A Quartz Tuning Fork-Based Immunosensor for Detection of Kidney Injury Molecule-1: A New Working Electrode for Electrochemical Applications

Kidney injury molecule-1 (KIM-1) is a Type I transmembrane glycoprotein and is a potential biomarker for detecting kidney damage, as its urinary levels fluctuate in cases of acute kidney injury. In this study, an electrochemical immunosensor was developed for the first time using a quartz tuning fork (QTF) working electrode to detect the KIM-1 biomarker. The gold-tipped QTF electrode surface was modified with 11-mercaptoundecanoic acid (11-MUA) to form a self-assembled monolayer (SAM). To construct the biosensor, extensive optimization studies were conducted on the fabrication parameters, followed by characterization and real urine sample testing to evaluate its applicability. Electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) methods were utilized in all electrochemical experiments. Morphological changes on the QTF electrode surface were examined using atomic force microscopy (AFM) and scanning electron microscopy (SEM). The developed electrochemical KIM-1 immunosensor demonstrated highly promising performance, exhibiting an exceptionally wide detection range (0.05-250 fg/mL). Furthermore, the dissociation constant (Kd) of the interaction between KIM-1 and its antibody was successfully calculated using the Hill equation, on the basis of the QTF-based system.