Engineering discoidal polymeric nanoconstructs with enhanced magneto-optical properties for tumor imaging

The invivo performance of nanoparticles is affected by their size, shape and surface properties. Fabrication methods based on emulsification and nano-precipitation cannot control these features precisely and independently over multiple scales. Herein, discoidal polymeric nanoconstructs (DPNs) with a diameter of 1000nm and a height of 500nm are demonstrated via a modified hydrogel-template strategy. The DPNs are obtained by mixing in one synthesis step the constituent polymers - poly(lactic acid-co-glycolic acid) (PLGA) and polyethylene glycol (PEG) dimethacrylate - and the payload with magneto-optical properties - 5nm ultra-small super-paramagnetic iron oxide nanoparticles (SPIOs) and Rhodamine B dye (RhB). The DPN geometrical features are characterized by multiple microscopy techniques. The release of the Rhodamine B dye is pH dependent and increases under acidic conditions by the enhanced hydrolysis of the polymeric matrix. Each DPN is loaded with ~100fg of iron and can be efficiently dragged by static and external magnetic fields. Moreover, the USPIO confinement within the DPN porous structure is responsible for a significant enhancement in MRI relaxivity (r2~500 (mMs)-1), up to ~5 times larger than commercially available systems. These nanoconstructs suggest a general strategy to engineer theranostic systems for anti-angiogenic treatment and vascular imaging. © 2013 Elsevier Ltd.