Scheme 1.
Schematic illustration of synthesis steps of our RGD2-conjugated dotted core-shell type ES-MION/GdON hybrid nanoparticles (FeGd-HN) with superhigh r1 and very low r2/r1 for high contrast T1-weighted MRI. (a): The seeds of ES-MIONs were synthesized using PAA as a stabilizer. (b): Gd3+ ions are adsorbed on the surfaces of ES-MION seeds via formation of ionic bonds between them and the –COOH groups from PAA, and then GdON are synthesized in situ on the surfaces of ES-MION seeds to form three different structures at different CGd. The dotted core-shell type FeGd-HN have superhigh r1 and very low r2/r1, and can be used for high contrast T1-weighted MRI. (c): The targeted ligand RGD2 is conjugated onto the surface of the dotted core-shell type FeGd-HN to construct FeGd-HN-RGD2 nanoparticles.