Synthesis and characterization of near-infrared fluorescent and magnetic iron zero-valent nanoparticles

•PEG coated iron nanoparticles by inverse microemulsion.•Synthesis of near-infrared fluorescent PEGylated nanoparticles.•PEG coated iron zero-valent nanoparticles with good magnetic properties.

Polyethylene glycol coated iron nanoparticles were synthesized by a microemulsion method, modified and functionalized. The polymer coating has a crucial role, preventing the iron oxidation and allowing the functionalization of the particles. The nanoparticles were characterized and their magnetic properties studied. A photochemical study of the iron nanoparticles conjugated with a near-infrared fluorescent dye, Alexa Fluor 660, confirmed that the fluorescent dye is attached to the nanoparticles and retains its fluorescent properties. The bioimages in red and near-infrared (NIR) region are favourable due to its minimum photodamage and deep tissue penetration. The nanoparticles obtained in this study present a good magnetic and fluorescent properties being of particular importance for potential applications in bioscience.