In spite of encouraging progress in recent years, the development of magnetic nanoparticles that can be used as drug delivery vectors remains a significant challenge for materials scientists. Among the multiple hurdles that must be overcome are the provision of a sufficiently high magnetic response, a high loading capacity for therapeutic or diagnosis materials and a sufficient degree of biocompatibility. In this work we describe the preparation of encapsulated magnetic nanoparticles consisting of a metallic iron core and an amorphous silica shell by using a modification of the arc-discharge method. This is a simple and inexpensive way to produce well-coated iron nanoparticles. The particles thus obtained present a much stronger magnetic response than any composite material produced up to now involving magnetic nanoparticles encapsulated in inorganic matrices, and the rich chemistry and easy functionalization of the silica outer surface make them promising materials for their application as magnetic carriers.

Support from the Spanish Nanoscience Action NAN200409270-C3-1/2 is gratefully acknowledged. One of the authors (MA) acknowledges the support of a contract from the ‘Juan de la Cierva´ programme (project PPQ2003-04986).

5 pages, 6 figures.

Peer reviewed