Molecules inside the cell were visualized by infrared light and fluorescence
Researchers have developed a new microscopy method for detailed visualization of processes inside a living cell at the molecular level. The study was published in the journal Nature Photonics.Physicists at the California Institute of Technology have developed a new microscopy technique. It combines two different methods - infrared spectroscopy and fluorescence microscopy - and allows the observation of biological processes in living cells with record detail at the level of individual molecules.
Fluorescence microscopy uses special markers - fluorescent tags - to tag certain molecules or other microscopic structures. When exposed to light at a certain wavelength, these structures begin to glow, and the microscope detects this glow.
Infrared spectroscopy analyzes the vibrations of chemical bonds holding atoms within a molecule together. In this method, the sample to be examined is irradiated with infrared light. This "bombardment" by photons causes the bonds of the molecules of the material to vibrate in such a way that their type can be determined. The vibrations of a triple bond "sound" different than those of a single bond, and the vibrations of a carbon atom bonded to another carbon atom are different from a carbon-nitrogen bond.
Researchers have developed a device that combines these two methods. First, the sample is stained with a fluorescent dye that binds to the molecules chosen for imaging. A pulse of infrared light is then directed at it with the frequency necessary to excite the bonds within the molecule. Next, a higher energy pulse is sent to the same bond, which causes the dye to glow. In doing so, different molecules can be labeled with different colors. As a result, the microscope can display whole cells or individual molecules in dynamics.
Fluorescence microscopy allows observation of individual molecules, but does not provide detailed information about their chemical structure. On the other hand, vibrational microscopy provides rich chemical information, but only works when the desired molecule is present in large numbers. The new technology combines the strengths of both methods, the developers say.