Photoswitchable Fluorescence

Photoswitchable fluorescence can switch between a fluorescent and non‐fluorescent state by exposing the protein to specific wavelengths of light: blue light typically activates the fluorophore in the bright fluorescent state, while longer‐wavelength light is used to image the fluorophore and eventually turn it into the dark state. This enables the fluorescence to be switched on and off hundreds of times without permanently photobleaching the molecule.