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.