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

A magnetic self-assembly electrochemical biosensor of Fe3O4/α-Fe2O3@Au-Apt/ssDNA/MCH based on magnetic Fe3O4/α-Fe2O3 heterogeneous nanosheets was constructed for the sensitive detection of Tau proteins, this biosensor revealed numerous advantages, including high sensitivity, a wide linear range, a lower detection limit, excellent selectivity, stability, and reproducibility, which suggested its excellent application prospect. [Display omitted] •A novel electrochemical biosensor based on magnetic Fe3O4/α-Fe2O3 heterogenous nanosheets was constructed.•The biosensor had the high sensitivity due to DNA aptamer.•The biosensor revealed lower detection limit and wider measuring range for the detection of Tau protein.•The biosensor displayed good specificity, excellent reproducibility, and favorable stability. 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 %.