Superresolution microscopy shows bigger picture

Superresolution microscopy techniques allow researchers to observe objects tens of nanometers in size on or inside cells. But the methods can keep an eye on patches only 100 μm or less on a side at a time, making it difficult to image multiple cells simultaneously.

Now, by coupling a photonic chip with a standard optical microscope, researchers have achieved superresolution fluorescence microscopy with a simpler setup and a wider field of view than conventional methods (Nat. Photonics 2017, DOI: 10.1038/nphoton.2017.55).

“You just need a basic microscope,” says Balpreet S. Ahluwalia of the Arctic University of Norway. “Our photonic chip technology can be retrofitted with any standard microscope to convert it into an optical nanoscope.” The chip allows Ahluwalia, Mark Schüttpelz of Bielefeld University, and coworkers to separate the illumination and detection pathways so the two don’t interfere with each other and to enable the use of lenses.

So far, the chips are limited to total internal reflectance fluorescence, or TIRF, excitation. “This limits the use to imaging structures up to 150–200 nm away from the waveguide surface,” Ahluwalia says. But that’s also a benefit, he says, because TIRF illumination allows researchers to look at thin slices with little interference from background signal.

Suliana Manley, a superresolution imaging expert at the Swiss Federal Institute of Technology, Lausanne, says the work “represents a significant advance in making TIRF microscopy more accessible because it doesn’t require an expensive TIRF objective.” For superresolution imaging, membrane biologists are most likely to benefit from the technology, she says.

“Anyone interested in large-field-of-view imaging will benefit from this,” Ahluwalia says. “Using our photonic chip, we can generate with a slight reduction in spatial resolution a superresolved image over an approximately 100-fold larger area dSTORM microscopy.”