Green emitting nitrogen-doped carbon dots as a dual recognition platform for sensitive and selective detection of...

Carbon dots (CDs) have been widely employed to fabricate various fluorescent chemosensors owing to their favorable photo-physicochemical properties and versatile surface modification feasibility. However, reports on CDs as a dual recognition platform for sensitive and selective detection of different analytes are very limited. In this study, highly negatively charged green emitting nitrogen-doped CDs were synthesized by a hydrothermal approach using 1,3,6-trinitropyrene and ascorbic acid as precursors, which subsequently self-assembled with positively charged methylviologen (MV²⁺) and polyethyleneimine (PEI) to form CDs-MV²⁺ and CDs-PEI nanocomposites, respectively, by electrostatic interaction and hydrogen bond. Based on the facts of forming tetrahedral anionic glucoboronate esters between organic boronic acids and diol-containing compounds, and a Meisenheimer complex between amino groups and 2,4,6-trinitrotoluene (TNT), CDs-MV²⁺ for glucose detection and CDs-PEI for TNT detection were surveyed. The CDs-based nanocomposites exhibited highly sensitive and selective responses to analytes by turning off or on the green emission of the CDs, showing a very good linearity in the ranges of 0.05-200 mM glucose with 0.036 mM of LOD for CDs-MV²⁺, and of 5-160 nM TNT with 3.2 nM of LOD for CDs-PEI. No matrix interferences were found. The proposed method is conducive to develop a dual/multiple targets sensing platform for detecting related or unrelated analytes.