Recent Advances in Elongated IONPs: From Preparation to Biomedical Applications

C. Moya, G. Bruylants

Magnetic magnetite (Fe3O4) and maghemite (γ-Fe2O3) Iron Oxide Nanoparticles (IONPs) have been the object of many investigations, focusing not only on the understanding of their fundamental properties, but also on their numerous applications. Their relative ease of production and functionalization, high saturation magnetization at room temperature, low magnetic anisotropy, and good biocompatibility have led to their use in a large variety of applications, ranging from environmental remediation to biomedical diagnostic and treatment. Historically, most studies have focused on spherical IONPs since they are the easiest to synthesize via reproducible experimental methodologies. There has however been a growing interest in recent years for elongated IONPs, such as nanorods, nanorices and nanospindles, as they posess novel or improved physical and chemical characteristics compared to their spherical counterparts, such as superior cell uptake and improved efficiency as magnetic resonance imaging (MRI) contrast agents. In this chapter, we summarize the main synthetic routes that have been reported over the last decade to prepare elongated Fe3O4 and γ-Fe2O3 IONPs. The crucial parameters influencing the particle morphology and composition are discussed and the physicochemical features of these IONPs are compared to those of nanospheres. The chapter also presents an overview of the current biomedical applications of elongated IONPs, such as magnetic separation, targeted drug delivery, MRI and magnetic hyperthermia. The prospects of these systems as new platforms for theragnostic agents are furthermore discussed.