Magnetic self-assembled label-free electrochemical biosensor based on Fe3O4/α-Fe2O3 heterogeneous nanosheets for the detection of Tau proteins

Abstract

A type of electrochemical biosensors based on magnetic Fe₃O₄/α-Fe₂O₃ heterogeneous nanosheets was constructed to detect Tau proteins for early diagnosis and intervention therapy of Alzheimer's disease (AD). Firstly, Fe₃O₄/α-Fe₂O₃ heterogeneous nanosheets were fabricated as the substrate to realize magnetic self-assembly and magnetic separation to improve current response, and Fe₃O₄/α-Fe₂O₃@Au-Apt/ssDNA/MCH biosensors were successfully constructed through the reduction process of chloroauric acid, the immobilizations of aptamer (Apt) and ssDNA, and the intercept process of 6-Mercapto-1-hexanol (MCH); the construction process of the electrochemical biosensor was monitored using Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), and the factors affecting the current response of this sensor (concentration of Fe₃O₄/α-Fe₂O₃@Au and Apt/ssDNA, incubation temperature and time of Tau) were explored and optimized using differential pulse voltammetry (DPV). Analyzing the performance of this sensor under optimal conditions, the linear range was finally obtained to be 0.1 pg/mL-10 ng/mL, the limit of detection (LOD) was 0.08 pg/mL, and the limit of quantification (LOQ) was 0.28 pg/mL. The selectivity, reproducibility and stability of the biosensors were further investigated, and in a really sample analysis using human serum, the recoveries were obtained in the range of 93.93 %-107.39 %, with RSD ranging from 1.05 % to 1.94 %.

Keywords: Aptamer; Electrochemical biosensor; Magnetic Fe(3)O(4)/α-Fe(2)O(3) heterogeneous nanosheets; Self-assembly; Tau proteins.