Tatsiana Kulahava

Macrophages have great significance in immune response, being important participants in innate immunity. They are capable of both directly and indirectly fighting pathogens by regulating the surrounding cells via biologically active substances. In response to various stimuli, macrophages may switch from basal step to a pro- or anti-inflammatory state, polarizing into the M1 or M2 phenotype. M1 macrophages have a pro-inflammatory phenotype, being activated under the influence of cell wall lipopolysaccharide from Gram-negative bacteria, or some pro-inflammatory cytokines. M2 macrophages acquire an anti-inflammatory phenotype upon activation of some immune response receptors (Fcγ and TLR), cytokines IL-4, IL-13, IL-10 and other stimuli. Macrophages are also capable of alleviating their immune response depending on the duration and/or frequency of inflammatory signal, thus developing immune tolerance effect. Of particular importance is tolerance to bacterial lipopolysaccharide, when the macrophages acquire refractoriness to repeated stimulation compared to the primary one, producing less cytokines and chemokines. The aim of our study was to assess the role of cytokines and chemokines CCL2, CXCL1, CXCL9, CXCL12, IL-1b, IL-4, IL-6, IL-7, IL-8, IL- 15, IL-22, TNFα on immune response of macrophages to lipopolysaccharide and emergence of immune tolerance. Primary monocytes were obtained from venous blood of healthy donors. E. coli lipopolysaccharide (LPS) was used to stimulate monocytes and differentiated macrophages. We have shown that pre-treatment of primary human macrophages with recombinant cytokines IL-4 and TNFα enhances the inflammatory response to repeated stimulation with lipopolysaccharide, i.e. weakens the development of tolerance. This effect was expressed as increased production of cytokines (TNFα, IL-6, IL-10) and IL-8 chemokine in presence of recombinant IL-4, and TNFα production with recombinant TNFα. At the same time, recombinant IL-4 was also able to enhance the inflammatory signal of macrophages upon a single LPS stimulation, thus increasing the TNFα and IL-8 secretion. We have shown that some cytokines may affect the tolerance of macrophages to LPS. This phenomenon may involve transition of macrophages from one polarization state to another, or to an intermediate step. Modulation of macrophage phenotype and its immune response opens the way to the development of new therapeutic approaches to inflammatory diseases, where tolerance to lipopolysaccharide plays a significant role in pathogenesis, such as sepsis and atherosclerosis.

Modification of 2-acetyl-3H-benzo[f]chromen-3-one and 2-[(2E)-3-phenylprop-2-enoyl]-3H-benzo[f]chromen-3-one has been performed for the first time via the reaction with indole. The resulting benzo­[f]coumarins have been found to exhibit antioxidant properties in model systems: they react with hydrogen peroxide and sodium hypochlorite and regulate redox state of rat C6 glioma cells, which is reflected in reduced concentration of intracellular hydrogen peroxide and increased level of reduced glutathione. The synthesized compounds in the presence of exogenous hydrogen peroxide exert a protective effect on the cells, acting as antioxidants and restoring the redox balance. 2-[3-(1H-Indol-3-yl)-3-phenylpropanoyl]-3H-benzo[f]khromen-3-one at a micromolar concentrations inhibited the rat C6 glioma cell proliferation by 25–35%.

Principal component analysis and K-means clustering of Raman spectra of glioma cells exposed to single-walled carbon nanotubes revealed their specific particle distribution, interaction with cell compartments, metabolism in autolysosomes, and cell death.

A systematic spectroscopic characterization of highly homogeneous water suspensions of ‘buckydiamonds’ comprising sp³ cubic nanodiamond (ND) core covered with disordered sp² shell densely decorated with oxygen-containing groups demonstrates the excitation-wavelength-dependent photoluminescence (PL) given by at least four types of specific structures on the ND surface (hydroxyl, C=O containing ketones, carboxylic anhydrides, and carboxyl groups). PL properties of NDs suspensions possess concentration-dependent behavior revealing tendency of NDs to agglomerate. PL of NDs has been found to be strongly sensitive to pH of the environment in wide range of pH values, i.e. 2–11. We disclosed the mechanisms of pH sensitivity of the ‘buckydiamond’ and proved that it can serve as all-optical sensor of tiny pH variations suitable for further exploitation for pH sensing locally in the area where NDs have been delivered for any purpose, e.g. bioimaging or therapeutic needs.

Efficient procedures have been developed for the allylation of structurally diverse ketones with methyl 3-(bromomethyl)but-3-enoates, and the possibility of using the allylation products in the target-oriented synthesis of new heterocyclic compounds has been demonstrated. Modification of benzo[f]coumarin derivatives at the keto group via Barbier allylation with methyl 3-(bromomethyl)but-3-enoate has been performed for the first time with the goal of subsequent formation of a lactone fragment. The synthesized benzo[f]coumarin derivatives have been characterized by spectral methods, and their ability to penetrate phospholipid bilayer has been estimated. These compounds have been found to affect neither viability nor proliferation of C6 rat glioma cells. The obtained benzo[f]coumarin derivatives exhibit antioxidant properties in model systems based on hydrogen peroxide and sodium hypochlorite.

Monitoring of tiny intracell temperature variations is of high importance to understand the mechanisms of exothermic/endothermic processes inside the living cells. Small shifts in thermal balance may drastically influence cell functioning and induce pathological conditions. By using biocompatible diamond single‐crystal microneedles enriched with nitrogen‐vacancy (NV)/silicon‐vacancy (SiV) color centers, this study demonstrates all‐optical in vitro temperature monitoring in the physiologically significant range (25–55 °C). Zero‐phonon line (ZPL) of SiV centers belonging to the “therapeutic window” is used to improve measurement precision via suppression of the tissue autofluorescence. The simultaneous detection of the NV and SiV fluorescence enables two‐band visualization of the living cells combined with the temperature sensing. This study demonstrates experimentally that temperature can be measured by lifetime, full‐width at half maximum, and peak position of SiV ZPL, while accuracy can be further improved by normalizing the photoluminescence (PL) ZPL peak intensity on the PL signal measured at the wavelength where it is temperature independent. According to performed numerical simulations diamond microneedles enable real‐time temperature measurements because their characteristic heating time is less than 10 ns. The results open a way toward accurate, noninvasive, precise, and real‐time monitoring of temperature variations accompanying intracellular biochemical reactions and processes on the single‐cell level.

A 3-acetyl analogue of 5-hydroxyindole was synthesised and evaluated for its effects on rat C6 glioma cell functions. It was found that 3-acetyl-5-hydroxy-2-methylindole at 10 μmol/L led to a sharp reduction of mitochondrial membrane potential, induction of autophagy and decrease of proliferation of C6 glioma cells. The compound’s effect was comparable to that of rotenone, an inhibitor of cell respiration.

We demonstrate that commercially available window tinting films could be used multifunctionally, i.e., for electromagnetic shielding and absorption at frequencies below 1 THz along with visible light and ultraviolet protection. The fine control of the film optical properties by their structural composition can also be used to extend their performance to the lower frequency ranges, i.e., terahertz and microwave. The electromagnetic properties of two types of thin protective films loaded with either carbon or iron oxide micro- and nano-inclusions were studied in microwave (12–18 GHz) and terahertz (0.2–1.0 THz) frequency ranges vs their inner structure. The reflection and transmission coefficients of studied tint films were investigated using waveguide and free space measurements and compared with theoretical modeling results. The effective sheet resistance was estimated from the experimental data.

In living organisms, redox reactions play a crucial role in the progression of disorders accompanied by the overproduction of reactive oxygen and reactive chlorine species, such as hydrogen peroxide and hypochlorous acid, respectively. We demonstrate that green fluorescence graphene quantum dots (GQDs) can be employed for revealing the presence of the hypochlorous acid in aqueous solutions and cellular systems. Hypochlorous acid modifies the oxygen-containing groups of the GQD, predominantly opens epoxide ring C–O–C, forms excessive C=O bonds and damages the carbonic core of GQDs. These changes, which depend on the concentration of the hypochlorous acid and exposure time, manifest themselves in the absorbance and fluorescence spectra of the GQD, and in the fluorescence lifetime. We also show that the GQD fluorescence is not affected by hydrogen peroxide. This finding makes GQDs a promising sensing agent for selective detecting reactive chlorine species produced by neutrophils. Neutrophils actively accumulate GQDs allowing to visualize cells and to examine the redox processes via GQDs fluorescence. At high concentrations GQDs induce neutrophil activation and myeloperoxidase release, leading to the disruption of GQD structure by the produced hypochlorous acid. This makes the GQDs a biodegradable material suitable for various biomedical applications.