Raman microscopy of rapidly frozen biological samples

We developed a technique for Raman imaging of rapidly frozen biological samples, maintaining low temperatures to extend exposure time and reduce damage. This method enhances sensitivity, as demonstrated with imaging exogenous and alkyne-tagged molecules in HeLa cells, and preserves the redox states of heme proteins, unlike chemically fixed samples. Using a microscopic freezing system with liquid propane, we achieve precise sample condition control, enabling seamless cryofixation and low-temperature Raman imaging, as well as super-resolution fluorescence imaging of the same sample regions.