Development of immunosensor platforms based on magnetic nanostructured

Thesis Type: Doctorate

Institution Of The Thesis: Gazi Üniversitesi, Fen Bilimleri Enstitüsü, Turkey

Approval Date: 2012




In this study, magnetic core-shell nanoparticles were synthesized for the selective binding of a specific antigen from a protein-antigen mixture with highly effective. Fistly, magnetic nanoparticles coated with silica, silver and polydopamine (PDA) layer. Then silica-coated nanoparticle surface was covered with 3-aminopropyltriethoxysilane (APTES), than silver-coated nanoparticle surface was covered with 11-mercaptoundecanoic acid (MUA) for easy immobilization of antibodies. Nanoparticles were characterized by Attenauted total reflectance fourier transform infrared spectroscopy (ATR-FT-IR), X-ray photoelectron spectroscopy (XPS), X-ray diffractometer (XRD), transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM). XPS results demonstrated that all the modification steps were done successfully. TEM images of the nanoparticles demonstrated that they were well dispersed. XRD results indicated that the crystallinity of the prepared nanoparticles did not change after the modification steps. VSM results showed that all of the prepared nanoparticles have superparamagnetic property at room tempererature. The immobilization of antibodies on nanoparticles was carried out to ensure specific binding of antigens. The selectivity of the anti-IgG antibody-immobilized PDA coated nanoparticles for IgG against that for Fbg, Hb, Mb and Lys was 74,4, 64,9, 59,8 and 54,6 ?? g/mg magnetic nanoparticles, respectively. In the same way, the anti-ferritin antibody-immobilized MUA modified nanoparticles adsorption capacities for ferritin with respect to the same proteins were 83,7, 76,3, 71,2 and 68,7 ? g/mg magnetic nanoparticles, respectively. It was concluded that, the selective antigen binding capacity of ferritin-immobilized PDA coated magnetic nanoparticles was relatively high compared with other core-shell nanoparticles from the protein mixture. As a result, the antibody immobilized nanoparticles represented high activity and strong affinity for the specific antigen.