Photodynamic therapy for onychomycosis: A systematic review

"Unveiling onychomycosis: Pathogenesis, diagnosis, and innovative treatment strategies"

Onychomycosis, a widespread fungal nail infection, manifests as discoloration, thickening, and detachment of nails, often affecting the surrounding skin. While dermatophytes were historically considered the primary causative agents, recent studies reveal a rise in non-dermatophyte mold (NDM) infections, particularly in warmer climates. Dermatophytes dominate toenail infections, while yeasts and molds also contribute to fingernail infections, with certain molds like Fusarium spp. and Scytalidium spp being notable culprits. Diagnostic challenges arise from elevated false-negative rates in conventional methods like microscopy and culture, particularly with NDM infections. Histology and polymerase chain reaction (PCR) offers higher accuracy, albeit requiring multiple confirmations due to contamination risks. Treatment options encompass oral antifungals with higher cure rates but significant side effects and topical treatments with milder side effects but inferior efficacy. Several ongoing research aims to enhance transungual delivery through various approaches for the treatment of onychomycosis. Recurrence rates underscore the importance of prompt treatment, footwear hygiene, and preventive measures like topical treatments to mitigate the risk of reinfection. Understanding the evolving fungal landscape in onychomycosis is critical for effective management and recurrence prevention strategies.

Photodynamic therapy in dermatology: established and new indications

Photodynamic therapy (PDT) is internationally established as an approved treatment option for in situ forms of keratinocytic skin cancer (actinic keratoses, Bowen's disease, basal cell carcinoma). For these indications, there are standardized treatment protocols using narrow-spectrum light sources or (artificial) daylight, the use of which is associated with successful healing, a low rate of lesion recurrence, and a very good cosmetic result. Daylight PDT is superior to conventional PDT in terms of significantly less pain and associated higher patient acceptance. Newer indications, for which no approval has yet been granted, but which nevertheless have sufficient evidence of efficacy according to the study situation, are inflammatory (lichen sclerosus, acne) and infectious dermatoses (viral warts, cutaneous leishmaniasis, atypical mycobacteriosis). In addition, PDT is increasingly being used in aesthetic dermatology with the aim of skin rejuvenation.

Novel Henna-Related Naphthazarine Photosensitizers for an Effective Photodynamic Therapy of Onychomycosis

Onychomycosis caused by, e.g., Trichophyton rubrum or Candida albicans is the most common human nail disease with a worldwide prevalence of more than 10%. The therapeutic efficacy of topical antimycotics for the treatment of onychomycosis proved to be inadequate in numerous studies on patients. The main reasons are, above all, the poor bioavailability of the active ingredients in the nail compartment, causing the requirement for extremely long application periods and correspondingly high demands on adherence by the patient. In the present study, we aimed to develop a more effective and prompt photodynamic approach for the treatment of onychomycosis. The principle of photodynamic therapy (PDT) for onychomycosis has already been investigated. However, these studies used photosensitizers such as methylene blue, which were neither optimized for their keratinophilic features nor for their bioavailability in the nail. Hence, we initiated a screening campaign using T. rubrum and C. albicans cell-based assays, infected bovine keratin models, and keratin-penetrating irradiation to identify suitable hit compounds for a PDT approach toward onychomycosis. Here, we report on the discovery of Henna/Lawson-derived keratinophilic naphthazarines that act as highly potent PDT antimycotic photosensitizers with photoresponsiveness when irradiated by light at a keratin-permeable wavelength (>500 nm, e.g., compounds 10 and 11 with PDT-IC50 = 1 and 3 nM, respectively, against T. rubrum), hence with superior efficacy than the positive controls nystatin and clotrimazole. Notably, our photodynamic approach not only affected the actual pathogens but also prevented reinfection of keratin models within 10 days, suggesting an additional efficacy against fungal spores. Compared to established concepts, our proposed PDT approach using the novel naphthazarine photosensitizers could enable an effective, precise, and sustainable therapy option for the future treatment of onychomycosis.

Glass Microneedles: A Case Study for Regulatory Approval Using a Quality by Design Approach

In this paper, a roadmap is provided for the regulatory approval of one of the exciting and dynamic drug delivery fields, microneedles, by using a Quality by Design approach to pharmaceutical product development. In this regard, a quality target product profile (QTPP) and the critical quality attributes (CQA) of microneedles are identified. A case study of the recently patented method of fabricating glass microneedles entirely from a therapeutic agent, thus eliminating the requirement for additional excipients is discussed. The glass microneedle, ArrayPatch, is a propriety wearable device with platform potential consisting of an array of sharp, but painless, dissolvable microneedles manufactured with 100% drug. The microneedles penetrate the skin on application and dissolve to deliver a locally effective dose. The in vitro characterization of the microneedle CQAs under WHO-guided stability conditions will be described to assess the manufacturing readiness of ArrayPatch.  A live technical video is also provided, presenting a unique procedure of jugular vein cannulation through the ear vein of a pig animal model to study the in vivo pharmacokinetics of ArrayPatch compared to standard-of-care marketed products.

Utility of devices for onychomycosis: a review

Onychomycosis is difficult to treat due to long treatment durations, poor efficacy rates of treatments, high relapse rates, and safety issues when using systemic antifungal agents. Device-based treatments are targeted to specific regions of the nail, have favorable safely profiles, and do not interfere with systemic agents. They may be an effective alternative therapy for onychomycosis especially with increasing reports of squalene epoxidase gene mutations and potential resistance to terbinafine therapy. In this review, we discuss four devices used as antifungal treatments and three devices used as penetration enhancers for topical agents. Lasers, photodynamic therapy, microwaves, and non-thermal plasma have the capacity to inactivate fungal pathogens demonstrated through in vivo studies. Efficacy rates for these devices, however, remain relatively low pointing toward the need to further optimize device or usage parameters. Ultrasound, nail drilling, and iontophoresis aid in improving the permeability of topical agents through the nail and have been investigated as adjunctive therapies. Due to the paucity in clinical data, their efficacy in treating onychomycosis has not yet been established. While the results of clinical studies point toward the potential utility of devices for onychomycosis, further large-scale randomized clinical trials following regulatory guidelines are required to confirm current results.

Contemporary Techniques and Potential Transungual Drug Delivery Nanosystems for The Treatment of Onychomycosis

The humanoid nail is considered an exceptional protective barrier that is formed mainly from keratin. Onychomycosis is the cause of 50% of nail infections that is generally caused by dermatophytes. Firstly, the infection was regarded as a cosmetic problem but because of the tenacious nature of onychomycosis and its relapses, these infections have attracted medical attention. The first line of therapy was the oral antifungal agents which were proven to be effective; nevertheless, they exhibited hepato-toxic side effects, alongside drug interactions. Following, the opportunity was shifted to the topical remedies, as onychomycosis is rather superficial, yet this route is hindered by the keratinized layers in the nail plate. A potential alternative to overcome the obstacle was applying different mechanical, physical, and chemical methods to boost the penetration of drugs through the nail plate. Unfortunately, these methods might be expensive, require an expert to be completed, or even be followed by pain or more serious side effects. Furthermore, topical formulations such as nail lacquers and patches do not provide enough sustaining effects. Recently, newer therapies such as nanovesicles, nanoparticles, and nanoemulsions have emerged for the treatment of onychomycosis that provided effective treatment with possibly no side effects. This review states the treatment strategies such as mechanical, physical, and chemical methods, and highlights various innovative dosage forms and nanosystems developed in the last 10 years with a focus on advanced findings regarding formulation systems. Furthermore, it demonstrates the natural bioactives and their formulation as nanosystems, and the most relevant clinical outcomes.

Antileishmanial activity of tetra-cationic porphyrins with peripheral Pt(II) and Pd(II) complexes mediated by photodynamic therapy approaches

Leishmaniasis is a seriously neglected disease that impacts more than one billion people in endemic areas of the globe. Several drawbacks are associated with the currently existing drugs for the treatment as low effectiveness, toxicity, and the emergence of resistant strains that demonstrates the importance of looking for novel therapeutic alternatives. Photodynamic therapy (PDT) is a promising novel alternative for cutaneous leishmaniasis treatment because its topical application avoids potential side effects generally associated with oral/parenteral application. A light-sensitive compound known as photosensitizer (PS) interacts with light and molecular oxygen to generate reactive oxygen species (ROS), which promote cell death by oxidative stress through PDT approaches. Here, for the first time, we demonstrate the antileishmanial effect of tetra-cationic porphyrins with peripheral Pt(II)- and Pd(II)-polypyridyl complexes using PDT. The isomeric tetra-cationic porphyrins in the meta positions, 3-PtTPyP, and 3-PdTPyP, exhibited the highest antiparasitic activity against promastigote (IC_50-pro = 41.8 nM and 46.1 nM, respectively) and intracellular amastigote forms (IC_50-ama = 27.6 nM and 38.8 nM, respectively) of L. amazonensis under white light irradiation (72 J cm^-2) with high selectivity (SI > 50) for both forms of parasites regarding mammalian cells. In addition, these PS induced the cell death of parasites principally by a necrotic process in the presence of white light by mitochondrial and acidic compartments accumulation. This study showed that porphyrins 3-PtTPyP and 3-PdTPyP displayed a promising antileishmanial-PDT activity with potential application for cutaneous leishmaniasis treatment.

The First Report of In Vitro Antifungal and Antibiofilm Photodynamic Activity of Tetra-Cationic Porphyrins Containing Pt(II) Complexes against Candida albicans for Onychomycosis Treatment

Onychomycosis is a prevalent nail fungal infection, and Candida albicans is one of the most common microorganisms associated with it. One alternative therapy to the conventional treatment of onychomycosis is antimicrobial photoinactivation. This study aimed to evaluate for the first time the in vitro activity of cationic porphyrins with platinum(II) complexes 4PtTPyP and 3PtTPyP against C. albicans. The minimum inhibitory concentration of porphyrins and reactive oxygen species was evaluated by broth microdilution. The yeast eradication time was evaluated using a time-kill assay, and a checkerboard assay assessed the synergism in combination with commercial treatments. In vitro biofilm formation and destruction were observed using the crystal violet technique. The morphology of the samples was evaluated by atomic force microscopy, and the MTT technique was used to evaluate the cytotoxicity of the studied porphyrins in keratinocyte and fibroblast cell lines. The porphyrin 3PtTPyP showed excellent in vitro antifungal activity against the tested C. albicans strains. After white-light irradiation, 3PtTPyP eradicated fungal growth in 30 and 60 min. The possible mechanism of action was mixed by ROS generation, and the combined treatment with commercial drugs was indifferent. The 3PtTPyP significantly reduced the preformed biofilm in vitro. Lastly, the atomic force microscopy showed cellular damage in the tested samples, and 3PtTPyP did not show cytotoxicity against the tested cell lines. We conclude that 3PtTPyP is an excellent photosensitizer with promising in vitro results against C. albicans strains.

Fractional CO2 laser - assisted methylene blue photodynamic therapy is a potential alternative therapy for onychomycosis in the era of antifungal resistance

BACKGROUND

Treatment of onychomycosis is challenging by virtue of the impact of nail disfigurement, the location of the fungi within the nail and reported antifungal resistance worldwide. Light-based technologies are promising primary or adjunctive therapeutic modalities. We aimed to compare the efficacy of photodynamic therapy and fractional CO2 laser monotherapy either alone or in combination for onychomycosis.

PATIENTS AND METHODS

This prospective randomized comparative study was conducted on 51 onychomycosis patients divided into three groups. In group A, patients were treated using 6 photodynamic therapy sessions using methylene blue and IPL (560 to 700 nm, fluence 12 J/cm2). Group B patients were treated using 6 bimonthly fractional CO2 laser sessions (10,600 nm, 1.600 mj energy and 0.6 mm density) and group C patients were treated using 6 combined fractional CO2 laser and photodynamic therapy sessions. Patients were evaluated mycologically, dermoscopically and clinically by calculation of proximal nail diameter percentage at baseline, monthly, at the end of treatment and after a 6-month follow-up period post-treatment.

RESULTS

Candida was the most commonly isolated organismin in 64.7%, 70.6% and 70.6% of the pateints in groups A, B and C, respectively. The dermoscopic findings in the total dystrophic onychomycosis was subungual hyperkeratosis in 6 patients (100%), longitudinal streaks and striae in 1 patient (16.7%). In dorsolateral subungual onychomycosis, jagged proximal edge in 31 patients (70.5%), and pigmentation in 30 patients (68.2%) were noted. In proximal subungual onychomycosis irregular matt patches were seen in 1 patient (100%). Proximal nail diameter percentage showed statistically significant improvement after treatment and 6 months follow up in the 3 studied groups. Mean increase of proximal nail diameter after treatment was highest in group C (52.94 ± 20.24), followed by group B (43.82 ± 21.03) and least in group A (35.29 ± 17.0). This difference was statistically significant (p = 0.044). Reported side effects were mild-moderate pain, discoloration and paronychia.

CONCLUSION

We conclude that fractional CO2 laser and photodynamic monotherapy, and their combination achieve high success rates, good patient satisfaction and safety profile. Fractional CO2-assisted photodynamic therapy is associated with the highest improvement over either fractional CO2 or photodynamic therapy alone.

An insight into photodynamic therapy towards treating major dermatological conditions

Photodynamic therapy (PDT), as the name suggests is a light-based, non-invasive therapeutic treatment method that has garnered immense interest in the recent past for its efficacy in treating several pathological conditions. PDT has prominent use in the treatment of several dermatological conditions, which consequently have cosmetic benefits associated with it as PDT improves the overall appearance of the affected area. PDT is commonly used for repairing sun-damaged skin, providing skin rejuvenation, curbing pre-cancerous cells, treating conditions like acne, keratosis, skin-microbial infections, and cutaneous warts, etc. PDT mediates its action by generating oxygen species that are involved in bringing about immunomodulation, suppression of microbial load, wound-healing, lightening of scarring, etc. Although there are several challenges associated with PDT, the prominent ones being pain, erythema, insufficient delivery of the photosensitizing agent, and poor clinical outcomes, still PDT stands to be a promising approach with continuous efforts towards maximizing clinical efficacy while being cautious of the side effects and working towards lessening them. This article discusses the major skin-related conditions which can be treated or managed by employing PDT as a better or comparable alternative to conventional treatment approaches such that it also brings about aesthetic improvements thereof.

Response surface methodological approach for optimization of photodynamic therapy of onychomycosis using chlorin e6 loaded nail penetration enhancer vesicles

Antimicrobial photodynamic inactivation (aPDI) has a tremendous potential as an alternative therapeutic modality to conventional antifungals in treatment of onychomycosis, yet the nail barrier properties and the deep-seated nature of fungi within the nails remain challenging. Therefore, the aim of this study was to prepare, optimize, and characterize Chorin e6 (Ce6) nail penetration enhancer containing vesicles (Ce6-nPEVs) and evaluate their photodynamic mediated effect against Trichophyton rubrum (T.rubrum); the main causative agent of onychomycosis. Optimization of the particle size and encapsulation efficiency of nPEVs was performed using a four-factor two-level full factorial design. The transungual delivery potential of the selected formulation was assessed in comparison with the free drug. The photodynamic treatment conditions for T.rubrum aPDI by free Ce6 was optimized using response surface methodology based on Box-Behnken design, and the aPDI effect of the selected Ce6-nPEVs was evaluated versus the free Ce6 at the optimized condition. Results showed that formulations exhibited high encapsulation efficiency for Ce6 ranging from 79.4 to 98%, particle sizes ranging from 225 to 859 nm, positive zeta potential values ranging from +30 to +70 mV, and viscosity ranging from 1.26 to 3.43 cP. The predominant parameters for maximizing the encapsulation efficiency and minimizing the particle size of Ce6-nPEVs were identified. The selected formulation showed 1.8-folds higher nail hydration and 2.3 folds improvement in percentage of Ce6 up-taken by nails compared to the free drug. Results of the microbiological study confirmed the reliability and adequacy of the Box-Behnken model, and delineated Ce6 concentration and incubation time as the significant model terms. Free Ce6 and Ce6-nPEVs showed an equipotent in vitro fungicidal effect on T.rubrum at the optimized conditions, however Ce6-nPEVs is expected to show a differential effect at the in vivo level where the advantage of the enhanced nail penetration feature will be demonstrated.

Aloe-emodin-mediated antimicrobial photodynamic therapy against dermatophytosis caused by Trichophyton rubrum

Trichophyton rubrum is responsible for the majority of dermatophytosis. Current systemic and topical antifungals against dermatophytosis are often tedious and sometimes unsatisfactory. Antimicrobial photodynamic therapy (aPDT) is a non-invasive alternative suitable for the treatment of superficial fungal infections. This work investigated the photodynamic inactivation efficacy and effects of aloe-emodin (AE), a natural photosensitizer (PS) against T. rubrum microconidia in vitro, and evaluated the treatment effects of AE-mediated aPDT for T. rubrum-caused tinea corporis in vivo and tinea unguium ex vivo. The photodynamic antimicrobial efficacy of AE on T. rubrum microconidia was evaluated by MTT assay. The inhibition effect of AE-mediated aPDT on growth of T. rubrum was studied. Intracellular location of AE, damage induced by AE-mediated aPDT on cellular structure and surface of microconidia and generation of intracellular ROS were investigated by microscopy and flow cytometry. The therapeutic effects of AE-mediated aPDT against dermatophytosis were assessed in T. rubrum-caused tinea corporis guinea pig model and tinea unguium ex vivo model. AE-mediated aPDT effectively inactivated T. rubrum microconidia in a light energy dose-dependent manner and exhibited strong inhibitory effect on growth of T. rubrum. Microscope images indicated that AE is mainly targeted to the organelles and caused damage to the cytoplasm of microconidia after irradiation through generation of abundant intracellular ROS. AE-mediated aPDT demonstrated effective therapeutic effects for T. rubrum-caused tinea corporis on guinea pig model and tinea unguium in ex vivo model. The results obtained suggest that AE is a potential PS for the photodynamic treatment of dermatophytosis caused by T. rubrum, but its permeability in skin and nails needs to be improved.

Photodynamic disinfection and its role in controlling infectious diseases

Photodynamic therapy is witnessing a revival of its origins as a response to the rise of multi-drug resistant infections and the shortage of new classes of antibiotics. Photodynamic disinfection (PDDI) of microorganisms is making progresses in preclinical models and in clinical cases, and the perception of its role in the clinical armamentarium for the management of infectious diseases is changing. We review the positioning of PDDI from the perspective of its ability to respond to clinical needs. Emphasis is placed on the pipeline of photosensitizers that proved effective to inactivate biofilms, showed efficacy in animal models of infectious diseases or reached clinical trials. Novel opportunities resulting from the COVID-19 pandemic are briefly discussed. The molecular features of promising photosensitizers are emphasized and contrasted with those of photosensitizers used in the treatment of solid tumors. The development of photosensitizers has been accompanied by the fabrication of a variety of affordable and customizable light sources. We critically discuss the combination between photosensitizer and light source properties that may leverage PDDI and expand its applications to wider markets. The success of PDDI in the management of infectious diseases will ultimately depend on the efficacy of photosensitizers, affordability of the light sources, simplicity of the procedures, and availability of fast and efficient treatments.

Hypericin-P123-photodynamic therapy in an ex vivo model as an alternative treatment approach for onychomycosis caused by Fusarium spp

BackgroundFusarium has been considered an opportunistic pathogen, causing several infections in humans, including onychomycosis. In addition, a high resistance to conventional antifungals has been linked to this genus. Photodynamic Therapy (PDT), known as a non-invasive therapy, can be an alternative treatment for fungal infections, based on the excitation of a photosensitizing compound (PS) by a specific length of light, causing damage to the target. The aim of this study was to evaluate the effects of a formulation of Hypericin (Hyp) encapsulated in Pluronic™ (P123), via photodynamic therapy (PDT), on planktonic cells and biofilms in Fusarium spp. using in vitro and ex vivo assays. Materials & Methods epidemiology studies about Fusarium spp. in onychomycosis was perfomed, carried out molecular identification, compared the antifungal activity of the conventional antifungals with PDT with encapsulated Hypericin (Hyp-P123), carried out detection of reactive oxygen species, and measured the antibiofilm effect of the Hyp-P123-PDT in vitro and in an ex vivo model of onychomycosis. Results Hyp-P123-PDT exhibited a fungicidal effect in vitro with reductions ≥ 3 log₁₀. ROS generation increased post-Hyp-P123-PDT in Fusarium spp. Hyp-P123-PDT showed a potent inhibitory effect on adhesion-phase and mature biofilms in vitro tests and an ex vivo model of onychomycosis (p<0.0001). Conclusion Hyp-P123-PDT had a potent effect against Fusarium spp., suggesting that photodynamic therapy with Hyp-P123 is a safe and promising treatment for onychomycosis in clinical practice.

Quality of life and therapeutic regimen management in onychomycosis patients and in vitro study of antiseptic solutions

Onychomycosis or tinea unguium (EE12.1) and Onychomycosis due to non-dermatophyte moulds (1F2D.5) (OM) is a fungal infection of the nail plates with a high prevalence that often affects vulnerable people with co-existing health problems. Gold standard pharmacological treatments for onychomycosis have been associated with low success rates and increasing antifungal resistance, suggesting that treatment outcome is dependent on multiple variables. Here, the prevalence of OM and quality of life were characterized in two vulnerable populations—Hospital patients and Homeless people. Comparing both groups, the most prevalent fungal species were identified in Hospital patients. Then, the in vitro fungicidal properties of the antiseptics povidone-iodine, polyhexamethylene biguanide-betaine, octenidine dihydrochloride, and a super-oxidized solution against two ATCC strains (Candida albicans and Aspergillus niger) and three clinical fungal isolates from Hospital patients (Candida parapsilosis, Trichophyton interdigitale, and Trichophyton rubrum) were tested. OM prevalence was high in both patient groups studied, who also reported a reduction in quality of life and concerns about the state of their feet. In addition, Hospital patients had a non-negligent therapeutic regimen management style. Antiseptics tested in vitro revealed antifungal properties. As antiseptics are low-cost and easy to apply and have few iatrogenic effects, the demonstration of fungicidal properties of these solutions suggests that they may constitute potential supportive therapeutics for OM.

Antibacterial Photodynamic Inactivation of Fagopyrin F from Tartary Buckwheat (Fagopyrum tataricum) Flower against Streptococcus mutans and Its Biofilm

The objective of this study was to determine reactive oxygen species (ROS) produced by fagopyrin F-rich fraction (FFF) separated from Tartary buckwheat flower extract exposed to lights and to investigate its antibacterial photodynamic inactivation (PDI) against Streptococcus mutans and its biofilm. ROS producing mechanisms involving FFF with light exposure were determined using a spectrophotometer and a fluorometer. S. mutans and its biofilm inactivation after PDI treatment of FFF using blue light (BL; 450 nm) were determined by plate count method and crystal violet assay, respectively. The biofilm destruction by ROS produced from FFF after exposure to BL was visualized using confocal laser scanning microscopy (CLSM) and field emission scanning electron microscope (FE-SEM). BL among 3 light sources produced type 1 ROS the most when applying FFF as a photosensitizer. FFF exposed to BL (5 and 10 J/cm2) significantly more inhibited S. mutans viability and biofilm formation than FFF without the light exposure (p < 0.05). In the PDI of FFF exposed to BL (10 J/cm2), an apparent destruction of S. mutans and its biofilm were observed by the CLSM and FE-SEM. Antibacterial PDI effect of FFF was determined for the first time in this study.

Investigation of the Dual-Stage Method of Active Er:YLF Laser Drug Delivery Through the Nail and Laser-Induced Transformations of the Drug Extinction Spectrum

BACKGROUND AND OBJECTIVE

A novel dual-stage method for active laser drug delivery (DSLADD) in the treatment of nail diseases is being presented. This method includes sequentially performed microporation of the nail with submillisecond pulses of Er:YLF laser radiation through a layer of an aqueous solution of drug deposited on the nail surface (Stage 1) and exposure this layer to the same laser radiation to deliver drug under the nail plate (Stage 2). The delivery of methylene blue (MB) as one of the possible drugs in the treatment of nail diseases is investigated. The influence of the thickness of the MB layer, as well as the energy and number of applied laser pulses, on the rate of active laser delivery is discussed. To illustrate the possible effect of delivery on the drug delivered, special attention is paid to the deformation of the extinction spectrum of MB solution after laser irradiation.

STUDY DESIGN/MATERIALS AND METHODS

Diode-pumped Er:YLF laser was used for DSLADD. The process of DSLADD under the nail plate was investigated using digital video microscopy. For different values of the thickness of MB solution layer applied to the nail plate and the energy of laser pulses, the number of laser pulses required to create a single through a microchannel in the nail plate and the number of laser pulses required to deliver the solution to the ventral side of the nail plate after its microporation were registered. The mass and the dose of MB solution penetrated under the nail plate, and the rate of MB solution delivery through a single microchannel was determined. Investigation of the influence of Er:YLF laser radiation parameters on the extinction spectrum of the drug was performed using a fiber spectrometer. The extinction spectra of the 0.001% aqueous solution of MB were recorded before and after exposure to a different number of Er:YLF laser pulses with the energy of 1-4 mJ.

RESULTS

It was found that the minimum number of laser pulses required for active Er:YLF laser drug delivery under the nail corresponds to the MB layer thickness of 100 μm and the laser pulse energy of 4 mJ. It is shown that in this case, the rate of active laser delivery of MB solution reaches 0.26 ± 0.03 mg/pulse. The radiation of the Er:YLF laser affects the shape of the extinction spectrum of the aqueous solution of MВ, which is associated with the transition of the dye from the monomeric to dimeric state. Depending on the laser pulse energy, the fraction of a certain conformational state in the aqueous MB solution can decrease or increase, stimulating a possible change in its photodynamic and antiseptic activity.

CONCLUSION

For the first time, a novel DSLADD through the nail has been described and investigated in vitro. It was demonstrated that at Er:YLF laser pulse repetition rate of f = 30 Hz, microporation of the nail plate and drug delivery through a single microchannel will be about 1.5 s. Lasers Surg. Med. © 2021 Wiley Periodicals LLC.

Onychomycosis: An Updated Review

Background: Onychomycosis is a common fungal infection of the nail.

Objective: The study aimed to provide an update on the evaluation, diagnosis, and treatment of onychomycosis.

Methods: A PubMed search was completed in Clinical Queries using the key term “onychomycosis”. The search was conducted in May 2019. The search strategy included meta-analyses, randomized controlled trials, clinical trials, observational studies, and reviews published within the past 20 years. The search was restricted to English literature. Patents were searched using the key term “onychomycosis” in www.freepatentsonline.com.

Results: Onychomycosis is a fungal infection of the nail unit. Approximately 90% of toenail and 75% of fingernail onychomycosis are caused by dermatophytes, notably Trichophyton mentagrophytes and Trichophyton rubrum. Clinical manifestations include discoloration of the nail, subungual hyperkeratosis, onycholysis, and onychauxis. The diagnosis can be confirmed by direct microscopic examination with a potassium hydroxide wet-mount preparation, histopathologic examination of the trimmed affected nail plate with a periodic-acid-Schiff stain, fungal culture, or polymerase chain reaction assays. Laboratory confirmation of onychomycosis before beginning a treatment regimen should be considered. Currently, oral terbinafine is the treatment of choice, followed by oral itraconazole. In general, topical monotherapy can be considered for mild to moderate onychomycosis and is a therapeutic option when oral antifungal agents are contraindicated or cannot be tolerated. Recent patents related to the management of onychomycosis are also discussed.

Conclusion: Oral antifungal therapies are effective, but significant adverse effects limit their use.Although topical antifungal therapies have minimal adverse events, they are less effective than oral antifungal therapies, due to poor nail penetration. Therefore, there is a need for exploring more effective and/or alternative treatment modalities for the treatment of onychomycosis which are safer and more effective.

European Dermatology Forum guidelines on topical photodynamic therapy 2019 Part 2: emerging indications - field cancerization, photorejuvenation and inflammatory/infective dermatoses

In addition to approved indications in non-melanoma skin cancer in immunocompetent patients, topical photodynamic therapy (PDT) has also been studied for its place in the treatment of, as well as its potential to prevent, superficial skin cancers in immune-suppressed patients, although sustained clearance rates are lower than for immune-competent individuals. PDT using a nanoemulsion of ALA in a daylight or conventional PDT protocol has been approved for use in field cancerization, although evidence of the potential of the treatment to prevent new SCC remained limited. High-quality evidence supports a strong recommendation for the use of topical PDT in photorejuvenation as well as for acne, refractory warts, cutaneous leishmaniasis and in onychomycosis, although these indications currently lack approvals for use and protocols remain to be optimized, with more comparative evidence with established therapies required to establish its place in practice. Adverse events across all indications for PDT can be minimized through the use of modified and low-irradiance regimens, with a low risk of contact allergy to photosensitizer prodrugs, and no other significant documented longer-term risks with no current evidence of cumulative toxicity or photocarcinogenic risk. The literature on the pharmacoeconomics for using PDT is also reviewed, although accurate comparisons are difficult to establish in different healthcare settings, comparing hospital/office-based therapies of PDT and surgery with topical ointments, requiring inclusion of number of visits, real-world efficacy as well as considering the value to be placed on cosmetic outcome and patient preference. This guideline, published over two parts, considers all current approved and emerging indications for the use of topical photodynamic therapy in Dermatology prepared by the PDT subgroup of the European Dermatology Forum guidelines committee. It presents consensual expert recommendations reflecting current published evidence.

Novel Drug Delivery Strategies for the Treatment of Onychomycosis

Onychomycosis accounts for 50% of all nail disease cases and is commonly caused by dermatophytes. It was primarily considered a cosmetic problem but has been garnering attention lately due to its persistent nature and difficult treatment with relapses. With prolonged treatment duration and high cost involved in treating onychomycosis, several attempts have been made in overcoming the rigid nail barrier. The conventional treatment of onychomycosis involves oral and topical therapy. The oral antifungal agents though quite effective, are hepato-toxic and cause drug-drug interactions. Topical therapy is more patient compliant being devoid of such adverse effects but it suffers from another setback of improper nail penetration. Amorolfine and ciclopirox nail lacquers are popular market products. Since decades, efforts have been made to enhance topical delivery for efficiently treating onychomycosis. Mechanical, physical and chemical methods have been employed. Despite all the attempts made, the nail delivery issues are far from being solved. Recently, the focus has shifted to novel drug delivery systems like nanoparticles, microemulsions, polymeric films and nail lacquers for enhanced drug permeation and localized therapy. The research around the world is exploring their potential as effective treatment options. This review intends to further explore the novel delivery strategies to treat a persistent fungal infection like onychomycosis.

Zinc pthalocyanine-loaded chitosan/mPEG-PLA nanoparticles-mediated photodynamic therapy for the treatment of cutaneous squamous cell carcinoma

Zinc pthalocyanine (ZnPc) is a second-generation photodynamic therapy (PDT) sensitizer with sufficient PDT activity for squamous cell carcinoma (SCC). ZnPc is hydrophobic and insoluble in water, which creates hurdles in systemic administration and hence restricts its use in clinic. Here we have loaded ZnPc on chitosan/methoxy polyethylene glycol-polylactic acid (CPP) nanoparticles to form Z-CPP to enhance PDT efficacy. In vitro and in vivo studies were performed to see dark toxicity of the compounds ZnPc, CPP and Z-CPP. Then PDT was done and its growth inhibitory effect on SCC cells was evaluated. In addition, reactive oxygen species (ROS) formation and apoptosis of cancer cells following PDT were studied. The results showed that the tested compounds exhibit no dark toxicity and the effect of PDT was significantly better with Z-CPP when compared to free ZnPc (P < .05). Photoactivation of Z-CPP led to a dose-dependent growth inhibition of cancer cells of >50% at 1 μM to >80% at 10 μM concentration. Also Z-CPP-treated cells had highest number of apoptotic cells and produced more ROS compared to free ZnPc-treated cells (P < .05). Hence, this study suggests that Z-CPP is a suitable pharmaceutical compound to increase PDT efficacy.

Challenges and Opportunities in the Management of Onychomycosis

Onychomycosis is an increasingly common fungal nail infection, chiefly caused by dermatophyte fungi. The disease is notoriously difficult to treat due to the deep-seated nature of fungi within the nail plate, prolonged treatment requirements, poor patient adherence and frequent recurrences. Given the poor efficacy of currently available topical and systemic therapies, there is a renewed interest in exploring alternative treatment modalities for onychomycosis. Natural therapies, physical treatments and various combination therapies have all shown potential for the management of onychomycosis, though research on many of these methods is still in preliminary stages. Further large, well-designed, randomised controlled trials are necessary to confirm the efficacy of these novel treatments in order to make formal recommendations regarding their use in the management of onychomycosis.

Near-infrared rechargeable "optical battery" implant for irradiation-free photodynamic therapy

As a minimal or noninvasive therapeutic method for tumors, photodynamic therapy (PDT) induced by the external laser irradiations has attracted great attentions. However, the UV-visible responsive property with low tissue penetration and photothermal effect from the prolonged irradiation impedes their further applications. Herein, a near-infrared (NIR) rechargeable "optical battery" for irradiation-free PDT is fabricated by embedding upconversion materials, persistent luminescence materials, photosensitizer into biocompatible polydimethylsiloxane. After 5 s quickly charged by 980-nm NIR laser, the PDT "optical battery" can generate green persistent luminescence and produce cytotoxic singlet oxygen for continuous irradiation-free PDT (∼30 min) without external irradiation. Due to deep tissue penetration and discontinuous short exposure of NIR light charging source, the "optical battery" can still be charged to continuously generate singlet oxygen in deep tissue (∼4 mm) with low photothermal effect. The PDT implant can be easily optimized in size and shape aiming at different nidus sites and achieved different functions by adding other functional components (e.g. CaO₂ for oxygen envolving to overcome hypoxia tumor). The effective tumor proliferation inhibiting capability of this NIR rechargeable "optical battery" may give rise to next generation of intelligent stimuli-responsive nanomedicine and noninvasive photo bio-stimulation research for future clinical applications.

Photodynamic therapy in 3D cancer models and the utilisation of nanodelivery systems

Photodynamic therapy (PDT) is the subject of considerable research in experimental cancer models mainly for the treatment of solid cancerous tumours. Recent studies on the use of nanoparticles as photosensitiser carriers have demonstrated improved PDT efficacy in experimental cancer therapy. Experiments typically employ conventional monolayer cell culture but there is increasing interest in testing PDT using three dimensional (3D) cancer models. 3D cancer models can better mimic in vivo models than 2D cultures by for example enabling cancer cell interactions with a surrounding extracellular matrix which should enable the treatment to be optimised prior to in vivo studies. The aim of this review is to discuss recent research using PDT in different types of 3D cancer models, from spheroids to nano-fibrous scaffolds, using a range of photosensitisers on their own or incorporated in nanoparticles and nanodelivery systems.

Effects of arginine-glycine-aspartic acid peptide-conjugated quantum dots-induced photodynamic therapy on pancreatic carcinoma in vivo

Quantum dots (QDs) conjugated with integrin antagonist arginine-glycine-aspartic acid (RGD) peptides (QDs-RGD) are novel nanomaterials with a unique optical property: a high molar extinction coefficient. Previously, we have shown that QDs-RGD demonstrate a photodynamic therapy (PDT) effect as new photosensitizers for the pancreatic cancer cell line SW1990 in vitro. Here, we investigate the application of QDs-RGD in mice bearing pancreatic tumors using PDT. To ensure that more photosensitizers accumulated in tumors, QDs-RGD were injected intratumorally. After selection of an adequate dosage for injection from analyses of biodistribution images captured by an IVIS system, PDT was initiated. Three groups were created according to different PDT procedures. In group 1, mice were injected with QDs-RGD intratumorally, and an optical fiber connected to a laser light was inserted directly into the tumor. Irradiation was sustained for 20 min with a laser light (630 nm) at 100 mW/cm2. In group 2, the laser optical fiber was placed around, and not inserted into, tumors. In group 3, PDT was conducted as in group 1 but without injection of QDs-RGD. After 28 days of observation, tumors on the back of mice in group 1 grew slowly (V/V0 =3.24±0.70) compared with the control groups, whose tumors grew quickly, and the mean V/V0 reached 6.08±0.50 (group 2) and 7.25±0.82 (group 3). Histology of tumor tissues showed more necrotic tissues, more inflammatory cells, and less vascular tissue in the PDT group than those in the control groups. These results suggest that QDs-RGD-mediated PDT, with illumination using an optical fiber inserted directly into the tumor, can inhibit the growth of SW1990 tumors with high efficiency in nude mice.