A magnetically induced self-assembled and label-free electrochemical aptasensor based on magnetic Fe3O4/Fe2O3@Au nanoparticles for VEGF165 protein detection

Based on magnetic Fe3O4/Fe2O3@Au nanoparticles (Fe3O4/Fe2O3@Au NPs), to detect an important tumor screening marker, vascular endothelial growth factor 165 (VEGF165), a label-free electrochemical aptasensor was constructed. Magnetic glassy carbon electrode (MGCE) after Fe3O4/Fe2O3@Au NPs surface modification by a magnetic-induced self-assembly technique was the platform. Fe3O4/Fe2O3@Au NPs were used as the signal amplifier to enhance electron transfer, which was essential for the detection of trace amounts of biological analytes, and were prepared via heating hydrolyzation-combustion calcination and trisodium citrate reduction. Meanwhile, aptamers bound to the as-prepared nanomaterial via Au-s bonds and specifically recognized VEGF165. The electrochemical properties of the aptasensor were evaluated with [Fe(CN)6]3−/4− as redox probes. When in optimal detection conditions, an excellent linear relationship (between 0.01 and 10 pg mL−1, R2 = 0.9973) was obtained for the electrochemical aptasensor. The limit of detection (LOD) and the limit of quantitation (LOQ) of the electrode were 0.01 and 0.03 pg mL−1. This proposed aptasensor exhibited favourable selectivity, stability, reproducibility, and regenerability. The results demonstrated that the sensor was promising to provide an efficient, accurate, and low-cost auxiliary detection method for the early screening of VEGF165-related diseases, which had important clinical practical value for the research of human precision medicine.