A highly sensitive osteocalcin immunosensor based on MWCNT - COOH/PVA/PEDOT:PSS modified electrode

Osteocalcin, a key biomarker of bone metabolism, is of significant clinical value for the diagnosis and management of osteoporosis through dynamic monitoring. The development of highly sensitive detection methods is therefore of great importance. This study developed a highly sensitive electrochemical immunosensor for osteocalcin detection based on a nanocomposite of carboxylated multi-walled carbon nanotubes (MWCNT-COOH), polyvinyl alcohol (PVA), and poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS). A uniform and stable nanocomposite film was prepared via a simple and rapid method involving physical blending and vortex dispersion. Osteocalcin (OC) antibodies were covalently immobilized onto the surface of a functionalized screen-printed electrode using an EDC/NHS coupling system. The detection principle relies on the specific antigen-antibody binding event hindering interfacial electron transfer, enabling the quantitative detection of OC via differential pulse voltammetry (DPV). Under optimal conditions, the sensor exhibited an excellent linear response (R² = 0.996) over a concentration range from 10 pg/mL to 100 μg/mL, with a detection limit of 1.2 pg/mL. Furthermore, the sensor demonstrated outstanding selectivity, reproducibility, and stability, showcasing its potential as a promising tool for the quantitative analysis of bone metabolism biomarkers in biological fluids.