ИСТИНА

Diamond nanoparticles – nanodiamonds (ND) attract much attention due to their intrinsic properties of nontoxicity and biocompatibility. However possible effects of these nanoparticles on biological structures starting from molecular and cellular levels, including blood components, have not been fully assessed so far. The aim of this work was to study the effect of ND on the microrheologic characteristics of human and rat blood at in-vitro incubation of blood samples with ND and in-vivo incubation after intravenous administration of ND into live rats. In our previous work [1], we studied various effects of ND on the components of blood plasma. The adsorption of blood plasma proteins on ND was analysed using UV-visible absorption measurements. We showed, in particular, that the adsorption of blood plasma proteins albumin and γ-globulin on ND sized 5 and 100 nm leads to structural transformations of the adsorbed molecules and, consequently, to a significant decrease in the protein functional activity. We also found that the influence of 5-nm ND on the protein structure and functions is more significant than that of 100-nm ND. We also studied the influence of ND on the oxygenation states and microrheological properties of red blood cells (RBC) in-vitro [2]. Measurements were facilitated using laser scanning fluorescence and Raman scattering spectroscopy, dynamic and diffuse light scattering techniques, and laser diffractometry. Diffuse light scattering from freshly drawn whole blood samples after their incubation with ND was used to study the effect of ND on the kinetics of RBC spontaneous aggregation and shear-induced disaggregation. Diffraction of laser beam on diluted suspensions of RBC before and after incubation with ND was implemented for quantitative measurements of the effect of ND on the ability of RBC to deform when subjected to shear stress in a flow cell. Optical trapping with laser tweezers was used to study the interaction of individual RBCs suspended in autologous plasma and/or in solutions of various macromolecules and ND. All measurements were performed in-vitro. Here we report on the latest results of our research, which combines our in-vitro and in-vivo expertise in cellular and in whole blood and animal models using state of the art laser methods and instruments. Importantly, we show that the ND in their as-prepared form and in physiological condition neither cause hemolysis nor affect the cell viability. Neither the oxygenation/deoxygenation states are altered when the ND interact with RBC. However, in some cases the ND affect the microrheologioc properties of RBC such as their ability to change their shape under shear stress as well spontaneous aggregation and shear–induced disaggregation parameters. This may be due to the ND sticking to RBC membrane as well as due to adsorption of blood plasma proteins on their surfaces, which we recorded by various laser techniques. The effects are particle size, concentration and surface functionalization dependent. The obtained results imply that controlling the blood (micro) rheologic properties is necessary during the ND application in the in-vivo experiments and clinical trials. Different techniques based on laser interaction with particles can be efficiently used for this purpose. We believe that this conclusion is true for all nanoparticles designed for biomedical applications albeit their administration into the organism is to be performed via blood flow. Further in-vivo experiments are of crucial importance for testing the results obtained in in-vitro conditions.