Highly Sensitive Detection of Human Serum Albumin Biomarker Using a Molecularly Imprinted Polymer‐Based Electrochemical Capacitance Sensor

Abstract This work presents a highly sensitive, label‐free, and redox probe‐free electrochemical sensor for human serum albumin (SA) based on a molecularly imprinted polymer (MIP) of electropolymerized poly(azo‐Bismarck Brown Y) on FTO electrodes. Successful imprinting creating specific recognition sites is confirmed spectroscopically and electrochemically. Comparative Electrochemical Impedance/Capacitance Spectroscopy (EIS/ECS) studies between the MIP and a non‐imprinted polymer (NIP) demonstrated effective molecular recognition through distinct interfacial changes upon SA rebinding. Detailed EIS/ECS analysis using capacitance and kinetic parameters elucidated the specific binding mechanism versus non‐specific effects at the electrochemical interface. Excellent analytical performance is achieved using real capacitance measurements at 0.1 Hz, yielding a linear response to log[SA] (0.25–3.0 ng mL −1 ) and an ultralow limit of detection (LOD) of 0.02 ng mL −1 . Isotherm analysis indicated complex binding involving both specific recognition and non‐specific adsorption. The sensor exhibits good selectivity against common interferents, although significant hemoglobin interference is observed at high concentrations. This study validates a robust, highly sensitive, probe‐free MIP‐capacitance sensor platform suitable for bioanalytical applications requiring trace biomarker quantification.