CC BY
18B-I-24
BIOMEDICAL PHOTONICS
Photoacceptors and photochemical processes determining the regulatory effect of visible laser radiation on various cell types
V. Plavskii, T. Ananich, O. Dudinova, J. Kruchenok, I. Leusenko, A. Mikulich, R. Nahorny, L. Plavskaya, A.
Tretyakova, A. Sobchuk, S. Yakimchuk
B.I.Stepanov Institute of Physics of the National Academy of Sciences of Belarus, Minsk, Belarus
This paper presents the results obtained using various types of cells (eukaryotes, prokaryotes, blood cells (erythrocytes), spermatozoa), indicating that the regulatory effect of low-intensity laser radiation in the visible region of the spectrum is based on a change in the redox state of cells. Spectral-fluorescence methods have been developed, allowing one to detect and identify for the first time the endogenous photosensitizers of the porphyrin and flavin types in all of the listed cell types. Among the tetrapyrrole compounds with sensitizing properties, metal-free porphyrins, such as protoporphyrin IX, coproporphyrin III, uroporphyrin III, and zinc complex of protoporphyrin IX predominate in cells. The concentration of these compounds is extremely low (C < 10-9 M); it depends on the type of cells and conditions of their cultivation. It was shown for the first time that at the same concentration of non-transformed and cancer cells in suspension, the concentration of porphyrin photosensitizers in the supernatant of cancer cells is approximately 1.5 times higher.
It has been established that light-induced formation of reactive oxygen species (ROS) in the result of excitation of endogenous sensitizers can influence the course of metabolic processes in the cell. It has been shown for the first time that the main contribution to cell inactivation by blue light is made not by singlet oxygen, but by hydrogen peroxide. At the same time, cancer cells accumulating higher concentrations of endogenous porphyrins are also characterized by greater sensitivity to the action of blue light compared to non-transformed cells. Depending on the concentration of ROS formed (singlet oxygen, hydroperoxide, superoxideanionradical), the exposure of light can lead both to stimulation of cellular processes and their inhibition, as well as to initiation of lethal outcome. As a rule, the dose dependence of such processes is a typical two-phase curve described by well-known Arndt-Schulz law: at low doses, a living organism responds to exposure with stimulation; as the dose increases, the stimulating effect reaches its maximum, then it is replaced by oppression, and with further increase of a dose, death of the organism is observed.
The complex of the performed studies showed the ability of laser radiation in the blue-green region of the spectrum a) to have a bactericidal and bacteriostatic effect on gram-negative and gram-positive bacteria and fungi [1]; b) to influence (both in the direction of stimulation and inactivation) the functional characteristics of spermatozoa of animals (motility, preservation, fertility) [2, 3]; c) to change the metabolic activity of somatic and cancer cells [4]; d) to initiate the release of hemoglobin molecules through the erythrocyte membrane in the absence of exogenous dyes-photosensitizers.
The conducted comparative studies of the biological effects of continuous, quasi-continuous, pulsed radiation of nano-and picosecond durations have shown the opportunity of significant enhancement of the stimulation effects through the use of quasi-continuous radiation. The differences in action of continuous, quasi-continuous and pulsed laser radiation of green spectral region can be explained with photochemical and photothermal effects initiated by a spatially inhomo-geneous distribution of temperatures and ROS concentrations in the cell due to the heterogeneity of the absorbed light energy during the pulse in the microregions, adjacent to the localization of molecules-acceptors of radiation, and free of them. The dependence of the biological action on the frequency of radiation modulation has also been established. The conditions under which a clear dependence of the magnitude of photobiological effects on the polarization of radiation is traced have been found.
[1] V. Plavskii, A. Mikulich, A. Tretyakova et al., Porphyrins and flavins as endogenous acceptors of optical radiation of blue spectral region determining photoinactivation of microbial cells, J. Photochem. Photobiol. B., vol. 183, pp. 172-183 (2018).
[2] V. Plavskii, A. Mikulich, N. Barulin et al., Comparative effect of low-intensity laser radiation in green and red spectral regions on functional characteristics of sturgeon sperm, Photochem. Photobiol., vol. 96, pp. 1294-1313 (2020).
[3] V. Plavskii, N. Barulin, A. Mikulich et al., Effect of continuous wave, quasi-continuous wave and pulsed laser radiation on functional characteristics of fish spermatozoa, J. Photochem. Photobiol. B., vol. 216, 112112 (2021).
[4] V. Plavskii, A. Mikulich, N. Barulin et al., Laser Therapies: Types, Uses and Safety (Nova Science Publishers Inc.), Chapter I, (2020).
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