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We study several regimes of fractional laser microablation using a pulsed Er : YAG laser for producing microchannels of different depth and incisions that allow transcutaneous delivery of particles of different size, namely, Al2O3 (27 μm), ZrO2 (smaller than 5 μm) and TiO2 (smaller than 100 nm). The shock wave regime was used both for enhancing the penetration of particles into the ablation zones and as an independent method of particle delivery into the skin. Based on optical coherence tomography we assessed the coherent depth of particle detection in the skin in 2 hours, 3 days and 10 days after the administration. The maximal localisation depth (up to 450 μm) was obtained for TiO2 nanoparticles in the regime of incisions with enhancement of particle penetration by pulses of a multiple-beam hydrodynamic shock wave. The results of the study can be useful for developing new methods of transcutaneous delivery of micro- and nanocarriers of medicinal preparations.

A forced by the coronavirus disease pandemic (COVID-19) approach to organization of multidisciplinary conference is described. A hybrid format combining both online and offline presentations is presented and advantages and disadvantages of the used approach are evaluated as well as the received feedback.

Griseofulvin is an antifungal antibiotic applying for the treatment of dermatophyte infections. The most common delivery route of this drug is oral. The dosage of griseofulvin varies depending on whether the drug is administered as a microsized or an ultramicrosized preparation. In order to avoid possible incidental systemic toxicity associated with the oral delivery route and reduce the therapeutic dose, a novel approach for the griseofulvin administration is proposed. Immobilization of the drug into mesoporous calcium carbonate particles together with their further ultrasonically-assisted topical application provides the efficient transdermal transportation. Accumulation of griseofulvin-loaded carriers inside hair follicles of the rat is demonstrated in vivo, allowing by this means the targeted delivery of the antifungal drug to the lesion area of skin. No significant toxicity of the system is shown for rat and human fibroblasts cells in vitro.

We present the optical characteristics of the mucosa and submucosa of human colon tissue. The experiments are performed in vitro using a LAMBDA 950 spectrophotometer in the 350 – 2500 nm spectral range. The absorption and scattering coefficients and the scattering anisotropy factor are calculated based on the measured diffuse reflectance and total and collimated transmittance spectra using the inverse Monte Carlo method.

One of the lines of development of modern medicine is theranostics consisting in simultaneous diagnosis and laser treatment with the use of multifunctional agents such as fluorescent indocyanine green that has photodynamic and photothermal properties. Diffusion of indocyanine green dissolved in water and aqueous solutions of alcohols (glycerol, propylene glycol and ethanol) into the dermis is studied by using backscattering spectroscopy. The coefficients of the dye diffusion into the dermis are obtained for the first time by using these solvents.

The delivery of gold nanoparticles (nanocages coated with a layer of silicon dioxide (40/20 nm)) dispersed in the solution (glycerol + polyethylene glycol-400, 1 : 1) into the skin tissue is studied experimentally in vivo. From the data of optical coherence tomography and histochemical analysis it follows that simple application of suspension of nanoparticles is not efficient enough for delivery of the particles into the skin as a result of passive dif- fusion. It is shown that fractional laser microablation of skin before the application of the suspension, followed by the topical treatment by ultrasound allows penetration through the epidermis layer and delivery of nanoparticles into dermis and hypodermis

The possibility of visualising the distribution of gold nanoparticles in liver by means of the method of optical coherence tomography is studied experimentally in model samples of beef liver in vitro and rat liver ex vivo. In the experiments we used the gold nanoparticles in the form of nanocages with resonance absorption in the near-IR spectral region. In the model studies the suspension of nanoparticles was applied to the surface of the sample, which then was treated with ultrasound. In the ex vivo studies the suspension of nanoparticles was injected to the laboratory rats intravenously. The image contrast and the optical depth of detection of blood vessels and liver structure components are calculated, as well as the depth of liver optical probing before and after the injection of nanoparticles. It was shown that the administration of the nanoparticle increases significantly the imaging contrast of liver blood vessels owing to the localisation of the nanoparticles therein.

A new method for delivering nanoparticles into the skin using the fractional laser microablation of its surface and the ultrasonic treatment is proposed. As a result of in vitro and in vivo studies, it is shown that the 290-nm laser pulses with the energy from 0.5 to 3.0 J provide the penetration of nanoparticles of titanium dioxide with the diameter 100 nm from the skin surface to the depth, varying from 150 to 400 lm. Histological testing of the skin areas, subjected to the treatment, shows that the particles stay in the dermis at the depth up to 400 lm no less than for three weeks.

Investigation of the diffusion of cytamines, a typical representative of which is cortexin, is important for evaluating the drug dose, necessary to provide sufOcient concentration of the preparation in the inner tissues of the eye. In the present paper, the cortexin diffusion rate in the eye sclera is measured using the methods of optical coherence tomography (OCT) and reŒectance spectroscopy. The technique for determining the diffusion coefOcient is based on the registration of temporal dependence of the eye sclera scattering parameters caused by partial replacement of interstitial Œuid with the aqueous cortexin solution, which reduces the level of the OCT signal and decreases the reŒectance of the sclera. The values of the cortexin diffusion coefOcient obtained using two independent optical methods are in good agreement.

The possibility of selective laser photothermolysis improvement for the removal of tattoo pigments due to the optical clearing of human skin is investigated. It is shown experimentally that the optical skin clearing increases the tattoo image contrast. Computer Monte Carlo simulations show that by decreasing the laser beam scattering in upper skin layers, it is possible to reduce the radiation power required for tattoo removal by 30%—40% and, therefore, to increase the the photothermolysis efficiency.

A double-wavelength laser scanning microphotometer with the high spectral and spatial resolutions is developed for studying the distribution of endogenic and exogenic dyes in biological tissues. Samples of hair and skin biopsy with hair follicles stained with indocyanine green are studied. The spatial distribution of indocyanine green and melanin in the biological tissue is determined from the measured optical transmittance.

Based on the digital image analysis and inverse Monte-Carlo method, the proximate analysis method is deve-loped and the optical properties of hairs of different types are estimated in three spectral ranges corresponding to three colour components. The scattering and absorption properties of hairs are separated for the first time by using the inverse Monte-Carlo method. The content of different types of melanin in hairs is estimated from the absorption coefficient. It is shown that the dominating type of melanin in dark hairs is eumelanin, whereas in light hairs pheomelanin dominates.

Changes in the optical properties of the eye sclera of a laboratory animal (rabbit) caused by the noninvasive administration of an immersion agent (aqueous glucose solution) into sclera are studied experimentally in vivo by the method of reflection spectroscopy and simulated numerically. The diffusion coefficients of glucose and water in sclera are estimated from simulations of optical clearing within the framework of the developed model as h(5.4±0.1)×10-7 and (5.8±0.2)×10-7 cm2 s-1, respectively. Experiments showed that the application of the glucose solution on the sclera allows the efficient control of its optical properties, which makes it possible to deliver the laser energy to internal eye tissues without considerable attenuation and distortions of its spatial distribution in laser diagnostics and therapy.

The optical properties of human skin, subcutaneous adipose tissue and human mucosa were measured in the wavelength range 400–2000 nm. The measurements were carried out using a commercially available spectrophotometer with an integrating sphere. The inverse adding–doubling method was used to determine the absorption and reduced scattering coefficients from the measurements.

The possibility of increasing the human-skin probing depth by the method of reflection confocal microscopy (RCM) upon decreasing the amplitude of spatial fluctuations of the refractive index of the upper skin layers is considered. A change in the probing depth is estimated by analysing the spatial distribution of the probability density of the effective optical paths of detected photons calculated by the Monte Carlo method. The results of the numerical simulation are interpreted within the framework of the possible application of RCM to the study of the human skin exposed to an immersion liquid compatible to it. A diffusion of the immersion agent into the skin depth involves the equalising of the refractive indices of the structural elements of near-surface skin layers, which in turn causes a decrease in the scattering intensity and a certain increase in the transparency of the upper tissue layers. It is shown that a decrease in the light scattering in the near-surface skin layers leads to a significant increase in the probing depth obtained with the RCM technique.

The paper describes a regular multidisciplinary conference and early carrier scientists' school ENVIROMIS as a tool for facilitation of cooperation of specialists in different fields of environmental sciences and users of research results. The conference addresses critically important issues occurring in environmental sciences, namely, crossing disciplinary borders of this multidisciplinary research area, young scientists' training and diminishing a gap between science and decision-making. The viability of the approach to the Schools organization is proved by the fact that single event turned into a series, quite a few young participants successfully defended their PhD thesis and a number of researchers became Doctors of Science, several international multidisciplinary projects, initiated at these conferences, have been successfully carried out. Researchers from Russia and foreign countries show undiminishing interest to these conferences.

Prominent Researcher and Educator, Honoured Scientist of the Russian Federation, Professor Valery V. Tuchin celebrated his seventieth birthday this year. V.V. Tuchin heads the Department of Optics and Biophotonics at N.G. Chernyshevsky Saratov State University and the Laboratory of Laser Diagnostics of Technical and Living Systems at the Institute of Precise Mechanics and Control of the Russian Academy of Sciences. He is a Vice-President of the Russian Photobiology Society. V.V. Tuchin is widely known for his achievements in optics of biological tissues, in developing methods of optical and laser measurements in biomedicine and nanobiophotonics, and in many other fields.

The spatiotemporal pattern of the dynamics of surface air temperature and precipitation and those bioclimatic indices that are based upon factors which control vegetation cover are investigated. Surface air temperature and precipitation data are retrieved from the ECMWF ERA Interim reanalysis and APHRODITE JMA datasets, respectively, which were found to be the closest to the observational data. We created an archive of bioclimatic indices for further detailed studies of interrelations between local climate and vegetation cover changes, which include carbon uptake changes related to changes of vegetation types and amount, as well as with spatial shifts of vegetation zones. Meanwhile, analysis reveals significant positive trends of the growing season length accompanied by a statistically significant increase of the sums of the growing degree days and precipitation over the south of West Siberia. The trends hint at a tendency for an increase of vegetation ecosystems' productivity across the south of West Siberia (55°–60°N, 59°–84°E) in the past several decades and (if sustained) may lead to a future increase of vegetation productivity in this region.