Research on the Adaptive Sensitivity Scanning Method for Ion Conductance Microscopy with High Efficiency and Reliability

The target region focused imaging method for scanning ion conductance microscopy

Scanning ion conductance microscopy (SICM) has developed rapidly and has wide applications in biomedicine, single-cell science and other fields. SICM scanning speed is limited by the conventional raster-type scanning method, which spends most of time on imaging the substrate and does not focus enough on the target area. In order to solve this problem, a target region focused (TRF) method is proposed, which can effectively avoid the scanning of unnecessary substrate areas and enables SICM to image the target area only to achieve high-speed and effective local scanning. TRF method and conventional hopping mode scanning method are compared in the experiments using breast cancer cells and rat basophilic leukemia cells as experimental materials. It was demonstrated that our method can reduce the scanning time for a single sample image significantly without losing scanning information or compromising the quality of imaging. The TRF method developed in this paper can provide an efficient and fast scanning strategy for improving the imaging performance of SICM systems, which can be applied to the dynamic features of cell samples in the fields of biology and pharmacology analysis.

Gauging surface charge distribution of live cell membrane by ionic current change using scanning ion conductance microscopy

The distribution of surface charge and potential of cell membrane plays an indispensable role in cellular activities. However, probing surface charge of live cells under physiological conditions, until recently, remains an arduous challenge owing to the lack of effective methods. Scanning ion conductance microscopy (SICM) is an emerging imaging technique for imaging a live cell membrane in its native state. Here, we introduce a simple SICM based imaging technique to effectively map the surface charge contrast distribution of soft substrates including cell membranes by utilizing the higher surface charge sensitivity of the ionic current when the nanopipette tip is close to the substrate with a relatively high current change. This technique was assessed on charged model substrates made of polydimethylsiloxane, and the surface charge sensitivity of ionic current change was supported by finite element method simulations. With this method, we can distinguish the surface charge difference between the cell membrane and the supporting collagen matrix. We also observed the surface charge change induced by the small membrane damage after 1% dimethyl sulfoxide (DMSO) treatment. This new SICM technique provides opportunities to study interfacial and cell membrane processes with high spatial resolution.