Fluorescence turn-on sensing of ascorbic acid based on a hyperbranched conjugated polyelectrolyte

A fluorescent turn-on detection for ascorbic acid has been developed based on hyperbranched conjugated polyelectrolyte. The fluorescence probe benefits from the high signal amplification from hyperbranched molecular structure of the conjugated polymer and produce fluorescence superquenching by Cu²⁺ ions with a detection limit down to the nanomolar range. Upon addition of ascorbic acid, the paramagnetic Cu²⁺ ions can be transformed into diamagnetic Cu¹⁺ ions, which inhibit the quenching and thus lead to fluorescence enhancement of the hyperbranched conjugate polymer. Other biologically relevant species, such as glucose, uric acid, L-arginine, and acetaminophen do not lead to significant fluorescence change of the conjugated polymer-Cu²⁺ complex, indicating that the hyperbranched conjugated polymer-Cu²⁺ complex can thus serve as an effective chemosensor to detect ascorbic acid.