Citrate-Induced Aggregation of Conjugated Polyelectrolytes for Al³⁺-Ion-Sensing Assays

Abstract

This work shows the sodium citrate induced efficient interpolymer π-stacking aggregation of the planar cationic conjugated polyelectrolyte poly­[{9,9-bis­[6′-(<i>N</i>,<i>N</i>-trimethylamino)­hexyl]-2,7-fluorenyleneethynylene}-<i>alt</i>-<i>co</i>-(1,4-phenylene)] dibromide (PFE) in aqueous solution, which results in the self-quenching of fluorescence. Using the citrate-induced aggregation properties of PFE and the strong chelation ability of citrate with aluminum ions (Al³⁺), a sensitive and selective Al³⁺-ion detection assay in aqueous solution was developed through monitoring of the fluorescence recovery of PFE. The fluorescence intensity recovery of PFE depends on the concentration of Al³⁺ ions, and linear fluorescence recovery was observed in the range of 0.5–9 μM. The limit of detection of this assay is 0.37 μM. Its simplicity and rapidity mean this assay shows promise for the real-time detection of Al³⁺