Researchers in Japan have shown that a glass surface embedded with self-assembled gold nanoparticles can improve resolution with a 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.
The researchers could improve resolution under a conventional widefield microscope to near the diffraction limit just by changing the surface under the cells. Though cells are usually imaged on plain glass, the researchers coated the glass surface with a self-assembled layer of gold nanoparticles covered with a thin layer of silicon dioxide, creating a so-called metasurface with special optical properties.