Red emissive carbon dots with an ultra-large Stokes shift for the multi-channel detection of pesticides

Abstract

Red emissive carbon dots (R-CDs) with an ultra-large Stokes shift of 324 nm were synthesized by the hydrothermal treatment of o-phenylenediamine (OPD) in an HNO₃ solution. Multichannels for the detection of pesticides were integrated on a single platform of R-CDs. One channel for detecting fludioxonil with a ratiometric method was designed by producing a fluorescence response to fludioxonil between the excitation and emission peaks with an ultra-large shift. One channel for the detection of imidacloprid with a fluorescent method was built using an inner filter effect (IFE) of imidacloprid on the excitation spectra of R-CDs, far away from its emission band, which can avoid interferences from self-absorption. Another channel for the detection of glyphosate with a fluorimetry and colorimetry dual-mode was constructed using glyphosate with negative charges to neutralize R-CDs with reverse charges, resulting in the aggregation of R-CDs and concentration-dependent fluorescence and absorption responses to glyphosate.