Highly Monodisperse Fe3O4@Au Superparamagnetic Nanoparticles as Reproducible Platform for Genosensing Genetically Modified Organisms

Several routes have been developed to prepare magnetic core–shell Fe3O4@Au nanoparticles (MNPs). However, only highly monodisperse MNPs are suitable for analytical applications. Herein, we describe the detection of GMO through the use of gold-coated MNPs with fine-tuned properties as platforms. The MNPs were prepared through a procedure that involves the preparation of Fe3O4 cores by thermal decomposition and their coating through reduction of a gold precursor. Different Fe3O4:Au precursor molar ratios (1:1; 1:4; 1:7) were tested on the Fe3O4 encapsulation. Monodisperse quasi-spherical core–shell Fe3O4@Au were obtained for the 1:4 and 1:7 ratios, in contrast, the 1:1 ratio did not lead to complete encapsulation of Fe3O4 cores. Therefore, the Fe3O4@Au obtained from higher Fe3O4:HAuCl4 ratios were tested as platforms for an electrochemical genoassay to detect MON810. The best performance was achieved with the Fe3O4@Au prepared from 1:4 ratio (10.0 ± 1.7 nm). A DNA probe covalently linked to a carboxylated s...