A Novel hig E Aptamer Biosensor Base on Core-Shell Fe3O4@Au Magnetic Composite Nanoparticles

In this paper, a novel hIg E aptamer biosensor was designed base on the core-shell Fe3O4@Au magnetic composite nanoparticles (Fe3O4@Au NPs). Firstly, Fe3O4@Au NPs were prepared by one-step reduction process with Fe3O4 nanoparticles (Fe3O4 NPs) as magnetic core and hydroxylamine hydrochloride as deoxidizer. Then, the morphology, composition, and properties of Fe3O4@Au NPs were characterized by scanning electron microscope (SEM), fourier translation infrared spectroscopy (FT-IR), vibrating sample magnetometer (VSM) and so on. Lastly, Human immunoglobulin E (hIg E) was used as the model analyte, a hIg E aptamer biosensor was presented which the hIg E antibody is covalently immobilized as the capture probe on Fe3O4@Au NPs surface, and hIg E aptamer was used as the detection probe. After the hIg E antigen was captured, the ascorbic acid 2-phosphate (AAP) formed ascorbic acid (AA) in the presence of alkaline phosphatase (ALP). The AA reduced the silver ions (Ag+) in the solution to silver metal that preferentially deposited on surface of the Fe3O4@Au NPs. The amount of deposited silver could be quantified using the electrochemical methods. The oxidation current of Ag0 was linear with the concertration of hIg E over the range 0.25~2.0 μg/mL. Therefore, the hIg E aptamer biosensor possessed higher sensitivity, low detection limit and rapid response speed.