Abstract
Iron oxide nanoparticles (IONP) have many possible uses including as MRI contrast agents, for drug delivery and cell labelling, but need to be stabilised and to be rendered biocompatible through appropriate coatings. Many current coatings are suboptimal, so we have investigated methodology to produce thin coatings using biocompatible polymers. We have produced uncoated IONP by a co-precipitation method in a range of sizes and subsequently coated the nanoparticles using poly(glycerol adipate) using the interfacial deposition method. To produce the necessary thin coatings a relatively small addition of polymer (approx. 0.1–0.2 mg polymer per 38 mg IONP) was necessary. A number of different PGA polymer variants with different physicochemical properties were used and the results suggested that the polymer properties also affected the coating process. Optimum coatings only a few nm thick (1–3 nm) were obtained with a linear poly(ethylene glycol)-PGA copolymer modified with 40% pendant oleic acid moieties. The resulting sterically stabilised IONP were stable against aggregation at and above physiological salt concentrations. Preliminary experiments demonstrated that the nanoparticles had relaxivity values comparable to commercially available IONP of a similar size and could be taken up readily by cells. This coating method therefore shows promise for a variety of medical applications.