Near-infrared fluorescent amphiphilic polycation wrapped magnetite nanoparticles as multimodality probes

Abstract

Construction of multifunctional/multimodality nanoparticles for cancer diagnosis and therapy has become an attractive area of investigation. In this report, we designed a multimodality nanoprobe for cell labeling, and can be detectable by both magnetic resonance and near infrared (NIR) fluorescence imaging. Multiple hydrophobic superparamagnetic iron oxide (SPIO) nanocrystals are self-assembled into nanocomposites in water phase with the help of partially alkylated hyperbranched polycation, polyethylenimine (PEI), which already conjugated with the indocyanine dye Cy5. 5 and can be used for cell imaging under NIR fluorescence imaging. The amphiphilic PEI/SPIO nanocomposites have a strong T 2 relaxivity. The iron uptake process in MCF-7/Adr displays a time dependent behavior. Confocal laser scanning microscopy reveals that the nanoprobes are internalized into the cytoplasm of MCF-7/Adr after 24 h labeling. Both MR and NIR fluorescence imaging showed strong image contrast against unlabeled cells. Under a clinical MRI scanner, labeled cells in gelatin phantom present much darker images than controlled ones. The T 2 relaxation rate of the labeled cells is 98. 2 s -1, significantly higher than that of the control ones of 2. 3 s -1. This study provides an important alternative to label MCF-7/Adr at optimized low dosages with high efficiency, and may be useful to label other biologically important cells and track their behaviors in vivo. © 2012 The Author(s).