How to prepare electron microscope samples
The main preparation methods for observation samples for transmission electron microscopy are:
1. Projection method
Under vacuum conditions, heavy metal atoms with strong electron scattering ability are used to spray the surface of the sample. This forms a strong contrast between the sample and the non-sprayed area, and the non-sprayed part becomes the projection of the sample. According to the projection, we The three-dimensional shape and height of the sample can be understood. This method is usually used to observe bacterial flagella or virus particles.
2. Negative staining method
Because this method stains the background of the sample to highlight the sample, it is called negative staining. Generally, the sample is surrounded by substances with high electron density that do not show any structure and do not react with the sample, such as the sodium salt of phosphotungstic acid. At the same time, the dye is also put into the interior of the observation object. In this way, it can not only display The shape can also reflect the internal structure of the sample to a certain extent. Bacterial cells, viruses, etc. can be observed using this method.
3. Ultrathin sectioning method
This is the most commonly used method because it allows viewing of fine structures inside cells or other samples. Usually, the sample must be fixed and dehydrated according to a certain procedure, then embedded in resin as a support, and cut into extremely thin slices using an ultramicrotome. Because only slices with a thickness of 20 to 100 nanometers can be observed with a transmission electron microscope, in general bacterial samples, one cell must be divided into 10 to 50 pieces.
When choosing an electron microscope, first check whether the scanning electron microscope manufacturer has complete certificates; secondly, check the contract of the scanning electron microscope manufacturer; thirdly, understand the services of the scanning electron microscope manufacturer; and thirdly, check the technical parameters of the scanning electron microscope.
In addition to the choice of scanning electron microscope manufacturer, when purchasing the corresponding scanning electron microscope, you also need to consider the performance and technical indicators of the scanning electron microscope. Whether it can meet our daily analysis needs, you also need to consider various factors when purchasing. technical parameters, so as to meet our testing and analysis requirements.
