Robotic Perforated Patch Clamp Based on Active Release Control of Perforating Materials

In recent years, the perforated patch clamp technique has been widely applied in cellular electrophysiology research due to its low mechanical disturbance and almost no loss of cellular content in cell membrane perforation process. However, the current passive release process of perforating materials prolongs the perforation process and easily disturbs the gigaseal formation process, significantly lowering the efficiency of perforated patch clamp operation. Addressing this, a robotic perforated patch clamp system was developed based on the active release control of perforating materials in this paper. First, a novel holding module of the patch micropipette integrated with an independently driven transmission channel of the perforating materials was developed for the first time. Then, through release tests of the perforating materials, the appropriate drive mode of transmission channel was determined to be the hydraulic mode with a faster response and higher stability. Further, the concentration gradient field of the perforating materials at the opening of the channel was modeled according to Fick’s law to prevent the false release of them in gigaseal formation process. Furthermore, a cell circuit model was developed to detect perforation degree online for feedback control of the perforating materials release. Experimental results on pyramidal neurons in mouse brain slices demonstrated that, in comparison to the traditional method with passive releases of perforating materials, the proposed system was capable of perforating cell membrane at an almost doubled throughput and with a 57% improvement in the success rate. In comparison to the traditional non-perforated whole-cell patch clamp method, the signal recording duration of neurons operated by our method was doubled due to its fewer negative influences on gigaseal and almost no cellular content loss.
Note to Practitioners
—The perforated patch clamp technique, utilizes the cell membrane-perforating molecules to drill subnanometer-sized conductive pores in the cell membrane aspirated into a micropipette for the measurement of cellular electrophysiological signals. Unfortunately, the poor controllability of the current passive release of perforating materials in the patch clamp operation easily leads to a long drug diffusion process, and also, disturbs the gigaseal formation between the aspirated cell membrane and micropipette, which is required for the measurement of the extremely weak cellular electrophysiological signals. For the first time, an active release control method of perforating materials was developed in this paper based on the self-developed novel three-channel holding device. With active release control of perforating materials, the proposed method was capable of perforating cell membranes at a doubled speed with a significantly higher success rate, and doubled recording duration in comparison to the traditional perforated patch clamp methods and non-perforated whole-cell patch clamp method, respectively, due to its fewer negative influences on gigaseal and almost no cellular content loss. With the above advantages, our robotic perforated patch clamp method may be applied in cellular electrophysiology research in the future.