Magnetic enhancement of iron oxide nanoparticles encapsulated with poly(D,L-latide-co-glycolide)

Iron oxide nanoparticles encapsulated (11) with poly(D,L-lactide-co-glycolide) (PLGA) having high magnetic susceptibility were prepared by an emulsification-diffusion method. The preparation method consists of emulsifying an aqueous solution of PLGA in ethylacetate and extracting the organic solvent into a water phase. After mutual saturation of the organic and the continuous phases, PLGA precipitated to encapsulate nanoparticles (1) by adding excess water. As the homogenization strength in the emulsification step and the agitation speed in the solvent diffusion step increased, the mean size of IONE (iron oxide nanoparticles encapsulated) was reduced to a limiting size. The images under SEM and TEM showed that IONE has almost a spherical shape with 90-180 nm and that iron oxide nanoparticles with 8-20 nm were embedded in the PLGA matrix. The magnetization of IONE was measured with vibrating sample magnetometer (VSM), varying the size from 120 to 180 nm. It is observed that the small IONEs have a high magnetic susceptibility. It is attributed that the packing densities of iron oxide nanoparticles and IONE increased as their sizes decreased. (c) 2004 Elsevier B.V. All rights reserved.