A Sensitive Sandwich-type Electrochemical Immunosensor Based on Signal Amplification Strategy of Hollow CuS Nanocomposites for BNP Detection.

Timely diagnosis and prognosis evaluation of heart failure (HF) urgently require highly sensitive, rapid, and reliable quantification of the critical biomarkers such as B-type natriuretic peptide (BNP). In this work, a novel sandwich-type electrochemical immunosensor was successfully constructed for highly sensitive and selective detection of BNP. Firstly, gold nanoparticles (AuNPs) and nitrogen-doped reduced graphene oxide/carboxylated multi-walled carbon nanotubes (N-rGO/CMWCNTs) were modified on the electrode surface for efficient capture antibody immobilization. Simultaneously, a core-shell structured HCuS@PDA@Pt nanocomposite was synthesized as a catalytic label. Quantification of BNP was achieved through specific immunorecognition and subsequent catalytic signal amplification. The proposed immunosensor demonstrated a wide linear detection range (1 pg mL-1-100 ng mL-1) and an ultra-low detection limit (0.25 pg mL-1) for BNP, along with superior selectivity, reproducibility, and stability. Especially, the biosensor exhibited excellent consistency with a commercial ELISA kit when analyzing real human serum samples. Furthermore, in a hypoxia-induced HF mice model, significantly elevated BNP levels due to cardiac stress were detected, confirming its ability to clearly distinguish between pathological and physiological states. The results validate the accuracy and reliability of the proposed biosensor for BNP detection in complex biological environments and highlight its promise for clinical diagnosis and monitoring applications.