A 3D spongy flexible nanosheet array for on-site recyclable swabbing extraction and subsequent SERS analysis of thiram

A sponge inspired three dimensional flexible aluminum foil based ZnO nanosheet array substrate is described for use in real-world surface enhanced Raman spectroscopic detection. Gold and silver nanoparticles were employed to form numerous hot spots on uniformly grown ZnO nanosheets on the substrate. This flexible spongy substrate can extract analytes (such as the fungicide thiram) from various complex sample surfaces by physical swabbing. Specifically, this substrate was applied to detect thiram on the surface of fruits and vegetables. Non-destructive recycling detection with a relative standard deviation of 6.1% was accomplished by monitoring the characteristic Raman peak at 1382 cm−1. This modified substrate has a low detection limit (0.2 ng cm−2 of thiram for apple and tomato), outstanding uniformity (relative standard deviation = 8.9%) and thermal stability (relative standard deviation = 0.9%).