A PEDOT enhanced covalent organic framework (COF) fluorescent probe for in vivo detection and imaging of Fe3+

Simple and accurate in vivo monitoring of Fe³⁺ is essential for gaining a better understanding of its role in physiological and pathological processes. A novel fluorescent probe was synthesized via in situ solid-state polymerization of 3,4-ethylenedioxythiophene (PEDOT) in the pore channels of a covalent organic framework (COF). The PEDOT@COF fluorescent probe exhibited an absolute quantum yield (QY) 3 times higher than COF. In the presence of Fe³⁺ the PEDOT@COF 475 nm fluorescence emission, 365 nm excitation, is quenched within 180 s. Fluorescence quenching is linear with Fe³⁺ in the concentration range of 0–960 μM, with a detection limit of 0.82 μM. The fluorescence quenching mechanism was attributed to inner filter effect (IEF), photoinduced electron transfer (PET) and static quenching (SQE) between PEDOT@COF and Fe³⁺. A paper strip-based detector was designed to facilitate practical applicability, and the PEDOT@COF probe successfully applied to fluorescence imaging of Fe³⁺ levels in vivo. This work details a tool of great promise for enabling detailed investigations into the role of Fe³⁺ in physiological and pathological diseases.