Visualized test of environmental water pollution and meat freshness: Design of Au NCs-CDs-test paper/PVA film for ratiometric fluorescent sensing of sulfide.

Visualized test of environmental water pollution: Design of Au NCs-CDs-test paper/PVA film for ratiometric fluorescent sensing of sulfide. [Display omitted] • A visual sensing platform for H 2 S and temperature was designed. • An orange and green dual-emitting Au NCs-CDs nanocomposite was prepared. • Au NCs-CDs-based test paper was used for S2− and H 2 S detection with smartphone. • Meat spoilage detection was realized by Au NCs-CDs PVA film. Hydrogen sulfide (H 2 S) is an environmental pollutant, and also the major released gas during the decay of meat products. To protect the ecological environment and human health, the establishment of a swift, convenient, and accurate detection method for H 2 S becomes essential. However, existing methods are still suffering from complex synthesis, high toxicity, poor visualization, and high detection limit. Herein, Au NCs-CDs nanocomposite-based test paper and polyvinyl alcohol (PVA) film are combined with a smartphone for sensitive and specific sulfide visualized monitoring. After the addition of sulfide, the fluorescence color changes from orange to green, achieving a quantitative linearity towards sulfide from 5 nM to 30 μM, with a low detection limit of 4.20 nM. The proposed method shows practicability in natural water samples. Furthermore, distinct fluorescence color variation is shown towards H 2 S originating from spoiled meat, showing the potential application prospect of Au NCs-CDs-PVA film as a meat freshness detector. [ABSTRACT FROM AUTHOR]