In this paper we studied the photodynamic activity (the rate of molecular oxygen utilization during irradiation) of methylene blue (MB) in erythrocyte suspensions in vitro. Using spectroscopy and confocal microscopy with fluorescent sensors for singlet oxygen and other active oxygen species, it was shown that with an increase in the MB concentration (10–100 mg/kg), the molar photodynamic activity decreases. It was found that 5–10% of the MB added to erythrocytes tightly binds to the erythrocyte membranes, and the generation of singlet oxygen (¹O₂) is suppressed in favor of type I reactions (formation of H₂O₂, O₂•⁻, •OH). Another 40% of the MB added to erythrocytes is converted into a colorless leuco form, but is reoxidized back to MB under photodynamic exposure. The maximum relative quantum yield of ¹O₂ generation (φΔ ) among those measured in erythrocyte suspensions was 0.014 for a 10 mg/kg MB concentration, which is an order of magnitude lower than the values for MB in organic solvents and for the aluminum sulfonated phthalocyanine comparison photosensitizer (PS) (φΔ = 0.38). Interaction with erythrocytes (aggregation, reduction to the leuco form, competition for oxygen) explains the decrease in the MB efficiency under physiological conditions compared to organic solvents. The obtained results are important from the point of view of optimizing the systemic use of MB in photodynamic therapy.

Non-surgical therapies are essential for reducing the progression rate of human papillomavirus-associated cervical intraepithelial neoplasia (CIN) from low-grade (CIN 1) to high-grade CIN (CIN 2/3) and subsequently to cervical cancer with minimal adverse reactions and complications in women, such as haemorrhaging, cervical stenosis, spontaneous abortion, and preterm birth.Photodynamic therapy (PDT) has garnered considerable attention as a non-invasive approach to CIN treatment in recent years. PDT works by applying photoactive compounds, known as photosensitizers, that accumulate in target cells. Subsequent exposure of these cells to light of a specific wavelength (photoactivation) occurs. This paper aims to review the clinical development of clinical research on the effectiveness of PDT with a 5-Aminolevulinic acid (5-ALA) photosensitiser for treating CIN 1-3 from the early preliminary studies to recent reports.Early PDT studies using lower concentrations of 5-ALA showed poor effectiveness, but recent research with a 20% concentration of 5-ALA demonstrated better outcomes. Larger studies, preferably conducted across multiple centres, are needed to establish the optimal number of PDT sessions required to eliminate HPV.

The difficulty of intraoperative delineation of glial tumors is due to the peculiarities of their growth along vessels and nerve fibers with infiltration of healthy white matter. Insufficiently complete removal of tumor tissues leads to recurrences, and excessive removal is fraught with neurological complications. Optical spectroscopy methods are characterized by high speed, accuracy and non-invasiveness, which determines the prospects of their use for intraoperative demarcation of the boundaries of such tumors. Fluorescence and diffuse reflectance spectroscopy have found wide application in intraoperative neuronavigation, mainly for detecting the edges of diffuse gliomas. At the same time, in recent years the direction of <i>ex vivo</i> spectral analysis of tumor samples using a combination of various optical spectroscopy methods, including both elastic and inelastic scattering spectroscopy, has been actively developed. Obviously, the ability to obtain spectra intraoperatively and on fresh specimens is different. The present article compares the results of the analysis of optical-spectral characteristics of intracranial tumors at intraoperative diagnosis and <i>ex vivo</i> analysis and proposes a mathematical model for interpretation of the observed dependencies.

The objective of this study was to investigate the effectiveness of high-intensity pulsed broadband irradiation in treating infected wounds. A morphological study was conducted on wound specimens from 105 Wistar rats, in which infected wounds were experimentally induced (three groups). The first group was treated with high-intensity pulsed broadband irradiation, the second group received traditional ultraviolet irradiation, and the third group was treated only with antiseptics. Monitoring was performed before treatment, on the 7th, 14th, and 21st days of treatment. Non-parametric statistical methods were used for data analysis. Prior to treatment, the wounds exhibited signs of the acute inflammation phase. By the 7th day, the first group’s wounds were in the proliferation phase. In the second and third groups, edema and infiltration persisted. By the 14th day, the first group’s wounds showed signs of granulation tissue formation and transition to the regeneration stage. In the second group, there was a reduction in infiltration, the appearance of new capillaries, and an increase in fibroblasts. In the third group, inflammatory symptoms persisted. By the 21st day, the first group showed remodeling of connective tissue with signs of delicate scar formation. In the second group, signs of connective tissue remodeling were observed, while in the third group, there was reduced infiltration with slow formation of new vessels. Thus, the use of high-intensity pulsed broadband irradiation in the early stages effectively mitigates inflammation, activates local immune response, and accelerates reparative processes.

A systematic review and meta-analysis was aimed to assess the effectiveness of palliative photodynamic therapy for unresectable malignant tumors of the biliary system in order to justify the feasibility of including photodynamic therapy (PDT) in the complex treatment of this category of patients. Publications in the databases PubMed Central, the bibliographic database of scientifi citations of the RSCI, and the Cochrane library were considered. Heterogeneity was assessed graphically using forest plots and statistically using tau2 and I2 statistics. A meta-analysis of 5-year survival revealed a statistically signifiantly longer pooled estimate of the survival period in groups where PDT was used – 339±161 days (95% CI 25-710; p < 0.001) compared to groups where PDT was not used – 83±16 days (95% CI 33-100; p < 0.001). Heterogeneity among studies was found to be statistically insignifiant (I2 = 29%, p = 0.23). A meta-analysis of the risk difference for adverse events revealed a statistically signifiantly lower risk (-0.2306; 95% CI -0.3917-0.0696; p = 0.005) of adverse events after PDT compared with the comparison group. Heterogeneity among studies was found to be statistically insignifiant (I2 = 0%, p = 0.35). There were no signifiant publication biases in either meta-analysis. The presented meta-analysis demonstrated that PDT may be the method of choice in the palliative complex treatment of patients with unresectable cholangicarcinomas, increasing the ˝ve-year survival of patients along with the absence of increased risks of postoperative complications in comparison with other methods of palliative surgical treatment.

The aim of this study was to analyze the immediate and long-term results of using photodynamic therapy (PDT) in patients with leukoplakia of the oral mucosa. The retrospective study included 223 patients with morphologically verified leukoplakia of the oral mucosa. Patients received treatment at the hyperthermia and photodynamic therapy department from 2013 to 2023. The average age was 51.9±8.9 years. Clinically, 211 patients (94.6%) had a flat form of the disease, 12 patients (5.4%) had a verrucous form. The photosensitizer (PS), based on chlorin e6, was administered intravenously once in doses of 1.7 to 2.5 mg/kg body weight. Irradiation of pathologically changed lesions was carried out 2-2.5 hours after the end of its infusion, using a semiconductor laser device “UPL PDT”, with a wavelength λ=665±5 nm. The laser radiation dose density varied from 25 to 100 J/cm², the power density from 0.07 to 0.32 W/cm², the duration of one irradiation field - from 2 to 13.5 minutes, depending on its linear dimensions. The severity of adverse reactions was assessed on days 1-30 after treatment using the CTCAE 4.03 scale. The immediate results of treatment were assessed up to 3 months after PDT, with morphological confirmation of the response to treatment. No serious adverse reactions were observed during PS infusion and irradiation. No symptoms of dermal phototoxicity were reported. During control examinations, up to 3 months after irradiation in patients with flat and verrucous forms, the frequency of complete regressions was 97.1% (n=205) and 58.3% (n=6) cases, partial regressions - 2,9% (n=7) and 25% (n=3) of cases, respectively. Objective response rates were observed at 100% and 83.3%, respectively. The period of observation of patients varies from 3 to 120 months. (average 66 months). The frequency of disease relapses during this period was 9%. Patients with partial regression and identified relapse were treated with repeated PDT sessions. PDT is a well-tolerated and effective treatment method for patients with leukoplakia of the oral mucosa, which has significant advantages over traditional methods of treating this precancerous pathology. These include minimal toxicity to the normal tissues surrounding the pathological foci due to the selective accumulation of PS in leukoplakia tissues, a slight risk of serious adverse reactions, the possibility of an outpatient session, the possibility of repeated treatment over a large area of damage and good cosmetic results).

The structural integrity of the skin, which acts as a barrier to keep harmful external substances out of the body, is compromised by wounds. The process of wound healing is a multifaceted and ever-changing phenomenon that entails the replacement of bodily tissues or damaged skin. It has been demonstrated that nanoparticles, especially silver nanoparticles, have anti-microbial and anti-inflammatory qualities that encourage cell migration and proliferation. Low level laser therapy has the potential to accelerate wound healing by stimulating cell regeneration after injury, reducing pain, and modulating the immune system. The aim of our study is to evaluate the healing process after treatment with silver nanoparticle and/or low level laser by measuring the serum levels of some pro-inflammatory cytokines (IL1b, IL6, and TNF-α), wound healing rate and histological analysis. Wounds were inflicted into 63 adult male albino mice (Mus musculus) and randomly divided into nine groups (7 per each). Control was left to normal healing. Other groups received a different treatment with laser, silver nanoparticle or both for 21 days. Injured skin was sampled for histopathological examination. Quantitative determination of TNFα, IL1 beta and IL6 were carried out using the sandwich enzyme-linked immunosorbent assay (ELISA) twice (day 2 and day 21). One-way and two-way analysis of variance (ANOVA) was used for statistical analysis. The results showed that the groups treated with silver nanoparticles and / or low-level laser promoted wound healing by reducing pro- inflammatory cytokines (IL1β, IL6 and TNFα) and showed significantly better wound closure with a significant reduction in wound size. At day 2 histopathological changes were very similar in different groups. When silver nanoparticles were applied, either alone or in combination with laser exposure, better granulation tissue and fibrosis also necrosis in the canter of the lesion and high score of re-epithelialization with less inflammation observed gradually till day 21. The results of this study suggested that silver nanoparticles and low-level laser have a wound healing potential, since topical treatment with silver nanoparticles and low-level leasers has effectively improved the wound healing process.

The purpose of the work is to follow the dynamics of changes in fluorescent signals in the near-surface layers of tissue of injured areas of the back of laboratory animals, which will allow, by indirect evidence, to evaluate the information content of fluorescence diagnosis for subsequent possible diagnostic monitoring of photodynamic therapy of the spinal cord. The model animals were Wistar rats. Two types of contusions were modeled: pneumo-contusion and contusion by a falling load. Methylene blue and indocyanine green were used as photosensitizers. Fluorescence measurements were carried out by imaging and spectrometric methods. A stroboscopic fluorescence imager with an excitation wavelength of 630 nm was used to acquire fluorescence images. The LESA-01-BIOSPEC spectrometer with a He-Ne laser excitation allowed to obtain spectra. It was shown that both methods make it possible to estimate the fluorescence value of methylene blue and indocyanine green in the tissues under study. Moreover, the photographic method also allows to obtain the spatial distribution of fluorescence. The general trend found in the data is a more intense and uniform fluorescence of the dorsal region of rats with methylene blue and a less intense, but more contrasting distribution of indocyanine green. The presented methods are non-invasive, which makes them attractive for diagnostic use. However, due to the shallow depth of signal reception, the condition of the spine can be determined only indirectly, by the condition of the near-surface layers of tissue that accumulate the photosensitizer.

Photodynamic therapy (PDT) is known as a routine treatment method in which cell survival index like viability plotted versus 1 O 2 concentration or light fluence in the form of a curve. In this paper, a mathematical model was proposed with ability of generating a mirrored-sigmoid curve which seems to be fitted to any experimental data relating to cell viability, survival probability or any cellular index representing living conditions through adjusting three parameters. It was validated by showing an excellent curve fitting relatively with data obtained from cancerous lung cells under ALA-PDT process in vitro. It was tried to define the relations between model’s parameters and biological/clinical factors with the curve regions of plateau (at low doses; non- sensitive part), steep (high-sensitive part), and steady state (at high doses; low-sensitive part). It seems this model could be excellently fitted to any data presenting the cell-living index versus the killer agent in «any cancer therapy technique (e.g. radiotherapy)». Although this claim showed to be correct for PDT, different relevant data of other researchers should also be used for this model and other usual models too, in order to compare their fitness rates.

Nanoparticles are used as drug carriers to increase the selectivity and effectiveness of therapy, as well as for combined therapy that utilizes different effects. Iron oxide nanoparticles are promising in this aspect. Due to magnetic properties, they can be used as a contrast agent for magnetic resonance imaging. Also, iron oxide nanoparticles could be coated with a photosensitizer for photodynamic therapy and their laser or magnetic heating can be used for phototherapy. Local enhancement of the electromagnetic field near iron oxide nanoparticles can increase the fluorescence intensity of photosensitizers and the efficiency of singlet oxygen generation. This paper presents the results of a study of iron oxide nanoparticles focused on the photophysical aspects of the formation of “hot spots” under laser irradiation. The photoinduced effects of iron oxide nanoparticles observed in in vitro experiments lead to the rupture of lysosomes. Theoretical modeling showed that the heating of iron oxide nanoparticles with a radius of 35 nm under the action of laser radiation is about 89°C and 19°C for wavelengths of 458 and 561 nm, respectively. Local field enhancement occurs in pairs of nanoparticles of various sizes and strongly depends on the distance between them. The maximum gain is achieved at small distances between nanoparticles. For a dimer of nanoparticles with radii of 10 and 35 nm at a distance of 1 nm, an enhancement factor of two orders of magnitude was obtained. The investigated phenomenon of «hot spots» is in demand for precision therapy, because the photo-induced processes occur at small distances between nanoparticles, in areas of their high accumulation.