Conjugated polymer-encapsulation-manipulated aggregation-induced electrochemiluminescence of tetraphenylethylene for sensitive malathion analysis

Abstract

Tetraphenylethylene (TPE) and its derivatives with tunable structure and excellent photoelectric performance have aroused great concern in the field of electrochemiluminescence (ECL), but improving their ECL efficiency remains an enormous challenge in ECL bioanalysis. Herein, an encapsulation-manipulated aggregation-induced ECL (EM-AIECL) strategy was explored to effectively boost the ECL efficiency of TPE. Large π-conjugated polymer poly[2,5-dioctyl-1,4-phenylene] (PDP) was creatively developed as encapsulation matrix to envelop TPE molecules via hydrophobic interactions. The resulting complex TPE@PDP nanoparticles (NPs) not only restricted the molecule motion of TPE due to space limitation, but also inhibited the aggregation-caused quenching effect caused by TPE crystals featuring dense aggregation structure. Furthermore, the robust electronic coupling between PDP and TPE aggregates enabled superior charge transport within TPE@PDP NPs, thus yielding strong AIECL. As compared to TPE crystals, TPE@PDP NPs showcased 3.87-fold enhancement of ECL intensity. Impressively, TPE@PDP NPs coupled a three-dimensional DNA walker-assisted multiple rolling circle amplification strategy to construct an ECL sensing platform for malathion analysis, and a wide linear range of 5.0 fM ∼ 0.5 μM and low limit of detection of 0.9 fM were obtained. EM-AIECL strategy provides a new idea for designing organic AIECL luminophors, and opens an avenue for detecting pesticides specifically and sensitively.