EDOT-pyrrole copolymer conductive nanoparticles and electrodes enhance galvanotaxis in Paramecium tetraurelia; a simple biological model for explorative experiments in therapeutic electrical stimulation

Abstract

The galvanotaxis response of Paramecium tetraurelia was explored as a preliminary model for in vitro electrostimulation of other eukaryotic cells. Interestingly, electrodes coated with 3,4-ethylenedioxythiophene (EDOT) – pyrrole (Py) copolymer induced galvanotaxis in a similar manner and with even greater efficiency than conventional electrodes. Furthermore, in the absence of agar bridges, there was no release of toxic species into the cell medium or any deleterious effects on cell viability after several cycles of electrostimulation for 1 min. The intrinsic cytotoxicity of the copolymer was also investigated in Paramecium tetraurelia and mammalian cell lines. The copolymer did not show any toxic effects at concentrations below 1 mg/ml. Finally, it was discovered that galvanotaxis can be increased by up to 150 % concerning the control (with electrostimulation of 3V for 60s) in Paramecium cells treated with 10 μg/mL copolymer particles for 1 h and that showed endocytosis. Galvanotaxis is voltage-dependent, as it only increases by 100 % at 1.5 V, suggesting a sensitive physiological level effect on the Ca2+ currents and voltage-dependent Ca2+ channels of the cilia.