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.