Magnetic tracer compositions

A pharmacologically acceptable magnetic nanoparticle suitable for administration to a subject, the magnetic nanoparticle having a polymer composition coating, the polymer composition comprising:

• (i) a polymeric steric stabilizer that promotes dispersion of the magnetic nanoparticle in a liquid, the polymeric steric stabilizer comprising (i) an anchoring polymer segment having one or more binding groups that bind the polymeric steric stabilizer to the magnetic nanoparticle, and (ii) a steric stabilizing polymer segment comprising a polyacrylamide-co-polyalkylene oxide block copolymer, wherein the anchoring polymer segment is different from the steric stabilizing polymer segment;
• and
• (ii) a polymeric targeting moiety, comprising (i) an anchoring polymer segment having one or more binding groups that bind the polymeric targeting moiety to the magnetic nanoparticle, (ii) a linking polymer segment consisting of polyacrylamide, wherein the anchoring polymer segment is different from the linking polymer segment, and (iii) one or more targeting groups, each targeting group independently being a monosaccharide group for selectively targeting monosaccharide receptors, or an antibody, an antibody fragment, or an inhibitor for selectively targeting Prostate Specific Membrane Antigen (PSMA);
• wherein the linking polymer segment has at least 10 more polymerized monomer residue units than the stabilizing polymer segment.