A novel electrochemical nano-aptasensor based on newly synthetized carbon dots for BNP detection in heart failure diagnosis

Brain natriuretic peptide (BNP) is a key biomarker for the diagnosis and monitoring of heart failure (HF), providing crucial information on cardiac function and disease progression. Conventional antibody-based detection methods, although reliable, suffer from high production costs, batch-to-batch variability, and the need for centralized laboratory infrastructure. In this work, we present a novel electrochemical aptasensor for point-of-care (POC) detection of BNP, designed to achieve high sensitivity and operational simplicity. The detection platform employs a BNP-specific DNA aptamer (A10), selected by SELEX, which exhibits strong binding affinity (Kd = 12 ± 1.5 nM). Screen-printed graphite electrodes (g-SPEs) were nanomodified with single-walled carbon nanotubes (SWCNTs) decorated with carbon dots (CDs), forming a hybrid nanostructure that enhances both conductivity and aptamer immobilization. The electrode surface was further functionalized with a polyadenosine (polyA) linker to enable controlled hybridization with a complementary polythymine-terminated (polyT) aptamer. This CD-SWCNT nanohybrid aptasensor demonstrated superior electrochemical performance, achieving an ultralow detection limit of 0.095 pg/mL (3 × standard deviation/sensitivity) and a linear range of 20–500 pg/mL, encompassing clinically relevant BNP levels. The sensor demonstrated high reproducibility, excellent recovery (90 ± 8 % at 200 pg/mL BNP), and negligible matrix interference (8.5 % variation in serum). Furthermore, the device retained 80 % of its activity after two months of storage at room temperature in dry conditions, proving the best stability over similar biosensors in the literature. These results highlight the potential of the proposed aptasensor as a robust, cost-effective, and portable diagnostic tool for rapid heart failure screening in POC applications.