Bilayer reconstitution of voltage-dependent ion channels using a microfabricated silicon chip

Painted bilayers containing reconstituted ion channels serve as a well defi ned model system for electrophysiological investigations of channel structu re and function. Horizontally oriented bilayers with easy solution access t o both sides were obtained by painting a phospholipid:decane mixture across a cylindrical pore etched into a 200-mum thick silicon wafer. Silanization of the SiO2 layer produced a hydrophobic surface that promoted the adhesio n of the lipid mixture. Standard lithographic techniques and anisotropic de ep-reactive ion etching were used to create pores with diameters from 50 to 200 mum. The cylindrical structure of the pore in the partition and the su rface treatment resulted in stable bilayers. These were used to reconstitut e Maxi K channels in the 100- and 200-mum diameter pores. The electrophysio logical characteristics of bilayers suspended in microchips were comparable with that of other bilayer preparations. The horizontal orientation and go od voltage clamping properties make the microchip bilayer method an excelle nt system to study the electrical properties of reconstituted membrane prot eins simultaneously with optical probes.