Ultrasensitive SERS Analysis of Liquid and Gaseous Putrescine and Cadaverine by a 3D-Rosettelike Nanostructure-Decorated Flexible Porous Substrate

Putrescine and cadaverine are toxic biogenic amines in spoiled food, which poses a serious threat to food security. In this work, we reported a highly sensitive three-dimensional (3D)-rosettelike surface-enhanced Ramanspectroscopy (SERS) substrate functionalized with ap-mercaptobenzoic acid(p-MBA) monolayer to detect liquid and gaseous putrescine and cadaverine inpork samples. The SERS substrate was made by a combination of the merit ofthe 3D morphology of ZnO nanorod arrays on aflexible porous poly(vinylidenefluoride) (PVDF) membrane and the in situ chemical growth of Aunanoparticle seeds on Aufilm-coated ZnO nanorods, which produced a 3D-rosettelike BigAuNP/Au/ZnO/P heterostructure with abundant SERS-activehot spots that significantly enhanced the localized surface plasmonic resonance(LSPR) effect and charge-transfer (CT) effect of Raman enhancement. ThisSERS substrate showed high sensitivity, reproducibility, stability, anduniformity. With thep-MBA molecular monolayer as the sensing interface, our SERS substrate realized the highly sensitive andquantitative detection of liquid putrescine and cadaverine within 10 min, with a limit of detection (LOD) of 3.2x10-16and 1.6x10-13M, respectively. Additionally, the sensor showed efficient SERS responses to gaseous amine molecules at low concentrations(putrescine: 1.26x10-9M, cadaverine: 2.5x10-9M). Further, the sensor was successfully applied to determine the total content of putrescine and cadaverine. Moreover, the practicability of this SERS sensor was verified by the measurement of liquid and gaseous amines in pork samples, and it showed great potential applications for sensitive detection of food spoilage