A correlation between mechanical and electrical properties of the synthetic hydrogel chosen as an experimental model of cytoskeleton

Abstract

The correlation between the electrochemical (Donnan) potential and volume swelling was studied for synthetic polyelectrolyte hydrogels considered as models of cytoskeleton gel-forming biopolymers. Hydrogels involving polyacrylic and polymethacrylic acids with varying network density were synthesized by a radical polymerization in aqueous solution. Electrical charge was introduced into the gel network by partial neutralization of monomer acids with several alkali and alkali earth (hydr)oxides. The electrochemical (Donnan) potential of synthetic gels was determined using conventional microelectrode tools for cell potential determination. It was demonstrated that the negative electrical potential of many anionic gels with various charges and network densities decreased with the decrease of equilibrium swelling, i.e., with the decrease in water content in the gel. It was shown that a drastic phase transition in the gel structure from a swollen to a compressed state induced by K⁺/Ca²⁺ exchange is accompanied by an analogous decrease in the absolute Donnan potential of the gels. A kinetic study demonstrated that the gel volume changed ahead of its electrical potential. This suggests that the volume phase transition in gel is the main cause of the electrical response. A similarity between the swelling/compression transition in synthetic gels and the volume changes in the cytoskeleton in the vicinity of the cell membrane was demonstrated. Based on the universal analogy between the properties of synthetic and natural polymer gels, a possible involvement of swelling of the gel-like cytoskeleton structures in electrical regulation in the cell was postulated.