Label-free, rapid and ratiometric detection of tetracyclines via guest stacking-induced emission triggered by MXene-derived nanosensors

Abstract

Facile, rapid and reliable detection of tetracyclines (TCs) residue in food and environment is of great significance to public safety. This work reports a novel guest stacking-induced emission (GSIE) effect triggered by MXene-derived nanosensors (TiO2/C quantum dots, QDs), which is used for label-free ratiometric fluorescence assays of TCs. The GSIE origin is revealed, which is the π-π stacking and J-aggregate formation of TCs molecules caused by the interaction of guest TCs with functionalized terminal groups of host TiO2/C QDs surface. Molecular planarity leads to the GSIE discrepancy of different TCs. The GSIE-based ratiometric fluorescence method is sensitive to TC with low limit of detection (32 nM) and shows excellent selectivity. The method is response-rapid (30 s) and linearly responsive in the ranges of 0.16–7.5 µM and 7.5–20 µM (R > 0.99), and can accurately detect trace TC in domestic water, honey and milk (recovery: 97.2–103.9 %). Furthermore, a paper microsensor-based point-of-care testing platform was developed for visual quantitative analysis and qualitative recognition of TCs. This is the first report that quantum dots as host sensors trigger the GSIE effect of guest molecules, and it creates a paradigm shift for MXene-based materials in sensing field and broadens the mechanism for TCs detection.