Lung surfactant negatively affects the photodynamic inactivation of bacteria-in vitro and molecular dynamic simulation analyses.

In the context of the rapid increase of antibiotic-resistant infections, in particular of pneumonia, antimicrobial photodynamic therapy (aPDT), the microbiological application of photodynamic therapy (PDT), comes in as a promising treatment alternative since the induced damage and resultant death are not dependent on a specific biomolecule or cellular pathway. The applicability of aPDT using the photosensitizer indocyanine green with infrared light has been successfully demonstrated for different bacterial agents in vitro, and the combination of pulmonary delivery using nebulization and external light activation has been shown to be feasible. However, there has been little progress in obtaining sufficient in vivo efficacy results. This study reports the lung surfactant as a significant suppressor of aPDT in the lungs. In vitro, the clinical surfactant Survanta® reduced the aPDT effect of indocyanine green, Photodithazine®, bacteriochlorin-trizma, and protoporphyrin IX against Streptococcus pneumoniae. The absorbance and fluorescence spectra, as well as the photobleaching profile, suggested that the decrease in efficacy is not a result of singlet oxygen quenching, while a molecular dynamics simulation showed an affinity for the polar head groups of the surfactant phospholipids that likely impacts uptake of the photosensitizers by the bacteria. Methylene blue is the exception, likely because its high water solubility confers a higher mobility when interacting with the surfactant layer. We propose that the interaction between lung surfactant and photosensitizer must be taken into account when developing pulmonary aPDT protocols.

Porphyrin nanoemulsion for antimicrobial photodynamic therapy: effective delivery to inactivate biofilm-related infections.

The management of biofilm-related infections is a challenge in healthcare, and antimicrobial photodynamic therapy (aPDT) is a powerful tool that has demonstrated a broad-spectrum activity. Nanotechnology has been used to increase the aPDT effectiveness by improving the photosensitizer's delivery properties. NewPS is a simple, versatile, and safe surfactant-free nanoemulsion with a porphyrin salt shell encapsulating a food-grade oil core with promising photodynamic action. This study evaluated the use of NewPS for aPDT against microorganisms in planktonic, biofilm, and in vivo models of infected wounds. First, the potential of NewPS-mediated aPDT to inactivate Streptococcus pneumoniae and Staphylococcus aureus suspensions was evaluated. Then, a series of protocols were assessed against S. aureus biofilms by means of cell viability and confocal microscopy. Finally, the best biofilm protocol was used for the treatment of S. aureus in a murine-infected wound model. A high NewPS-bacteria cell interaction was achieved since 0.5 nM and 30 J/cm2 was able to kill S. pneumoniae suspension. In the S. aureus biofilm, enhanced efficacy of NewPS-aPDT was achieved when 100 µM of NewPS was applied with longer periods of incubation at the light dose of 60 J/cm2. The best single and double-session protocol reduced 5.56 logs and 6.03 logs, respectively, homogeneous NewPS distribution, resulting in a high number of dead cells after aPDT. The in vivo model showed that one aPDT session enabled a reduction of 6 logs and faster tissue healing than the other groups. In conclusion, NewPS-aPDT may be considered a safe and effective anti-biofilm antimicrobial photosensitizer.

Impact of PVC microplastics in photodynamic inactivation of Staphylococcus aureus and MRSA.

Photodynamic processes have found widespread application in therapies. These processes involve photosensitizers (PSs) that, when excited by specific light wavelengths and in the presence of molecular oxygen, generate reactive oxygen species (ROS), that target cells leading to inactivation. Photodynamic action has gained notable attention in environmental applications, particularly against pathogens and antibiotic-resistant bacteria (ARB) that pose a significant challenge to public health. However, environmental matrices frequently encompass additional contaminants and interferents, including microplastics (MPs), which are pollutants of current concern. Their presence in water and effluents has been extensively documented, highlighting their impact on conventional treatment methods, but this information remains scarce in the context of photodynamic inactivation (PDI) setups. Here, we described the effects of polyvinyl chloride (PVC) microparticles in PDI targeting Staphylococcus aureus and its methicillin-resistant strain (MRSA), using curcumin as a PS under blue light. The presence of PVC microparticles does not hinder ROS formation; however, depending on its concentration, it can impact bacterial inactivation. Our results underscore that PDI remains a potent method for reducing bacterial concentrations in water and wastewater containing ARB, even in highly contaminated scenarios with MPs.

Photobleaching Kinetics and Effect of Solvent in the Photophysical Properties of Indocyanine Green for Photodynamic Therapy.

Indocyanine green is an attractive molecule for photodynamic therapy due to its near infrared absorption, resulting in a higher tissue penetration. However, its quantum yields of the triplet and singlet state have been reported to be low and then, reactive oxygen species are unlikely to be formed. Aiming to understand the ICG role in photodynamic response, its photobleaching behavior in solution has been studied under distinct conditions of CW laser irradiation at 780 and 808 nm, oxygen saturations and solvents. Sensitizer bleaching and photoproduct formation were measured by absorption spectroscopy and analyzed using the PDT bleaching macroscopic model to extract physical parameters. ICG photobleaching occurs even at lower oxygen concentrations, indicating that the molecule presents more than one way of degradation. Photoproducts were produced even in solution of less than 4 % oxygen saturation for both solvents and excitation wavelengths. Also, the amplitude of absorption related to J-dimers was increased during irradiation, but only in 50 % PBS solution. The formation of photoproducts was enhanced in the presence of J-type dimers under low oxygen concentration, and the quantum yields of triplet and singlet states were one order of magnitude and two times higher, respectively, when compared to ICG in distilled H2 O.

Hydrogen peroxide preoxidation as a strategy for enhanced antimicrobial photodynamic action against methicillin-resistant Staphylococcus aureus.

Antimicrobial photodynamic treatment (aPDT) is a photooxidative process based on the excitation of a photosensitizer (PS) in the presence of molecular oxygen, under specific wavelengths of light. It is a promising method for advanced treatment of water and wastewater, particularly targeting disinfection challenges, such as antibiotic-resistant bacteria (ARB). Research in improved aPDT has been exploring new PS materials, and additives in general. Hydrogen peroxide (H2O2) a widely applied disinfectant, mostly in the food industry and clinical settings, present environmentally negligible residuals at the usually applied concentrations, making it friendly for the water and wastewater sectors. Here, we explored the effects of preoxidation with H2O2 followed by blue light-mediated (450 nm) aPDT using curcumin (a natural-based PS) against methicillin-resistant Staphylococcus aureus (MRSA). Results of the sequential treatment pointed to a slight hampering in aPDT efficiency at very low H2O2 concentrations, followed by an increasing cooperative effect up to a deleterious point (≥7 log10 inactivation in CFU mL-1), suggesting a synergistic interaction of preoxidation and aPDT. The increased performance in H2O2-pretreated aPDT encourages studies of optimal operational conditions for the assisted technology and describes potentials for using the described strategy to tackle the issue of ARB spread.

Carnot Cycles in a Harmonically Confined Ultracold Gas across Bose-Einstein Condensation.

Carnot cycles of samples of harmonically confined ultracold 87Rb fluids, near and across Bose-Einstein condensation (BEC), are analyzed. This is achieved through the experimental determination of the corresponding equation of state in terms of the appropriate global thermodynamics for non-uniform confined fluids. We focus our attention on the efficiency of the Carnot engine when the cycle occurs for temperatures either above or below the critical temperature and when BEC is crossed during the cycle. The measurement of the cycle efficiency reveals a perfect agreement with the theoretical prediction (1-TL/TH), with TH and TL serving as the temperatures of the hot and cold heat exchange reservoirs. Other cycles are also considered for comparison.

Investigation on the in vitro anti-Trichophyton activity of photosensitizers.

Onychomycosis is the most common disease caused by fungal nail infections, and often caused by dermatophytes. This infection is very resistant to antifungal treatments, and promising Photodynamic Therapy (PDT) mediated treatments has been presented as a multitarget tracking. Optimization of PDT guide for uptake time, concentration of photosensitizers (PS) and the light dose to inactivate Trichophyton mentagrophytes. Curcumin derivatives, porphyrin Chlorin e6 (CHL-E6) and Chlorin-P6-6-N-butylamide-7-methyl-ester (CHL-butyl) were evaluated. PS photobleaching was observed on the hyphae photosensitized over the time, correlating the PS concentration and light dose of antifungal PDT. Porphyrin, Curcumin, Chl-e6 and Chl-butyl concentrations of 2.5 µg/mL, 0.025 µg/mL, 10 µg/mL and 5 µg/mL respectively, under illumination of 10.5 J/cm2 were the best antifungal conditions found in the study. Curcumin, in low concentrations, and chlorin were the PSs with higher activity anti-T. mentagrophytes.

Effect of curcumin-encapsulated Pluronic® F-127 over duo-species biofilm of Streptococcus mutans and Candida albicans.

To assess the effect of curcumin-encapsulated Pluronic® F-127 (Cur-Plu) during antimicrobial photodynamic therapy (aPDT) over duo-species biofilm of Streptococcus mutans and Candida albicans. Thermal analysis, optical absorption, and fluorescence spectroscopy were evaluated. Minimum inhibitory concentration (MIC) and minimum bactericidal/fungal concentration were obtained. The biofilms were cultured for 48 h at 37 °C and treated according to the groups: P + M + L + (photosensitizer encapsulated with Pluronic® F-127 + light); P + D + L + (photosensitizer incorporated in 1% DMSO + light); P - M + L + (no Pluronic® F-127 + light); P - D + L + (1% DMSO + light); P - L + (Milli-Q water + light); P + M + L - (photosensitizer encapsulated with Pluronic® F-127 no light); P + D + L - (photosensitizer in 1% DMSO, no light); P - M + L - (Pluronic® F-127 no light); P - D + L - (1% DMSO, no light); P - L - (Milli-Q water, no light; negative control group); CHX (0.2% chlorhexidine, positive control group); and NYS (Nystatin). Dark incubation of 5 min was used. The groups that received aPDT were irradiated by blue LED (460 nm, 15 J/cm2). Cell viability of the biofilms was performed by colony-forming units (CFU/mL) and confocal microscopy. Two-way ANOVA followed by Tukey's post hoc test was used at a significance level of 5%. P + D + L + and P + M + L + groups exhibited better log-reduction for both Candida albicans and Streptococcus mutans biofilms than P - M + L + , P - L + , and P - D + L + experimental groups. Furthermore, P + M + L + and P + D + L + showed greater reduction for Candida albicans than for Streptococcus mutans. aPDT mediated by Cur-Plu can be a potential strategy for biofilm control against duo-species biofilm of Streptococcus mutans and Candida albicans.

Total mouth photodynamic therapy mediated by red LED and porphyrin in individuals with AIDS.

Due to the immune changes resulting from HIV/AIDS infection, systemic and local infections throughout the body are common. The use of high activity antiretroviral therapy has been widely used during treatment, which, added to the use of antibiotics, antifungals, and the patients' own immunocompromised state, cause important changes in the oral microbiota. The emergence of pathological microorganisms and with high resistance to drug therapies are frequent and cause serious damage to the oral health of these patients. In this sense, antimicrobial photodynamic therapy (aPDT) appears as a promising alternative in the control of these oral infections. The aim of the study was to test the effectiveness of a therapeutic protocol for total oral aPDT mediated by a 660-nm red LED (light-emitting diode) associated with porphyrin in individuals with AIDS. Patients were selected by exclusion criteria and randomly distributed into groups to test the effectiveness of antimicrobial aPDT with 50 µg/ml porphyrin associated with the red LED. Before and after the treatments, saliva samples were collected and processed in duplicate in selective culture media. Colonies were counted and the results obtained in Log10 CFU/ml and tested statistically. It was concluded that aPDT was effective in reducing oral enterobacteria, in addition to reducing Streptococcus spp. and general count of microorganisms, when considering the numbers of TCD4 and TCD8 lymphocytes.

PANI-WO3·2H2O Nanocomposite: Phase Interaction and Evaluation of Electronic Properties by Combined Experimental Techniques and Ab-Initio Calculation.

The development of conjugated polymer-based nanocomposites by adding metallic particles into the polymerization medium allows the proposition of novel materials presenting improved electrical and optical properties. Polyaniline Emeraldine-salt form (ES-PANI) has been extensively studied due to its controllable electrical conductivity and oxidation states. On the other hand, tungsten oxide (WO3) and its di-hydrated phases, such as WO3·2H2O, have been reported as important materials in photocatalysis and sensors. Herein, the WO3·2H2O phase was directly obtained during the in-situ polymerization of aniline hydrochloride from metallic tungsten (W), allowing the formation of hybrid nanocomposites based on its full oxidation into WO3·2H2O. The developed ES-PANI-WO3·2H2O nanocomposites were successfully characterized using experimental techniques combined with Density Functional Theory (DFT). The formation of WO3·2H2O was clearly verified after two hours of synthesis (PW2 nanocomposite), allowing the confirmation of purely physical interaction between matrix and reinforcement. As a result, increased electrical conductivity was verified in the PW2 nanocomposite: the DFT calculations revealed a charge transfer from the p-orbitals of the polymeric phase to the d-orbitals of the oxide phase, resulting in higher conductivity when compared to the pure ES-PANI.

PLGA-PVA-PEG Single Emulsion Method as a Candidate for Aminolevulinic Acid (5-ALA) Encapsulation: Laboratory Scaling Up and Stability Evaluation.

One of the most widely used molecules used for photodynamic therapy (PDT) is 5-aminolevulinic acid (5-ALA), a precursor in the synthesis of tetrapyrroles such as chlorophyll and heme. The 5-ALA skin permeation is considerably reduced due to its hydrophilic characteristics, decreasing its local bioavailability and therapeutic effect. For this reason, five different systems containing polymeric particles of poly [D, L-lactic-co-glycolic acid (PLGA)] were developed to encapsulate 5-ALA based on single and double emulsions methodology. All systems were standardized (according to the volume of reagents and mass of pharmaceutical ingredients) and compared in terms of laboratory scaling up, particle formation and stability over time. UV-VIS spectroscopy revealed that particle absorption/adsorption of 5-ALA was dependent on the method of synthesis. Different size distribution was observed by DLS and NTA techniques, revealing that 5-ALA increased the particle size. The contact angle evaluation showed that the system hydrophobicity was dependent on the surfactant and the 5-ALA contribution. The FTIR results indicated that the type of emulsion influenced the particle formation, as well as allowing PEG functionalization and interaction with 5-ALA. According to the 1H-NMR results, the 5-ALA reduced the T1 values of polyvinyl alcohol (PVA) and PLGA in the double emulsion systems due to the decrease in molecular packing in the hydrophobic region. The results indicated that the system formed by single emulsion containing the combination PVA-PEG presented greater stability with less influence from 5-ALA. This system is a promising candidate to successfully encapsulate 5-ALA and achieve good performance and specificity for in vitro skin cancer treatment.

Synergetic antimicrobial effect of chlorin e6 and hydrogen peroxide on multi-species biofilms.

Antimicrobial photodynamic therapy (aPDT) has been considered as a potential alternative to antibiotics for the treatment of biofilm infections. There is evidence that an additional H2O2 enhances the antimicrobial efficacy of aPDT. However, the minimum H2O2 concentration to achieve this synergistic effect is unclear. A saliva-derived multi-species biofilm was treated with the photosensitizer chlorin e6 (Ce6, 50 µM), H2O2 (0.3, 3.3, 33.3 mM), or their combination for 5 min, followed by no irradiation or irradiation at 15 J (cm2)-1 (λ = 450 nm or 660 nm), with or without oxygen. Biofilm viability and metabolic activity were evaluated. The combination of 33.3 mM H2O2 and Ce6-aPDT strongly enhanced antimicrobial efficacy compared with either component alone, irrespective of oxygen availability and irradiation wavelength. In particular, the combination resulted in a 6.6-log colony forming unit (CFU) reduction anaerobically under blue irradiation. This combination is a promising treatment for biofilm infections, especially those thriving in an anaerobic microenvironment.

The effect of combined curcumin-mediated photodynamic therapy and artificial skin on Staphylococcus aureus-infected wounds in rats.

Healing wounds represent a major public health problem, mainly when it is infected. Besides that, the antibiotics misuse and overuse favor the development of bacterial resistance. This study evaluated the effects of antimicrobial photodynamic therapy (aPDT) combined with artificial skin on disinfection of infected skin wound in rats. Twenty-four Wistar rats were randomly distributed into 4 groups (n = 6): (i) control-untreated; (ii) aPDT-treated with curcumin-mediated aPDT (blue light); (iii) artificial skin-treated with artificial skin alcohol-based; and (iv) aPDT plus artificial skin-treated with aPDT associated with artificial skin alcohol-based. For the in vivo model, a full-thickness biopsy with 0.80 cm was performed in order to inoculate the microorganism Staphylococcus aureus (ATCC 25923). The aPDT was performed with a curcumin gel and a blue LED light (450 nm, 80 mW/cm2) at the dose of 60 J/cm2 and the treatment with alcohol-based artificial skin was done with the topical application of 250 µL. Additional animals were submitted to aPDT combined with the artificial skin. After treatments, the number of colony-forming units (CFU) and the damage area were determined. Data were analyzed by two-way repeated measures ANOVA and Tukey tests. The highest reduction of the bacterial viability was observed in the PDT plus artificial skin group (4.14 log10), followed by artificial skin (2.38 log10) and PDT (2.22 log10) groups. In addition, all treated groups showed higher relative area of wound contraction (36.21% for the PDT, 38.41% for artificial skin, and 35.02% for PDT plus artificial) in comparison with the control group. These findings provide evidence for the positive benefits of aPDT with blue light and curcumin associated with artificial skin to decontaminate and accelerate the wound contraction.

Follow-up of pressure ulcer treatment with photodynamic therapy, low level laser therapy and cellulose membrane.

OBJECTIVE: A pressure ulcer (PU) is an area of tissue trauma caused by continuous and prolonged pressure, often associated with hospitalised patients immobilised due to neurological problems, negatively affecting their quality of life, and burdening the public budget. The aim of this study was to report the follow-up, for 45 weeks, of three patients with neurological lesions due to trauma who subsequently developed PUs, and who were treated with a combination of photodynamic therapy (PDT), low level laser therapy (LLLT) and cellulose membrane (CM). METHOD: PDT was mediated by the photosensitiser curcumin on a 1.5% emulsion base. Blue LED light at 450 nm was delivered continuously for 12 minutes at an irradiance of 30mW/cm2 and total energy delivered to the tissue was 22J/cm2. LLLT was performed with 660 nm laser, punctuated and continuous, twice a week with parameters: spot size 0.04cm2, power of 40mW, 10 seconds per point, fluence of 10J/cm2 and irradiance of 1000mW/cm2. RESULTS: All PUs had a significant reduction (range: 95.2-100%) of their area after 45 weeks of follow-up and two PUs had complete healing at 20 weeks and 30 weeks. All of the PUs showed a reduction in contamination with the PDT treatments in different proportions. CONCLUSION: From the results obtained, we conclude that the combination of PDT, LLLT and CM is a promising treatment for PU healing.

Acute effect of photobiomodulation using light-emitting diodes (LEDs) on baroreflex sensitivity during and after constant loading exercise in patients with type 2 diabetes mellitus.

To evaluate the photobiomodulation (PBM) effect on the cardiovascular autonomic control, analyzed by baroreflex sensitivity (sequence method), during constant load exercise and recovery in diabetic men, we evaluated 11 men with type 2 diabetes (DM2) (40-64 years). The constant workload exercise protocol (TECC) was performed on two different days, 14 days apart from each other, to guarantee PBM washout period. After PBM by light-emitting diode (LED) irradiation (150 J or 300 J or placebo), 10 min of rest (REST) was performed. After this period, the volunteer was positioned on a cycloergometer to start the test (1-min rest, 3-min free-load heating, 6-min constant workload-EXERCISE, 6-min free-load cool-down, 1-min rest) followed by a sitting period of 10 min (RECOVERY). The constant workload corresponded to 80%VO2GET (gas exchange threshold) identified by a previous cardiopulmonary exercise test (CPET). PBM was applied in continuous mode, contact technique, bilaterally, on both femoral quadriceps and gastrocnemius muscle groups. The electrocardiogram R-R intervals (BioAmp FE132) and the peripheral pulse pressure signals (Finometer PRO) were collected continuously throughout the protocol. Stable sequences of 256 points were chosen at REST, EXERCISE, and RECOVERY. The baroreflex sensitivity (BRS) was computed in time domain according to the sequence method (αseq). The comparison between therapies (150 J/300 J/placebo) and condition (REST, EXERCISE, and RECOVERY) was performed using the ANOVA two-way repeated measures test. There was no interaction between therapy and conditions during the TECC. There was only the condition effect (p < 0.001), showing that the behavior of αseq was similar regardless of the therapy. Photobiomodulation with 150 J or 300 J applied previously to a moderate-intensity TECC in DM2 was not able to promote cardiovascular autonomic control changes leading to an improvement in BRS.

Entropy of a Turbulent Bose-Einstein Condensate.

Quantum turbulence deals with the phenomenon of turbulence in quantum fluids, such as superfluid helium and trapped Bose-Einstein condensates (BECs). Although much progress has been made in understanding quantum turbulence, several fundamental questions remain to be answered. In this work, we investigated the entropy of a trapped BEC in several regimes, including equilibrium, small excitations, the onset of turbulence, and a turbulent state. We considered the time evolution when the system is perturbed and let to evolve after the external excitation is turned off. We derived an expression for the entropy consistent with the accessible experimental data, which is, using the assumption that the momentum distribution is well-known. We related the excitation amplitude to different stages of the perturbed system, and we found distinct features of the entropy in each of them. In particular, we observed a sudden increase in the entropy following the establishment of a particle cascade. We argue that entropy and related quantities can be used to investigate and characterize quantum turbulence.

Short-term and long-term effects of osteoporosis on incisor teeth and femoral bones evaluated by Raman spectroscopy and energy dispersive X-ray analysis in ovariectomized rats.

There are few published data on the relationship between loss of bone mass due to osteoporosis and poor tooth quality. This study analyzed the effects of osteoporosis on incisor teeth and femoral bones using optical techniques in rats. Twenty female Wistar rats aged 6 months (n = 20) were randomized into two groups: control group, non-ovariectomized rats (n = 10); ovariectomy group, ovariectomized rats to induce osteoporosis (n = 10). Each group was subdivided randomly into two groups containing five rats each as follows. Control group 1: non-ovariectomized rats euthanized at the age of 9 or 3 months post-ovariectomy (n = 5); Control group 2: non-ovariectomized rats euthanized at the age of 1 year or 6 months post-ovariectomy (n = 5); ovariectomy group 1: ovariectomized rats euthanized at the age of 9 months or 3 months post-ovariectomy (n = 5); ovariectomy group 2: ovariectomized rats euthanized at the age of 1 year or 6 months post-ovariectomy (n = 5). The incisor teeth and femoral bones of Wistar rats were removed to perform Raman spectroscopy using an excitation laser at 785 nm. In addition, an energy-dispersive X-ray spectrometer system was used to evaluate calcium (Ca) and phosphorus (P). The main findings included significant changes (p < 0.05) for phosphate and carbonate band areas for both incisor teeth and femur bones. In addition, there was significant negative correlation between the P concentration and phosphate/carbonate ratio (lower P content-larger ratio, p < 0.05) for incisor teeth and femoral bones. The proline and CH2 wag band areas were significantly reduced only for the incisor teeth (p < 0.05). Therefore, Raman spectroscopy assessed the compositional, physicochemical and structural changes in hard tissue. The current study also pointed out the possible action mechanisms of these changes, bone fracture risk and dental fragility. It is important to emphasize that poor dental quality may also occur due to osteoporosis.

Photodithazine-mediated antimicrobial photodynamic therapy against fluconazole-resistant Candida albicans in vivo.

This study evaluated the efficacy of antimicrobial Photodynamic Therapy (aPDT) against fluconazole-resistant Candida albicans in a murine model of oral candidosis. Mice were inoculated with two clinical isolates (R10, R15) and one reference strain (ATCC) of resistant C. albicans to produce oral candidosis. After inoculation, aPDT mediated by Photodithazine® (PDZ) and LED light was performed. The use of PDZ or light only was also investigated. Additional animals were treated with Nystatin (NYS). Untreated or healthy mice were also evaluated. Microbiological evaluation was performed by recovering C. albicans from the tongue via colony-forming units. Animals were killed 24 hours after treatments, and the tongues were removed for histological analysis. Data were analyzed by one-way ANOVA and Tukey test (P < .05). The results demonstrated that all strains showed the same behavior after aPDT and NYS treatment. A significant reduction in C. albicans viability was achieved after both treatments for R15 and ATCC. No significant reduction was verified for C. albicans R10 submitted to aPDT or NYS. The histological analysis revealed that aPDT did not cause side effects on tissues. aPDT was effective for inactivation of two fluconazole-resistant C. albicans of the three strains evaluated.

Topical and intradermal delivery of PpIX precursors for photodynamic therapy with intense pulsed light on porcine skin model.

In order to purposely decrease the time of the photodynamic therapy (PDT) sessions, this study evaluated the effects of PDT using topical and intradermal delivery of two protoporphyrin (PpIX) precursors with intense pulsed light (IPL) as irradiation source. This study was performed on porcine skin model, using an IPL commercial device (Intense Pulse Light, HKS801). IPL effect on different administration methods of two PpIX precursors (ALA and MAL) was investigated: a topical cream application and an intradermal application using a needle-free, high-pressure injection system. Fluorescence investigation showed that PpIX distribution by needle-free injection was more homogeneous than that by cream, suggesting that a shorter drug-light interval in PDT protocols is possible. The damage induced by IPL-PDT assessed by histological analysis mostly shows modifications in collagens fibers and inflammation signals, both expected for PDT. This study suggested an alternative protocol for the PDT treatment, possibility half of the incubation time and with just 3 min of irradiation, making the IPL-PDT, even more, promising for the clinical treatment.

Vascular Effects of Photodynamic Therapy with Curcumin in a Chorioallantoic Membrane Model.

Photodynamic Therapy (PDT) is a treatment that requires light, a photosensitizing agent, and molecular oxygen. The photosensitizer is activated by light and it interacts with the oxygen that is present in the cellular microenvironment. The molecular oxygen is transformed into singlet oxygen, which is highly reactive and responsible for the cell death. Therefore, PS is an important element for the therapy happens, including its concentration. Curcumin is a natural photosensitizer and it has demonstrated its anti-inflammatory and anti-oxidant effects that inhibit several signal transduction pathways. PDT vascular effects of curcumin at concentrations varying from 0.1 to 10 mM/cm² and topical administration were investigated in a chick Chorioallantoic Membrane (CAM) model. The irradiation was performed at 450 nm, irradiance of 50 mW/cm² during 10 min, delivering a total fluence of 30 J/cm². The vascular effect was followed after the application of curcumin, with images being obtained each 30 min in the first 3 h, 12 h, and 24 h. Those images were qualitatively and quantitatively analyzed with a MatLAB®. Curcumin was expected to exhibit a vascular effect due to its angio-inhibitory effect. Using curcumin as photosensitizer, PDT induced a higher and faster vascular effect when compared to the use of this compound alone.