A colorimetric and smartphone dual-channel sensor for highly sensitive detection of acetone based on chemically driven redox-cycling system

Herein, a colorimetric and smartphone dual-channel sensor has been constructed for the sensitive detection of acetone based on a chemically driven redox-cycling reactive system. In the redox-cycling system, o -phenylenediamine (OPD) acted as the colorimetric substrate. Initially, colorless OPD was oxidized by Cu 2+ ions to generate Cu + ions and light yellow 2,3-diaminophenazine (DAP). The Fenton-like reaction between hydrogen peroxide (H 2 O 2 ) and generated Cu + ions initiated the production of Cu 2+ ions and hydroxyl radicals (·OH). The resulting ·OH and reproduced Cu 2+ ions could further catalyze other OPD molecules, leading to the formation of more light yellow DAP molecules, with a distinct ultraviolet absorption peak appearing at 440 nm. And this process continued until all OPD was completely consumed in the cycling reaction system. Interestingly, acetone was introduced into the redox-cycling system, leading to a colorless solution and a reduction of absorbance intensity at 440 nm. Based on this phenomenon, a colorimetric sensor with excellent sensitivity and selectivity has been designed for the visual detection of acetone. The sensor exhibited a linear correlation with acetone concentrations within the range of 2 μM to 5 mM, achieving a detection limit of 0.5 μM. Notably, RGB color space analysis was performed for the quantitative detection of acetone with the assistance of a smartphone. The results were in good agreement with the data obtained via UV-visible absorption spectroscopy. Furthermore, the strategy realized the rapid detection of acetone in real tap water, river water, and lake water samples. Graphical abstract