The Cytotoxicity indices (IC50) of Keggin’s phosphorus-molybdenum heteropoly acids (HPCAs) and their sodium and potassium salts on dog kidney cells (MDSC) were determined. The antiviral activity of these compounds against topical strains of influenza A (H3N2 and H1N1) was revealed. The dependence of the biological properties of polyoxometalates (POMs) on the elemental composition of their molecules has been confirmed. It has been shown that when some of the molybdenum atoms are replaced by vanadium atoms, HPCA and their salts acquire higher cytotoxicities, which increase monotonically as the number of substitutions increases. For the first time, the dependence of the biological activity of HPCA and their salts on the mass of cations has been established and interpreted. In vivo (on white outbred mice) the values of semi-lethal doses (DL50) of these compounds were established. For aqueous solutions of sodium and potassium salts of GPCA in a wide range of concentrations (from 0.05 μM to 15 μM), the values of the toxicity index (It) were determined on the model of motile cells. It has been established that GPCA and their salts are classified as moderately dangerous toxic substances and have selective antiviral activity, which at low concentrations (less than 15 μM) for influenza A strains is manifested mainly by a decrease in hemagglutination activity (HA).

Correlations between the immunomodulatory properties of heteropoly acids (HPAs) and the stiffness of target cells, which depend on the content of membrane cholesterol, are established. A molecular model of the cellular activation of immunoactive cytokine (CT) genes by heteropoly acids is constructed. The specific features of the immunomodulatory properties of HPAs in relation to healthy and cancer cells (HFFs, A549, and L41 lines) are discussed. A mechanism for the formation of increased antiviral activity of HPAs against (+)ssRNA viruses is proposed. We substantiate the possibility of the increased nonspecific antiviral activity of HPAs against pandemic strains of SARS-CoV-2, inactivation of which may involve HPA-activated cytokines.

The antiviral activity of Keggin heteropolyacids (HPAs) against the human influenza A/California/07/09 (H1N1) pdm09 virus is studied in MDCK cell culture. Transmission electron microscopy reveals new features of the destruction of viral particles by HPAs. A proton-anion model that considers the main biochemical processes leading to the destruction of enveloped viruses: the depletion of membrane cholesterol by HPA anions, acidification of the M1 matrix protein by protons of the medium, and anion lysis of lipid membranes, is proposed. The Arrhenius dependences of the biological properties of HPAs on temperature are predicted. The general mechanism for the formation of high biological activity HPAs is described, which is underlined by the anion depletion of cholesterol in bilipid membranes, a new effect in the biochemistry of polyoxometalates.

The results of an electron microscopic study of the effect of heteropoly acids (HPAs) with a Keggin structure on particles of influenza A/Aichi/1/68 (H3N2) and A/California/07/09 (H1N1) pdm09 viruses are presented. It is shown that the action of HPAs on viral particles leads to a complete (or partial) removal of transmembrane glycoproteins and the destruction of matrix protein M1, which manifests itself in the deformations and destruction of viral membranes. Using the A/California/07/09 (H1N1) pdm09 viruses as an example, it is shown that the efficiency of the destruction of the viral envelope by HPAs depends on the medium in which the viruses are cultured. The mechanism of destruction is proposed, which involves the extraction of cholesterol, etching of phospholipids, and the formation of pores in the lipid membrane as a result of the action of heteropolyanions. It is assumed that the penetration of protons through the formed pores can lead to the destruction of the matrix protein M1.

Методом времяпролетной масс-спектрометрии вторичных ионов (ToF-SIMS) исследованы изменения состава плазматических мембран (ПМ) фибробластов эмбриона человека под воздействием наноразмерных анионов кремний-молибденовой кислоты (КМК). Измерены и интерпретированы зависимости масс-спектров основных липидов ПМ от концентрации КМК, коррелирующие с их послойными распределениями и со сродством холестерина к фосфолипидам. Обнаружен новый для биохимии клетки эффект – значительное снижение относительного содержания в ПМ холестерина и сфингомиелина под воздействием многозарядных анионов гетерополикислоты (ГПК). Для водных растворов КМК при концентрации С ~ 10мкМ/л и периода воздействия 48 ч обнаружено, что количество холестерина в ПМ снижается в 2–2.5 раза, при этом количество сфингомиелина уменьшается на 20–25%. Предложен новый механизм начального воздействия ГПК на плазматические мембраны, сводящийся к селективному травлению многозарядными анионами. Согласно предлагаемому механизму на первом этапе взаимодействия аниона полиоксометаллата с клеткой осуществляется экстракция из ПМ холестерина и сфингомиелина – основных регуляторов проницаемости и микровязкости ПМ. Как следствие возросшей проницаемости ПМ в клетках возможно ускорение жизненно важных трансмембранных и латеральных процессов.

In the framework of the theory of tunneling resonance electron-vibrational spectroscopy, taking into account the interelectron (Coulomb) interaction, which is essential for ultrasmall metal nanoparticles (≤5 nm), a model is constructed that quantitatively explains the results of published spectroscopic experiments carried out using scanning tunneling microscopy, in which for nanoparticles of gold (Au NPs) deposited on pyrolytic graphite, previously there were observed equidistant series of negative differential resistances with periods of 0.1–0.5 V. It was found that series with sufficiently large periods (~0.3–0.5 V), having growing (by the measure of increasing voltage on the nanocontact) envelopes correlate with the sizes of Au NPs and are formed by the Coulomb blockade mechanism. Series with small periods (~0.1 V) correspond to vibrational transitions of atomic particles adsorbed on the surface of Au NPs. A new size effect was discovered for the first time, consisting in the increased adsorption ability of ultrasmall gold nanoparticles having the same sizes (≈3.2 nm) as particles with increased catalytic activity. The new adsorption effect gives a direct and affirmative answer to the frequently discussed question of the “intrinsic” Au NP superactivity, which is not related to the properties of carriers.

This paper reports a study of the inhibitory and immunomodulating activity of phosphoric and silicon heteropoly acids with Keggin anions ([ХМ(1)12 – nМ(2)nО40]–m, where X = P, Si; M = Мо, W, and V; m = 3, 4, 5) toward human embryonic fibroblast cells using MTT and polymerase chain reaction techniques. The correlation between the inhibitory activity of heteropoly acids and their anion charge has been shown and interpreted.

The influence of a microwave radiation on the prompt fluorescence (PF) excited in molecular crystals by an ultrashort laser pulse is theoretically considered in the work. Laser pulse excites organic molecule to the lowest singlet state S1 and simultaneously produces a pair of localized triplet excitons in its singlet state. The subsequent emission from the S1 level and emission from the singlet spin component of the triplet pair combine to produce PF. Unlike the steady-state RYDMR, the pulsed method proposed in this work allows the two emission channels to be discriminated. A microwave-induced contribution to the PF-decay curve is shown to be bell-shaped and contain oscillatory component. By measuring the amplitude of these oscillations one can estimate relationship between the partial transition rates controlling the decay process.

We used time-of-flight secondary ion mass spectrometry (ToF-SIMS) to study changes in the composition of the plasma membranes of human fetal fibroblasts under the action of nanosized anions of silicon molybdic acid. The dependences of the mass spectra of the main lipids of the plasma membranes on the silicon molybdate concentration were measured and interpreted; the dependences correlate with the layer-by-layer distributions and with the affinity of cholesterol for phospholipids. A new effect for cell biochemistry was discovered, that is, a significant decrease in the relative concentrations of cholesterol and sphingomyelin in plasma membranes under the effect of multiply charged heteropoly anions (HPAs). In aqueous silicon molybdate solutions with a concentration of c ≈ 10 µM/L and an exposure time of 48 h, the amount of cholesterol in plasma membranes decreased by 2–2.5 times, while the amount of sphingomyelin decreased by 20–25%. A new mechanism is proposed for the initial effect of HPA on plasma membranes, which consists of selective etching by multiply charged anions. According to the proposed mechanism, cholesterol and sphingomyelin, the main regulators of permeability and microviscosity of plasma membranes, are extracted from the plasma membrane at the first stage of the interaction of the polyoxometallate anion with the cell. As a consequence of the increased permeability of the plasma membranes in cells, acceleration of vital transmembrane and lateral processes may occur.

A model of tunneling multiresonant electronic transitions in nanocontacts containing ultrasmall nanoparticles with adsorbed atoms has been developed. Mechanisms of the formation of series of equidistant negative differential resistances in tunneling spectra of these structures have been analyzed. The possibility of the coexistence of equidistant series of two types, Coulomb and vibrational, has been shown. The signatures for identification of these series have been formulated. Tunneling spectra of ultrasmall metal nanoparticles containing information on their electron vibrational subsystems have been interpreted.

The pulsed version of the reaction yield detected magnetic resonance (RYDMR) method is theoretically considered for the reaction scheme according to which the annihilation of triplet excitons in a molecular crystal occurs. Analytical expressions are obtained that describe the kinetics of prompt fluorescence decay with time under the conditions of its excitation by an ultrashort laser pulse. The corresponding shape of the decay curves of prompt fluorescence is determined. It is shown that the obtained curves can be used for a more detailed determination of the reaction rate constants than in the case of the stationary version of the RYDMR method.

A phenomenological model has been proposed for tunneling electron spin resonance (ESR) of an isolated surface spin situated in a scanning tunneling microscope (STM), which explains the dependence of features (local maxima) of the tunneling current on the radio-frequency (RF) electric field and on the position of the tip with respect to the spin. A crossover of the line shape of the resonance signals, whose nature in weak and strong pumping fields corresponds to Lorentzian and Fano resonances, respectively, has been interpreted. New ESR–STM effects that are linear and nonlinear in the RF field and are promising for developing the methods of controlling spin qubits have been predicted.