Anton Senenko

We disclose the self-assembly and evolution of DASA monolayers on a gold surface, as observed using scanning tunneling microscopy (STM).

Understanding nanoscale mechanisms responsible for the recently discovered ferroelectric nematics can be helped by direct visualization of self-assembly of strongly polar molecules. Here, we report on scanning tunneling microscopy studies of monomolecular layers of a ferroelectric nematic liquid crystal on a reconstructed Au(111) surface. The monolayers are obtained by deposition from a solution at ambient conditions. The adsorbed ferroelectric nematic molecules self-assemble into regular rows with tilted orientation, resembling a layered structure of a smectic C. Remarkably, each molecular dipole in this architecture is oriented along the same direction giving rise to polar ferroelectric ordering.

The development of an effective therapy aimed at restoring muscle dysfunctions in clinical and sports medicine, as well as optimizing working activity in general remains an urgent task today. Modern nanobiotechnologies are able to solve many clinical and social health problems, in particular, they offer new therapeutic approaches using biocompatible and bioavailable nanostructures with specific bioactivity. Therefore, the nanosized carbon molecule, C₆₀ fullerene, as a powerful antioxidant, is very attractive. In this study, a comparative analysis of the dynamic of muscle soleus fatigue processes in rats was conducted using 50 Hz stimulation for 5 s with three consistent pools after intraperitoneal administration of the following antioxidants: C₆₀ fullerene (a daily dose of 1 mg/kg one hour prior to the start of the experiment) and N-acetylcysteine (NAC; a daily dose of 150 mg/kg one hour prior to the start of the experiment) during five days. Changes in the integrated power of muscle contraction, levels of the maximum and minimum contraction force generation, time of reduction of the contraction force by 50% of its maximum value, achievement of the maximum force response, and delay of the beginning of a single contraction force response were analyzed as biomechanical markers of fatigue processes. Levels of creatinine, creatine phosphokinase, lactate, and lactate dehydrogenase, as well as pro- and antioxidant balance (thiobarbituric acid reactive substances, hydrogen peroxide, reduced glutathione, and catalase activity) in the blood of rats were analyzed as biochemical markers of fatigue processes. The obtained data indicate that applied therapeutic drugs have the most significant effects on the 2nd and especially the 3rd stimulation pools. Thus, the application of C₆₀ fullerene has a (50–80)% stronger effect on the resumption of muscle biomechanics after the beginning of fatigue than NAC on the first day of the experiment. There is a clear trend toward a positive change in all studied biochemical parameters by about (12–15)% after therapeutic administration of NAC and by (20–25)% after using C₆₀ fullerene throughout the experiment. These findings demonstrate the promise of using C₆₀ fullerenes as potential therapeutic nanoagents that can reduce or adjust the pathological conditions of the muscular system that occur during fatigue processes in skeletal muscles.

Effective targeting of metastasis is considered the main problem in cancer therapy. The development of herbal alkaloid Berberine (Ber)-based anticancer drugs is limited due to Ber’ low effective concentration, poor membrane permeability, and short plasma half-life. To overcome these limitations, we used Ber noncovalently bound to C₆₀ fullerene (C₆₀). The complexation between C₆₀ and Ber molecules was evidenced with computer simulation. The aim of the present study was to estimate the effect of the free Ber and C₆₀-Ber nanocomplex in a low Ber equivalent concentration on Lewis lung carcinoma cells (LLC) invasion potential, expression of epithelial-to-mesenchymal transition (EMT) markers in vitro, and the ability of cancer cells to form distant lung metastases in vivo in a mice model of LLC. It was shown that in contrast to free Ber its nanocomplex with C₆₀ demonstrated significantly higher efficiency to suppress invasion potential, to downregulate the level of EMT-inducing transcription factors SNAI1, ZEB1, and TWIST1, to unblock expression of epithelial marker E-cadherin, and to repress cancer stem cells-like markers. More importantly, a relatively low dose of C₆₀-Ber nanocomplex was able to suppress lung metastasis in vivo. These findings indicated that сomplexation of natural alkaloid Ber with C₆₀ can be used as an additional therapeutic strategy against aggressive lung cancer.

Lyotropic chromonic liquid crystals (LCLCs) combine a very high packing density (intramolecular separation is about 3.4 Å within aggregates) with an ability to form ordered structures that are transferable from a water solution to a dry film. We show that the electric current in a dry film of LCLC aggregates is sensitive to the distance between the molecules in the aggregates and that it depends on the ambient humidity. Thus, by measuring the electric current through an LCLC film printed onto a substrate with predesigned electrodes and integrated circuits, we can measure the humidity. A humidity sensor based on LCLCs has high sensitivity, a fast response, and short recovery times.

Cisplatin (Cis-Pt) is the cytotoxic agent widely used against tumors of various origin, but its therapeutic efficiency is substantially limited by a non-selective effect and high toxicity. Conjugation of Cis-Pt with nanocarriers is thought to be one option to enable drug targeting. The aim of this study was to estimate toxic effects of the nanocomplex formed by noncovalent interaction of C₆₀ fullerene with Cis-Pt against Lewis lung carcinoma (LLC) cells in comparison with free drug. Scanning tunneling microscopy showed that the minimum size of C₆₀–Cis-Pt nanoparticles in aqueous colloid solution was 1.1 nm whereas that of C₆₀ fullerene was 0.72 nm, thus confirming formation of the nanocomplex. The cytotoxic effect of C₆₀–Cis-Pt nanocomplex against LLC cells was shown to be higher with IC₅₀ values 3.3 and 4.5 times lower at 48 h and 72 h, respectively, as compared to the free drug. 12.5 µM Cis-Pt had no effect on LLC cell viability and morphology while C₆₀–Cis-Pt nanocomplex in Cis-Pt-equivalent concentration substantially decreased the cell viability, impaired their shape and adhesion, inhibited migration and induced accumulation in proapoptotic subG1 phase. Apoptosis induced by the C₆₀–Cis-Pt nanocomplex was confirmed by caspase 3/7 activation and externalization of phosphatidylserine on the outer surface of LLC cells with the double Annexin V-FITC/PI staining. We assume that C₆₀ fullerene as a component of the C₆₀–Cis-Pt nanocomplex promoted Cis-Pt entry and intracellular accumulation thus contributing to intensification of the drug’s toxic effect against lung cancer cells.

Among organic semiconductors, rubrene (C42H28, 5,6,11,12-tetraphenyltetracene, Rub) is extensively studied in recent years, since it exhibits interesting physical properties such as very high charge carrier mobilities in organic field-effect transistors at room temperature. Rub is used as a laser dye and as a fluorescent dopant in other organic light-emitting diodes (OLEDs) to improve the characteristics such as lifetime, stability, color, and brightness. However, there are controversies as to the Rub degradation both in the bulk state and thin layers. So, the better understanding of these phenomena is crucial for improving the performance of organic devices. In this work, we present the results on complex studies of the molecular structure, morphology, and photoluminescence (PL) of Rub layers deposited on freshly cleaved KBr(100) and Au(111) substrates by vacuum thermal evaporation. Additionally, the two-component vacuum deposited (VD) Rub-tetracene (Tc) films were studied. Special attention was paid to the susceptibility of films to the oxidation under ambient conditions. The chemical structure and molecular ordering in the obtained VD thin organic films were evaluated by FTIR spectroscopy, and the structure of the very first Rub layers on atomically smooth Au(111) surfaces was studied with scanning tunneling microscopy (STM). From the changes in the peaks position and the intensity of room-temperature PL spectra of the films with time, the degradation kinetics of the Rub emission is analyzed.

We discovered the phenomenon of liquid crystal (LC) alignment on a photosensitive chalcogenide glass film As₂₀Se₈₀ after irradiation of the LC in the isotropic phase with polarised light. The photoalignment was observed after cooling of the LC to the nematic phase. Quality of the photoalignment depended on an initial phase state of the LC. If the photoalignment was uniform at the irradiation of the isotropic phase of the LC that initially was pre-aligned in the nematic phase, the irradiation of the cell being filled in the isotropic phase resulted in inhomogeneous photoalignment. The orientation of the LC strongly depended on the geometry of the irradiation the LC in the cell. In the case of the direct irradiation of the chalcogenide surface, the photoorientation of the LC was stable. On the contrary, the irradiation of the chalcogenide surface through the LC layer led to the temporal photoalignment that diminished within few days. The results are explained in the frame of the model that suggests two mechanisms of photoalignment. The first one is related to a light-induced anisotropy on chalcogenide layer and the second one involves a LC in the process. We assume that an anisotropic light-induced desorption of LC molecules from the chalcogenide layer is the origin of last kind of photoalignment. The asymmetry of the photoalignment properties at the irradiation from the different sides of the chalcogenide surface is explained by producing different surface structures at the irradiation from the different sides.