Self-assembled magnetic fluorescent polymeric micelles for magnetic resonance and optical imaging

Stable and cytocompatible hybrid PEGylated micelles with multimodal imaging capabilities are described. The F₃O₄-encapsulated polymeric micelles composed of cores containing magnetic nanoparticles and polyethylene glycol (PEG) shells are synthesized by self-assembly of amphiphilic poly(HFMA-co-VBK)-g-PEG copolymers and oleic acid stabilized Fe₃O₄ nanoparticles. The Fe₃O₄ magnetic nanoparticles in the core produce T₂-weighted MR imaging functionalities, whereas the small fluorescent monomer carbazole in the polymer shell introduces good fluorescent properties. The multifunctional micelles exhibit excellent paramagnetic properties with the maximum saturation magnetization of 9.61emu/g and transverse relaxivity rate of 157.44mm^-1S^-1. Invivo magnetic resonance imaging (MRI) studies reveal enhanced contrast between the liver and spleen. Fluorescence spectra show characteristic emission peaks from carbazole at 350nm and 365nm and vivid blue fluorescence can be observed by 2-photon confocal scanning laser microscopy (CLSM). Invivo optical imaging demonstrates the unique fluorescent characteristics of the Fe₃O₄-encapsulated polymeric micelles in the liver and spleen and the excellent multifunctional properties suggest potential clinical use as nanocarriers in magnetic resonance imaging and optical imaging. © 2013 Elsevier Ltd.