Live Cell Imaging Using Photoswitchable Diarylethene-Doped Fluorescent Polymer Dots.

Fluorescence photoswitching using nanomaterials has recently emerged as a promising approach for the imaging of biological targets. However, despite intensive research efforts during the last decade, practical microscopy of biological targets using photoswitchable nanoparticles in real time remains challenging. To address this problem, we have developed live macrophage cell imaging and single particle imaging methods, using photoswitchable fluorescent diarylethene-doped polymer nanoparticles (P-dots) under Xe lamp irradiation. We established a 34-times prolonged "off-state", using P-dots doped with a diarylethene-containing methoxy substituent, upon visible-light irradiation using a Xe lamp and a green fluorescent protein filter cube. To demonstrate the practicality of doped P-dots imaging, we imaged lysosomes in macrophage cells, and observed 11-times slower recovery of the fluorescence from the "off-state" to the "on-state", indicating their potential for cellular imaging.