High Spatial Resolution Observation of Temporin A at Cell Membranes Using Scanning Ion Conductive Microscopy

The electrochemical visualization of molecules binding at the plasma membrane of single cells is important, but challenging. Here, the binding of Temporin A at the plasma membrane of a single living A549 cell is imaged using high spatial resolution scanning ion conductive microscopy (SICM). A relatively steep approach curve is observed at the binding region, compared with that at the non-binding cellular membrane. This difference is ascribed to the neutralization of the negative charges at the cellular membrane by the positively charged Temporin A through electrostatic binding. The pit-like structure of the plasma membrane is visualized in the SICM image, exhibiting unhomogeneous binding of Temporin A at the cell, and providing direct evidence about the interaction of Temporin A with certain regions of the membrane. The information will facilitate a deeper understanding of the cytotoxicity of Temporin A for the treatment of lung cancer. Moreover, the successful visualization of this process is an example of an electrochemical strategy that could be used to study other molecular interactions at cellular membranes.