Design and Physicochemical Characterization of a Multifunctional Maisine-Based Microemulsion Incorporating...

Multifunctional nanocarriers capable of integrating imaging, magnetic functionality, and controlled drug delivery represent an important research topic in cancer nanomedicine. Herein, Mn-doped (Fe₃O₄) magnetite nanoparticles (MNPs) were engineered and incorporated into a Maisine CC-based oil-in-water microemulsion (ME) to obtain a multifunctional nanoplatform for magnetic resonance imaging (MRI), hyperthermia, and controlled drug release. A series of Mn-doped MNPs (1-10% Mn:Fe₃O₄) was synthesized by coprecipitation. X-ray diffraction confirmed the preservation of the cubic spinel upon Mn incorporation. The Mn incorporation resulted in MNPs made of crystallites (~9-12 nm) whose magnetic properties were improved. Also, 10% Mn led to a very good magnetic heating efficiency under alternating magnetic fields with a specific absorption rate of ~111 W·g^-1. The obtained MNPs proved to be T₂-weighted MRI contrast agents, with an increase in the r₂ values up to ~844 mM^-1·s^-1 after incorporation into ME. The optimized composition of Mn_10% was subsequently loaded with doxorubicin (DOX) and integrated into ME. Drug-release studies revealed a biphasic profile, characterized by an initial burst phase followed by sustained release up to 48 h. These findings demonstrate that dopant-engineered MNPs combined with a ME carrier can provide a versatile platform for integrating magnetic hyperthermia potential, T₂-weighted MRI contrast enhancement, and controlled chemotherapeutic delivery within a single nanostructured system.