International Scientific Journals
of Scientific Technical Union of Mechanical Engineering "Industry 4.0"

In this pilot study, microfluidic flow analysis and atomic force microscopy (AFM), are used, to determine microrheological properties of the blood – aggregation, and deformability of erythrocytes in women with preeclampsia (PE). The aggregation of red blood cells (RBCs) is evaluated with the microfluidic system BioFlux, by applying an experimental approach and image analysis created by the authors of this study. The elastic properties of erythrocytes are defined by Young’s modulus, using AFM. The aggregation index of erythrocytes and their elastic modulus are statistically significantly increased in patients with PE, in comparison to healthy normotensive pregnant women. In addition, it is found that the RBCs are less deformable and the interaction between them in aggregates is stronger in women with preeclampsia as compared with healthy pregnant women.

The goal of the present study is to evaluate the elastic properties (Young’s modulus) of erythrocytes from healthy donors and patients with type 2 diabetes mellitus (T2DM), by using an atomic force microscope (AFM). Morphological and mechanical characteristics of red blood cells are studied in parallel by PeakForce QNM (Quantitative NanoMechanical Mapping) mode of AFM Dimensional ICON Bruker NanoScope V9 Instrument. Young’s modulus is calculated based on the mathematical model of Johnson-Kendall-Roberts by the application of the “two-point method”. AFM images of the erythrocytes from the healthy donors show that erythrocytes with a normal biconcave shape predominate. In patients with T2DM, the so-called erythrocyte polymorphism is studied. The Young’s modulus of erythrocytes, in patients with T2DM, significantly statistically increases by 27% (p≤0,001), compared to the data of healthy donors. The studied Young’s modulus by AFM can be used in clinical practice as a precise biomarker for the state of the red blood cells in T2DM.

The article studies the mechanisms of energy exchange and transformations, which occur in a measuring instrument (probe) of an atomic force microscope (AFM) in the process of studying solid surfaces of materials. Mathematical modeling of the heating process of individual elements of the measuring unit of the atomic force microscope at the preparatory, final stages and the scanning stage of the surface under study was carried out. At the same time, such energy components of the processes occurring in the AFM control unit were taken into account. By minimizing the factors (heat dissipation due to friction of the probe on the surface), which negatively affect both the results of the monitoring and the condition of the probe and the surface, stable operation modes of the AFM are established. The solution of the equivalent thermal scheme of an atomic force microscope is presented, which confirms the adequacy of the mathematical models obtained.

It has been established that in the study of a solid surface by atomic force microscopy, the hydrophobic interaction is more advantageous due to a decrease in the interaction forces between the probe and the liquid adsorbed on the surface under study. Despite the fact that silicon is a hydrophobic material, it has been shown that the material acquires hydrophilic properties in air, as a result of which the use of carbon-modified probes has been proposed. An approach to experimental statistical modeling is proposed, based on the experiment planning method, which shows that with a scanning speed of 12 μm / s, a scanning step of up to 82 nm and a delay time before scanning of 6 ms, the interaction force between the probe and the adsorbed liquid reaches minimum values. As a result of the research, it was found that with a decrease in the scanning speed, a scanning step and an increase in the delay time of the probe before measurement, the interaction between the probe and the liquid membrane is hydrophobic. It is shown that by changing the initial parameters, it is possible to control the hydrophobic interaction between the probe and the liquid. It has been established that increased air humidity leads to hydrophilic interaction. This is due to the increase in the thickness of the adsorbed liquid layer on the surface under study.