Polyelectrolyte nanocapsules containing iron oxide nanoparticles as MRI detectable drug delivery system

The term "theranostic"has been designated for a material that combines the modalities of therapy and diagnostics. For example, theranostic nanoparticles deliver therapeutic drugs and diagnostic imaging agents at the same time within one dose. The aim of our work was to develop the method of formation of polyelectrolyte nanocapsules containing iron oxide nanoparticles as MRI visible drug delivery system. The nanocapsules were prepared by encapsulation of nanoemulsion droplets in hybrid shell formed by the layer-by-layer deposition of biocompatible polyelectrolytes, poly-L-glutamic acid (PGA), poly-L-lysine (PLL) and Fe2O3 nanoparticles. The outer layer of nanocapsules was tailored for biomedical applications by the adsorption of pegylated polyelectrolyte ( PGA-g-PEG). The average size of synthesized nanocapsules was around 150 nm and they were stable in cell culture medium containing serum. Using T-2 and T-1 NMR relaxation measurements as well as relaxation time weighted images with 9.4T preclinical MRI scanner we demonstrated that hybrid nanocapsules can be detected due to a locally altered contrast in the MR image. Thus, they may become a promising platform for future theranostic applications.