A closed bipolar electrochemiluminescence sensing platform based on quantum dots: A practical solution for biochemical analysis and detection

Many quantum dots (QDs) are considered as excellent electrochemiluminescence (ECL) fluorophores with high quantum yields (QYs) and good stability. However, their ECL efficiency dramatically decreases in the aqueous solution compared to that in organic phase, which significantly limits their applications in bioanalysis. In this study, we developed a new sensing strategy via the combination of a closed bipolar electrode and electrochemiluminescence (CBP-ECL) system, which allows the separation of sensing in aqueous media and generation of ECL in organic media. Two kinds of QDs, CdSe/ZnS and CsPbBr3 were applied as ECL fluorophores in this system, and stable, high QYs ECL signals were achieved. The resulting sensing platform demonstrated high sensitivity for the detection of H2O2 with a linear range of 0.02-12 mM and the limit of detection (LOD) of 9.2 x 10(-8) M when CdSe/ZnS QDs were used as ECL reagents. We envision that this system can be widely employed in any kind of bioanalysis which can produce the electrochemical currents in the detecting cell. More importantly, we expect this system could break through the limitation of the fluorophores, especially those with solvent dependent ECL signals such as aggregation-induced emission (AIE) molecules, or most of the hydrophobic dyes.