Plasmonic Ag/PMMA/Eu nanocomposite for sensitive dual mode detection of malachite green.

Accurate and efficient determination of malachite green (MG) in aquaculture is crucial for ensuring environment and food safety. Herein, we present a dual-response fluorescence probe based on an Ag/PMMA/Eu nanocomposite for the sensitive detection of MG with low concentration and single droplet. The luminescence properties of the Ag/PMMA/Eu nanocomposite and the fluorescence resonance energy transfer (FRET) effect between Eu and MG are significantly improved due to the localized surface plasmon resonance (LSPR) effect. The dual-response system enables the detection of MG through both luminescence intensity and energy transfer efficiency using the Ag/PMMA/Eu nanocomposite as a detection platform in the range of 0-10.78 µmol/L. The detection limit reaches as low as 0.5 nmol/L, a significant improvement over the 0.11 µmol/L limit achievable by pure Eu film alone, demonstrating superior sensitivity compared to traditional fluorescence detection techniques. The results indicate that the nanocomposite significantly boosts the sensitivity of the dual-mode sensors. In addition, the sensor successfully detects MG residues in lake water, highlighting the Ag/PMMA/Eu nanocomposite's potential to advance high sensitivity, selectivity, stability, and accurate detection in food security and biological analysis.