Universidad de Santiago de Compostela 1 article published in JoVE Chemistry Synthesis of Functionalized Magnetic Nanoparticles, Their Conjugation with the Siderophore Feroxamine and its Evaluation for Bacteria Detection Diana Martínez-Matamoros1, Socorro Castro-García1, Gabriela Ojeda Romano2, Miguel Balado3, Jaime Rodríguez1, Manuel L. Lemos3, Carlos Jiménez1 1Centro de Investigacións Científicas Avanzadas (CICA), Departamento de Química, Facultade de Ciencias, Universidade da Coruña, 2Centro de Investigacións Científicas Avanzadas (CICA), Unidad de Comunicación y Divulgación, Universidade da Coruña, 3Department of Microbiology and Parasitology, Institute of Aquaculture, Universidade de Santiago de Compostela This work describes protocols for the preparation of magnetic nanoparticles, its coating with SiO2, followed by its amine functionalization with (3-aminopropyl)triethoxysilane (APTES) and its conjugation with deferoxamine using a succinyl moiety as a linker. A deep structural characterization description and a capture bacteria assay using Y. enterocolitica for all the intermediate nanoparticles and the final conjugate are also described in detail.