A Simple Chromone–Derived Fluorescent “Turn–On” Probe for Accurate Detection of Al3+ Ions: Applications in Food Analysis, Test Strips and Bioimaging

Abstract

To address the toxicity concerns of Al3+ resulting from its widespread use, colorimetric fluorescence sensors offer an attractive solution. In this study, we developed a simple chromone–functioned fluorescent probe NMA for accurate detection of Al3+ through dual colorimetric and fluorometric channels. Upon chelating with Al3+ in a 1:1 stoichiometric ratio, NMA exhibited a significant fluorescence enhancement at 510 nm, alongside a rapid, visible color change. The pronounced fluorescence increase is attributed to the enhanced chelation–induced fluorescence (CHEF) effect. The detection limit of NMA for Al3+ was calculated to be 9 nM, well below the thresholds set by the World Health Organization. The binding mechanism of NMA with Al3+ ions was further investigated using 1H NMR and FT–IR analysis, and corroborated by density functional theory (DFT) calculations. Notably, NMA exhibited remarkable capabilities for Al3+ detection both in food samples and living cells. Additionally, a smartphone–assisted platform enabled efficient monitoring of Al3+ in environmental samples, highlighting NMA’s potential for practical applications.

Keywords: Aluminum ions, Fluorescence Probe, real-world samples, fluorescence bio-imaging, test strip