Micelles as nanocarriers of fluorescent and magnetic dendrimers for potential bimodal imaging applications

Bimodal magnetic-fluorescent materials that integrate magnetic and fluorescent properties have attracted significant attention due to their potential applications in biomedical imaging, biosensing, and therapeutic diagnosis. Tetra-amido-TEMPO 1, a compound that combines a fluorescent oligo (styryl)benzene dendrimer core with TEMPO radicals in its four branches was synthesized and used to form micelles with CTAB in water. DLS and Cryo-TEM techniques revealed the formation of micelles exhibiting a narrow particle size distribution, with an average hydrodynamic diameter ranging from 95 to 140 nm. After micellization, the ultraviolet–visible absorption and fluorescence emission intensities of micelles increased with tetra-amido-TEMPO concentration and EPR spectroscopy demonstrated consistent three-line spectra in the micelles, with the integrated area directly proportional to the amount of tetra-amido-TEMPO present. Besides, sufficient contrast enhancement in the proton T₁ relaxation time-weighted magnetic resonance images in vitro proved their ability to act as magnetic resonance imaging (MRI) contrast agents. These tetra-amido-TEMPO/CTAB micelles offer an aqueous-compatible system for this bimodal fluorescent-magnetic molecule, showcasing proof of concept of their potential for biomedical applications.