Au-g-C3N4@MIL-100/Pt@CuS-induced self-accelerated dual-quenching ECL-RET strategy for sensitive sST2 detection

A novel dual-quenching electrochemiluminescence (ECL) immunosensor based on ECL resonance energy transfer (ECL-RET) strategy was developed for sensitive detection of soluble suppression of tumorigenicity 2 (sST2) protein. The sensor developed a self-accelerated ECL emitter composed of Au-decorated graphitic carbon nitride (g-C₃N₄) nanosheets and Materials of Institute Lavoisier-100(Fe) (MIL-100(Fe)). In this system, the reversible Fe²⁺/Fe³⁺ redox cycling in MIL-100(Fe) markedly enhanced the ECL emission from the g-C₃N₄/S₂O₈²⁻ pair by promoting the generation of sulfate radical. Simultaneously, the incorporated Au nanoparticles facilitated electron transfer and provided abundant sites for biomolecular immobilization, collectively establishing a robust "signal-on" state. Signal quenching was achieved using Pt@CuS nanoflowers as synergistic ECL quenchers. Their high antibody-loading capacity and efficient ECL-RET capability acted in concert to drastically reduce the signal, thereby inducing a pronounced "signal-off" state. The optimized "on-off" ECL immunosensor demonstrated a satisfactory linear range (0.001-100 ng mL⁻¹) and an ultralow detection limit of 0.547 pg mL⁻¹ for sST2. This work established a reliable platform for sST2 quantification, holding substantial potential for advancing heart failure research and clinical early diagnosis.