Fig. 4. (a) Schematic of layer-by-layer technique to form the magnetic luminescent nanoparticles. Reproduced from ref. 85 with permission from American Chemical Society, copyright 2004. (b) Surface functionalization of magnetic nanosphere (MNSs) conjugation of amine-functionalized QDs to the surface of carboxylate-functionalized MNSs by NHS/EDC coupling method. Below are the respective HRTEM image of the MNSs before (left) and after (right) the surface modification. Reproduced from ref. 87 with permission from American Chemical Society, copyright 2010. (c) Schematic presentation of the fabrication of magnetofluorescent polyelectrolyte nanocomposites (MagFL-PEN) through electrostatic assembly and (d) SEM and TEM (inset) images of MagFL-PEN after adsorption of QD800(COOH). Reproduced from ref. 88 with permission from American Chemical Society, copyright 2011.