Stanford creates microscope for observing cells without labels — ScienceDaily
Researchers at Stanford University have created the iISM microscopic system, which makes it possible to observe in real time the movement and interaction of small structures inside living cells without using fluorescent labels. As ScienceDaily reports, the device provides a resolution of about 120 nanometers — an unprecedented level of detail for a label-free imaging method.
Combining two methods
The technology is called Interferometric Image Scanning Microscopy, or iISM. It combines interferometric microscopy of scattered light with approaches borrowed from advanced confocal microscopes. A laser illuminates the cell, while its internal structures scatter part of the light. Because this signal is weak, the system uses interference to amplify it.
The team also used an array detector that collects dozens or hundreds of images of the same area from different perspectives. A computational method then combines these measurements, improving image sharpness, contrast, accuracy and depth.
Less light and longer observations
Many modern microscopy methods use fluorescent substances to label individual cell structures. However, only a limited number of objects can usually be labeled simultaneously, and the signal may fade over time due to photobleaching. In addition, such labels can sometimes affect the behavior of the structures being studied.
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iISM makes it possible to monitor many cell components for a longer period and requires substantially less illumination power than comparable high-contrast label-free methods. A lower level of illumination reduces the risk of photodamage to living cells. The developers emphasize that the new system is intended to complement, rather than replace, fluorescence microscopy.
Research on drugs, infections and plants
A description of the development was published in the journal Light: Science and Applications. Areas in which the system is already being used or is planned to be used include observing interactions among plant cells, fungi and bacteria, studying the penetration of an anticancer drug into a cell, and analyzing changes in the shape of red blood cells under the influence of malaria infection.
The senior author of the work is William E. Moerner, a professor of chemistry at Stanford University and a recipient of the 2014 Nobel Prize in Chemistry for contributions to the development of super-resolution fluorescence microscopy. The researchers continue to improve the device to make it accessible to specialists from various fields of biology.
