Enhanced Raman microscopy enables clearer chemical imaging of cryofixed samples
Raman image of snap-frozen HeLa cells with high signal-to-noise ratio and wide field of view. Image acquisition time was 10 hours. The distribution of Raman signals from cytochromes (750 cm-1), lipids (2850 cm-1), and proteins (2920 cm-1) are shown in green, red, and blue, respectively. Credit: Science Advances (2024). DOI: 10.1126/sciadv.adn0110
Understanding the behavior of the molecules and cells that make up our bodies is extremely important for medical progress. This continues to require a clear picture of what is happening beyond what is visible. In a study recently published in Science Advances, researchers from Osaka University reported a method to obtain high-resolution Raman microscopy images.
Raman microscopy is a useful technique for imaging biological samples because it can provide chemical information about specific molecules (such as proteins) involved in body processes. However, the Raman light emitted by biological samples is very weak, so the signal can be buried in background noise, resulting in poor images.
Researchers have developed a microscope that can maintain the temperature of pre-frozen samples during acquisition. This allows them to generate images that are up to eight times brighter than those previously achieved with Raman microscopy.
“One of the main reasons why images become blurry is the movement of what you are trying to see,” explains Kenta Mizushima, lead author of the study. “By imaging frozen samples that cannot move, we were able to use longer exposure times without damaging the sample. This results in higher signal, higher resolution, and a wider field of view compared to the background. ” Because this technique does not use staining or requires chemicals to fix cells in place, it provides a highly representative view of processes and cell behavior. can.
Schematic diagram of the sample area of the developed cryolaman microscope. Place the coverslip containing cultured cells on the sample mount and touch the metal plate (left). The refrigerant enters through the inlet and the hole in the metal plate and quickly freezes in direct contact with the sample. Sample temperature is controlled by a metal plate with liquid nitrogen circulation and an internal heater (right). Credit: Science Advances (2024). DOI: 10.1126/sciadv.adn0110
The researchers were also able to confirm that the freezing process preserved the physicochemical state of various proteins. This gives cryofixation the distinct advantage of being able to accomplish things that are not possible with chemical fixation methods.
“Raman microscopy adds a complementary option to the imaging toolbox,” said lead author Katsumasa Fujita. “The fact that it not only provides images of cells, but also information about the distribution of molecules and specific chemical states, is extremely useful as we continually strive to achieve the most detailed understanding possible.”
This new technology enables detailed analysis of biological samples in combination with other microscopy techniques, and is expected to contribute to a wide range of fields of biological science, including medicine and pharmacy.
Further information: Kentaizushima et al. Raman microscopy of cryofixed biological specimens for high-resolution and sensitive chemical imaging, Science Advances (2024). DOI: 10.1126/sciadv.adn0110
Provided by Osaka University
Citation: Enhanced Raman microscopy provides clearer chemical imaging of cryo-fixed samples (December 24, 2024) https://phys.org/news/2024-12-raman-microscopy-clearer- Retrieved December 24, 2024 from chemical-imaging.html
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