Search for: All records

Scanning ion conductance microscopy (SICM) offers the ability to obtain nanoscale resolution images of the membranes of living cells. Here, we show that a dual-barrel nanopipette probe based potentiometric SICM (P-SICM) can simultaneously map the topography and surface potential of soft, rough and heterogeneously charged surfaces under physiological conditions. This technique was validated and tested by systematic studies on model samples, and the finite element method (FEM) based simulations confirmed its surface potential sensing capability. Using the P-SICM method, we compared both the topography and extracellular potential distributions of the membranes of normal (Mela-A) and cancerous (B16) skin cells. We further monitored the structural and electrical changes of the membranes of both types of cells after exposing them to the elevated potassium ion concentration in extracellular solution, known to depolarize and damage the cell. From surface potential imaging, we revealed the dynamic appearance of heterogeneity of the surface potential of the individual cell membrane. This P-SICM method provides new opportunities to study the structural and electrical properties of cell membrane at the nanoscale. 

Abstract In‐depth understanding of the biophysicochemical interactions at the nano–bio interface is important for basic cell biology and applications in nanomedicine and nanobiosensors. Here, the extracellular surface potential and topography changes of live cell membranes interacting with polymeric nanomaterials using a scanning ion conductance microscopy‐based potential imaging technique are investigated. Two structurally similar amphiphilic conjugated polymer nanoparticles (CPNs) containing different functional groups (i.e., primary amine versus guanidine) are used to study incubation time and functional group‐dependent extracellular surface potential and topographic changes. Transmembrane pores, which induce significant changes in potential, only appear transiently in the live cell membranes during the initial interactions. The cells are able to self‐repair the damaged membrane and become resilient to prolonged CPN exposure. This study provides an important observation on how the cells interact with and respond to extracellular polymeric nanomaterials at the early stage. This study also demonstrates that extracellular surface potential imaging can provide a new insight to help understand the complicated interactions at the nano–bio interface and the following cellular responses.