Fluorescent probes for catecholamine sensing: A critical review from molecular recognition to biomedical and doping applications

Catecholamines (CAs), including dopamine (DA), norepinephrine (NE), and epinephrine (EP), are key neurotransmitters and neuroendocrine mediators involved in physiological homeostasis, disease progression, and doping-related performance modulation. Although numerous fluorescent probes for CA sensing have been reported, the field still lacks a scenario-oriented evaluation that connects recognition chemistry with biological dynamics, matrix complexity, and practical testing requirements. Herein, we critically review fluorescent probes for CA sensing from the perspectives of molecular recognition, signal transduction, and application readiness. Rather than simply cataloguing individual studies, this review compares boronic-acid complexation, oxidative cyclization, amine-triggered reactions, supramolecular host-guest recognition, dual-site/dual-locked designs, genetically encoded sensors, and multimodal imaging probes in terms of selectivity, reversibility, response kinetics, tissue penetration, matrix tolerance, and translational potential. Particular attention is given to the gap between well-controlled in vitro responses and real biological or anti-doping scenarios, where fast temporal changes, structurally similar interferents, and complex biofluids can compromise analytical reliability. Finally, we identify unresolved issues and future directions, including reversible real-time monitoring, NIR/NIR-II imaging, standardized validation in biological matrices, integration with portable and smartphone-assisted platforms, and the use of chemigenetic or bio-derived recognition elements. This review is intended to guide the rational development of next-generation catecholamine probes for neurochemical research, clinical diagnosis, and doping prescreening.