EURASIAN JOURNAL OF MEDICAL AND
NATURAL SCIENCES
Innovative Academy Research Support Center
IF = 7.921
Volume 5 Issue 8, August 2025 ISSN 2181-287X
Page 75
EVALUATION OF THE EFFECTIVENESS OF
PHOTODYNAMIC THERAPY USING A NON-COHERENT
LIGHT SOURCE WITH A WAVELENGTH OF 660 NM IN AN
EXPERIMENT
Fozilova Sarvinoz Tursunboy Qizi
E-mail: vionadark84@gmail.com
Ozodbekova Sitora Alisher qizi
E-mail: Sozodbekova@gmail.com
Adilov Abdujabbor Abdukayumovich
E-mail: abdujabboradilov1@gmail.com
Saidmuratov Behruz Salaydin O`g`li
E-mail: Behruzsaidmurodov030@gmail.com
Kimyo International University in Tashkent, Uzbekistan
Musaeva Shahlo Najatovna
Scientific adviser:
E-mail: musayeva.shahlo.83@mail.ru
Kimyo International University in Tashkent, Uzbekistan
https://doi.org/10.5281/zenodo.16942003
ARTICLE INFO
ABSTRACT
Received: 18
th
August 2025
Accepted: 24
th
August 2025
Online: 25
th
August 2025
The increasing incidence of malignant neoplasms of various
localizations is making them an increasingly serious problem
for modern medicine, both in clinical practice and in
prevention. Unfortunately, the proportion of advanced cases
remains high, and tumor recurrences are often poorly
responsive to repeated treatment and are accompanied by
significant complications. This underscores the urgent need to
improve methods for the diagnosis and treatment of cancer.
KEYWORDS
Photodynamic
therapy
(PDT), 5-aminolevulinic acid
(ALA),
fiber-optic
light,
cancer
treatment,
cytotoxicity,
lymphocyte
culture, Ehrlich tumor cells,
red
light
irradiation,
photosensitizer, in vitro
model, cell viability, trypan
blue assay, non-coherent
light, phototoxic effect.
Photodynamic therapy (PDT) is a promising and rapidly developing approach to cancer
treatment. Its progress directly depends on the development of specialized systems generating
light in the 600–660 nm range. An important role is also played by both already known and
new, more effective and accessible photosensitizers, as well as in-depth scientific studies aimed
at revealing the mechanisms of the photodynamic effect. Evaluating the effectiveness of PDT is
complicated by the fact that the photodynamic effect itself manifests minimally, and the death
of tumor cells becomes evident only after a significant period of time.
In cancer treatment, photodynamic therapy (PDT) can be used both radically, with the
goal of complete tumor destruction, and palliatively, to improve the patient's quality of life. This
method is characterized by high selectivity, allowing healthy organs and tissues to be
EURASIAN JOURNAL OF MEDICAL AND
NATURAL SCIENCES
Innovative Academy Research Support Center
IF = 7.921
Volume 5 Issue 8, August 2025 ISSN 2181-287X
Page 76
preserved, as well as providing a good cosmetic effect. In addition, PDT can be performed
repeatedly without the risk of serious local or systemic complications. Photochemotherapy
represents another promising direction in the diagnosis and treatment of various types of
cancer. This approach uses photosensitizers (external or internal), which, when activated by
light, initiate chemical reactions in biological tissues
Research Objective:
To develop a laboratory (in vitro) model based on cell cultures for studying the effect of
light exposure transmitted through fiber-optic systems in combination with a photosensitizer
– a 10% solution of 5-aminolevulinic acid.
Materials and Methods
Due to the significant number of variables that can influence the course of photodynamic
therapy (PDT), appropriate experimental models were selected. To assess the effectiveness of
PDT, studies were conducted in two directions: in vivo and in vitro. Peripheral blood obtained
from healthy individuals was used as a biological substrate, and isolated cells of Ehrlich's mouse
ascitic tumor were also involved. A specialized device for photodynamic therapy was used to
carry out the therapeutic exposure. The most important component determining the
mechanism of action is the absorption and excitation spectrum of the photosensitizer used.
To create a lymphocyte culture, peripheral blood samples were taken from healthy
volunteers. The culturing process was carried out using the whole blood method, following the
technique developed by Arakaki D.T. and Sparkes R.S. in 1963. The main principle of this
method is as follows: lymphocytes in peripheral blood culture are activated by
phytohemagglutinin (PHA) – a purified mitogen derived from beans. Under the influence of
PHA, lymphocytes begin to actively divide (enter the mitotic cycle) each day. The greatest
number of dividing cells (mitoses) is observed 72 hours after the start of culturing. After this
stage, the cells were incubated with the photosensitizer, 5-aminolevulinic acid, at a
temperature of 37°C for three hours. They were then irradiated with a non-coherent light
source with a wavelength of 660 nm for 30 minutes. At the same time, isolated cells of Ehrlich's
mouse ascitic tumor were irradiated for 20 minutes.
To determine the quantitative indicator of cytotoxicity, the cells were stained with trypan
blue. Then, using light microscopy with 400x magnification, the number of stained (i.e., dead)
cells was counted. For this, the cell suspension was applied as a thick drop onto a microscope
slide and mixed with an equal volume of a 0.1% trypan blue solution.
The value of cytotoxic activity (CTA) was determined using the following formula:
CTA (%) =
𝑨
𝑩
× 100
,
Where
A
– number of dead cells;
B
– total number of examined cells.
Statistical data processing.
Statistical data are presented as M±m (where M – arithmetic mean; m – standard
deviation). For statistical analysis, the software package Statistica 5.0 was used. Comparison of
independent groups was carried out using the Mann–Whitney test (T-test), and for the analysis
of relative indicators, Fisher’s t-test was applied. Differences between groups were considered
statistically significant at a probability level of p < 0.05.
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Research results and their discussion.
In the course of the study, it was found that photodynamic therapy (PDT) causes cell
death, including cancer cells, through direct phototoxic action. To implement this approach, a
portable device using red radiation was developed. Its purpose is the destruction of malignant
tumor cells as part of a comprehensive cancer treatment. The therapeutic effect is achieved by
activating a photosensitized reaction that is triggered by photons of light from the optical
emitter.
The initial study of the new laser device using fiber-optic technology was aimed at studying its
effect on a lymphocyte cell culture from healthy volunteers. It was found that the simultaneous
use of a photosensitizer (5-aminolevulinic acid) and irradiation with non-coherent light at a
wavelength of 660 nm causes a pronounced cytotoxic reaction (56%). This effect was
statistically significantly higher than with the separate application of the photosensitizer (25%)
or light (20%), as well as compared to the control (18%).
Table 1. Exposure to a non-coherent light source with a wavelength of 660 nm on a
culture of lymphocytes from healthy donors
Exposure
Number of viable
cells
Number of dead
cells
Cytotoxic effect
(CTE), %
Control, n = 100
82
18
18 ± 3.86
Photosensitizer (PS), n
= 100
75
25
25 ± 4.35
PS + light irradiation,
n = 100
44
56
56 ± 5.0*
Light irradiation,
n = 100
80
20
20 ± 4.02
*- р<0.05
At the second stage, mouse Ehrlich ascites tumor cells were incubated for 3 hours with a
photosensitizer (5-aminolevulinic acid) at 37°C. Then the cells were subjected to 20 minutes of
irradiation with non-coherent light at a wavelength of 660 nm (see Table 2).
Table 2.Exposure to a non-coherent light source with a wavelength of 660 nm on
isolated Ehrlich ascites tumor cells.
Exposure
Number of viable
cells
Number of dead
cells
Cytotoxic effect
(CTE), %
Control, n = 100
79
21
21 ± 4.1
Photosensitizer (PS), n
= 100
73
27
27 ± 4.5
PS + light irradiation,
n = 100
38
62
62 ± 4.9*
Light irradiation,
n = 100
84
16
16 ± 3.7
*- р<0.05
During the analysis of the effect of non-coherent radiation with a wavelength of 660 nm
and 5-aminolevulinic acid on Ehrlich ascites tumor cells, it was found that monotherapy with
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Volume 5 Issue 8, August 2025 ISSN 2181-287X
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each of these factors caused minimal toxic response. The combined use of the photosensitizer
and irradiation resulted in a pronounced cytotoxic effect, reaching 62%.
In the next stage of the study, a model of an experimental Ehrlich sarcoma strain in mice
was used. Three animals with implanted Ehrlich tumors were intraperitoneally injected with
0.5 ml of a 5-aminolevulinic acid solution (concentration of 30 µg/ml in sterile water for
injection) 3 and 20 hours before the start of irradiation (see Tables 3 and 4)
Table 3. Exposure to a non-coherent light source with a wavelength of 660 nm on
Ehrlich ascites tumor cells 3 hours after the administration of the photosensitizer.
Exposure
Number of
viable cells
Number of dead
cells
Cytotoxic effect
(CTE), %
Control, n = 100
97
3
3 ± 1.7
PS + light irradiation, n =
300 cell/ 3 animals
101
199
66.3 ± 2.7*
*- р<0.05
Table 4. Exposure to a non-coherent light source with a wavelength of 660 nm on
Ehrlich ascites tumor cells 20 hours after the administration of the photosensitizer.
Exposure
Number of
viable cells
Number of dead
cells
Cytotoxic effect
(CTE), %
Control, n = 100
96
4
4 ± 3.9
PS + light irradiation, n =
300 cell/ 3 animals
117
183
61.0 ± 2.8*
*- р<0.05
It was found that exposure to a non-coherent light source (660 nm, 30 minutes) and 5-
aminolevulinic acid had a significant toxic effect on Ehrlich ascites tumor cells, causing the
death of 66.3% and 61.0% of the cells, respectively. The duration of the preliminary exposure
to the photosensitizer (3 or 20 hours) did not affect the degree of toxicity.
Conclusions
1.The experiment on lymphocyte culture showed that monotherapy with the
photosensitizer (5-aminolevulinic acid) or standalone exposure to a non-coherent light source
with a wavelength of 660 nm caused minimal toxicity. Combined exposure to the
photosensitizer and light resulted in 56% cytotoxicity.
2.The experiment with Ehrlich ascites tumor cells revealed that both the use of 5-
aminolevulinic acid as a photosensitizer and irradiation with non-coherent light at 660 nm
individually caused minimal toxic effects. However, combined exposure to the photosensitizer
and light led to a cytotoxic effect of 62%.
3.The study demonstrated that 30-minute exposure to non-coherent light with a
wavelength of 660 nm, in combination with the photosensitizer 5-aminolevulinic acid, caused
significant toxicity (66.3% and 61.0%, respectively) in Ehrlich ascites tumor cells. This effect
was observed regardless of whether the cells were incubated with the photosensitizer for 3 or
20 hours.
EURASIAN JOURNAL OF MEDICAL AND
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