Cleaning Patch Clamp Pipettes Enables their Reuse

Abstract

Patch-clamp recording is a gold-standard technique for the measurement of membrane voltage and current fluctuations in electrically active cells. From the advent of the technique in the 1970s, it has been widely accepted that using a new, un-contaminated pipette to patch-clamp every cell is a critical requirement to form a high-quality seal with the cell and yield a successful recording. However, exchanging pipettes between each cell is a manual and time-consuming task that requires dexterity and interrupts the otherwise-automated flow of the experiment.We circumvent the need to manually exchange pipettes by instead creating a conceptually simple cleaning procedure that enables their reuse. This automated cleaning procedure consists of dipping used pipettes into a commercially available detergent, pneumatically forcing the detergent into the tip, and rinsing the tip in a non-cytotoxic solution.Pipettes cleaned in this fashion for 31 seconds yielded successful recordings at a rate similar to that of new pipettes (cleaned pipettes: 90%, n=50; new pipettes: 86%, n=50) in human embryonic kidney (HEK) cultures and mouse brain slice tissue (cleaned: 59%, n=46; new: 50%, n=18). The pipette tip was confirmed to be contamination-free using Scanning Electron Microscopy (SEM). A single pipette could be cleaned repeatedly; we measured no significant decreases in seal resistance or recording quality over 10 patch-clamp recordings and cleaning cycles with a single pipette (n=5 pipettes). Passive and active electrical characteristics of cells did not degrade over successive cleaning cycles. These findings suggest that pipettes that undergo the cleaning procedure are as effective as new pipettes and do not alter the characteristics of the recording. Aside from obvious advantages in time, effort and cost of replacing pipettes, reusing a single pipette reduces experimental variability and most critically, is a major step towards fully automating patch-clamp electrophysiology experiments.