Dispersion of Hydrophobic Co Supracrystal in Aqueous Solution.

Assembly of nanoparticles into supracrystals provides a class of materials with interesting optical and magnetic properties. However supracrystals are mostly obtained from hydrophobic particles and therefore cannot be manipulated in aqueous systems limiting their range of applications. Here we show that hydrophobic shaped supracrystals self-assembled from 8.2 nm cobalt nanoparticles can be dispersed in water by coating the supracrystals with lipid vesicles. A careful characterization of these composites objects provides insights into their structure at different length scales. The composite, suspended in water, retains the crystalline structure and paramagnetic properties of the starting material, which can be moved with an applied magnetic field.