A novel fluorescent nanosensor based on small-sized conjugated polyelectrolyte dots for ultrasensitive detection of...

A novel nanosensor is developed for selective and highly sensitive detection of phytic acid (PA) based on small-sized conjugated polyelectrolyte dots (Pdots) fabricated from a new conjugated polymer (P1) by a modified reprecipitation method. P1 featuring a π-delocalized backbone bearing meta-substituted pyridyl groups can be endowed with enhanced flexibility and hence is beneficial for the synthesis of ultrasmall Pdots (i.e. Pdot-1, ∼3.8 nm in average diameter) as well as for the binding of Fe³⁺, thus leading to the obvious fluorescence quenching of Pdot-1 (∼444 nm) in the presence of Fe³⁺ via an electron transfer (ET) process. In addition, phytic acid with six phosphate groups exhibits strong chelating ability. When phytic acid is added, phytic acid readily binds to Fe³⁺ and the fluorescence of Pdot-1 around 444 nm can be recovered, rendering the supersensitive and selective sensing of PA. Under the optimum conditions, this ultra-small Pdot-based nanoprobe favors the fluorescent determination of PA with the detection limit as low as 10 nM. Particularly, Pdot-1 with bright blue fluorescence exhibits low cytotoxicity. Furthermore, the small-sized and biocompatible Pdot-1 can be applied to the sensitive fluorescence assay for PA in cell extracts and the efficient imaging of PA in live cells.