Gelatinous lanthanide coordination polymer with aggregation-enhanced antenna effect for ratiometric detection of endogenous alkaline phosphatase

Aggregation-induced emission (AIE) and antenna effect (AE) are two significant behaviors that have attracted increasing attention. However, it is challenging to achieve the synergistic effect of AIE and AE in luminescent materials for more extensive applications. Here, four gelatinous Ln(3+) coordination polymers (Ln-CPs) are synthesized by self-assembly of ciprofloxacin (CIP), adenosine monophosphate (AMP), and Ln(3+) ions in aqueous medium. Encouragingly, a remarkable increase in the characteristic fluorescence of Ln(3+) and a significant decrease in CIP are observed along with increasing concentration of Ln-CPs, which is attributed to the large aggregates formed by self-assembly that strictly constrain the intramolecular motions of antenna ligands, thereby achieving the aggregation-enhanced AE. More meaningfully, Eu-CP not only shows a rice-like morphology at high aggregation state, but also provides an opportunity for the selective detection of alkaline phosphatase (ALP). A new flower-like polymer is formed upon incubating Eu-CP with ALP, accompanied by the fluorescence quenching of Eu3+ and recovery of CIP, a ratiometric determination of ALP in the range of 0.1-6.0 U center dot L-1 is thus achieved. Additionally, ALP assay in human serum and bioimaging in living cells have been successfully performed. This research opens a new horizon for the fabrication of Ln(3+)-based luminescent materials with promising applications.

Automated summary

This study successfully synthesized four gelatinous Ln(3+) coordination polymers by self-assembly of ciprofloxacin, adenosine monophosphate, and Ln(3+) ions in water medium. It was found that the characteristic fluorescence of Ln(3+) significantly increased and the concentration of ciprofloxacin decreased with the increasing concentration of Ln-CPs, which was attributed to the aggregation-enhanced antenna effect due to the large aggregates formed by self-assembly.