Superparamagnetic Hyperbranched Polyglycerol‐Grafted Fe₃O₄ Nanoparticles as a Novel Magnetic Resonance Imaging Contrast Agent: An In Vitro Assessment

Abstract

Abstract Hyperbranched polyglycerol‐grafted, magnetic Fe 3 O 4 nanoparticles (HPG‐grafted MNPs) are successfully synthesized by surface‐initiated ring‐opening multibranching polymerization of glycidol. Reactive hydroxyl groups are immobilized on the surface of 6–9 nm Fe 3 O 4 nanoparticles via effective ligand exchange of oleic acid with 6‐hydroxy caproic acid. The surface hydroxyl groups are treated with aluminum isopropoxide to form the nanosized macroinitiators. The successful grafting of HPG onto the nanoparticles is confirmed by infrared and X‐ray photoelectron spectroscopy. The HPG‐grafted MNPs have a uniform hydrodynamic diameter of (24.0 ± 3.0) nm, and are very stable in aqueous solution, as well as in cell culture medium, for months. These nanoparticles have great potential for application as a new magnetic resonance imaging contrast agent, as evidenced by their lack of cytotoxicity towards mammalian cells, low uptake by macrophages, excellent stability in aqueous medium and magnetic fields, and favorable magnetic properties. Furthermore, the possibility of functionalizing the hydroxyl end‐groups of the HPG with cell‐specific targeting ligands will expand the range of applications of these MNPs.