Synthesis and Characterization of Hybrid Core-Shell Fe3 O4 /SiO2 Nanoparticles for Biomedical Applications

Abstract

The creation of markers that provide both visual and quantitative information is of considerable importance for the mapping of tissue macrophages and other cells. We synthesized magnetic and magneto-fluorescent nanomarkers for the labeling of cells which can be detected with high sensitivity by the magnetic particle quantification (MPQ) technique. For stabilization under physiological conditions, the markers were coated with a dense silica shell. In this case, the size and zeta-potential of nanoparticles were controlled by a modified Stober reaction. Also, we developed a novel facile two-step synthesis of carboxylic acid-functionalized magnetic SiO 2 nanoparticles, with a carboxyl polymer shell forming on the nanoparticles before the initiation of the Stober reaction. We extensively characterized the nanomarkers by transmission electron microscopy, electron microdiffraction, and dynamic and electrophoretic light scattering. We also studied the nanoparticle cellular uptake by various eukaryotic cell lines. KEYWORDS magnetic nanoparticles, surface modification, magnetic detection, silicium dioxide, cell labeling. ABBREVIATIONS MPI-magnetic particle imaging; MPQ-magnetic particle quantification; TEOS-tetraethyl orthosilicate; m-cit-citrate-coated magnetic particles; m-CMD-carboxymethyl dextran-coated magnetic particles; m-cit-SiO 2-magnetic particles coated by SiO 2 via an intermediate citrate coating; m-CMD-SiO 2-magnetic particles coated by SiO 2 via an intermediate carboxymethyl dextran coating.