Label-free electrochemical aptasensor based on magnetic α-Fe2O3/Fe3O4 heterogeneous hollow nanorods for the detection of cancer antigen 125

A label-free electrochemical aptasensor based on magnetic α-Fe2O3/Fe3O4 heterogeneous hollow nanorods was developed for the detection of cancer antigen 125 (CA125). Magnetic α-Fe2O3/Fe3O4 heterogeneous hollow nanorods were successfully prepared by the hydrolysis-calcination method, functionalized with polyethyleneimine (PEI), and modified with HAuCl4 to form magnetic α-Fe2O3/Fe3O4-Au nanocomposites with a layer of 5 nm gold nanoparticles (Au NPs) on the surface. The magnetic α-Fe2O3/Fe3O4-Au nanocomposites were used to fix the DNA-aptamer probe to amplify the current signal. The intensity of the current signal was proportional to the concentration of CA125, indicating that the sensor was a turn-on sensor. The linear range of the electrochemical aptasensor was 5-125 U/mL (R2 = 0.9975), and the limit of detection (LOD) was 2.99 U/mL. The electrochemical aptasensor exhibited favorable specificity, reproducibility, and stability. The analytical performance of the aptasensor in real serum samples was also investigated.