We have developed nanoparticle coatings that are water dispersible, have a strong affinity for binding to magnetic nanoparticles, and can be easily modified for attaching the coating to biological materials. The nanoparticle coatings comprise a polyacrylic acid based backbone onto which PEG-based oligomers are appended by modifying the native carboxyl groups of the PAA backbone. The PEG-based oligomers include functional groups on their terminal ends, which are chosen to provide a certain function. Some of the terminal functional groups bind the coatings to the nanoparticle's surface, while others provide reactive sites for binding other compounds to the coating. The method we developed for making these coatings allows one to tune the number and type of PEG-based oligomers appended to the PAA backbone based on the desired properties of the coating.
In accordance with a composition aspect of the invention, the nanoparticle coatings comprise repeating polyacrylic acid monomers covalently bound together in an aliphatic chain having a plurality of carboxylic acid functional groups and modified carboxylic acid functional groups extending there from. A first portion of the modified carboxylic acid functional groups are modified by a PEG oligomer having a terminal methoxy functional group and a second portion of the modified carboxylic acid functional groups are modified by a PEG oligomer having at least one terminal catechol group.
