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RESEARCH PRODUCT

Microwave synthesis of core-shell structured biocompatible magnetic nanohybrids in aqueous medium

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In the past decade, biocompatible magnetic nanohybrids, i.e. materials consisting of an inorganic core encapsulated by a biocompatible polymeric corona, went throw various developments in biomedical applications especially in the fields of diagnosis and therapy. Numerous descriptions of their syntheses can be found in the literature (Zhang et al., 2002; Flesch et al., 2004; Fan et al., 2007; etc). These two-steps protocols often describe the use of organic or aqueous solvents, classical thermal heating, long time reaction as well as fastidious exchange and drying steps. In recent years, microwave heating has been proven to be a very original technology for nanoparticles synthesis due to its almost instantaneous “in core” heating of materials in a homogeneous and selective way. As a consequence, this technology allows an interesting control over crystallization rate and size of the nanomaterials (Bellon et al., 2001; Michel et al., 2001; etc). The formation of magnetic nanoparticles is usually realized in aqueous medium. However, the functionalization of magnetic nanoparticles is mainly conducted in organic solvent. For further biomedical applications, it seems favorable to realize these different grafting steps maintaining initial aqueous medium, thus avoiding the solvent exchanges and the particles drying. In this context, we can summarize the objective of this chapter as the study of new methods to obtain core-shell structured nanohybrids in aqueous medium from iron oxide nanoparticles and water-soluble biocompatible polymers. Is it possible to obtain iron oxide colloidal suspension and well-defined nanohybrids with simplified protocols and relatively short microwave heating time? This chapter is divided is three part, consisting for the first one, of a general presentation of biocompatible magnetic nanohybrids (properties, applications and synthesis). The second part deals with the principles of microwave heating and the description of microwave-assisted synthesis of inorganic nanoparticles. Finally, the last part is dedicated to the use of microwave heating towards magnetic nanohybrid synthesis compared to classical thermal heating process with a focus on nanoparticles characterization (morphology, size and grafted amount of polymer).