Rational fluorination strategy enables an ultrasensitive copper (II) fluorescent probe for dynamically monitoring copper metabolism in Parkinson's disease and copper-based pesticide residues in crops.

Copper(II) (Cu2 +) is an indispensable trace element yet poses significant risks to human health and ecosystems when its homeostasis is disrupted-evident in neurodegenerative disorders and environmental contamination from copper-based pesticides. Current detection methods often fall short in real-time analysis, biocompatibility, or field deployment. To overcome these limitations, we designed a small-molecule fluorescent probe, FDCI-Cu(II), that enables specific, sensitive, and multifunctional Cu2+ detection across biological and environmental settings. Its intelligent structure combines a fluorine-modified dicyanoisophorone fluorophore for enhanced blood-brain barrier (BBB) penetration and in vivo stability with a 2-picolinic acid chelator for high-affinity copper recognition. Fluorine incorporation not only promotes brain uptake but also enhances the overall reaction kinetics, leading to a fast turn-on response and ultrasensitive detection (limit of detection = 2.06 nM). Empirical validation in the MPTP‑induced Parkinson's disease mouse model confirmed superior BBB permeability and selective copper visualization. Beyond bioimaging, FDCI-Cu(II) demonstrated excellent performance in complex environmental and agricultural matrices. It achieved accurate quantification of Cu2+ in real‑world samples such as Xuanwu Lake water and living crops, and successfully competed for Cu2+ from organic pesticide complexes (e.g., copper quinolate). Furthermore, its integration into a point‑of‑care testing (POCT) format enables rapid on‑site monitoring. This work highlights FDCI-Cu(II) as a unified molecular tool bridging neurological research and environmental monitoring, offering real‑time detection capability and proven dual‑scenario applicability in both brain tissue and agricultural/environmental samples.