Application of Liquid Scanning Electron Microscopy in Single Molecule Characterization of Biological Samples

The localization and distribution of cell membrane proteins play an important role in the occurrence and development of diseases, and in-situ characterization of nanoscale membrane proteins requires single molecule level technology. To achieve high-resolution imaging of biological samples in the liquid environment, a single molecule imaging technology based on scanning electron microscopy (SEM) was developed. A combination of scanning transmission imaging device and a commercial liquid chip device were used to observe the distribution and polymerization state of membrane protein EGFR in triple negative breast cancer (TNBC) cells. Results show that the images resolution reaches about 2-3 nm. The experimental conditions of the ESEM included an accelerating voltage of 30 kV, a beam current of 10^-10 A in a high vacuum environment. Because ZnS@CdSe quantum dots and gold particles have higher atomic number than liquids and organisms, better contrast and signal-to-noise ratio in imaging were obtained. This technology provides an advanced in-situ method and observation platform for high-resolution imaging in the cell biology field.