Background. Currently, the problem of radical removal of pigmented skin formations with good clinical and aesthetic results remains open. These formations, including congenital giant pigmented nevi (CGPN), are found at birth in 2 % of newborns; acquired nevi are registered in 75 % of children. They can be large in size and quite often are located on visible parts of the body, creating psychological problems in children and leading to aesthetic discomfort. In adulthood, various complications may develop including malignancy which may develop in 10% of patients. Management of pigmented skin formations causes both medical and psychological problems. So, it is reasonable to solve them in childhood. Modern various techniques for the removal of pigmented nevi are not always effective; besides, they are often followed by various complications, like relapses (in 6–41 %) and skin scarring (in 6 %). Such a situation requires development of new highly effective techniques for removing various pigmented nevi, including laser light. Recently, separate works on the application of “blue” (λ = 450 nm) laser light and infrared (λ = 10.6 μm) laser light generated by periodic CO2 laser for the discussed pathology have appeared.Purpose. To conduct a comparative experimental study on the effects of “blue” (λ = 450 nm) laser light and infrared (λ = 10.6 μm) laser light generated by pulsed periodic CO2 laser at the skin of laboratory rats in order to find out promising parameters for surgical removal of pigmented skin formations.Material and methods. Laser devices “Lasermed 10-03” (LLC RIK, Russia) generating in “blue” (λ = 450 nm) and pulsed periodic CO2 laser “ALDAN” (IOF RAS, Russia) generating in infrared (λ = 10.6 μm) laser light were used. In present in vivo experiment, pigmented skin of laboratory rats was exposed to laser light. Exposure zones were compared; features and regeneration terms were analyzed too.Results. The researchers registered specific effects in skin irradiation with laser light as well as in terms of wound regeneration. They also identified optimal parameters of “blue” (λ = 450 nm) and infrared (λ = 10.6 μm) laser light for the removal of CGPN and pigmented skin formations.Conclusion. The obtained results of the present comparative experimental trial have outlined prospects for the application of “blue” (λ = 450 nm) laser light and infrared laser light (λ = 10.6 μm) generated by pulsed periodic CO2 laser for surgical removal of pigmented skin formations.

The results of a study of the analytical characteristics of a mass spectrometric method based on atmospheric pressure laser plasma-induced ionization in the negative ion detection mode. The investigation focuses on the determination of 2,4-dinitrophenol, 2,5-dinitrophenol, 2-nitro-4-chlorophenol, 2,4-dichlorophenol, 2,4-dinitrotoluene, m -dinitrobenzene, and 3,3'-dinitrobiphenyl. Depending on their chemical properties, nitroaromatic compounds are ionized to form deprotonated molecules and/or molecular ions (radical anions). Calibration dependences for these compounds were plotted, and sensitivity coefficients were determined. The research demonstrates that sensitivity depends on the nature and position of substituents in the aromatic ring. The limits of detection for nitroaromatic compounds were estimated to be within the range 1–30 pg.

An Erratum to this paper has been published: https://doi.org/10.1134/S1061934822370018

The process of $\text{Au}+$ and $\text{Au}$ -ions formation on a surface of nanostructured gold plate under pulsed laser irradiation with energy density below plasma threshold is studied. The role of nanoscale objects produced on the surface under laser irradiation higher than the plasma threshold in the ion formation process is discussed.

The article reviews the achievements and problems of opto(photo)acoustics in recent years for biomedical applications in real media and real optoacoustic (OA) conversion modes. Optoacoustics is a developed and competitive area. There has been significant progress in laser sound generation technology and in the technique of receiving, processing and interpreting signals. Research on applied optoacoustics problems in inhomogeneous biomedical media—liquid samples and biological tissues—is developing in several directions: imaging, detection of impurities in low concentrations, flow cytometry, and theranostics. Depending on the conditions, several conversion mechanisms can contribute to the informative sound response—linear and nonlinear thermoelastic mechanisms, which acquire additional features during laser irradiation of suspensions, as well as inhomogeneous biological tissues. The joint contribution of thermoelastic mechanisms and laser-induced cavitation mechanism that develops on inhomogeneities also manifests itself. The progress in biomedical optoacoustic technologies presupposes a full account of the conditions of OA conversion as applied to a specific problem. As it turned out, publications on laser sound generation in real media are already numerous and are in need of structuring. It is impossible to ignore the upcoming transition to the clinical application of OA imaging systems in the near future.

Trained detection dogs distinguish between urine samples from healthy organisms and organisms with malignant tumors, suggesting that the volatile urine metabolome contains information about tumor progression. The aim of this study was to determine whether the stage of tumor growth affects the chemical differences in the urine of mice and to what extent the "olfactory image of disease" perceived by dogs coincides with the "image of disease" recorded by the mass spectrometer. We used a novel laser ionization mass spectrometry method and propose a mass spectrometric analysis without detailed interpretation of the spectrum of volatile metabolomes in urine. The mass spectrometer we use works without sample preparation and registers volatile organic compounds in air at room temperature without changing the pH of the sample, i.e. under conditions similar to those in which dogs solve the same problem. The experimental cancer models were male BDF-f1 hybrid mice transplanted with hepatocarcinoma tissue, and similar mice transplanted with healthy liver tissue were used as controls. Our data show that both dogs and our proposed laser mass spectrometry method are able to detect both the entire spectrum of volatile organic compounds associated with the disease and minor changes in this spectrum during its course.

Vacuum UV radiation from laser-induced plasma is used to ionise volatile organic compounds (VOCs) released by living organisms during their mass spectrometric analysis at atmospheric pressure without sample preparation. It is shown that the probability of ionisation of organic compounds with different ionisation potentials and proton affinity at atmospheric pressure in the argon flow weakly depends on the compound parameters and can be 3.6 × 10−5 – 1.4 × 10−4. The VOC spectra of mouse and human biological fluids are obtained without sample preparation at room temperature of the sample. The possibility of using the proposed method for the diagnosis of pathological changes is demonstrated.

Pulsed vacuum ultraviolet (VUV) radiation (80–180 nm) emitted by laser plasma produced on a metal target is used in mass spectrometry to ionize volatile organic compounds at atmospheric pressure. The parameters of light emitted by the laser plasma generated by a pulsed Nd:YAG laser radiation at a wavelength of 1064 nm, power density of about 70 GW/cm2, and pulse energy of 250 µJ have been determined using emission spectroscopy. During the first several nanoseconds, the plasma emission spectrum does not contain any pronounced spectral lines and can be described as the emission spectrum of a blackbody with a temperature of 5.5 × 104–105 K (the temperature depends on the ambient gas pressure). This radiation provides ionization of water, oxygen, and nitrogen molecules, as well as argon atoms. It is shown that the mechanisms of ionization of organic compounds under VUV irradiation in argon are based on the reaction of proton transfer from ionized water molecules and reactions of organic compounds with oxygen ions.

The results of a study of the pathways of ion formation from organic compounds in Atmospheric Pressure Laser Plasma Ionization (APLPI) are presented. The instrumental implementation of the method is based on its combination with a high-resolution mass analyzer. Solid dosage forms and also physiologically active compounds were studied. It was found that the main pathways leading to the formation of positively charged ions are the following: protonation; addition of ammonium, synthesized in the ion source; and photoionization. In the negative ionization mode, deprotonated molecules, anion adduct ions, and molecular ions are formed. In both modes, ions formed as a result of the preliminary oxidation of analyte molecules in the ion source and their subsequent ionization were detected. A possibility of using the APLPI for the rapid analysis of pharmaceutical drugs without sample preparation is demonstrated.

A method of rapid mass spectrometric analysis of volatile organic compounds (VOC) of biological samples at atmospheric pressure has been developed. The method uses laser plasma radiation for ionization of VOC molecules. Multivariate statistics was used for the mass spectra analysis. The possibility of identification of progressing oncological process in mice with analyzing the composition of VOCs of the urine samples was showcased.

Laser desorption of organic compound ions from specially prepared surfaces is known as surface-assisted laser desorption/ionization (SALDI). In this work the properties of a SALDI ion emitter obtained by two-stage laser treatment of crystalline silicon surface have been investigated. The laser surface treatment leads to the formation of a layer with nanoscale objects—quantum dots (QDs) less than 10 nm in size, providing laser desorption of organic compound ions. A change in the desorbing laser wavelength from 351 to 263 nm at comparable laser-exposed spot sizes and fluences results in a sharp decrease in the formation efficiency for MH+ ions and appearance of ions M+ for the same analytes. The effect is apparently determined by the spectral properties of the quantum dots formed on the silicon surface under laser irradiation.

A novel technique for real time mass spectrometric analysis of bioorganic samples at atmospheric pressure without any pretreatment based on laser ablation of the sample and ionization of the vapor plume by laser plasma radiation was developed. The potential of the method was showcased in drug screening, mass spectrometric imaging of biological tissues, tissue type and oncologic decease presence identification

Removing children traumatic scars, resulting from various injuries and surgeries, is still actual problem. Unlike conventional laser skin resurfacing removal of sizeable amount of tissue is required for such treatment. To decrease the injury rate a special laser with the pulse duration below 20 μs was used. The data of 6 years successful method application are presented (over 250 patients).

Therapeutic effect with ENT diseases can be achieved removing the infected surface epithelial layer by laser ablation. To reduce adverse effects a CO 2 laser with pulse duration below 20 μs is needed. The laser treatment significantly reduced bacteria content in the mucosa right after the procedure in 89% of 54 patients. After 6 months, 78% of patients had stable improvement.

Continuous wave (CW) CO 2 lasers have been in common medicine use for over 40 years. Tissue dissection using CW lasers is accompanied by high heating of adjacent tissue. This effect is highly useful during the soft tissue surgery due to its ability to prevent bleeding. However, there exist problems that require tissue removal without adjacent layers heating. For example: scar removal from skin surface, microbial films removal from surfaces of ENT organs in otolaryngology, ablation of biological tissues for mass spectrometric analysis and so on. In these cases pulsed laser radiation is needed because pulse duration narrowing dramatically decreases the heat transfer out of the irradiated region during ablation of tissue.

The atmospheric pressure mass spectrometric detection efficiency of organic species (tofisopam and verapamil) was measured by means of the laser ablation of dried solution drops containing known amount of the analyte. Ablated molecules were ionized by an atmospheric pressure laser plasma cell and then introduced in the TOF mass-spectrometer. The spot was formed by dripping 2 mu l of solution on the stainless steel substrate and consequent drying. Then it was scanned by an intense ablating beam of various lasers (CO2, Nd:YAG and femtosecond fiber laser) until the spot was completely eroded during the non-stop MS-analysis of ablated material. The sensitivity was defined as the ratio of the total ion current integral of the relevant mass peaks to the amount of molecules in the spot. All the tested lasers are suitable for the ablation and subsequent MS-detection of organic species in dried solution spots given enough power deposition is provided. The measured sensitivity values reach 0.1 ions/fg of tested analytes.

The efficiency of laser desorption/ionization of twenty compounds from the surface of amorphous silicon is studied as a function of proton affinity (PA) and gas-phase basicity (GB). The values of GB and PA are obtained from quantum-chemical calculations using the density functional theory in the B3LYP model with the 6–311++G(3df,3pd) basis set. The values of GB lie in the range from 845 to 977 kJ/mol. The efficiency of laser desorption/ionization exponentially depends on the GB and PA values and for the studied compounds varies from 7 × 10−6 to 1.4 × 10−2.

A new method was developed for the mass spectrometric analysis of organic and bioorganic compounds, which involves laser ablation with the ionisation of its products by laser-plasma radiation and enables analysing gaseous, liquid, and solid substances at atmospheric pressure without sample preparation. The capabilities of this method were demonstrated by the examples of fast pharmaceutical composition screening, real-time atmosphere composition analysis, and construction of the mass spectrometric images of organic compound distributions in biological materials.

A novel approach to the rapid screening of pharmaceutical drugs by surface assisted laser desorption-ionization (SALDI) mass spectrometry with the rotating ball interface coupled with temperature programmed thermal desorption has been developed. Analytes were thermally desorbed and deposited onto the surface of amorphous silicon substrate attached to the rotating ball. The ball was rotated and the deposited analytes were analyzed using SALDI. The effectiveness of coupling SALDI mass spectrometry with thermal desorption was evaluated by the direct and rapid analysis of tablets containing lidocaine, diphenhydramine and propranolol without any sample pretreatment. The overall duration of the screening procedure was 30÷40 sec. Real urine samples were studied for drug analysis. It is shown that with simple preparation steps, urine samples can be quantitatively analyzed using the proposed technique with the detection limits in the range of 0.2÷0.5 ng/ml.

The role of laser irradiation in the processes of laser desorption/ionisation from silicon surfaces is considered. The basic functions of laser irradiation (chemical activation of the ion emitter surface, laser-induced ionisation of chemical compounds and ion desorption) are established and analysed.