A ratiometric fluorescent nanoprobe for formaldehyde imaging in Arabidopsis thaliana.

Formaldehyde (FA), a highly reactive carbonyl species, plays essential roles in cellular metabolism but can induce cytotoxicity when present at elevated levels. Sensitive and reliable detection of FA in biological systems is therefore crucial for understanding its physiological functions and pathological implications. In this study, a fluorescent nanoprobe (DR-NP647/573) was constructed by co-encapsulating two fluorophores-dicyanoisophorone-based DISE as the FA-responsive unit and Rhodamine B as the internal reference-within pluronic F-127. This design enables ratiometric fluorescence detection, providing improved resistance to environmental fluctuations and instrumental variation compared with single-emission probes. DR-NP647/573 displays a pronounced ratiometric response toward FA, with high sensitivity (detection limit: 0.81 μM) and a rapid reaction within 6 min. The probe also exhibits excellent stability and selectivity under physiological conditions. Importantly, when applied to Arabidopsis thaliana root tip tissues, DR-NP647/573 enabled clear ratiometric imaging of FA, demonstrating its suitability for visualizing endogenous FA in plant systems. These findings highlight the potential of this nanoprobe as a robust analytical tool for investigating FA dynamics in complex biological environments.