A team from University of California, Berkeley, and the Lawrence Berkeley National Laboratory, California, has invented a new technology that combines spectroscopy with super-resolution microscopy to produce the first “true-colour” super-resolution microscope. Called SR-STORM (Spectrally Resolved Stochastic Optical Reconstruction Microscopy), the technique allows researchers to examine cell structures with very high spectral and spatial resolution and enables new ways to study disease processes.
Reporting their discovery in Nature Methods, Professor Ke Xu and his co-authors describe how SR-STORM gives full spectral and spatial information for each molecule and opens the door to high-resolution intracellular imaging of multiple components and local chemical environments, such as pH variations. What’s more, the technique is high-throughput, able to deliver spatial and spectral information for millions of single molecules in about five minutes, compared to several minutes for a single frame of image comprising tens of molecules using conventional scanning-based techniques.
Professor Xu says, “SR-STORM builds on STORM, a super-resolution microscopy method based on single-molecule imaging and photoswitching. We devised a dual-objective system with two microscope lenses facing each other to simultaneously image the front and back of a cell. The single-molecule image collected by one objective lens is dispersed into spectrum while the other image is used for single-molecule localization. Vitally, both images are separately projected onto two different areas of the iXon Ultra 897’s EMCCD detector. This led to the new concept of spectrally resolved super-resolution microscopy, where every molecule is spatially localized to 10-nanometer precision while also being fully resolved spectrally. In this way, crosstalk-free 3D super-resolution microscopy was achieved for four dyes that were only 10 nm apart in emission spectrum.”
“When we looked for detectors capable of providing the speed required for SR-STORM imaging while retaining excellent levels of sensitivity, we selected the Andor iXon Ultra 897 electron multiplying CCD camera. The quality and sensitivity of these cameras, together with the large detector, is ideal for our novel application.”
According to Orla Hanrahan, product specialist at Andor, applications for SR-STORM are likely to be in fundamental research and cell biology, with every chance it will lead to medical applications. “Professor Xu’s work gives us new opportunities to look at cell structures, how they’re built up and whether there’s any degradation of those structures in diseases. Many diseases are caused either by an invading pathogen or degradation of a cell’s internal structure. Alzheimer’s, for example, may be related to degradation of the cytoskeleton inside neurons. The cytoskeleton system is comprised of a host of interacting subcellular structures and proteins, and the team’s technique will enable research on the interactions between these different targets with an unprecedented number of colour channels and spatial resolution.” Andor
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