Real-Time and <i>In Situ</i> Monitoring of Pesticide Uptake and Transportation in Plants Using Surface-Enhanced Raman Scattering Nanosensors

High Resolution Image Download MS PowerPoint Slide Pesticides are essential for maintaining the global crop productivity and food security. Improving their efficiency and minimizing their environmental impact require a detailed understanding of their uptake and translocation in plants. However, existing techniques for tracking pesticides in living plants are largely destructive, ex situ, and incapable of real-time monitoring, which limits progress toward sustainable agriculture. To address this gap, we developed noninvasive, ratiometric surface-enhanced Raman scattering (SERS) nanosensors that enable in situ, real-time mapping of pesticide dynamics in plants. The nanosensors feature gap-enhanced gold nanorods (AuNNRs) with 4-mercaptobenzonitrile (4-MBN) embedded in the nanogap as a stable internal standard for ratiometric SERS quantification. Once delivered into the leaf intercellular spaces, the nanosensors create functional “sensor-equipped” plants for real-time mapping of pesticide distribution. Using this platform, we compared pesticide translocation under different application methods. The results show that root-irrigated tricyclazole moves upward in a concentration- and time-dependent manner, whereas foliar-sprayed pesticides are poorly absorbed due to the barrier posed by the leaf cuticle. Furthermore, commercial tricyclazole formulations are taken up and transported more efficiently than pure reagent-grade compounds. This SERS-based sensing strategy offers a powerful tool for optimizing pesticide delivery and supports the development of precision agriculture practices that are aimed at sustainability.