Preparation of surface plasmon resonance biosensor based on magnetic core/shell Fe3O4/SiO2 and Fe3O4/Ag/SiO2 nanoparticles

In this paper, surface plasmon resonance biosensors based on magnetic core/shell Fe3O4/SiO2 and Fe3O4/Ag/SiO2 nanoparticles were developed for immunoassay. With Fe3O4 and Fe3O4/Ag nanoparticles being used as seeding materials, Fe3O4/SiO2 and Fe3O4/Ag/SiO2 nanoparticles were formed by hydrolysis of tetraethyl orthosilicate. The aldehyde group functionalized magnetic nanoparticles provide organic functionality for bioconjugation. The products were characterized by scanning electronic microscopy (SEM), transmission electronic microscopy (TEM), FTIR and UV–vis absorption spectrometry. The magnetic nanoparticles possess the unique superparamagnetism property, exceptional optical properties and good compatibilities, and could be used as immobilization matrix for goat anti-rabbit IgG. The magnetic nanoparticles can be easily immobilized on the surface of SPR biosensor chip by a magnetic pillar. The effects of Fe3O4/SiO2 and Fe3O4/Ag/SiO2 nanoparticles on the sensitivity of SPR biosensors were also investigated. As a result, the SPR biosensors based on Fe3O4/SiO2 nanoparticles and Fe3O4/Ag/SiO2 nanoparticles exhibit a response for rabbit IgG in the concentration range of 1.25–20.00 μg ml−1 and 0.30–20.00 μg ml−1, respectively.