Toluidine blue O directly and photodynamically impairs the bioenergetics of liver mitochondria: a potential mechanism of hepatotoxicity.

Toluidine blue O (TBO) is a phenothiazine dye that, due to its photochemical characteristics and high affinity for biomembranes, has been revealed as a new photosensitizer (PS) option for antimicrobial photodynamic therapy (PDT). This points to a possible association with membranous organelles like mitochondrion. Therefore, here we investigated its effects on mitochondrial bioenergetic functions both in the dark and under photostimulation. Two experimental systems were utilized: (a) isolated rat liver mitochondria and (b) isolated perfused rat liver. Our data revealed that, independently of photostimulation, TBO presented affinity for mitochondria. Under photostimulation, TBO increased the protein carbonylation and lipid peroxidation levels (up to 109.40 and 119.87%, respectively) and decreased the reduced glutathione levels (59.72%) in mitochondria. TBO also uncoupled oxidative phosphorylation and photoinactivated the respiratory chain complexes I, II, and IV, as well as the FoF1-ATP synthase complex. Without photostimulation, TBO caused uncoupling of oxidative phosphorylation and loss of inner mitochondrial membrane integrity and inhibited very strongly succinate oxidase activity. TBO's uncoupling effect was clearly seen in intact livers where it stimulated oxygen consumption at concentrations of 20 and 40 µM. Additionally, TBO (40 µM) reduced cellular ATP levels (52.46%) and ATP/ADP (45.98%) and ATP/AMP (74.17%) ratios. Consequently, TBO inhibited gluconeogenesis and ureagenesis whereas it stimulated glycogenolysis and glycolysis. In conclusion, we have revealed for the first time that the efficiency of TBO as a PS may be linked to its ability to photodynamically inhibit oxidative phosphorylation. In contrast, TBO is harmful to mitochondrial energy metabolism even without photostimulation, which may lead to adverse effects when used in PDT.

Formulation and performance evaluation of emulgel platform for combined skin delivery of curcumin and propolis.

The environment can modify the physiology and body protective function of the skin. Propolis (PRP) and curcumin (CUR) possess important antioxidant and antimicrobial properties, and they can be administered in a combined way and using photodynamic therapy (PDT). Emulgels can control drug release due to the physicochemical properties of the gel and the emulsion. They constitute a good strategy for achieving an improved platform for the combined delivery of PRP and CUR. There are no other studies of emulgels composed of PRP and CUR and their performance as antimicrobial and skin healing using or not PDT. This study aimed to investigate the effect of Carbopol 934 P (C934P), 974 P (C974P) or polycarbophil (PC) on physicochemical stability, antioxidant activity, drug release profile, antimicrobial activity, and ex vivo skin permeation and retention of emulgels containing PRP and CUR. Formulations containing C974P or PC displayed improved stability and antioxidant activity. They displayed activity against Staphylococcus aureus and modified (extended) drug release, governed mainly by non-Fickian anomalous transport. C974P and PC resulted in improved emulgels for combined CUR and PRP delivery, allowing the drugs to cross the stratum corneum, and permeate the epidermis, reaching the dermis. The selected emulgels are candidates for further studies to prove their action and benefits to skin health.

Thermoresponsive Hydrogel-Loading Aluminum Chloride Phthalocyanine as a Drug Release Platform for Topical Administration in Photodynamic Therapy.

Phthalocyanine aluminum chloride (Pc) is a clinically viable photosensitizer (PS) to treat skin lesions worsened by microbial infections. However, this molecule presents a high self-aggregation tendency in the biological fluid, which is an in vivo direct administration obstacle. This study proposed the use of bioadhesive and thermoresponsive hydrogels comprising triblock-type Pluronic F127 and Carbopol 934P (FCarb) as drug delivery platforms of Pc (FCarbPc)-targeting topical administration. Carbopol 934P was used to increase the F127 hydrogel adhesion on the skin. Rheological analyses showed that the Pc presented a low effect on the hydrogel matrix, changing the gelation temperature from 27.2 ± 0.1 to 28.5 ± 0.9 °C once the Pc concentration increases from zero to 1 mmol L-1. The dermatological platform showed matrix erosion effects with the release of loaded Pc micelles. The permeation studies showed the excellent potential of the FCarb platform, which allowed the partition of the PS into deeper layers of the skin. The applicability of this dermatological platform in photodynamic therapy was evaluated by the generation of reactive species which was demonstrated by chemical photodynamic efficiency assays. The low effect on cell viability and proliferation in the dark was demonstrated by in vitro assays using L929 fibroblasts. The FCarbPc fostered the inhibition of Staphylococcus aureus strain, therefore demonstrating the platform's potential in the treatment of dermatological infections of microbial nature.

Thermo- and pH-Responsive Gelatin/Polyphenolic Tannin/Graphene Oxide Hydrogels for Efficient Methylene Blue Delivery.

Gelatin (GE), amino-functionalized polyphenolic tannin derivative (TN), and graphene oxide (GO) were associated to yield thermo- and pH-responsive hydrogels for the first time. Durable hydrogel assemblies for drug delivery purposes were developed using the photosensitizer methylene blue (MB) as a drug model. The cooling GE/TN blends provide brittle physical assemblies. To overcome this disadvantage, different GO contents (between 0.31% and 1.02% wt/wt) were added to the GE/TN blend at 89.7/10.3 wt/wt. FTIR and RAMAN spectroscopy analyses characterized the materials, indicating GO presence in the hydrogels. Incorporation studies revealed a total MB (0.50 mg/mL) incorporation into the GE/TN-GO hydrogel matrices. Additionally, the proposed systems present a mechanical behavior similar to gel. The GO presence in the hydrogel matrices increased the elastic modulus from 516 to 1650 Pa. SEM revealed that hydrogels containing MB present higher porosity with interconnected pores. Dissolution and swelling degree studies revealed less stability of the GE/TN-GO-MB hydrogels in SGF medium (pH 1.2) than SIF (pH 6.8). The degradation increased in SIF with the GO content, making the polymeric matrices more hydrophilic. MB release studies revealed a process controlled by Fickian diffusion. Our results point out the pH-responsible behavior of mechanically reinforced GE/TN-GO-MB hydrogels for drug delivery systems purposes.

Mucoadhesive polymeric films comprising polyvinyl alcohol, polyvinylpyrrolidone, and poloxamer 407 for pharmaceutical applications.

Polyvinyl alcohol (PVA) and polyvinylpyrrolidone (PVP) have been extensively studied for their use in film formation. Poloxamer 407 (P407) is a block copolymer that has thermo-responsive and surfactant properties when used in pharmaceutical systems. These polymers are already used in liquid or semi-solid systems for ocular and parenteral drug delivery. However, the effect of P407 presence in solid pharmaceutical films composed of different PVA:PVP ratios have not been investigated yet. Therefore, this work investigated the influence of P407 added to the binary polymer mixture of PVA and PVP for the development of solid films aiming for pharmaceutical applications. The rheological properties of dispersions were investigated, and films were prepared by solvent casting method using different P407:PVA:PVP ratios according to a factorial design 23 (plus center point). The mechanical and in vitro mucoadhesive properties of films, as well as the disintegration time were investigated. Systems presented high mechanical resistance, mucoadhesion, and disintegration timeless than 180 s. It was found that higher concentrations of PVA increase mechanical properties and decrease disintegration time, and higher proportions of PVP and P407 increased mucoadhesion. The films could be classified as fast disintegrating films and represent a promising alternative for modifying drug delivery and pharmaceutical applications.

Hypericin photodynamic activity in DPPC liposomes - part II: stability and application in melanoma B16-F10 cancer cells.

Hypericin (Hyp) is considered a promising photosensitizer for Photodynamic Therapy (PDT), due to its high hydrophobicity, affinity for cell membranes, low toxicity and high photooxidation activity. In this study, Hyp photophysical properties and photodynamic activity against melanoma B16-F10 cells were optimized using DPPC liposomes (1,2-dipalmitoyl-sn-glycero-3-phosphocholine) as a drug delivery system. This nanoparticle is used as a cell membrane biomimetic model and solubilizes hydrophobic drugs. Hyp oxygen singlet lifetime (τ) in DPPC was approximately two-fold larger than that in P-123 micelles (Pluronic™ surfactants), reflecting a more hydrophobic environment provided by the DPPC liposome. On the other hand, singlet oxygen quantum yield values (ΦΔ1O2) in DPPC and P-123 were similar; Hyp molecules were preserved as monomers. The Hyp/DPPC liposome aqueous dispersion was stable during fluorescence emission and the liposome diameter remained stable for at least five days at 30 °C. However, the liposomes collapsed after the lyophilization/rehydration process, which was resolved by adding the lyoprotectant Trehalose to the liposome dispersion before lyophilization. Cell viability of the Hyp/DPPC formulation was assessed against healthy HaCat cells and high-metastatic melanoma B16-F10 cells. Hyp incorporated into the DPPC carrier presented a higher selectivity index than the Hyp sample previously solubilized in ethanol under the illumination effect. Moreover, the IC50 was lower for Hyp in DPPC than for Hyp pre-solubilized in ethanol. These results indicate the potential of the formulation of Hyp/DPPC for future biomedical applications in PDT treatment.

Hypericin photodynamic activity. Part III: in vitro evaluation in different nanocarriers against trypomastigotes of Trypanosoma cruzi.

Chagas is a parasitic endemic disease caused by the protozoan Trypanosoma cruzi. It represents a strong threat to public health due to its strong resistance against commonly available drugs. We studied the in vitro ability to inactivate the trypomastigote form of this parasite using photodynamic inactivation of microorganisms (or antimicrobial Photodynamic Therapy, aPDT). For this, we chose to use the photosensitizer hypericin (Hyp) formulated in ethanol/water (1% v/v) and Hyp loaded in the dispersion of different aqueous nanocarrier systems. These included polymeric micelles of F-127 and P-123 (both Pluronic™ surfactants), and liposomal vesicles of phospholipid 2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC). These systems with Hyp had their activity compared against trypomastigote forms under light and in the dark. Hyp revealed a high level of effectiveness to eradicate protozoa in vitro. Samples at concentrations higher than 0.8 µmol L-1 of Hyp in Pluronic micelles showed efficacy even in the dark, with the EC50 around (6-8) µmol L-1. Therefore, Hyp/Pluronics can be used also as a chemotherapeutic agent. The best result for EC50 is at approximately 0.31 µmol L-1 for illuminated systems of Hyp in F-127 micelles. For Hyp in P-123 micelles under light, the results also led to a low EC50 value of 0.36 µmol L-1. The highest value of EC50 was 2.22 µmol L-1, which was found for Hyp/DPPC liposomes under light. For the Hyp-free (ethanol/water, 1% v/v)/illuminated group, the EC50 value was 0.37 µmol L-1, which also is a value that shows effectiveness. However, in free-form, Hyp is not protected against blood components, unlike when Hyp is loaded into the nanocarriers.

Biomedical Platform Development of a Chlorophyll-Based Extract for Topic Photodynamic Therapy: Mechanical and Spectroscopic Properties.

Photodynamic therapy (PDT) is a therapeutic modality that has shown effectiveness in the inactivation of cancer cell lines and microorganisms. Treatment consists of activating the photosensitizer (PS) upon light irradiation of adequate wavelength. After reaching the excited state, the PS can handle the intersystem conversion through energy transfer to the molecular oxygen, generating reactive oxygen species. This especially applies to singlet oxygen (1O2), which is responsible for the selective destruction of the sick tissue. Photosensitizing compounds (chlorophylls and derivatives) existing in the spinach extract have applicability for PDT. This study aimed to develop and characterize the thermoresponsive bioadhesive system composed of Pluronic F127 20.0%- and Carbopol 934P 0.2% (w/w) (FC)-containing chlorophyll-based extract 0.5% (w/w) (FC-Chl). Mechanical and rheological properties, in vitro release, sol-gel transition temperature, and ex vivo permeability of the spinach extract PS components (through pig ear skin) were investigated. Furthermore, photodynamic activity of the system was accessed through uric acid and time-solved measurements. The sol-gel transition temperature obtained for the FC-Chl system was 28.8 ± 0.3 °C. Rheological and texture properties of the platform were suitable for use as a dermatological system, exhibiting easy application and good characteristics of retention in the place of administration. In vitro release studies showed the presence of two distinct mechanisms that reasonably obey the zero-order and first-order kinetics models. PS components presented skin permeability and reached a permeation depth of 830 µm (between the epidermis and dermis). The photodynamic evaluation of the FC-Chl system was effective in the degradation of uric acid. The quantum yield (ΦΔ1O2) and life time (τ1O2) of singlet oxygen showed similar values for the spinach extract and the isolated chlorophyll a species in ethanol. These results allowed for the classification of the FC-Chl platform as potentially useful for the delivery of the chlorophyll-based extract in the topic PDT, suggesting that it is worthy for in vivo evaluation.

Unveiling One-Dimensional Supramolecular Structures Formed through π-π Stacking of Phenothiazines by Differential Pulse Voltammetry.

Organic-based nanomaterials can be self-assembled by strong and directional intermolecular forces such as π-π interactions. Experimental information about the stability, size, and geometry of the formed structures is very limited for species that easily aggregate, even at very low concentrations. Differential pulse voltammetry (DPV) can unveil the formation, growth, and also the stability window of ordered, one-dimensional, lamellar self-aggregates formed by supramolecular π stacking of phenothiazines at micromolar (10-6  mol L-1 ) concentrations. The self-diffusion features of the species at different concentrations are determined by DPV and used to probe the π staking process through the concept of the frictional resistance. It is observed that toluidine blue and methylene blue start to self-aggregate around 9 µmol L-1 , and that the self-aggregation process occurs by one-dimensional growth as the concentration of the phenothiazines is increased up to around 170 µmol L-1 for toluidine blue and 200 µmol L-1 for methylene blue. At higher concentrations, the aggregation process leads to structures with lower anisometry.

Screening and In Vitro Evaluation of Mucoadhesive Thermoresponsive System Containing Methylene Blue for Local Photodynamic Therapy of Colorectal Cancer.

PURPOSE: Photodynamic therapy (PDT) with methylene blue (MB) constitutes a potentially useful modality for colorectal cancer treatment. The limitations of the formulations containing MB are problems of administration and the inability to get the closeness contact at the site during the appropriate residence time. Present study aimed to develop and characterize mucoadhesive thermoresponsive system containing MB designed as platform for colorectal cancer therapy. METHODS: Formulations composed of different amounts of poloxamer 407 (Polox), Carbopol 934P (Carb), and MB were developed and characterized as rheological, compressional, mucoadhesive and syringeability properties, toxicity, photodynamic action, in vitro MB release profile, and ex vivo MB intestinal permeation. RESULTS: The different compositions resulted in formulations with distinctive macroscopic characteristics and wide range of gelation temperatures. The compressional flow, mucoadhesive, syringeability, and rheological properties were significantly influenced by temperature and/or composition. The MB release from formulation was governed by anomalous transport. In addition, it was observed that MB permeated the intestinal membrane; the formulation possesses photodynamic activity and low toxicity. CONCLUSIONS: The data obtained from the system composed of 20% Polox, 0.15% Carb, and 0.25% MB indicated a potentially functional role in PDT of the colorectal cancer and suggest it is worthy of clinical evaluation.

Photodynamic Inactivation Mediated by Erythrosine and its Derivatives on Foodborne Pathogens and Spoilage Bacteria.

The purpose of the present study was to evaluate the efficacy of photodynamic inactivation (PDI) mediated by erythrosine (ERY) and its ester derivatives erythrosine methyl ester (ERYMET) and erythrosine butyl ester (ERYBUT) on foodborne pathogens and spoilage bacteria. We evaluated Staphylococcus aureus ATCC 25923, Aeromonas hydrophila ATCC 7966, Salmonella enterica serotype Typhimurium ATCC 14028, Escherichia coli ATCC 25922, and Pseudomonas aeruginosa ATCC 27853. The toxicity of all of the compounds was assessed in VERO cells. PDI mediated by ERY and its derivatives combined with a light-emitting diode was performed at different concentrations and exposure times. S. aureus was more photosensitive than Gram-negative bacteria to ERY, ERYMET, and ERYBUT. The ERY-mediated PDI of S. aureus induced a significant reduction of 4.0 log CFU/ml at a light dose of 40 J/cm(2). ERYMET and ERYBUT at lower light doses than ERY completely eradicated S. aureus. When photoirradiated with ERY at light doses of 156 and 234 J/cm(2), A. hydrophila was completely eradicated. ERYBUT was more efficient in the PDI of A. hydrophila than ERYMET, even at 1 x 10(-5) M and lower light doses. Salmonella Typhimurium, E. coli, and P. aeruginosa required higher concentrations of photosensitizers to reduce cell survival. ERYBUT and ERY may be promising photosensitizing agents against A. hydrophila and S. aureus. They were effective at reducing bacterial counts at nontoxic concentrations. The photoinactivation rate of the evaluated bacteria decreased in the following order: S. aureus > A. hydrophila > E. coli > S. Typhimurium > P. aeruginosa.

Biosorption potential of synthetic dyes by heat-inactivated and live Lentinus edodes CCB-42 immobilized in loofa sponges.

Lentinus edodes CCB-42 was immobilized in loofa sponges and applied to the biosorption of the synthetic dyes congo red, bordeaux red and methyl violet. Live immobilized microorganisms achieved average decolorations of congo red, bordeaux red and methyl violet of 97.8, 99.7 and 90.6 %, respectively. The loofa sponge was the support and the coadjuvant promoting dye adsorption. The biosorption conditions were optimized for each dye, yielding 30 °C, pH 5.0 and a 12 h reaction time for congo red; 25 °C, pH 3.0 and 36 h for bordeaux red; and 25 °C, pH 8.0 and 24 h for methyl violet. Operational stability was evaluated over five consecutive cycles, with both bordeaux red and congo red exhibiting decolorations above 90 %, while the decoloration of methyl violet decreased after the third cycle. In the sixth month of storage, congo red, bordeaux red and methyl violet had decolorations of 93.1, 79.4 and 73.8 %, respectively. Biosorption process best fit the pseudo-second-order kinetic and Freundlich isotherm models. Maximum biosorption capacity of heat-treated L. edodes immobilized in loofa sponge was determined as 143.678, 500.00 and 381.679 mg/g for congo red, bordeaux red and methyl violet, respectively. Treatment with immobilized L. edodes reduced the phytotoxicity of the medium containing dyes. FT-Raman experiments suggested the occurrence of interactions between loofa sponge fibers, L. edodes and dye. L. edodes CCB-42 immobilized in loofa sponges represents a promising new mode of treatment of industrial effluents.

Silver Nanoparticles In Situ Synthesized and Incorporated in Uniaxial and Core-Shell Electrospun Nanofibers to Inhibit Coronavirus.

In the present study, we sought to develop materials applicable to personal and collective protection equipment to mitigate SARS-CoV-2. For this purpose, AgNPs were synthesized and stabilized into electrospinning nanofiber matrices (NMs) consisting of poly(vinyl alcohol) (PVA), chitosan (CHT), and poly-ε-caprolactone (PCL). Uniaxial nanofibers of PVA and PVA/CHT were developed, as well as coaxial nanofibers of PCL[PVA/CHT], in which the PCL works as a shell and the blend as a core. A crucial aspect of the present study is the in situ synthesis of AgNPs using PVA as a reducing and stabilizing agent. This process presents few steps, no additional toxic reducing agents, and avoids the postloading of drugs or the posttreatment of NM use. In general, the in situ synthesized AgNPs had an average size of 11.6 nm, and the incorporated nanofibers had a diameter in the range of 300 nm, with high uniformity and low polydispersity. The NM's spectroscopic, thermal, and mechanical properties were appropriate for the intended application. Uniaxial (PVA/AgNPs and PVA/CHT/AgNPs) and coaxial (PCL[PVA/CHT/AgNPs]) NMs presented virucidal activity (log's reduction ≥ 5) against mouse hepatitis virus (MHV-3) genus Betacoronavirus strains. In addition to that, the NMs did not present cytotoxicity against fibroblast cells (L929 ATCC® CCL-1TM lineage).

Evaluation of the photodynamic activity of xanthene dyes on Artemia salina described by chemometric approaches.

The development of drugs for photodynamic therapy (PDT) is an important area of research due to their growing use in medical applications. Therefore, it is important to develop new bioassay methods for PDT photosensitizers that are inexpensive, easy to handle and highly sensitive to environmental conditions. Xanthene dyes (fluorescein, rose bengal B, erythrosine B and eosin Y) with LED light sources were investigated using Artemia salina as a bioindicator of photodynamic activity. In this study, three factors were investigated: (i) photosensitizers concentration, (ii) the LED irradiation time and (iii) the waiting time between the addition of the photosensitizers and the beginning of the irradiation. To analyze the photo-killing of A. salina, it was employed a 2³ full factorial design. The death of A. salina was related to dye structure and the interaction between the irradiation time and the photosensitizers concentration. About 60% of crustaceans death was obtained using rose bengal B, which presentes the highest quantum yield of singlet oxygen due to the number of iodide substituents in the xanthenes ring. The proposed bioassay using A. salina, xanthene dyes and LED irradiation was found suitable for quantitative PDT drug evaluation.

Development of Environmentally Responsive Self-Emulsifying System Containing Copaiba Oil-Resin for Leishmaniasis Oral Treatment.

Leishmaniasis is a disease caused by protozoa species of the Leishmania genus, and the current treatments face several difficulties and obstacles. Most anti-leishmanial drugs are administered intravenously, showing many side effects and drug resistance. The discovery of new anti-leishmanial compounds and the development of new pharmaceutical systems for more efficient and safer treatments are necessary. Copaiba oil-resin (CO) has been shown to be a promising natural compound against leishmaniasis. However, CO displays poor aqueous solubility and bioavailability. Self-emulsifying drug delivery systems (SEDDS) can provide platforms for release of hydrophobic compounds in the gastrointestinal tract, improving their aqueous solubilization, absorption and bioavailability. Therefore, the present work aimed to develop SEDDS containing CO and Soluplus® surfactant for the oral treatment of leishmaniasis. The design of the systems was accomplished using ternary phase diagrams. Emulsification and dispersion time tests were used to investigate the emulsification process in gastric and intestinal environments. The formulations were nanostructured and improved the CO solubilization. Their in vitro antiproliferative activity against promastigote forms of L. amazonensis and L. infantum, and low in vitro cytotoxicity against macrophages were also observed. More studies are necessary to determine effectiveness of SOL in these systems, which can be candidates for further pharmacokinetics and in vivo investigations.

Recent advances of Pluronic-based copolymers functionalization in biomedical applications.

The design of polymeric biocompatible nanomaterials for biological and medical applications has received special attention in recent years. Among different polymers, the triblock type copolymers (EO)x(PO)y(EO)x or Pluronics® stand out due its favorable characteristics such as biocompatibility, low tissue adhesion, thermosensitivity, and structural capacity to produce different types of macro and nanostructures, e.g. micelles, vesicles, nanocapsules, nanospheres, and hydrogels. However, Pluronic itself is not the "magic bullet" and its functionalization via chemical synthesis following biologically oriented design rules is usually required aiming to improve its properties. Therefore, this paper presents some of the main publications on new methodologies for synthetic modifications and applications of Pluronic-based nanoconstructs in the biomedical field in the last 15 years. In general, the polymer modifications aim to improve physical-chemical properties related to the micellization process or physical entrapment of drug cargo, responsive stimuli, active targeting, thermosensitivity, gelling ability, and hydrogel formation. Among these applications, it can be highlighted the treatment of malignant neoplasms, infectious diseases, wound healing, cellular regeneration, and tissue engineering. Functionalized Pluronic has also been used for various purposes, including medical diagnosis, medical imaging, and even miniaturization, such as the creation of lab-on-a-chip devices. In this context, this review discusses the main scientific contributions to the designing, optimization, and improvement of covalently functionalized Pluronics aiming at new strategies focused on the multiple areas of the biomedical field.

Electrospinning in personal protective equipment for healthcare work.

Protection in many service areas is mandatory for good performance in daily activities of workers, especially health areas. Personal protective equipment (PPE) is used to protect patients and health workers from contamination by harmful pathogens and body fluids during clinical attendance. The pandemic scenario caused by SARS-CoV-2 has shown that the world is not prepared to face global disease outbreaks, especially when it comes to the PPE of healthcare workers. In the last years, the world has faced a deficiency in the development of advanced technologies to produce high-quality PPE to attend to the exponential increasing demand. Electrospinning is a technology that can be used to produce high-quality PPE by improving the protective action of clothing. In the face of this concern, this manuscript presents as focus the potential of electrospinning to be applied in protective clothing. PPE mostly used by healthcare workers are also presented. The physico-chemical characteristics and production processes of medical textiles for PPE are addressed. Furthermore, an overview of the electrospinning technique is shown. It is important to highlight most research about electrospinning applied to PPE for health areas presents gaps and challenges; thus, future projections are also addressed in this manuscript.

Photo-responsive polymeric micelles for the light-triggered release of curcumin targeting antimicrobial activity.

Nanocarriers have been successfully used to solubilize, deliver, and increase the bioavailability of curcumin (CUR), but slow CUR release rates hinder its use as a topical photosensitizer in antimicrobial photodynamic therapy. A photo-responsive polymer (PRP) was designed for the light-triggered release of CUR with an effective light activation-dependent antimicrobial response. The characterization of the PRP was compared with non-responsive micelles comprising Pluronics™ P123 and F127. According to the findings, the PRP formed photo-responsive micelles in the nanometric scale (< 100 nm) with a lower critical micelle concentration (3.74 × 10-4 M-1, 5.8 × 10-4 M-1, and 7.2 × 10-6 M-1 for PRP, F127, P123, respectively, at 25°C) and higher entrapment efficiency of CUR (88.7, 77.2, and 72.3% for PRP, F127, and P123 micelles, respectively) than the pluronics evaluated. The PRP provided enhanced protection of CUR compared to P123 micelles, as demonstrated in fluorescence quenching studies. The light-triggered release of CUR from PRP occurred with UV light irradiation (at 355 nm and 25 mW cm-2) and a cumulative release of 88.34% of CUR within 1 h compared to 80% from pluronics after 36 h. In vitro studies showed that CUR-loaded PRP was non-toxic to mammal cell, showed inactivation of the pathogenic microorganisms Candida albicans, Pseudomonas aeruginosa, and methicillin-resistant Staphylococcus aureus, and decreased biofilm biomass when associated with blue light (455 nm, 33.84 J/cm2). The findings show that the CUR-loaded PRP micelle is a viable option for antimicrobial activity.

In vitro antifungal activity of curcumin mediated by photodynamic therapy on Sporothrix brasiliensis.

BACKGROUND: Sporothrix brasiliensis is a pathogenic dimorphic fungus that affects humans and animals causing sporotrichosis. The treatment of this disease with conventional antifungals commonly results in therapeutic failures and resistance. Therefore, this study aimed to evaluate the in vitro effect of curcumin (CUR) mediated by photodynamic therapy (PDT) in its pure state and incorporated into pharmaceutical formulation in gel form, on the filamentous and yeast forms of S. brasiliensis. METHODS: Cells from both forms of the fungus were treated with pure curcumin (PDT-CUR). For this, CUR concentrations ranging from 0.09 to 50 µM were incubated for 15 min and then irradiated with blue LED at 15 J/cm². Similarly, it was performed with PDT-CUR-gel, at lower concentration with fungistatic action. After, a qualitative and quantitative (colony forming units (CFU)) analysis of the results was performed. Additionally, reactive oxygen species (ROS) were detected by flow cytometry. Results PDT with 0.78 µM of CUR caused a significant reduction (p < 0.05) in cells of the filamentous and yeast form, 1.38 log10 and 1.18 log10, respectively, in comparison with the control. From the concentration of 1.56 µM of CUR, there was a total reduction in the number of CFU (≥ 3 log10). The PDT-CUR-gel, in relation to its base without CUR, presented a significant reduction (p < 0.05) of 0.83 log10 for the filamentous form and for the yeast form, 0.72 log10. ROS release was detected after the PDT-CUR assay, showing that this may be an important pathway of death caused by photoinactivation. Conclusion PDT-CUR has an important in vitro antifungal action against S. brasiliensis strains in both morphologies.