Superparamagnetic ferrite nanoparticles (MFe 2 O 4 , where M = Fe, Co, Mn) were synthesized through a novel one-step aqueous coprecipitation method based on the use of a new type of alkaline agent: the alkanolamines isopropanolamine and diisopropanolamine. The role played by the bases on the particles' size, chemical composition, and magnetic properties was investigated and compared directly with the effect of the traditional inorganic base NaOH. The novel MFe 2 O 4 nanomaterials exhibited high colloidal stability, particle sizes in the range of 4−12 nm, and superparamagnetic properties. More remarkably, they presented smaller particle sizes (up to 6 times) and enhanced saturation magnetization (up to 1.3 times) relative to those prepared with NaOH. Furthermore, the nanomaterials exhibited improved magnetic properties when compared with nanoferrites of similar size synthesized by coprecipitation with other bases or by other methods reported in the literature. The alkanolamines were responsible for these achievements by acting both as alkaline agents and as complexing agents that controlled the particle size during the synthesis process and improved the spin rearrangement at the surface (thinner magnetic "dead" layers). These results open new horizons for the design of waterdispersible MFe 2 O 4 nanoparticles with tuned properties through a versatile and easily scalable coprecipitation route.

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We describe the synthesis and characterization of a superparamagnetic nanoobject that consists of a mesoporous iron trimesate-based MOF (i.e., MIL-100(Fe)) whose surface is coated with maghemite nanoparticles. This nano-object combines excellent colloidal stability, low cytotoxicity, and high anti-tumoral activity. It can be used in vivo as an efficient MRI contrast agent because of its excellent relaxivity. All of these properties make this nano-object a potential candidate as a bimodal therapeutic nanovector coupling drug-delivery and MRI properties.