An indicator-free and magnetically induced self-assembled electrochemical aptamer nano-biosensors towards the supersensitive detection of high mobility group A1

High mobility group A1 (HMGA1) proteins are often overexpressed in tumor cells but undetectable in normal adult tissues, and their expression level is related to the malignant degree of tumors, chemotherapy resistance and drug sensitivity. Therefore, HMGA1 proteins can act as tumor biomarker for diagnosis, treatment, and prognosis of tumors. In this work, the indicator-free and magnetically induced self-assembled electrochemical aptamer nano-biosensors based on α-Fe 2 O 3 /Fe 3 O 4 magnetic heterogeneous nanoparticles (MHNPs) were developed for supersensitive detection of HMGA1 proteins. Firstly, α-Fe 2 O 3 /Fe 3 O 4 MHNPs with an average diameter of 89 nm were prepared via the hydrothermal and calcination-reduction process, and gold nanoparticles with an average particle size of approximately 5.3 nm were immobilized on α-Fe 2 O 3 /Fe 3 O 4 MHNPs to form α-Fe 2 O 3 /Fe 3 O 4 @Au magnetic nanocomposites (MNCs), and then aptamers were immobilized through Au-S covalent bonds to construct electrochemical aptamer nano-biosensors for sensitive detection of HMGA1 proteins. The construction process and performances of the nano-biosensors were systematically characterized and optimized using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and differential pulse voltammetry (DPV). The electrochemical aptamer nano-biosensors revealed excellent analytical performance with a linear detection equation: I (μA) = 6.989 lgC+42.9424 (R 2 =0.994), exhibiting a robust linear detection range of 1 pg·mL -1 to 0.01 μg·mL -1 . The limit of detection and the limit of quantification were 0.35 pg·mL -1 and 1.17 pg·mL -1 , respectively; The nano-biosensor exhibited outstanding reproducibility (relative standard deviation (RSD) = 1.36%), long-term stability (82.93% signal retention after 20 days), and remarkable anti-interference capability against common biological interferents. All the results demonstrated the promising clinical application of the electrochemical aptamer nano-biosensors.