1. Introduction

Nanotechnology is a scientific discipline involving multiple hard sciences such as chemistry, physic, biology, engineering, among others. The occurrence of novel properties when materials are reduced to nanosizes is the main reason for the scientific and technological interest in such discipline. In particular nanomedicine, that is nanotechnology applied to medicine, has suffered an exponential grow in the last decades. The possibility to target the drug to the diseased site, by avoiding side effects and lowering the required doses, strongly impulses the development of this kind of technology. Magnetic nanotechnology presents the additional advantage related to nanosystems that may be easily guided by the aid of an external magnetic field. This property improves the targeting capability and increases their potential in biomedical applications such as target drug delivery or MRI diagnostic. Iron oxides based nanosystems are currently the favorites to achieve these kinds of issues due to multiple reasons, but mainly to their low toxicity and biocompatibility. However, surface modification is often required to gain in stability, improve their physicochemical properties or even to raise the reactivity by means of functional groups incorporation. Silica appears as a highly attractive material to assess this objective.

In the Introductory section the general aspects of nanotechnology and nanomedicine are highlighted. Principles of iron oxides nanoparticles and their silica coat are described.