Fluorescent paper sensor based on green emissive carbon nanodots for visual detection of acid orange II in food samples

Abstract

This work for the first time presents a visual fluorescence paper sensor for accurate and on-site detection of acid orange II (AO2) in food matrix, where green-emissive carbon nanodots (G-CDs) were exploited. The as-synthesized G-CDs had an average particle size of 3.9 ± 0.7 nm and displayed green emission at 511 nm upon excitation at 450 nm. When there existed AO2, the G-CDs fluorescence was effectively suppressed via inner filter effect (IFE) and dynamic interaction. The as-prepared G-CDs probe achieved a 0.01–25.0 μM linear scope and a 36.5 nM limit of detection. Particularly, owing to a distinguishable reduction in G-CDs emission intensity by a smartphone application, a visual probing platform along with a nanopaper-based device were be developed for recognizing AO2. The corresponding detection limits were severally 0.61 μM and 1.39 μM. Success was achieved in applying our fluorescence approaches for detecting AO2 in Yuba, chili powder, sunflower seeds, tomato paste and orange juice samples, attaining desirable results. The present work underlines the potential of smartphone-integrated nanopaper based on CDs as an encouraging candidate for on-site AO2 recognition in food matrix.