We investigated the cell adhesion and growth of a series of thermoresponsive copolymers of N-isopropylacrylamide (NIPA) and N-tert-butylacrylamide (NtBA) above their lower critical solubility temperatures (LCST). It was found that cell adhesion and growth on the solvent cast films improved with increasing the NtBA content in the copolymers. The improvement was dependent on cell line. The surfaces of copolymers were analysed by atomic force microscopy. The topography of polymer films was not dependent on composition. The differences in the cell attachment and growth were attributed to the variation of surface energy with composition. The surface energy of copolymers decreased with the increase in the NtBA content. We conclude that poly(N-isopropylacrylamide) (poly(NIPA)) is a relatively poor substrate for cell growth and proliferation. However, its ability to support cell growth can be significantly improved by suitable modification.

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We propose a method of creation of a 3D matrix consisting of native collagen fibers and natural polysaccharide chitosan. The collagen-chitosan hydrogels maintain viability and prolipherative activity of embryonic stem cells obtained from internal cells of mouse blastocyst. The proposed system forming hydrogels in situ can be used in cell therapy for immobilization and targeted delivery of stem cells.

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Abstract. The present report gives the main results obtained in the studies of dlelectrophoresls of cellular suspensions by the optical technique of registration. The description of this technique and its comparison with the earl~er developed microscopic techniques of cell dielectrophoresls is given. It is shown that the frequency dependences of the orientation and pearlchain-formation effect of cells in the electric fleld and the effect of their dielectrophoretic precipitation on the electrodes, called orientation and dlelectrophoretlc spectra, respectively, depend on the conductivity and pH of suspension as well as on the adsorption of substances on the cell surface. The conclusion is advanced that the method of cellular dielectrophoresis is a promising one for the analysis of electrical and morphological properties of cells and for the study of the influence of physical and chemical factors on the living cells.