Ratiometric Mycotoxin Detection in Living Plants With Dual‐Emissive Nanosensors

Early diagnosis of fungal infections in crops is essential for mitigating yield losses, yet most detection strategies rely on destructive assays that are incompatible with in situ monitoring. Among major fungal pathogens, Fusarium species pose a significant threat to global agriculture and produce the phytotoxin fusaric acid (FA), a key biomarker of early infection. Here, we develop a non-destructive, ratiometric optical nanosensor that integrates aggregation-induced emissive carbon dots within a zeolitic imidazolate framework (CD@ZIF-8) for selective FA detection in living plants. By rationally tuning the balance between dispersed and aggregated CDs within the ZIF-8 framework, we generated a dual-emissive nanosensor with distinct blue and red fluorescent signals that enable self-referencing readouts. Upon exposure to FA, interactions with CD@ZIF-8 quench the blue emission while leaving the red aggregation-induced emission stable, thereby affording highly selective ratiometric sensing. Integrating CD@ZIF-8 into plant-compatible microneedle patches enables minimally invasive sampling of plant interstitial fluid, allowing FA detection in Fusarium-infected crops before visible symptoms and discrimination from abiotic and bacterial stresses. This work establishes an integrated, self-referenced nanosensing platform for non-destructive plant diagnostics, laying the foundation for early disease surveillance in precision and climate-resilient agriculture.