Superparamagnetic iron oxides formulated in polylactide-co-glycolide/ D-alpha-tocopherol polyethylene glycol 1000 succinate (PLGA/TPGS) nanoparticles for high contrast MRI

摘要

Nano-sized polymeric drug carriers have played promising part for improving the therapeutic effect of drug by providing the drug, properties to enact in a sustained and long circulating manner. Iron oxide (IOs) nanoparticles on the other hand are useful in biomedicine for T2-weigheted magnetic resonance imaging (MRI), to visualize fine details using MRI especially the reticulo-endothelial system (RES), the place where they accumulate the most after administration. The idea of this work is to combine the sustained and long circulating property of the polymeric nanoparticles on the functionality of the IOs, so as to provide long circulating MRI contrast agent. We have used PLGA (a co-polymer of lactic acid and glycolic acid) as a model polymer, D-alpha-tocopherol polyethylene glycol 1000 succinate (TPGS) as surfactant and hydrophobic IOs synthesized by thermal decomposition. Encapsulation of IOs in the polymer matrix was done using a modified nanoprecipitation method, the difference in chemistry between the drug and the IOs was exploited, and parameter optimization was done, the IOs distribution in the polymeric matrix was observed to vary with the method of choice i.e. single emulsion method or nanoprecipitation method. The synthesized IOs PLGA/TPGS hybrid nanoparticles were tested invivo using xenograft mice for their ability to target tumour through enhanced permeability and retention (EPR).