Carbonized polymer dots with dual‐wavelength emission for labeling nucleoli in live cells through hydrogen bonding‐induced aggregation

We prepared carboxyl‐containing carbonized polymer dots (CPDs) with dual‐wavelength emission through a simple hydrothermal method. The CPDs emit blue light in live cells under the excitation at 405 nm, and show green fluorescence in cytoplasm and nucleoli when excited at 488 nm. No fluorescence can be seen in nuclei except nucleoli under the excitation at 488 nm, which means that the CPDs have excellent ability of labeling nucleoli in live cells with low background interference. This ability of the CPDs is derived from the aggregation induced by the hydrogen bonding between the carboxyl groups of the CPDs and the hydroxyl groups of ribonucleic acid at nucleoli. Fluorescence and cell culture passage experiments prove that the CPDs have no strong interaction with RNA, and all of them can be excreted out of cells in a couple of days. In vivo imaging for Caenorhabditis elegans indicates that the CPDs show the possibility of labeling nucleoli in live organisms in real‐time.