27141
title and abstract
Superparamagnetic Hollow Hybrid Nanogels as a Potential Guidable Vehicle System of Stimuli-Mediated MR Imaging and Multiple Cancer Therapeutics.
Hollow hybrid nanogels were prepared first by co-assembly of the citric acid-coated superparamagnetic iron oxide nanoparticles (SPIONs) (44 wt%) with the graft copolymer (56 wt%) comprising acrylic acid and 2-methacryloylethyl acrylate units as the backbone and poly(ethylene glycol) and poly(N-isopropylacrylamide) as the grafts in aqueous phase of pH 3.0 into the hybrid vesicle structure, followed by in situ covalent stabilization via the photo-initiated polymerization of MEA residues within vesicles. The resultant hollow nanogels, though slightly swollen, satisfactorily retain the structural integrity while the medium pH being adjusted to 7.4. Confining SPION clusters to such a high level (44 wt%) within the pH-responsive thin gel layer remarkably enhances the transverse relaxivity (r2) and renders the MR imaging highly pH-tunable. For example, with the pH being adjusted from 4.0 to 7.4, the r2 value can be dramatically increased from 138.5 to 265.5 mM-1 s-1. The DOX-loaded hybrid nanogels also exhibit accelerated drug release in response to both pH reduction and temperature increase due to the substantial disruption of the interactions between drug molecules and copolymer components. With magnetic transport guidance toward the target and subsequent exposure to alternating magnetic field, this DOX-loaded nanogel system possessing combined capabilities of hyperthermia and stimuli-triggered drug release showed superior in vitro cytotoxicity against HeLa cells as compared to the case with only free drug or hyperthermia alone. This work demonstrates that the hollow inorganic/organic hybrid nanogels show great potential to serve as a multimodal theranostic vehicle functionalized with such desirable features as guidable delivery of stimuli-mediated diagnostic imaging and hyperthermia/chemotherapies.