Single-Layered Graphitic-C3N4 Quantum Dots for Two-Photon Fluorescence Imaging of Cellular Nucleus

A promising, safe, and economic fluorescent probe, g‐C3N4 single‐layered QDs, is introduced for two‐photon fluorescence imaging of the cellular nucleus for the first time. The large two‐photon absorption cross section, the high photostability, good biocompatibility and non‐toxicity, negligible photothermal effect, and specific interaction with DNA render the single‐layered g‐C3 N4 QDs as a promising candidate for in vivo and in vitro two‐photon fluorescence imaging and further biomedical applications.