Dual-emitting BP-CdTe QDs coupled with dual-function moderator TiO₂ NSs for electrochemiluminescence ratio bioassay

The limitation of the selection of dual-emitting luminophor and dual-function moderator makes the construction of single-luminophor-based electrochemiluminescence (ECL) ratio strategy extremely challenging. This work developed black phosphorus nanosheet loaded with CdTe quantum dots (BP-CdTe QDs) as dual-emitting luminophor, and TiO₂ nanosheets (NSs) as dual-function moderator to construct single-luminophor-based ECL ratio biosensor for amyloid-β protein (Aβ) detection. The BP-CdTe QDs modified glassy carbon electrode (GCE) firstly captured the anti-Aβ₁, and then the target Aβ. Finally, the secondary antibody composites containing N,N-diethylethylenediamine (DEDA) and TiO₂ NSs were captured on the electrode surface. DEDA in the secondary antibody composites and S₂O₈^2- added in the detection solution served as the anodic and cathodic co-reactants, respectively, and TiO₂ NSs as co-reaction accelerator can simultaneously enhance two emissions. The increase of target concentration made the two signals show different increasing trend, thus achieving a sensitive ratio detection of target Aβ with the detection limit of 21 fg/mL. The dual-emitting BP-CdTe QDs coupled with dual-function moderator TiO₂ NSs provide an attractive single-luminophor-based ECL ratio platform for bioassay, which can not only be applied to the detection of Aβ, but also to the detection of other disease biomarkers.