Construction of a biocompatible supramolecular sensor for fluorescence imaging of Nitric oxide in plant tissues.

Nitric oxide (NO) serves as a crucial signaling molecule regulating plant growth and stress responses, and its dynamic monitoring is crucial. This work presents a red-emitting aggregation-induced emission (AIE) supramolecular fluorescent sensor (β-CD/AIENAP) constructed through β-cyclodextrin encapsulation of organic AIE-active molecules (AIENAP). The extension of the material's conjugated structure red shifts the emission wavelength and improves the tissue penetration ability. Meanwhile, β-CD encapsulation restricts intramolecular motion, thereby enhancing fluorescence while improving biocompatibility and cell permeability. Density functional theory calculations verify both the luminescence mechanism and NO-responsive characteristics. The developed probe demonstrates rapid NO response (2 min) via specific triazole formation, exhibiting a large Stokes shift (180 nm), exceptional selectivity, and ultrahigh sensitivity (LOD = 77 nM). Through confocal imaging technology, the sensing system successfully realized the dynamic tracking of the dynamic spatial and temporal distribution of endogenous NO in plants, and systematically studied the NO response characteristics under different abiotic stresses in plants. Exogenous NO application experiments further validate stress resistance regulation. This study provides not only a novel nanosensor for plant NO detection but also an essential tool for analyzing NO signaling transduction and crop stress resistance mechanisms.