Single molecular hyperbranched nanoprobes for fluorescence and magnetic resonance dual modal imaging

We designed and synthesized a gadolinium(III)-decorated hyperbranched polyglycerol with a fluorescent polyhedral oligomeric silsesquioxane core (POSS–HPG–Gd), and demonstrated its application as a single-molecular nanoprobe for fluorescence and magnetic resonance dual imaging. The nanoprobe exhibited a uniform size with a mean diameter of 6 ± 1 nm revealed by transmission electron microscopy. POSS–HPG–Gd showed absorption and emission maxima at 405 and 570 nm in water, respectively, with a quantum yield of 41 ± 1%. Fluorescence cell imaging by confocal laser scanning microscopy using MCF-7 cancer cells as a model cell line revealed that the nanoprobe had been successfully internalized into the cytoplasm with high brightness, low cytotoxicity and good photostability. Further magnetic resonance imaging study demonstrated that POSS–HPG–Gd can serve as a promising probe for fluorescence and magnetic resonance dual modal imaging.