Facile synthesis of dual emission carbon dots for the ratiometric fluorescent detection of 2,4,6-trinitrophenol and cell imaging

Carbon dots (CDs) with dual emission property can provide a convenient way to construct a ratiometric fluorescent sensor, which contributes to accurate determination of the target analytes. In this work, we present a simple and effective route to prepare dual emission CDs (DE-CDs) through the solvothermal reaction of o-phenylenediamine and ethanolamine. Under the excitation of UV light, DE-CDs not only show two distinguishable fluorescent emission peaks (430 nm, 550 nm), but also exhibit good water solubility and ratio fluorescence stability. The synthesized DE-CDs were employed as a ratiometric fluorescent sensor for the sensitive and selective detection of 2,4,6-trinitrophenol (TNP). Under optimal analysis conditions, a good linear relationship was obtained with the TNP concentration range from 0.2 to 50 µM and the limit of detection can reach 50 nM. The proposed method was applied successfully for the TNP detection in real water samples with recoveries of 86.8–116.3%. Furthermore, cell imaging experiments confirm the feasibility of visualizing intracellular TNP in live HeLa cells.