Scanning Electrochemical Microscopy. 40. Voltammetric Ion-Selective Micropipet Electrodes for Probing Ion Transfer at Bilayer Lipid Membranes

Voltammetric ion-selective micropipet electrodes for use in scanning electrochemical microscopy (SECM) for detection of potassium ion were fabricated. These used pulled borosilicate capillaries with tip orifice radii of 0.7−20 μm with silanized inner walls filled with a solution of 10 mM valinomycin and 10 mM ETH 500 in dichloroethane. The electrodes were characterized by determining the steady-state tip current for K+ concentrations of 0.05−0.3 mM. The tips were used in the SECM feedback and generation−collection modes to study K+ transfer through gramicidin channels in a horizontal bilayer lipid membrane (glycerol monooleate).