Highly sensitive SERS detection of pesticide residues based on multi-hotspot buckypaper modified with gold...

To effectively extract target analytes from complex sample surfaces is of great significance for the practical application of surface-enhanced Raman scattering (SERS) spectroscopy. A plasmonic substrate with multiple "hotspots" for highly sensitive detection of pesticide residues were prepared successfully by assembling gold nanoparticles on buckypaper (AuNPs-BP). The substrate exhibited high SERS enhancement and excellent detection sensitivity, with a detection limit (LOD) of 2.03 × 10^-11 M and 6.88 × 10^-12 M for the probe molecule R6G and MB, respectively. Combined with 3D finite-difference time-domain (3D-FDTD) simulation, the excellent SERS performance of the substrate was attributed to the enhancement of the electromagnetic field around the "hotspots". Additionally, the substrates exhibited excellent flexibility, allowing easy contact with irregular surfaces and facilitating the collection of target molecules on the sample surface. Using a portable Raman spectrometer, the substrate achieved in situ analysis of chlorpyrifos residues on peach, with a LOD as low as 6.8 × 10^-11 M. The method showed high accuracy, with a recovery value ranging from 94.2 % to 115.5 %. The results indicate that the substrate has great potential for rapid and highly sensitive detection of pollutants, especially on non-planar surfaces.