An Electrochemiluminescence immunosensor based on terbium metal-organic gel emitter and CoMnO3 electrocatalyst for the sensitive detection of N-terminal pro-brain natriuretic peptide

The construction of a sensitive electrochemiluminescence (ECL) immunosensor for the detection of N-terminal pro-brain natriuretic peptide (NT-proBNP) is demonstrated in this paper using terbium metal-organic gel (Tb-MOG) as an ECL emitter. Firstly, stable ECL signal was obtained using the easily synthesized Tb-MOG as the emitter and persulfate (S₂O₈²⁻) as the co-reactant. Secondly, the reduction of S₂O₈²⁻ was catalyzed by the introduction of CoMnO₃ nanoflower as a co-reaction promoter, which further enhanced the ECL intensity. When mixed-valence transition metal ions (Co³⁺/Co²⁺ and Mn⁴⁺/Mn³⁺) were reversibly transformed in CoMnO₃, the production of sulfate radical anion (SO₄^•–) was greatly enhanced. Additionally, the unique nanoflower structure of CoMnO₃ possesses a large specific surface area, enhancing its catalytic performance. Thanks to the well-established sensing strategy, the resultant ECL immunosensor exhibited satisfactory performance in accurately detecting NT-proBNP, with a linear concentration range of 10 fg/mL to 100 ng/mL and a detection limit of 2.1 fg/mL, offering great promise for clinical translation and broader heart failure diagnosis.