Electrostatic co-assembly of magnetic nanoparticles and fluorescent nanospheres: a versatile approach toward bimodal nanorods

The elaboration of multimodal nanoparticles stimulates tremendous interest owing to their numerous potentialities in many applicative fields like optoelectronics, photonics and especially bioimaging. The concomitant association of various properties (optical, electrochemical, magnetic) allows for the use of complementary stimuli in order to probe the interactions between the nanoparticles and their surroundings.Nanoparticles (NPs) have thus become highly praised tools to image cells and tissues with a large contrast compatible with the dimensions of biological materials and the existence of quantum confinement effects induced by the reduced dimensions. In this context, the combination of magnetism and emissive properties such as fluorescence appears particularly attractive for non-invasive investigations, cell sorting or drug vectorization. Therefore, combining both fluorescence and magnetism requires the delicate construction of hybrid assemblies. Most of the magnetic nanoparticles are made of metallic oxides or alloys, e.g. gamma-Fe2O3, Fe3O4, FePt, while the target fluorescent entities are often organic dyes or quantum dots (QDs).
Comment: 9 figures, 1 table, 7 pages - to appear in Small 2009