User-Friendly Multifunctional Red-Emissive Carbon Dots for Rapid Cell Nucleus Staining via Targeting Nuclear Proteins.

Cytoarchitectural staining is of great importance in disease diagnosis and cell biology research. This study developed user-friendly multifunctional red-emissive carbon dots (R-CDs) for rapid cell nucleus staining via targeting nuclear proteins. R-CDs, simply prepared by electrochemical treatment of 1,2,4-benzenetriamine, exhibit strong emission at 635 nm when excited at 507 nm. The R-CDs can rapidly stain the nucleus of human SH-SY5Y, HepG2, and HUH-7 cells with a high signal-to-noise ratio owing to fluorescence enhancement after entering the nucleus. Compared to conventional cytosolic dyes such as Hoechst and DAPI, R-CDs are cheaper, more highly dispersed in water, and more stable (requiring no stringent storage conditions). The R-CDs show stable optical properties with insignificant photobleaching over 7 days and salt resistance up to 2 M of NaCl. More importantly, R-CDs, possessing a positive charge, allow rapid staining of live cells (3 min) and dead cells (10 s) in saline. According to kinetic variation, R-CDs can distinguish live cells from dead cells. Staining exhibits high efficiency in onion epidermal cells,