Microscopy Techniques Combine to Create More Powerful Imaging Device

Lu Wei If you imagine yourself peering through a microscope, you probably picture looking at a glass slide with an amoeba, or maybe a human cell, or perhaps even a small insect of some kind. But microscopes can see much more than these small living things, and a new type of microscopy developed at Caltech is making it easier to see the very molecules that make up living things. In a paper appearing in the journal Nature Photonics , researchers from the lab of Lu Wei , assistant professor of chemistry and investigator with the Heritage Medical Research Institute, demonstrate what they are calling bond-selective fluorescence-detected infrared-excited spectro-microscopy, or BonFIRE. BonFIRE combines two microscopy techniques into one process with greater selectivity and sensitivity, enabling researchers to visualize biological processes at the unprecedented single-molecule level and understand biological mechanisms from a molecular point of view. "With our new microscope, we can now visualize single molecules with vibrational contrast, which is challenging to do with existing technologies." says Dongkwan Lee, study co-author and chemical engineering graduate student. One technique involved in BonFIRE is fluorescence microscopy, which images molecules and other microscopic structures by tagging them with fluorescent chemical markers, causing them to glow when imaged. The other technique is vibrational microscopy, which makes use of natural vibrations in the bonds that hold together the atoms of a molecule.