Highly Efficient Electrochemiluminescence of Cyanovinylene-Contained Polymer Dots in Aqueous Medium and Its Application in Imaging Analysis.

Luminescent semiconducting polymer dots (Pdots) have attracted intense attention in the field of electrochemiluminescence (ECL) due to their nontoxic features. For utilizing the nontoxic Pdots to achieve sensitive ECL bioimaging detection, this work studied the ECL behaviors of poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-(1-cyanovinylene-1,4-phenylene)] (CN-PPV) Pdots in aqueous solution, which introduced an electron-withdrawing cyano group to p-phenylenevinylene for enhancing the luminescent efficiency. The CN-PPV Pdots could be both electrochemically oxidized to a positively charged state and electrochemically reduced to a negatively charged state, which led to annihilation of ECL emission. The order of oxidation and reduction greatly influenced the annihilation behavior. In the presence of tri-n-propylamine (TPrA) or SO as a coreactant, the CN-PPV Pdots showed strong band gap ECL emission at 602 nm, which followed two different routes and gave ECL efficiencies of 11.22% and 1.84% (vs Ru(bpy)/TPrA), respectively. The high ECL efficiency allowed CN-PPV Pdots/TPrA system for ECL imaging analysis. As a proof-of-methodology, an ECL imaging method was designed via the chelating interaction of metal ions and Pdots to achieve high selectivity. The proposed ECL imaging chip-based sensor exhibited excellent analytical performance for Fe with a wide linear range from 100 pM to 100 μM and a detection limit of 67 pM. Compared with the ECL methods based on the direct intensity measurement, the developed ECL imaging method possesses the advantages of simplicity, rapid, and high-throughput and has application potential in monitoring water and food quality.