The present invention relates to relates to a nanoparticle that includes a shell formed from a first monomer having a first charge and a second monomer different than the first monomer. The first and second monomers are copolymerized, and the shell encapsulates a core region and is associated with a charged entity having a second charge of opposite sign to the first charge. The present invention further relates to a nanoparticle having a neutral charge. The present invention further relates to nanoparticle dispersions, methods of making the nanoparticle, methods of method of imaging, methods of delivering drugs, and methods of delivering a high concentration of contrast enhancing and/or imaging agents.
