The paper presents the results of a study on the accumulation of three dierent compounds of water-soluble asymmetric cationic porphyrins by the bacteria S. aureus, S. epidermidis, S. haemolyticus and E. faecalis using ow cytouorimetry and uorescence microscopy. The studied microorganisms were a sample (n=4) of isolates from biomaterial (wound discharge) from patients with wound infections (burn wound, trophic ulcer, infection of the surgical area, etc.). The tested strains showed resistance to 1-7 antibiotics, two strains were carriers of the mecA gene. Porphyrins containing heterocyclic fragments (benzoxazole, N-methyl benzimidazole, and benzothiazole residues) on the periphery of the porphyrin cycle can accumulate in bacterial cells to varying degrees: porphyrin with N-methyl benzimidazole penetrates bacteria to a greater extent, and the uorescence signal is most intense for S. aureus and E. faecalis after incubation with this species. connections. There is some heterogeneity in the bacterial cell population with respect to the ability to accumulate porphyrins, and the presence of bacterial lysis has been proven. S aureus after incubation with S-porphyrin and subsequent photodynamic inactivation under the inuence of light. The data obtained determine the prospects for further study of compounds and determination of their bactericidal potential.

The use of protoporphyrin IX fluorescence imaging in skin tumors is limited by the complexity of light propagation in tissues. A non-invasive scat- tering anisotropy test (comparison of the fluorescence pattern of a tumor with that of a point source applied to the same spot) would be useful in distinguishing between cases of subsurface tumor growth and local fluorescence pattern distortions. However, the knowledge is missing of whether the distribution from an external light source would be representative. The experiment described here addressed the correlation between patterns in which light is dispersed from an external and an internal source within the same area of the skin. A pig’s head was chosen as the model. Four zones of interest were identified, all different in optical properties. The wavelength of the light source was selected as to simulate the PpIX fluorescence. The correspondence of light distribution patterns was quantified using the correlation method. The results have clearly demon- strated the strong relationship between the fluorescence distribution pattern of a tumor and the condition/topography of the surrounding tissues and proved the possibility of using an external light source to assess the local scattering anisotropy of the skin in vivo.

When studying the optical properties of photosensitizers, it is assumed that their fluorescence intensity depends linearly on concentration. How- ever, there are many factors that need to be taken into account. At low photosensitizer concentrations, a part of the excitation radiation energy is lost beyond the volume of the excited solution, and due to local or one-directional registration, a large part of isotropically emitted fluorescence radiation is also not registered. At higher concentrations, the loss of fluorescence light increases due to its partial re-absorption by the photosensi- tizer molecules and subsequent isotropic re-emission with quantum yield much lower than 1, and further increase of concentration leads to partial aggregation of PS, and to the following decrease of effective fluorescence. At high absorption, fluorescence is excited only in a limited volume close to the excitation radiation source, leading to higher significance of light registration geometry. This should be taken into account in fluorescence diagnostics and navigation using this characteristic.

This article reviews clinical experience in treating skin neoplasms using photodynamic therapy with combined ultrasound and fluorescence diag- nostics for neoplasms in the nose, lateral face, and adjacent areas. Injectable forms of chlorine-type drugs were used as photosensitizers – photodi- tazine or photoran at a dose of 0.7 to 2.5 mg per kilogram of patient body weight. The drug was administered intravenously for 30 minutes 2.5-3.0 hours before tumor irradiation. Of 107 observations over a 9-month observation period, one case of marginal tumor recurrence in the treatment area was detected. Thus, the recurrence rate was 0.93%. The results show that three-dimensional tumor visualization for the H-zone with complex noninvasive diagnostics allows achieving high efficiency in photodynamic therapy of non-melanoma tumors of the above anatomical localizations.

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 main aspects of automatization of photodynamic therapy (PDT) planning include several key areas related to improving accuracy, efficiency and personalization of treatment. Mathematical modeling of light propagation makes it possible to calculate the distribution of light energy in biotissues taking into account their optical characteristics and pathology geometry. At the same time the use of optical diagnostic methods allows not only to plan but also to control in real time the photodynamic effect with parameters adjustment depending on the degree of photosensitizer photobleaching and the hemoglobin oxygen saturation, as well as to determine the optical properties of tissues exactly in the exposure area. These methods also make it possible to personalize the effect, since it is based not on a priori information about averaged properties of organs and tis- sues, but on dynamically changing and measurable parameters. The use of photodynamic therapy for tumor diseases of the gastrointestinal tract has shown effectiveness as an adjunct to surgical treatment, as well as for tumors of small size and as a method of palliative treatment. At the same time from the point of view of light propagation in tissues the walls of gastrointestinal tract organs represent rather complex multilayer structures, optical properties of which depend on physiological state and pathologies developing in the organ. These circumstances make the task of automation of planning of photodynamic therapy of GI organs urgent and nontrivial. In this paper we review the methods that solve this problem.