Micro- and nanostructural characteristics of 3D porous carriers ElastoPHB-3D.

Microstructure of the surface and micro- and nanostructure of the internal surface of 3D porous carrier ElastoPHB-3D were studied by methods of electron microscopy and atomic force microscopy. Biological properties of ElastoPHB-3D samples were evaluated using culture of L929 mouse fibroblasts. High porosity and pore size of biodegradable matrixes ElastoPHB-3D and their good biofunctional properties as the substrate for cell culturing allow us to recommend ElastoPH-3D as a promising carrier for cell transplantation and creation of artificial organs.

[A comparative analysis of the two approaches to the evaluation of thrombogenic qualities of the biomaterials in vitro]. / Sravnitel'nyi analiz dvukh podkhodov k otsenke trombogennosti biomaterialov v usloviiakh in vitro.

The paper contains an analysis of thrombogeneticity of biomaterials in vitro with regard for the changing time of recalcification of the platelet-free and platelet-related human blood plasma after incubation with a studied sample. Two sizeless thrombogeneticity parameters are suggested for describing the thrombogeneticity of studied biomaterials irrespective of a incubation-medium composition. It was demonstrated by the example of glass granules, which were modified by various immobilized functional groups, that the measuring of re-calcification time performed after samples' incubation secures a more objective assessment of platelet-resistant properties of materials. The relative index of thrombogeneticity of biomaterials (with the above glass granules being the controls), unlike the standardized parameter, opens up the possibility to study comparatively the activating action exerted on the coagulating and anti-coagulating blood systems of the studied samples, which differ by the ratios of their surface squares to the incubation-medium volume.

[Interaction of heparin with amino group-containing materials]. / Vzaimodeistvie geparina s aminosoderzhashchimi materialami.

The influence of the glass surface immobilized aminogroups nature and the experiments conditions on the interactions between heparin and aminogroups containing surface was studied using total internal reflections fluorescence. It was shown, that the nature of the terminating aminogroup, but not its mobility or the amount of the aminogroups in the main chain, is the major factor influencing the heparin adsorbtion from individual solution. Both the nature of terminating aminogroup and its mobility determine heparin adsorption on the aminogroups containing surfaces from the blood plasma proteins containing solution. Heparin irreversibly adsorbed from individual solution is not replaced by blood plasma proteins. The tertiary aminogroups containing surface adsorbs maximal quantity of the heparin.

[Competitive adsorption of human fibrinogen on an amorphic quartz surface]. / Konkurentnaia adsorbtsiia fibrinogena cheloveka na poverkhnosti amorfnogo kvartsa.

The kinetics of adsorption of fibrinogen on the surface of amorphous quartz from binary solutions containing human serum albumin and gamma-globulin was studied by the method of fluorescence of total internal reflection. A model of energetically nonhomogeneous interactions in the surface/protein system was used to explain the mechanism of competitive adsorption of proteins.

[Comparative effectiveness of the use of hematological methods to analyze the procoagulant activity of biological materials]. / Sravnitel'naia éffektivnost' primeneniia gematologicheskikh metodov dlia analiza prokoaguliantnoi aktivnosti meditsinskikh materialov.

Whether clinical hematological methods by employing two parameters: (plasma recalcification time (PRT) and activated partial thromboplastin time (ACTT) can be used to examine the procoagulant activity of the surface of biological materials was comparatively studied. The method PRT was shown to be sensitive and reproducible while ACTT failed to significantly record differences in the procoagulant activities of various materials. The authors chose the optimal protocol for evaluating the blood compatibility of biological materials: the surface area/plasma volume ratio is more than 150 cm2/ml, the incubation time of samples is no less than 180 sec at 37 degrees C and continuous mixing.

[Interaction of heparinized polymer materials with plasma proteins and thrombocytes]. / Vzaimodeistvie geparinizirovannykh polimernykh materialov s belkami plazmy krovi i trombotsitami.

The interaction of heparinized polymer materials with human plasma proteins (serum albumin (SA), fibrinogen (F), antithrombin III (AT-III)) and platelets was studied. The level of SA and F adsorption irreversibility was demonstrated to depend on the mode of heparin immobilization. There was a negative correlation between the parameters of protein adsorption and the level of adsorbed AT-III. The relationship of the count of platelets adhered to the surface of heparinized polymer materials, to the time of contact was shown to be extreme. There was a correlation between the count of adhesive platelets and the parameters of plasma protein and AT-III adsorption. Based on experimental evidence, a scheme was proposed, which describes the impact of protein adsorption processes on the anticoagulative activity of surface-bound heparin, It is concluded that AT-III plays a particular role as the major component of the adsorption layer that is responsible for the nature of interactions of polymer materials with blood at the protein and cellular levels.

An N-substituted polyurea coating with high affinity for heparin.

A new N-substituted polyurea with tertiary amino groups in the polycarbamidic chain (NPUTA) has been synthesized. The polymer is soluble in C1-C4 alcohols, has high adhesion to polar molds, and has high H2O uptake (130-150%). The material can be coated on many biomaterials (polyurethanes, charcoal hemosorbents, cellulosic hemodialysis membranes), and high amounts of heparin can be adsorbed onto treated surfaces. NPUTA cast from 0.5-3.5% ethanol solutions can absorb large amounts of heparin from anti-coagulant solution (40-60 micrograms/cm2) and heparinized plasma. Heparin release into phosphate buffered saline (PBS) solution or plasma is minimal. The influence of NPUTA solution concentration and pre-absorbed heparin on the protein adsorption, platelet adhesion, surface induced hemolysis, and complement activation of these films has been investigated. Radiolabeled protein assays, radiolabeled platelet assays, and other methods were used. It was shown that modified surfaces for the listed materials, with heparinization, demonstrate improved in vitro blood compatibility without any changes in functional properties. For example, treatment with NPUTA/heparin does not reduce sorption of middle molecules by activated charcoal hemosorbent, while markedly and significantly decreasing platelet adhesion and complement activation. NPUTA/heparin modified, glutaraldehyde treated bovine pericardium exhibited significantly reduced calcification in a rat subcutaneous implant model. Other ex vivo circulation experiments also confirm the blood compatibility of different NPUTA treated surfaces.

The interaction of heparinized biomaterials with human serum, albumin, fibrinogen, antithrombin III, and platelets.

The influence of the method of heparin (HEP) immobilization on human serum albumin (HSA), fibrinogen (FG), and antithrombin III (AT-III) adsorption, platelet adhesion, and activation on the surface of polyvinylchloride, polyurethane Vitur, and a copolymer of styrene and divinylbenzene was measured. The negative correlation between the degree of irreversibility of plasma protein adsorption and the amount of adsorbed AT-III for HEP, immobilized onto the polymer surface passivated with HSA, FG, and plasma was found. The same negative correlation was observed between the amount of AT-III adsorbed on these systems and the number of adhered platelets. Schemes of the interaction of surface bound-HEP with AT-III, including the influence of an irreversibly adsorbed protein layer and adhered platelets, have been proposed. The essential role of AT-III in heparinized biomaterials/platelet interaction has been shown. A new method of combined immobilization of HEP and platelet adhesion inhibitor has been elaborated on.

[Structural and chemical transformations of heat-processed polyacrylonitrile fibers and characteristic parameters of their interactions with thrombocytes and plasma proteins]. / Strukturno-khimicheskie prevrashcheniia termoobrabotannykh poliakrilonitril'nykh volokon i kharakteristicheskie parametry ikh vzaimodeistviias trombotsitami i belkami plazmy krovi.

A suitable for analysis of the effect of structural and chemical changes on haemocompatibility of polymers is polyacrylonitrilics (PNA), which, depending on the thermo-processing (temperature, medium), make a number of materials, differing in structure and properties. A comparative analysis of physical and chemical initial properties as well as of thermically processed PNA fibres was made. By the methods of radioisotope and of fluoroscent spectroscopy the kinetics of early stages of adsorption of plasma albumine (AS) and of plasma fibrinogen (FG), the kinetics of desorption of pre-adsorbed plasma albumine in a model solution, and thrombocyte adhesion of the PNA surface were studied. The extreme nature of the irreversability degree in albumine and fibrinogen adsorption, the effective coefficients of the albumine desorption speed, and the number of bound thrombocytes at the temperature increase in thermal processing were found, and better quantitative criteria of haemocompatibility in vitro for PNA, processed thermally in the air. The achieved results can be explained by occurrence of, in a number of studied PNA fibres, an optimum ratio of the dispertion and polar superficial surrounding energy.