Grating/microcavity arrays on lily petal replicas as dual-functional SERS substrates for rapid monitoring of thiram on fruit surface and malachite green in surface water
摘要
A dual-functional biomimetic surface-enhanced Raman scattering (SERS) substrate composed of grating/microcavity arrays (GCA) was developed for on-site monitoring of pesticides on fruit peels and in surface water. The hierarchical GCA structure was fabricated by molding a negative polydimethylsiloxane (PDMS) replica from lily petals, followed by the generation of grating wrinkles through oxygen plasma treatment. After the deposition of silver nanoparticles (Ag NPs) through magnetron sputtering, the optimal Ag NPs@GCA substrate exhibits high sensitivity, good uniformity, and reproducibility. Moreover, due to its optical transparency, mechanical stability, and hydrophobic properties, the Ag NPs@GCA substrate combined with a handhold Raman spectrometer can be used for on-site determination of pesticides in real samples. The limit of detection (LOD) for thiram on the surfaces of apples, pears, and cherry tomatoes were 2.86 × 10−7, 5.03 × 10−7, and 7.25 × 10−7 M, respectively. For malachite green, the LODs were 9.04 × 10−8 M in lake water and 4.83 × 10−7 M on fish scales. The results indicate the developed dual-functional Ag NPs@GCA substrate has great potential for applications in food safety assessment and environmental pollutant monitoring.
Graphical abstract