New material turns regular microscopes into superresolution

A new material is bringing superresolution capabilities to conventional microscopes, offering more in-depth imaging of finer, smaller structures and details in specimens.

A team at the University of California, San Diego developed the material to shorten the wavelength of light as it illuminates a sample, allowing it to image in higher resolution. The technology features a microscope slide coated with a light-shrinking hyperbolic metamaterial comprised of nanometers-thin alternating layers of silver and silica glass. According to the researchers, as light passed through, the wavelengths shortened and scattered to generate a series of random high-resolution speckled patterns. “When a sample is mounted on the slide, it gets illuminated in different ways by this series of speckled light patterns,” the researchers say, “which creates a series of low-resolution images.” All of them are pieced together by a reconstruction algorithm to produce a high-resolution image.

A commercial inverted microscope was used in their study. The new material allowed the team to image fine features, such as actin filaments, in fluorescently labeled Cos-7 cells; they note that such features are not clearly discernible using the microscope alone. Specifically, the researchers could clearly distinguish tiny fluorescent beads and quantum dots that were spaced 40 to 80 nm apart.

With a resolution limit of 200 nm, conventional light microscopes can’t image subcellular structures. Electron microscopes have the resolution to do that, but can’t be used to image living cells without the samples being placed inside a vacuum chamber. The new technology combines these features, providing conventional light microscopes the ability to image live subcellular structures at a resolution of up to 40 nm.

Now, they’re working to incorporate “high speed, superresolution, and low phototoxicity in one system for live cell imaging” and expand into the 3D space. Reference: Y. U. Lee et al., Nat. Commun. (2021); doi.org/10.1038/s41467-021-21835-8.