Ionoelastomer junctions between polymer networks of fixed anions and cations

Soft ionic conductors have enabled stretchable and transparent devices, but liquids in such devices tend to leak and evaporate. In this study, we demonstrate diodes and transistors using liquid-free ionoelastomers, in which either anions or cations are fixed to an elastomer network and the other ionic species are mobile. The junction of the two ionoelastomers of opposite polarity yields an ionic double layer, which is capable of rectifying and switching ionic currents without electrochemical reactions. The entropically driven depletion of mobile ions creates a junction of tough adhesion, and the stretchability of the junction enables electromechanical transduction.

Modification of Poly(ethylene terephthalate) Surfaces by Linear Poly(vinyl amine)

The feasibility of fixing linear poly(vinyl amine) (PVAm) onto the surface of a poly(ethylene terephthalate) (PET) foil is shown. Pretreatment of the PET foil for PVAm anchoring is UV irradiation generated by an excimer lamp (λ = 222 nm). Thereby newly formed COOH-groups are able to build up in situ an ionic double layer with PVAm by proton transfer. The properties of the modified PET foil like wetting performance and electric conductivity are significantly improved by this treatment.

Guanidinium analogues as probes of the squid axon sodium pore. Evidence for internal surface charges.

We have investigated the reduction of steady state sodium channel currents by a monovalent and a divalent guanidinium analogue. The amount of block by the divalent compound at a constant membrane potential was dramatically reduced by an increase in the internal salt concentration. Channel block by the monovalent molecule was a less steep function of salt concentration. These results would be expected if there were negative charges near the sodium pore that produced a local accumulation of the cationic blocking ions. According to this view, the ionic strength dependence of block results from changes in surface potential. The divalent blocker would be expected to be more sensitive to ionic strength owing to its larger valence. Our results can be quantitatively described by a simple ionic double-layer model with an effective surface charge density of about -1 e/250 A2 in the vicinity of the pore.

Redifferentiation, cellular elongation and the cell surface during lens regeneration

(1) Dorsal irises from normal and lentectomized eyes of the newt Notophthalmus viridescens were cultured in vitro in the presence of colchicine (1·25 × 10−3 to 2·5 × 10−6 M), vinblastine sulfate (4·4 × 10−8) and cytochalasin B (20µg/ml). Explants were treated for 24 h and implanted into host eyes of previously lentectomized newts. (2) In regenerates treated with colchicine at stages prior to the onset of lens fiber formation, cellular elongation was inhibited or considerably delayed. Cytochalasin B has no effect on lens fiber differentiation when compared with regenerates treated with its solvent, dimethyl sulfoxide. (3) Colchicine-treated regenerates showed no detectable fluorescence when stained with anti-newt lens fluorescent antibodies, suggesting that cells in which cellular elongation was inhibited were unable to synthesize lens specific proteins. (4) Ultrastructural observations of elongating lens regenerate cells showed microtubules present in the cytoplasm parallel to the axis of elongation. Microtubules were not observed in depigmented cells from colchicine-treated regenerates. Characteristic vinblastine-induced microtubule crystals were present in depigmented cells from vinblastine-treated regenerates. (5) Experiments using cell electrophoresis showed that neuraminidase-sensitive groups were detectable at the ionic double layer of cells from implanted regenerates at stages where lens fiber differentiation occurs. Cells from colchicine-treated regenerates showed no significant reduction of their electrophoretic mobility after neuraminidase treatment. This suggests that the appearance of some cell surface components in the redifferentiated cell may also be colchicine sensitive and probably mediated by microtubules.