Nucleus-targeted N-doped carbon dots via DNA-binding for imaging of hypochlorous in cells and zebrafish

We reported N-doped CDs (MTCDs) with excellent nucleus-targeted ability for selectively detecting ClO − . MTCDs can be easily prepared using m -phenylenediamine and 1,2,3-propanetricarboxylic acid as precursors through a solvothermal method. The maximum excitation/emission wavelengths were located at 444/513 nm, with QYs calculated to be 11.4 %. The fluorescence of MTCDs could be selectively quenched by ClO- upon the other ions, reactive oxygen species (ROS) and reactive nitrogen species (RNS). The quenching coefficient showed a good linearity versus C ClO - in the range of 1–100 μM, with detection limit of 0.48 μM. MTCDs were found to have splendid nuclear localization capabilities in MCF-7, Hela and H1299 cells and were successfully applied to image ClO − in cell nucleus and zebrafishes. During the nuclear localization mechanism study, we found a very interesting phenomenon: MTCDs were rare negatively charged CDs targeting nucleus by binding to the groove of DNA through hydrogen bond, which were different with most reported positively charged nucleus-targeted CDs via electrostatic adsorption. This finding proved that negatively charged CDs could also win the nucleus-targeted ability. Besides, this work provided a new strategy for designing nucleus-targeted CDs as well as the research of targeted release of drugs and cancer treatment.