Fluorescent Superparamagnetic Polylactide Nanoparticles by Combination of Miniemulsion and Emulsion/Solvent Evaporation Techniques

Biodegradable and fluorescent polylactide nanospheres loaded with iron oxide particles of different sizes (either 10 or 25 nm) were prepared by the combination of miniemulsion and emulsion/solvent evaporation techniques. Dynamic light scattering (DLS) and transmission electron microscopy (TEM) studies indicate that the obtained particles have uniform and spherical shape with an average size between 80-120 nm. The size of the particles mainly depends on the molecular weight of the used polylactide. The iron oxide content and the encapsulation homogeneity were determined from the thermogravimetric analysis and preparative ultracentrifugation, respectively. The obtained particles displayed superparamagnetic properties. Additional incorporation of the hydrophobic fluorescent dye gives the possibility to employ the obtained composite particles as model markers in order to study, for example, cellular uptake mechanism.