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

Arsenic (As ³⁺ ) contamination in food and biological systems is harmful to human health; therefore, it is urgent to develop a sensitive and rapid method for As ³⁺ detection. Herein, a fluorescence and colorimetric dual-mode sensing approach was developed using a nitrogen and sulfur co-doped yellow emissive carbon dots (Y-CD). The coordination of amino and sulfur groups in Y-CD with As ³⁺ leads to changes of 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 for eliminating the need of sophisticated equipment. The proposed method exhibited a low detection limit of 1 mM As ³⁺ , rapid response within 5 minutes, and was applied for As ³⁺ detection in both oysters and living cells, demonstrating its robustness in complex matrices.