[The influence of physical-chemical characteristics of surface modified copper nanoparticles on E. coli cell population growth suppression and on electrostatic properties of their membranes].

The biological activity of copper nanoparticles, able to suppress growth of E. coli cells population under contact interactions, was explored. Three types of samples with oxide layers of various sizes, thickness and composition were used in experiments. It was found out, that an increase in electron density on the external membrane of E. coli correlated with copper nanoparticles suppression capability and with lower activation energy of electron transfer on bacteria. The analysis of experimental data helps to correct conditions for obtaining nanoparticles with certain properties of their surface oxide layers. The character of temperature dependence of electron density reveals the electron type of conductivity in contact area of E. coli and nanoparticles. These results help to find approach to understanding the nature of toxic influence of copper nanoparticles on E. coli cells under contact interaction.

[Copper-induced change in the ESR signal of hemoglobin nitrosyl complexes in wound by the action of copper nanoparticles].

The results concerning changes in the ESR signal of hemoglobin nitrosyl complexes in wound tissues in the course of healing by the action of ointments with copper nanoparticles (patent N2460532, Russia) are presented. It is shown that the wound healing process modified by the influence of copper nanoparticles demonstrates the increase in the ESR signal amplitude for :hemoglobin nitrosyl complexes as compared with controls (the ointment base without nanoparticles). Planimetric measurements of wound area through reparation course indicate an active process of wound healing for injuries treated with copper nanoparticles in the ointment, resulting in lessening half-reparation time up to 5.0 times as compared with controls (treatment with the ointment base). The paper discusses the role of copper nanoparticles, NO and their potential synergistic effect on the skin wound regeneration.

[Mechanism of the toxic action of copper nanoparticles on Escherichia coli bacteria].

Some features of contact interaction of Escherichia coli with Cu nanoparticles 75-100 nm in diameter have been studied. The analysis of variations in the amplitude of fluorescence of the negatively charged probe 1-anilinonaphthalene-8-sulfonate (ANS) in Gouy-Chapmen coordinates indicates an increase (in the absolute value) in the electrostatic potential of E. coli external membrane during the contact with Cu nanoparticles. The increase in the electrostatic potential correlates with the bacteriostatic influence on the growth of bacterial population. The calculations of tryptophan fluorescence quenching by iodide in the presence of Cu nanoparticles with the use of the Stern-Volmer equation revealed an increase in the constant of dynamic quenching and the availability of the fluorophore to suppressor.

[Main results of research reported by the Center's Department of Innovation in Radiotherapy].

The efficacy of multimodality conservative treatment for prostate and bladder cancer and cervical carcinoma was improved due to integration of such modem modalities as intra-arterial chemotherapy, local hyperthermia and hyperglycemia and combination of local and systemic radiomodifiers. Our methods use criteria of actual survival and are intended to raise it.

[Changes in the electrical characteristics of the internal surface of cytoplasmic membrane of bacteria Escherichia coli after the binding of microdoses of copper ions by its external surface].

The effect of microdoses of copper ions bound with the external surface of the cytoplasmic membrane of Escherichia coli spheroplasts on the charge density of its superficial structures was investigated by the ESR method. Positively charged spin probes of KAT(n)-type and the newly synthesized KAT15 were used. The experimental data were analyzed using the formalism of Gouy-Chapman theory. The binding of microdoses of copper ions by the external surface of the cytoplasmic membrane changed the value of charge density on the membrane internal surface.

[Structural modifications of the surface of Escherichia coli bacteria and copper-induced permeability of plasma membrane].

The effect of Cu2+ on the structural organization of the cell surface of Escherichia coli bacteria during the induction of conductivity of a plasma membrane was studied. A fluorescent study did not reveal any substantial changes in the microviscosity of lipids by the action of copper ions. At the same time, a substantial reorganization of membrane proteins during plasmolysis was observed. A model of the copper-induced structural reorganization of membrane lipids was constructed, according to which the reorganization leads to the opening in the membrane of channels of nonspecific conductivity for cations. The opening of conductivity channels results from the break of disulfide bonds in critical membrane proteins during the interaction with Cu+, which form either due to the reduction of Cu2+ on specific sites of cell surface or by means of external reducing agents.

[Dielectric characteristics of intact and copper-modified bacteria Escherichia coli]. / Diélektricheskie kharakteristiki intaktnykh i med'modifitsirovannykh bakterii Escherichia coli.

The dielectric parameters of the intact and Cu(2+)-modified concentrated Escherichia coli populations in the frequency range of alternating current 20 Hz-100 MHz were studied. It was found that Cu(2+)-ions in low concentrations, which are mainly absorbed by active centres of the outer cell surface, change the dielectric characteristics of the inner membrane and simultaneously increase the conductivity of plasma membrane in the frequency-independent region 10(5)-10(6) Hz. It was concluded that the disturbances in the barrier properties of plasma membrane by the action of Cu2+ are closely related to changes in the dielectric parameters of intact bacteria.

[Interaction of E. coli cells with ascorbic acid and sodium nitrite studied by ESR method]. / Issledovanie metodom EPR vzaimodeistviia kletok E. coli s askorbinovoi kislotoi i nitritom natriia.

Ascorbic acid, an effective modulator and regulator of cell metabolism, was shown to induce the production of nitric oxide in E. coli cells. This process was detected by EPR spectroscopy as the generation of a spectral signal typical of nitrosyl-iron-sulfur centers (Fe-S-NO) under anaerobic conditions. Incubation of E. coli cells in the presence of ascorbic acid under aerobic conditions was shown to be accompanied by sodium nitrite formation. It is suggested that ascorbic acid is capable of supporting the system of energy supply to cells in hypoxia caused by reduced oxygen content or treatment with sodium nitrite.

[Sulfur ligands within the cluster formations of copper at its strong'binding sites on the cytoplasmic membrane of Escherichia coli]. / Sernye ligandy v sostave klasternykh obrazovanii medi v mestakh ee sil'nogo sviazyvaniia tsitoplazmaticheskoi membranoi bakterii Escherichia coli.

The analysis of the saturation curves of ESR signals revealed a decrease in the relaxation rate of fast-relaxation Cu(I) complexes on the cytoplasmic membrane of E. coli after the interaction of these bacteria with low concentrations of SH-reagents. It was concluded that the observed changes are associated with the reorganization of Cu clusters due to the binding of SH groups incorporated into the clusters N-ethylmaleimide or Ag(I).

[Electron spin resonance determination of copper binding site on Escherichia coli cell membrane]. / Issledovanie metodom elektronnogo paramagnitnogo rezonansa tsentrov medi v mestakh ee sil'nogo cviazyvaniia s tsytoplasmatichesko'i membrano'i bakteri'i Escherichia coli.

The electron-spin relaxation of Escherichia coli cytoplasmic membrane strong binding Cu-centers was investigated by means of the microwave power saturation of the electronic spin resonance signal. It has been established, that copper centres in the strong binding sites of the cytoplasmic membrane E.coli may be represented in the following way: 1) isolate copper complexes with small speed of the spin-lattice relaxation; 2) isolate copper complexes with increased speed of spin-lattice relaxation by means of interaction with rapidly relaxation centres; 3) dipol-binding clasters; 4) ESR-nondetectable at T = 40 K, exchange-binding clasters, which cause increasing of the spin-lattice relaxation speed for isolate copper complexes.

[Analysis of the binding site of copper with intact and Escherichia coli bacteria modified by N-ethylmaleimide by ESR]. / Analiz mest sviazyvaniia medi s intaktnymi i modifitsirovannymi N-étilmaleimidom bakteriiami Escherichia coli metodom EPR.

Characteristics of copper binding sites in the bacteria E. coli were studied using ESR spectroscopy. It was found that these cations had high local density on the strong binding range represented by the two type sites. The former include nitrogen and oxygen ligands and the second ones--sulfur of the thiol biomolecules. The weak coupling Cu(II) sites of E. coli represent more polar nitrogen-oxygen environment. Blocking SH-groups by N-ethylmaleimide makes them inaccessible for copper ligation, sharply increases the percentage of ESR-detectable copper of the strong-binding sites and prevents the membrane breakdown by these cations. The results suggest that the Cu(2+)-induced membrane damage is the effect of Cu2+ binding with the SH-containing sites of the bacterial membrane.

[The copper-dependent accumulation of magnesium in Escherichia coli]. / Med'-zavisimoe nakoplenie magniia v Escherichia coli.

Cu2(+)-induced accumulation of Mg ions by E. coli cells has been studied. The accumulation was demonstrated to take place only when the cell had endogenous energetic resources. The data obtained and their correlation with the data on Cu2+ binding by bacterial cells and Cu2(+)-dependent streptomycin accumulation allowed to conclude that copper induced nonspecific potential-dependent influx of cations into cells.

[The role of surface and transmembrane potentials in copper binding by Escherichia coli cells]. / Rol' poverkhnostnogo i transmembrannogo potentsialov v sviazyvaniia medi kletkami Escherichia coli.

Cu2+-induced accumulation of Mg2+ ions by E. coli cells has been studied. The accumulation was demonstrated to take place only when the cell had endogenous energy resources. The data obtained and their correlation with the data on Cu2+ binding by bacterial cells and Cu2+-dependent streptomycin accumulation allowed to conclude that copper induced nonspecific potential-dependent influx of cations into cell.