Hour-glass SiO2 coating increases the performance of planar patch-clamping

Obtaining high-throughput electrophysiology recordings is an ongoing challenge in fundamental ion channel biophysics and drug discovery. One particular area of development is the replacement of glass pipettes with planar devices in order to increase the throughput. However, successful patchclamp recording depends on an ideal surface coating that promotes and stabilizes giga-seals formation. Here, we describe a method for designing chips that are suitable for planar patchclamping. The method was based on a correlation study taking into account dimension and size of the pores, surface roughness and chip capacitance. The influence of these parameters on the quality of the seal was then assessed. Plasma-enhanced chemical vapour deposition (PECVD) of SiO2 led to a tighter seal and resistance than a flat, thermal SiO2 surface. The performance of PECVD chips was validated assessing BK(Ca) and low conductance IRK1 potassium channels and endogenous cationic currents recordings from CHO and HEK-293 cells. We assume that the systematic investigation of chip parameters to improve seal quality will result in the production of reliable chips for planar patch-clamp applications allowing electrophysiological recordings from a wide range of cell lines, primary cultures and isolated native cells.