Self-assembled (SA) bilayer molecular coating on magnetic nanoparticles

Protectively and functionally coated magnetic nanoparticles are of special interest because of their important technological applications in diverse fields, ranging from biotechnology to transportation. In this paper, monolayer and bilayer surfactant coating on magnetite (Fe3O4) nanoparticles has been obtained using the self-assembly method. Magnetic properties such as magnetization, ZFC and FC curves, blocking temperature, hysteresis loop, coercivity and remanent magnetization of the SAM and bilayer coated magnetite nanoparticles have been investigated. The results show the efficacy of our synthesis approach not only to protect magnetic nanoparticles via surfactant-mediated self-assembly but also their stable suspension in a variety of appropriate liquid media. The superparamagnetic nature of the magnetic nanoparticles remains unchanged with self-assembled coatings and paves the way for their use in colloid suspension for device applications. (C) 2001 Published by Elsevier Science B.V.