Lateral flow assay with dual-emission nitrogen-doped carbon dots for ratiometric fluorescent determination of nitrite in food

Abstract

Nitrite ion (NO2–), renowned for its potent antiseptic properties and color-preserving abilities, potentially leads to carcinogenesis and hypertension if consumed excessively. Herein, a ratiometric fluorescent probe exhibits specific response to NO2– using nitrogen-doped carbon dots (N-CDs) with a low detection limit (LOD) as low as 52 nM and a low quantification limit (LOQ) of 173 nM. Initially, the emission peaks at 495 nm and 415 nm decrease as result of the internal filtration effect (IFE). With further increasing NO2– concentration, the reaction between NO2– and N-CDs forms an azoic compound (N-CDs@NO2–), which promotes the instant quenching of the emission peak at 415 nm through fluorescence resonance energy transfer (FRET). Moreover, portable N-CDs/LFASs devices with smartphone are successfully applied to visually identify NO2– with the exceptional LOD, achieving excellent recoveries and high precision in real sample. Therefore, this newly N-CDs/LFASs offers a reliable means for the NO2– detection, showcasing potential applications.