Conjugated Polymer-Based Hydrogel Film for a Fast and Sensitive Detection of Fe(Ⅲ) in Vegetables.

Fluorescent film sensors are ideal for the real-time outdoor detection of heavy metal ions of Fe, but they are limited because of their low sensitivity and long response time due to their special structure. In this work, we constructed a fluorescent hydrogel for the specific detection of Fe, utilizing poly(9-fluorenecarboxylic acid) (PFCA) as the sensing moiety and sodium alginate (SA) as the cross-linking substrate, which exhibited a rapid and selective recognition of Fe among a panel of 16 anions and 21 cations. It can sense Fe at 0.1 nM immediately owing to the porous network structure of the film that provided enhanced ion transport channels and active sites, and the "molecular line effect" of polymer PFCA. Moreover, we successfully applied this platform to detect Fe in four different vegetable samples. This work provides an innovative and effective strategy for fabricating green and sustainable fluorescent sensors.