Oil core-PEG shell nanocarriers for in vivo MRI imaging

Oil-in-water emulsions represent a promising carrier for in vivo imaging because of the possibility to convey poorly water-soluble species. To promote accumulation at the tumor site and prolong circulation time, reduction of carrier size and surface PEGylation plays a fundamental role. In this work a novel, simple method to design an oil-core/PEG-shell nanocarrier is reported. A PEG-shell is grown around a monodisperse oil-in-water nanoemulsion with a one-pot method, using the radical polymerization of poly(ethylene glycol)diacrylate. PEG polymerization is triggered by UV, obtaining a PEG-shell with tunable thickness. This core-shell nanosystem combines the eluding feature of the PEG with the ability to confine high payloads of lipophilic species. Indeed, the core is successfully loaded with a lipophilic contrast agent, namely super paramagnetic iron oxide nanocubes. Interestingly, it is demonstrated an in vitro and an in vivo MRI response of the nanocapsules. Additionally, when the nanosystem loaded with nanocubes is mixed with a fluorescent contrast agent, indo-cyanine green, a relevant in vitro photoacoustic effect is observed. Moreover, viability and cellular uptake studies show no significant cell cytotoxicity. These results, together with the choice of low cost materials and the scale up production, make this nanocarrier a potential platform for in vivo imaging.