Ligand-Induced Red-Emitting Copper Nanoclusters for Selective Fluorescence Determination of Aluminum Ions

Abstract

Monitoring levels of excessive aluminum ions (Al 3+ ) is crucial as it can harm the immune system, reduce enzyme activity, cause cell death, and damage environmental and biological systems. Developing a fast and efficient Al 3+ ion determination method is the key to addressing this issue. In this work, red-emitting fluorescent copper nanoclusters (CuNCs) were synthesized using N-acetyl-L-cysteine (NAC) as a ligand and CuCl 2 •2H 2 O through a facile procedure. The NAC-CuNCs exhibited a large Stokes shift and displayed remarkable luminescence properties. A method for detecting Al 3+ through a fluorescence probe was proposed. Its fluorescence mechanism was also explored. The probe showed rapid responsiveness (within 1 min) to Al 3+ ion determination. The detection limit for Al 3+ was found to be 19.7 nM, which is significantly lower than the WHO's value and most reports, with a linear range of 0−52.9 μM. The determination of Al 3+ concentrations in actual water using the fluorescence probe yielded satisfactory outcomes. Moreover, the visual detection of Al 3+ ions was also achieved through a smartphone, which can enhance its fast and practical detection.