavelengths (650, 405, and 532 nm) were used in continuous mode with different values of applied fluences: 10, 20 and 30 J/cm² for the in vitro study and 10 J/cm² for the in vivo study, without and with photosensitizing dyes.ResultsNo growth inhibition was obtained on yeast cells in saline solution without photosensitizers. The maximum inhibition of growth (100%) was obtained with 405 nm diode laser and curcumin at any used fluence. No growth inhibition was observed for yeast cells cultured on solid medium after laser application without dyes. An inhibition was observed after laser application when curcumin and erythrosine were added to the medium.The survival curves of G. mellonella larvae infected with C. albicans with or without the different dyes and after laser application showed a statistically significant difference (p < 0.001) in comparison with the proper control groups.ConclusionsThese results show the efficacy of photodynamic inactivation exploiting a suitable combination of light and dyes against C. albicans and the potential of photodynamic therapy for the treatment of candidal infections.     

Novel cationic-chalcone phthalocyanines for photodynamic therapy eradication of S. aureus and E. coli bacterial biofilms and MCF-7 breast cancer

New tetrasubstituted zinc (II) and indium (III) phthalocyanines bearing dimethylamino chalcone group (complexes 3 and 4) as well as their quaternized analogs (3a and 4a) have been assessed for their photodynamic therapy (PDT) of cancer as well as photodynamic antimicrobial chemotherapy activities against biofilms and planktonic cultures of pathogenic bacteria of Staphylococcus aureus and Escherichia coli. Compared to the non-quaternized phthalocyanines 3 and 4, the cationic phthalocyanines 3a and 4a exhibit a higher photodynamic inactivation against the planktonic cells with log reduction values above 9 at a concentration of 1.25 µM. This was attributed to the positive charge which enhances cellular uptake. More interestingly, 3a and 4a show a higher photodynamic inactivation (less than 3% of S. aureus survived) on their biofilm counterparts thanks to their stronger affinity to these cells. 3a and 4a Pcs also exhibited interesting PDT activity against MCF-7 cancer cells giving IC₅₀ values of 17.9 and 7.4 μM, respectively following 15 min irradiation. The obtained results in this work show that the positively charged phthalocyanines 3a and 4a are potential antibacterial photosensitizers that show some selectivity toward the Gram-positive and Gram-negative bacteria as well as MCF-7 breasts cancer cells.     

Evaluation of photo-activated disinfection effectiveness with methylene blue against Porphyromonas gingivalis involved in endodontic infection: An in vitro study

BackgroundEradication or suppression of microbial pathogens is a major goal in endodontic infection therapy. Sub-lethal doses of photo-activated disinfection (sPAD) as a new treatment method might be able to control the microorganisms involved in endodontic infections normally treated with PAD. This study evaluated the effect of sPAD using methylene blue (MB) in combination with diode laser irradiation on the growth and biofilm formation ability of Porphyromonas gingivalis as an endodontic pathogen.Materials and methodsThe anti-microbial and anti-biofilm potential of sPAD against P. gingivalis were assessed at sub-lethal doses of MB and irradiation by diode laser on colony forming unit and crystal violet assays, respectively.ResultsMB-sPAD using 25 μg/mL at a fluency of 117.18 J/cm² and 50–100 μg/mL at a fluency of 93.75 J/cm² significantly P. gingivalis growth when compared to the control. MB at 100 μg/mL at a fluency of 117.18 J/cm² in MB-mediated PAD showed a significant inhibitory effect on biofilm formation in P. gingivalis compared with MB-sPAD.ConclusionHigh doses of MB-mediated sPAD exhibited anti-microbial and anti-biofilm potential activity, whereas lower doses of MB-mediated sPAD did not display this ability. Therefore, the dose of PAD used in vivo should be taken into account for endodontic treatment.     

Influences of Microbubble Diameter and Ultrasonic Parameters on In Vitro Sonothrombolysis Efficacy

PurposeTo quantify the effects of microbubble (MB) size, elasticity, and pulsed ultrasonic parameters on in vitro sonothrombolysis (ultrasound [US]-mediated thrombolysis) efficacy.Materials and MethodsMonodispersive MBs with diameters of 1 μm or 3 μm were exposed to pulsed US (1 MHz or 3 MHz) to lyse rabbit blood clots. Sonothrombolysis efficacy (clot mass loss) was measured as functions of MB size and concentration, ultrasonic frequency and intensity, pulse duration (PD), pulse repeat frequency (PRF), and duty factor.ResultsSonothrombolysis at 1 MHz was more effective using 3-μm MBs and at 3 MHz using 1-μm MBs. Sonothrombolysis was more effective at 1 MHz when≥75% of MBs remained intact, especially for 3-μm MBs; improving sonothrombolysis by increasing PRF from 100 Hz to 400 Hz at 3 MHz was associated with increasing 3-μm MB survival. However, 60% of 1-μm MBs were destroyed during maximal sonothrombolysis at 3 MHz, indicating that considerable MB collapse may be required for sonothrombolysis under these conditions.ConclusionsThe ability to control MB size and elasticity permits using a wide range of US parameters (eg, frequency, intensity) to produce desired levels of sonothrombolysis. Comparable, maximal sonothrombolysis efficacy was achieved at 20-fold lower intensity with 3-μm MBs (0.1 W/cm²) than with 1-μm MBs (2.0 W/cm²), a potential safety issue for in vivo sonothrombolysis. US parameters that maximized MB survival yielded maximal sonothrombolysis efficacy except with 1-μm MBs at 3 MHz where most MBs were destroyed.     

In vitro evaluation of the intensifying photodynamic effect due to the presence of plasmonic hollow gold nanoshells loaded with methylene blue on breast and melanoma cancer cells

BackgroundHypoxia is one of the most important limiting factors in photodynamic therapy that can reduce the effectiveness of this treatment. By designing a nanocomplex of plasmonic nanoparticles and photosensitizers with similar optical properties, the rate of free oxygen radical production can be increased and the efficiency of photodynamic therapy can be improved. in this study, we tried to use the outstanding capacities of hollow gold nanoshells (HGNSs) as a plasmonic nanocarrier of methylene blue (MB) to improve the performance of photodynamic therapy.Methods and materialAfter synthesis and optimization of hollow gold nanoshells loaded with Methylene blue (HGNSs-PEG-MB), the characteristics of MB, HGNSs, HGNSs-PEG, HGNSs-PEG-MB, and their toxicity at different concentrations on the cell lines was determined. After determining of optimum concentration of nano agents, irradiation of cell was performed with non-coherent of light source with 670 nm wavelength and an intensity of 14.9 mW/cm². Twenty-four hours after irradiation, an MTT assay was used to determine cell survival percentage. To compare the results, we defined different indexes such as treatment efficiency (TE), synergism ratio (SYN), and the amount of exposure required for 50% cell death (ED50). All the tests were repeated at least four times on the DFW and MCF-7 cancer cell lines.ResultsFor combination therapies with Lumacare irradiated HGNSs-PEG-MB, the UC index was less than one for all concentrations (P < 0.05). Also, the IC50 index for this nanostructure in non-irradiated conditions and less than 9 min irradiation time was lower than other treatment groups (P < 0.05). ED50 amounts for HGNSs-PEG-MB in all concentrations were greater than the other groups. TE Index was also reported to be greater than 1 in all irradiation conditions and concentrations.ConclusionIn this study, HGNSs-PEG in the role of nanocarriers for methylene Blue was used. The results showed that irradiated HGNSs-PEG-MB by 670 nm light severely induced cell death and greatly improved the efficiency of photodynamic therapy in melanoma and breast cancer cells.     

Antimicrobial photodynamic therapy for infectious stomatitis in snakes: Clinical views and microbiological findings

BackgroundAntimicrobial photodynamic therapy (APDT) has been broadly investigated as an alternative to treat localized infections, without leading to the selection of resistant microorganisms. Infectious stomatitis is a multifactorial disease frequently reported in captive snakes characterized by infection of the oral mucosa and surrounding tissues. In this study, we investigated methylene blue (MB)-mediated APDT to treat infectious stomatitis in snakes and verified the resistance phenotype and genotype before and after APDT.MethodsThree Boid snakes presented petechiae, edema and caseous material in their oral cavities. MB (0.01%) was applied on the lesions and after 5 min they were irradiated using a red laser (λ = 660 nm), fluence of 280 J/cm², 8 J and 80 s per point, 100 mW, spot size 0.028 cm² and fluence rate of 3.5 W/cm². APDT was repeated once a week during 3 months. Samples of the lesions were collected to identify bacteria and antibiotic resistance profiles. To analyze the clonality of bacterial isolates before and after APDT, isolates were subjected to ERIC PCR analysis.ResultsSnakes presented clinical improvement such as reduction of inflammatory signs and caseous material. Pseudomonas aeruginosa and Escherichia coli were present in all snakes; Klebsiella pneumoniae and Morganella morganii were also identified in some animals. We also observed that the oral microbiota was completely replaced following APDT. However, K. pneumoniae isolates before and after APDT were a single clone with 100% of genetic similarity that lost resistance phenotype for seven antibiotics of four classes.ConclusionsThese results show that APDT can be used to treat infectious stomatitis in snakes.     

Periopathogens differ in terms of the susceptibility to toluidine blue O-mediated photodynamic inactivation

BackgroundThe main goal of periodontal therapy is to eliminate the infection spreading in periodontium. Antimicrobial photodynamic therapy may be applied in order to eradicate pathogens remaining in periodontal tissues after conventional mechanical debridement, to improve the treatment results. The aim of this in vitro study was to evaluate the susceptibility of selected key periopathogens to toluidine blue O-mediated photodynamic inactivation and the influence of photosensitizer’s concentration and light dose on the effectiveness of this process.MethodsFollowing bacterial strains were used in the experiments: Porphyromonas gingivalis ATCC 33277, Aggregatibacter actinomyctemecomitans ATCC 33384, Fusobacterium nucleatum ATCC 10953. Toluidine blue O (TBO) was used in concentration ranging from 0.004 to 0.5 mg/mL. Irradiation was performed by a non-laser red light source.ResultsComplete eradication of P. gingivalis was obtained upon the application of TBO in the concentration of 0.1 mg/mL and the highest light dose. A, actinomycetemcomitans was, in turn, not susceptible to photodynamic inactivation regardless of the dosimetric parameters applied. High viability reductions were also obtained for F. nucleatum, however no complete eradication. The effectiveness of photodynamic inactivation of susceptible periopathogens was dependent on the light dose and photosensitizer’s concentration.ConclusionsPeriopathogens differ in terms of their susceptibility to photodynamic inactivation. Antimicrobial PDT may be valuable in the treatment of those cases of periodontal disease, in which P. gingivalis is a dominating pathogen. Microbiological examination prior to clinical application of aPDT may be recommended.     

Enhancement of photodynamic bactericidal activity of curcumin against Pseudomonas Aeruginosa using polymyxin B

BackgroundPseudomonas aeruginosa (P. aeruginosa) is an emerging opportunistic pathogen, which can cause bacterial skin diseases such as green nail syndrome, interdigital infections and folliculitis. Curcumin-mediated antimicrobial photodynamic therapy (aPDT) has been demonstrated as a promising therapeutic option for the treatment of skin infection though its inactivation of gram-negative bacteria such as P. aeruginosa.Materials and methodsIn the present study, we examined the adjuvant effect of polymyxin B on the antibacterial activity of curcumin-mediated aPDT against P. aeruginosa. P. aeruginosa was treated with curcumin in the presence of 0.1–0.5 mg/L polymyxin B and irradiated by blue LED light (10 J/cm²). Bacterial cultures treated with curcumin alone served as controls. Colony forming units (CFU) were counted and the viability of P. aeruginosa was calculated after aPDT treatment. The possible underlying mechanisms for the enhanced killing effects were also explored.ResultsThe killing effects of curcumin-mediated aPDT against P. aeruginosa was significantly enhanced by polymyxin B (over 2-log reductions). Moreover, it was also observed that addition of polymyxin B in the curcumin-mediated aPDT led to the apparent bacterial membrane damage with increased leakage of cytoplasmic contents and extensive DNA and protein degradation.DiscussionThe photodynamic action of curcumin against P. aeruginosa could be significantly enhanced by the FDA-approved drug polymyxin B. Our results highlight the potential of introducing polymyxin B to enhance the effects of aPDT treatment against gram-negative skin infections, in particular, P. aeruginosa.     

Photodynamic inactivation of Candida albicans biofilm: Influence of the radiant energy and photosensitizer charge

BackgroundThe aim of this study is to investigate the photoinactivation of C. albicans biofilm on acrylic resin discs (the standard material for dental prosthesis) using the photosensitizers Methylene Blue and a Protoporphyrin IX.MethodsEighteen thermally activated Methyl Methacrylate Polymers were used for the biofilm growth of Candida albicans ATCC 10231. Two photosensitizers were tested: methylene blue (50 μM) and protoporphyrin IX (10 μM). Two custom-made LEDs emitting at 660 nm and 630 nm with approximately 800 mW each were used for the irradiation, with duration ranging from 2 to 10 min.ResultsThis study demonstrates that MB decreased the aPDT CFUs by approximately two orders of magnitude, but the protoporphyrin was ineffective.ConclusionThe aPDT with MB significantly reduces (but does not sterilize) the amount of CFU after 10 min of irradiation, and it is not dose-dependent. The lack of effect of the protoporphyrin is likely because the negative charges of the proteoglycans present in the extracellular matrix repel the negative charges of the PS, thus preventing its diffusion in the cells.     

Antifungal effect of a new photosensitizer derived from BODIPY on Candida albicans biofilms

BackgroundPhotodynamic therapy (PDT) may be an alternative treatment of Candida albicans (C. albicans) infections. The aim of this study was to investigate the antifungal effect of PDT mediated by a new photosensitizer (PS) derived from BODIPY (BDP-4L) on C. albicans biofilms.MethodsC. albicans biofilms were incubated with BDP-4L of different concentrations and then irradiated at the light doses of 1.8, 3.6, 5.4, 7.2 and 9.0 J/cm². XTT reduction assay was conducted to determine the PS concentration and PDT parameters. Confocal light scanning microscopy (CLSM) and scanning electron microscope (SEM) were used to visualize and quantify the effect of BDP-4L on C. albicans biofilms after PDT.ResultsC. albicans biofilms were inactivated in light dose-dependent and PS concentration-dependent manners using BDP-4L as PS. Without irradiation, no inactivation effect was observed when PS concentrations varied from 5 μM to 80 μM. 40 μM PS with 3.6 J/cm² irradiation resulted in a significant reduction of 83.8% in biofilm metabolic activities. CLSM assay demonstrated that cell viability was obviously inhibited by 82.6%. SEM images revealed ruptured and rough cell surface, indicating increased cell membrane permeability after PDT.ConclusionsOur results suggested that BDP-4L mediated PDT exhibited a favorable antifungal effect on C. albicans biofilms.     

Efficacy of malachite green mediated photodynamic therapy on treatment of Cutaneous Leishmaniasis: In vitro study

BackgroundLeishmaniasis is a common zoonotic disease that is transmitted by phlebotomus and causes several clinical conditions, from self healing lesion to deadly internal organ involvement. Photodynamic therapy (PDT) is a treatment method that leads to the generation of cytotoxic species and consequently to cell death and tissue destruction by visible light in the presence of a photosensitizer and oxygen. The aim of this study was to investigate effect of malachite green (MG)-mediated PDT in Leishmania tropica (L. tropica) promastigotes.Material and methodsParasites were incubated with 0.19, 0.39, 1.56, 3.25 and 6.25 μM of MG for one hour and subjected to 46.4 J/cm² light irradiation. Trypan blue assay was used to evaluate the viability of the cells and mitochondirial activity alteration was determined by MTT. Morphological changes were analyzed by Giemsa staining and Scanning electron microscopy (SEM) analyses. Flow cytometry was used to quantify the fluorescence emitted by cell volume, JC-1, Cell Cycle and Annexin V/PI staining reagents.ResultsMalachite green mediated photodynamic therapy at 1.56 and 3.125 μM decreased the viability of the L. tropica promastigotes and induced changes in the mitochondrial membrane potential. L.tropica promastigotes was bloked in G0/G1 phase. The morphology of the parasite was affected at the 1.56 and 3.125 μM MG+PDT, resulting in rounded cells with loss of flagellum and irregular shape.ConclusionsThis study demonstrated that antileishmanial effects through mitochondrial dysfunction, cell cycle arrest, and apoptosis-like cell death to parasites. This work showed PDT with MG effectedparasites. Therefore, MG-mediated PDT may provide a promising approach for L. tropica promastigotes.