Construction of the indicator-free electrochemical biosensor with magnetically self-assembly based on Fe3O4/α-Fe2O3 magnetic heterogeneous nanorods for the ultra-sensitive detection of CYFRA 21-1 DNA.

Introduction: Lung cancer prevalence rate has been rising steadily in recent years, for the prevention and treatment, the detection of tumor marker CYFRA 21-1 DNA demonstrates its significance. Methods: In this work, an electrochemical biosensor was constructed for sensitive detection of CYFRA 21-1 DNA based on the novel developed Fe3O4/α-Fe2O3 magnetic heterogeneous nanorods (MHNRs). Firstly, Fe3O4/α-Fe2O3 MHNRs were prepared by hydrothermal-calcination method, and then Fe3O4/α-Fe2O3@Au magnetic nanocomposites (MNCs) were obtained though gold-coating. Subsequently, the magnetic self-assembling electrochemical biosensor based on Fe3O4/α-Fe2O3@Au MNCs was successfully constructed, which was verified by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). To optimize the biosensor's experimental conditions and evaluate its performance, differential pulse voltammetry (DPV) was conducted. Results and Discussion: The results showed that the detection range of CYFRA 21-1 DNA was 10 pM-10 μM, the limit of detection (LOD) was 1.5 pM. The biosensor exhibited excellent selectivity, reproducibility, and stability; the relative standard deviation (RSD) was 2.01%. The average recovery rate in the spiked diluted human serum samples was 101.4%, and the RSD was ≤5.2%, indicating that the biosensor possessed promising prospect.