Electrochemical Characteristics of the Oxidation of Sulfur- and Iron-Containing Compounds by Acidophilic Microorganisms.

The electrochemical features of the interactions of sulfur- and iron-containing compounds (ferrous sulfate, elemental sulfur, pyrite tailings, cysteine, sodium thiosulfate) with a model acidophilic consortium, including the genera Leptospirillum, Sulfobacillus, Acidithiobacillus, Ferroplasma, and Acidiplasma, were studied. The method of cyclic voltammetry recorded redox processes at the electrode/solution interface in the presence of the studied sulfur- and iron-containing compounds. In general, the modeling consortium led to the intensification of these processes. The characteristics of the diffuse layer near the electrode/solution interface were studied using electrochemical impedance spectroscopy. The introduction of microorganisms and/or substrates into the supporting electrolyte led to a decrease in the slope and can be interpreted as evidence of their effect on the diffusion part of the double layer. Its contribution decreases in favor of ion transport. All this, in general, does not contradict the assumption of cell adsorption on the electrode surface. Confocal laser scanning microscopy confirmed this assumption and showed cell adhesion to the surface. The data obtained confirm the importance of bioelectrochemical processes of the studied group of microorganisms in biotechnological processes associated with the leaching of metals from sulfide ores.

A CdSe/ZnS quantum dot-based platform for the delivery of aluminum phthalocyanines to bacterial cells.

Enhancement of optical properties of photosensitizers by additional light-harvesting antennas is promising for the improvement of the photodynamic therapy. However, large number of parameters determine interactions of nanoparticles and photosensitizers in complex and, thus the photodynamic efficacy of the hybrid structure. In order to achieve high efficiency of energetic coupling and photodynamic activity of such complexes it is important to know the location of the photosensitizer molecule on the nanoparticle, because it affects the spectral properties of the photosensitizer and the stability of the hybrid complex in vitro/in vivo. In this work complexes of polycationic aluminum phthalocyanines and CdSe/ZnS quantum dots were obtained. We used quantum dots which outer shell consists of polymer with carboxyl groups and provides water solubility and the negative charge of the nanoparticle. We found that phthalocyanine molecules could penetrate deeply into the polymer shell of quantum dot, leading thereby to significant changes in the spectral and photodynamic properties of phthalocyanines. We also showed that noncovalent interactions between phthalocyanine and quantum dot provide possibility for a release of the phthalocyanine from the hybrid complex and its binding to both Gram-positive and Gram-negative bacterial cells. Also, detailed characterization of the nanoparticle core and shell sizes was carried out.

Cytotoxic and Immunochemical Properties of Viscumin Encapsulated in Polylactide Microparticles.

Biodegradable polylactide microparticles with encapsulated cytotoxic protein viscumin were obtained via the ultrasound-assisted supercritical fluid technique. The size of the microparticles was 10-50 µM, as shown by electron microscopy. The time course of viscumin release from microparticles was studied using an immunoenzyme test system with anti-viscumin monoclonal antibodies. It was found that 99.91% of the cytotoxic protein was incorporated into polymer microparticles. Only 0.08% of the initially encapsulated viscumin was released from the microparticles following incubation for 120 h in a phosphate-buffered saline at neutral pH. Importantly, the method of ultrasonic dry supercritical fluid encapsulation failed to alter both the cytotoxic potency and the immunochemical properties of the encapsulated viscumin. Thus, this procedure can be used to generate biodegradable polylactide microparticles with encapsulated bioactive substances.

[In vitro fluorescence assay to study the folding of Kv ion channels].

A fluorescence assay to check the folding of potassium Kv channels expressed in vitro has been developed. For this aim, the fluorescently labeled channel blocker, recombinant agitoxin of yellow scorpion was employed. The level of expression of various Kv channels in vitro has been tested. It has been demonstrated that Kv2 channels form clusters on the cell surface, which are not associated with actin filaments. On the other hand, Kv10 channels form larger clusters, which are associated with actin, indicating the principal differences in the organization of cytoplasmic domains of Kv2 and Kv10 channels.