Electrochemical Immunosensor Prototype for N-Terminal Natriuretic Peptide Detection in Human Saliva: Heart Failure Biomedical Application

NT-proBNP is the gold standard biomarker for early diagnostics of heart failure, disease prevention, and stratified and individualized patient care. In this work, we aim to develop a novel ultra-sensitive immunosensor for direct NT-proBNP detection in human artificial saliva (AS), which represents an intriguing biological matrix potentially rich in biomarkers. The immunosensor will enhance the sensitivity of detection, reduce measurement time, and enable the simultaneous detection of various biomarkers. The developed biosensor, based on gold working microelectrodes (WEs), was biofunctionalized using 4-carboxymethyl aryl diazonium (CMA) to immobilize anti-NT-proBNP antibodies. The deposition of CMA onto the gold surface of the microelectrodes was accomplished using cyclic voltammetry (CV). The binding between NT-proBNP antibodies and NT-proBNP antigens was tracked using electrochemical impedance spectroscopy (EIS) in conjunction with the standard addition method. A linear detection response within the range of 1–20 pg/mL for NT-proBNP detection in PBS and artificial saliva was demonstrated, with good selectivity in the presence of other potential interfering biomarkers (interleukin 6 (IL-6), interleukin 10 (IL-10), and interleukin 1 β (IL-1β)). The developed immunosensor shows great promise for rapid and accurate analysis in biomedical applications.