A Stomata-Infiltratable SERS Nanosensor for Real-Time Monitoring of Hydrogen Sulfide Dynamics in Plants

Hydrogen sulfide (H₂S) is a key gaseous regulator in plant stress responses, but its spatiotemporal dynamics in living plants remain poorly understood due to the lack of noninvasive sensing tools. Here, we report a stomata-infiltratable SERS nanosensor based on Au@Ag@SiO₂ core-shell nanoparticles for real-time monitoring of endogenous H₂S. The sensor, with an enhancement factor of ∼6.07 × 10⁹ and a detection limit of 15 nM, efficiently infiltrates leaves of diverse species (Arabidopsis, spinach, and tomato). Real-time monitoring revealed that H₂S accumulation kinetics are stress-specific and occur within 20 min of stress onset, preceding visible phenotypic damage. Notably, the nanosensor enabled visualization of stress-induced H₂S transmission between neighboring plants, suggesting a role for H₂S as an airborne signal in plant-to-plant communication. Furthermore, a species-dependent kinetic framework describing systemic signal propagation was established. This work demonstrates a versatile SERS-based platform for noninvasive monitoring of gaseous signaling molecules in plants.