Colorimetric and fluorescence dual-mode detection of arsenic in oysters and living cells using N/S doped carbon dots.

Arsenic (As3+) contamination in food and biological systems is harmful to human health; therefore, it is urgent to develop a sensitive and rapid method for As3+ detection. Herein, a fluorescence and colorimetric dual-mode sensing approach was developed using nitrogen and sulfur co-doped yellow emissive carbon dots (Y-CDs). The coordination of amino and sulfur groups in Y-CDs with As3+ leads to changes in the Y-CD dispersion state, which induces a significant red shift in the absorption spectra and a decrease in fluorescence intensities. A smartphone-assisted detection approach was employed to eliminate the need for sophisticated equipment. The proposed method exhibited a low detection limit of 1 µM As3+ and rapid response within 5 minutes and was applied for As3+ detection in both oysters and living cells, demonstrating its robustness in complex matrices.