Bamboo-like fiber structured AuNR–ZnO–ZnCdS/ZnS hybrid sensor for ultrasensitive zearalenone detection in food safety applications

Zearalenone (ZEN) is a mycotoxin produced by the genus Fusarium (Fusarium spp.) and is a common contaminant in various crops. It can bioaccumulate in the food chain and spread to human populations, thereby representing a potential threat to public health. In this study, an optic fiber sensor (OFS) based on localized surface plasmon resonance (LSPR) was investigated for ZEN detection. A fusion-spliced structured fiber composed of a multimode fiber (MMF) and a special nanomaterial doped fiber (NDF) was utilized in this study, with the NDF designed into a bamboo-like tapered section. Subsequently, gold nanorods (AuNRs), zinc cadmium sulfide/zinc sulfide quantum dots (ZnCdS/ZnS-QDs), and zinc oxide nanowires (ZnO-NWs) were bonded to the optical fiber through chemical modification and physical adsorption. Finally, the ZEN aptamer was chemically modified for attachment to the fiber taper area. The specific binding of ZEN and its aptamer form an aptamer-antigen complex, which results in a redshift of the absorption spectrum peak. This feature makes it possible to detect ZEN in various concentrations. The measurements showed that the developed OFS had a limit of detection (LOD) of 0.65 ng/mL for ZEN detection. ‌The experimental results demonstrated that the sensor exhibited good performance in repeatability tests, selectivity tests, and actual sample analysis, which fully proved the applicability of the sensor in complex matrices.