Researchers have demonstrated that placing cells on a plasmonic metasurface of self-assembled gold nanoparticle can improve the resolution of images of living cells taken in real-time under a widefield fluorescence microscope. The metasurface effectively confines light emission from parts of the cell near the metasurface to a nano-thickness plane, providing a simple method to improving both axial and lateral resolution.

Now, researchers in Japan have shown that a glass surface embedded with self-assembled gold nanoparticles can improve resolution with little added cost even using a conventional widefield microscope, facilitating high-resolution fluorescence microscopy capable of high-speed imaging of living cells.

Because optical microscopes magnify light to obtain detailed images of a structure, the size of objects that can be distinguished has long been limited by diffraction — a property of light that causes it to spread when passing through an opening.

Researchers have been developing techniques to overcome these limits with highly advanced optical systems, but many of them depend on the use of strong lasers, which can damage or even kill living cells, and scanning of the sample or processing of multiple images, which inhibits real-time imaging.

«Recent techniques can produce stunning images, but many of them require highly specialized equipment and are incapable of observing the movement of living cells,» says Kaoru Tamada, distinguished professor at Kyushu University’s Institute for Materials Chemistry and Engineering.

Imaging cells using real-time fluorescence microscopy methods, Tamada and her group found that they could improve resolution under a conventional widefield microscope to near the diffraction limit just by changing the surface under the cells.

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