Microfabricated teflon membranes for low-noise recordings of ion channels in planar lipid bilayers

We present a straightforward, accessible method for the fabrication of micropores with diameters from 2 to 800 mum in films of amorphous Teflon (Teflon AF). Pores with diameters less than or equal to40 mum made it possible to record ion fluxes through ion channels in planar bilayers with excellent signal characteristics. These pores afforded: i), stable measurements at transmembrane voltages up to 460 mV; ii), recordings at low noise levels (0.4 pA rms at 4.3 kHz bandwidth); iii), recordings at high effective bandwidth (10.7 kHz); and iv), formation of multiple planar lipid bilayers in parallel. Microfabricated pores in films of Teflon AF made it possible to examine, experimentally and theoretically, the influence of the pore diameter on the current noise in planar bilayer recordings. Reducing the pore diameter below 40 mm mainly increased the stability of the planar bilayers, but had only a small effect on the level of the current noise. The low-noise properties of bilayer recordings on micropores in Teflon AF films were exploited to record the smallest conductance state of alamethicin (24 pS) at an unprecedentedly high bandwidth of 10.7 kHz.