Аспекти використання особливостей лазерного випромінювання для оптимізації діагностичних методів при курації пацієнтів з генералізованими захворюваннями пародонта

Abstract

The aim of the research is to study the possibilities of using laser radiation (biofluorescence, elastic scattering) for diagnostic purposes to optimize and identify periodontopathogenic microorganisms. Materials and methods. For the biofluorescence fixation experiment, we used a 632.8 nm helium neon laser, 3mW; a 668 nm Lika surgeon M semiconductor laser, 30–250 mW; the Ocean Optics USB4000 miniature fiber optic spectrometer; quartz light guides, tripods; reference strains of microorganisms: Escherichia coli, Candida albicans, Klebsiella pneumoniae, Proteus mirabilis, Corynebacterium pseudodiphtheriae, Staphylococcus aureus, Staphylococcus epidermidis cultured on agar; a laptop with SpectraSuite software. The elastic scattering angular distribution was analyzed on the developed experimental platform. The excitation source was a 532 nm continuous-wave (CW) laser (TEM00 mode) with a power of <50 mW. The elastic scattering angular distribution in the anterior and posterior hemispheres for aqueous suspensions of Staphylococcus aureus and Escherichia coli was investigated. Results. During the first part of the experiment, the colonies of the reference microorganisms were alternately irradiated by laser radiation beam first from neon laser helium, then from semiconductor laser. The reflection spectrum was recorded by the Ocean Optics USB4000 spectrometer and processed on a laptop using SpectraSuite software. The samples were irradiated at different angles (90 °, 45 °) in the dark, on a dark substrate. The radiation power of helium neon laser was stable – 3mW, and the radiation power of semiconductor varied in the range of 30-100mW. After irradiation of all the samples of cultures, as described above, and after the spectrograms processing, we did not get confirmation of the theory of biofluorescence: basically the spectrometer recorded only the spectrum of the reflected laser radiation. In the second part of the experiment, we investigated the elastic scattering angular distribution in the anterior and posterior hemispheres for aqueous suspensions of Staphylococcus aureus and Escherichia coli which have different spatial form factors. It was shown that complete integral extinction into the anterior hemisphere is linearly proportional to the bacterial concentration estimated by the McFarland standard on a certified device. A more detailed analysis of the elastic scattering angular distribution showed that the suspension of Staphylococcus aureus had a decrease in scattering in the anterior hemisphere and enhanced scattering in the posterior hemisphere compared with a suspension of bacteria Escherichia coli. The presented method can be applied to solve the problem of classification of microorganisms by the modelling of the elastic scattering angular distribution on the basis of models of elementary scatters with different form factors according to the Mie theory. Conclusion. The experiments on the study of biofluorescence of colonies of bacteria have not confirmed the possibility of recording specific spectra from each of the strains. However, the results of the study of elastic scattering in the suspensions of microorganisms indicated the possibility of determining the structural and concentration features of their content, namely to differentiate the rod shaped flora from the coccoid, and to estimate the relative number of particles in the suspension. The development of this technology can greatly simplify the diagnostics without the use of expensive and technologically difficult research methods in the future Key words: periodontal pathogen, biofluorescence, Mie theory, intensity of elastic optical scattering.