Critical Point Drying

For cells, bacteria, biological tissues and other biological samples with high water content, when performing Scanning Electron Microscopy (SEM)Before observation, a complete sample preparation procedure is usually required. Common processes includeGlutaraldehyde Fixation, Dehydration, Critical Point Drying (CPD), and metal conductive coatingThe same steps are taken to ensure that the sample can maintain its original morphology and structure in a high vacuum environment.

The main purpose of the critical point drying method is to use after the sample is dehydrated.The characteristics of carbon dioxide transitioning from liquid to gas at the critical point.to avoid the shrinkage, collapse, or structural deformation of the sample caused by the surface tension generated during liquid evaporation. Through this method, the three-dimensional structure and surface morphology of biological samples can be effectively preserved.

After completing the critical point drying, the sample is usually furtherA layer of conductive film such as platinum or gold is coated.to enhance the conductivity of the sample and reduce the electron beam accumulation effect, allowing for clear high-resolution images to be obtained in SEM. This technology is widely used inCell morphology observation, microbial structure analysis, biological tissue surface morphology research, and biomedical materials microstructure analysis. and other fields.

After the cells undergo pre-treatment, critical point drying, and are coated with a platinum conductive film, they enterIn the scanning electron microscope (SEM), observe the gold nanoparticles, approximately 200nm, that are attached to the cell surface.