<p>Ultrasmall<b> </b>manganese ferrite nanoparticles display interesting features in
bioimaging and Fenton nanocatalysis. However, little is known about how to
optimize these nanoparticles to achieve simultaneously the highest efficiency
in both types of applications. Herein, we present a cost-efficient synthetic
microwave method that enables manganese ferrite nanoparticles to be produced with
excellent control in size, chemical composition and colloidal stability. We
show how the reaction’s pH has a substantial impact on the Mn incorporation into
the nanoparticles and the level of Mn doping can be finely tailored to a wide
range (Mn<sub>x</sub>Fe<sub>3-x</sub>O<sub>4</sub>, 0.1 ≤ x ≤ 2.4). The
magnetic relaxivities (1.6 ≤ r<sub>1 </sub>≤ 10.6 mM<sup>-1</sup>s<sup>-1</sup>
and (7.5 ≤ r<sub>2 </sub>≤ 29.9 mM<sup>-1</sup>s<sup>-1</sup>) and Fenton/Haber-Weiss
catalytic properties measured for the differently doped nanoparticles show a
strong dependence on the Mn content and, interestingly, on the synthetic reaction’s
pH. Positive contrast in magnetic resonance imaging is favored by low Mn
contents, while dual mode magnetic resonance imaging contrast and catalytic
activity increases in nanoparticles with a high degree of Mn doping. We show
that this is valid in solution, in a murine model and intracellularly
respectively. Besides, this synthetic protocol allows core-radiolabeling for
high-sensitive molecular imaging while maintaining relaxometric and catalytic
properties. All of these results show the robust characteristics of these multifunctional
manganese ferrite nanoparticles as theranostic agents.</p>
Manganese Ferrite Nanoparticles Encapsulated into Vitamin E/Sphingomyelin Nanoemulsions as Contrast Agents for High‐Sensitive Magnetic Resonance Imaging
