Facile synthesis of multifunctional nanoparticles encoded with quantum dots and magnetic nanoparticles: cell tagging and MRI.

In this study, fluorescence-encoded magnetic biocompatible nanoparticles (NPs) were constructed from CdSe@ZnS quantum dots (QDs) and FeO nanoparticles with a one-step reprecipitation-encapsulation method. The resultant hybrid NPs exhibit small size (∼130 nm in diameter), highly bright QDs, two-color emissions (green and red) under single-wavelength excitation, easy separation with a magnet and efficient cellular internalization. Energy transfer between the incorporated QDs was studied to better tailor the encoded fluorescence, and 11 barcodes were obtained by adjusting the ratio of green and red QDs.