There is provided a microparticle composition suitable for molecular imaging, the composition comprising microparticles, wherein the microparticles comprise: a core microparticle structure having a central area and a shell, and wherein the core microparticle structure comprises (i) a phosphatidylcholine lipid: (ii) a phosphatidylethanolamine lipid comprising at least one maleimide moiety; and (iii) an alkoxylated fatty acid.