Silicon Nanoparticles as Amplifiers of the Ultrasonic Effect in Sonodynamic Therapy

The possibility of using mesoporous silicon nanoparticles as amplifiers (sensitizers) of therapeutic ultrasonic exposure were studied experimentally in vitro and in vivo. The combination of nanoparticles and ultrasound led to a significant inhibition of Hep-2 cancer cell proliferation and Lewis lung carcinoma growth in mice. These results indicated good prospects of using silicon nanoparticles as sensitizers for sonodynamic therapy of tumors.

Application of Laser Correlation Spectroscopy for Measuring Virus Size

Dynamic light scattering method or laser correlation spectroscopy was applied to evaluation of the size of viruses. We measured correlation functions of the light scattered by human immunodeficiency viruses (HIV) and hepatitis A viruses (HAV) and found that size of HIV-1 (subtype A and B) and HAV virions were 104 nm and 28 nm, respectively. Comparison of these findings with electron microscopy data for fixed samples of the same viruses showed good agreement of the results.

[On a Possible Mechanism of the Effect of Microwave Radiation on Biological Macromolecules]

A model describing the process of dissociation of hydrogen bonding in water clusters when irradiated by electromagnetic field in the microwave range is suggested. The model is also applicable for the case of rupture of the covalent bond of the water molecule cluster. If the energy absorption occurs at the interface of water and polymer clusters (e.g., DNA, chitosan), degradation of the polymer chain is possible.

Radio frequency radiation-induced hyperthermia using Si nanoparticle-based sensitizers for mild cancer therapy

Offering mild, non-invasive and deep cancer therapy modality, radio frequency (RF) radiation-induced hyperthermia lacks for efficient biodegradable RF sensitizers to selectively target cancer cells and thus avoid side effects. Here, we assess crystalline silicon (Si) based nanomaterials as sensitizers for the RF-induced therapy. Using nanoparticles produced by mechanical grinding of porous silicon and ultraclean laser-ablative synthesis, we report efficient RF-induced heating of aqueous suspensions of the nanoparticles to temperatures above 45-50 °C under relatively low nanoparticle concentrations (<1 mg/mL) and RF radiation intensities (1-5 W/cm(2)). For both types of nanoparticles the heating rate was linearly dependent on nanoparticle concentration, while laser-ablated nanoparticles demonstrated a remarkably higher heating rate than porous silicon-based ones for the whole range of the used concentrations from 0.01 to 0.4 mg/mL. The observed effect is explained by the Joule heating due to the generation of electrical currents at the nanoparticle/water interface. Profiting from the nanoparticle-based hyperthermia, we demonstrate an efficient treatment of Lewis lung carcinoma in vivo. Combined with the possibility of involvement of parallel imaging and treatment channels based on unique optical properties of Si-based nanomaterials, the proposed method promises a new landmark in the development of new modalities for mild cancer therapy.

Particles of liquid-crystalline dispersions formed by (nucleic acid-rare earth element) complexes as a potential platform for neutron capture therapy

Microscopic size particles of the cholesteric double-stranded DNA (RNA) liquid-crystalline dispersions, containing the ions of the rare earth elements in their content, have been obtained for the first time. The properties of these particles differ from those of classical DNA cholesterics noticeably. The local concentration of the rare earth elements in a particle reaches 200 mg/ml. The particles of the liquid-crystalline dispersion of the (DNA-gadolinium) complex maintain the properties for a long time. The combination of the microscopic size of particles, high concentration of gadolinium in particles and their stability opens a way to practical application of this new biomaterial.

Nanoconstructions based on double-stranded nucleic acids

We describe the formation and properties of nanoconstruction that consists of the double-stranded DNA molecules located at distance of 35-50 A in the spatial structure of particles of their cholesteric liquid-crystalline dispersions and cross-linked by artificial nanobridges. The resulting nanostructures possess the peculiar spatial and optical properties.

[Aspartate aminotransferase activity as dependent on the degree of serum dilution]

Dependence of the enzymatic reaction rate V. catalyzed by aspartate aminotransferase, on concentration of standard human blood serum Moni-trol I ("Dade", Switzerland) was studied. In the range of moderate dilutions, which did not exceed 1.3-times, the V value altered in accordance with the blood serum concentration C. Under conditions of extensive dilutions dependence of V on blood serum concentration became complicated. The non-linear type of V dependence on blood serum concentration appears to be due to deaggregation of the enzyme molecules with formation of more active fragments as a result of blood serum dilution. Two parameters should be used for characteristics of blood serum aspartate aminotransferase activity: the enzymatic activity of undiluted blood serum as well as the ratio between specific activities of the enzyme in an associated from and the products of its dissociation, i.e. when C-1 and C-0, respectively.

[Toxoplasmosis and the epidemiological status of the population. II. The determination of the intensity of toxoplasmosis transmission]

The possibility of using the primary epidemiological unit, force of infection, as a criterion for evaluating the intensity of the transfer of toxoplasmosis among the population at the focus of infection has been established. The comparison of data obtained in different regions indicates that the level of the force of infection is, in general, low, but it can vary within a wide range. The problem of the suitability of using the force of infection as a criterion for dividing territories into zones with respect to toxoplasmosis is discussed.

[Toxoplasmosis and the epidemiological status of the population. I. The general characteristics of the basic epidemetrons]

The general characteristic of the main indices, or epidemic values (epidemetrons) is presented and the possibility of their use for characterizing the epidemiological state of the population in the foci of toxoplasmosis is evaluated.