Magnetic Block Ionomer Complexes: Perfect Union between Well-defined Ionic- Nonionic Block Copolymers and Iron Oxide Nanoparticles for Applications in Nanomedicine

摘要

Multifunctional nanocarriers comprising a combination of therapeutic and imaging agents are of great interest for delivering drugs and tracking their biodistribution. With an aim to develop nanocarriers with high drug loadings that integrate imaging agents into one system, we herein report antibiotic-laden magnetic block ionomer complexes (MBICs) based on assembly of block ionomers with nanomagnetite and cationic drugs (fig. 1). The magnetite core was synthesized via reduction of Fe(III) acetylacetonate, which allows formation of discrete particles. Well-defined poly(ethylene oxide-b- acrylate) (PEO-b-PAA) nonionic-anionic block copolymers were synthesized through controlled free-radical polymerization (ATRP). The polymer was bound to the magnetic nanoparticle surfaces via ligand adsorption of the carboxylic acid segment of PAA, thereby creating a double corona structure with a nonionic PEO shell and an ionic layer of PAA. The polymeric nature of the PAA enhances binding through cooperative adsorption. The portion of carboxylates that are not attached to the magnetite provide binding sites for loading cationic drugs via ionic complexation. PEO was chosen as a block copolymer segment to improve biocompatibility and aid in dispersion in water through interparticle steric repulsion. The multi-cationic antibiotic, gentamicin, was employed as a model for encapsulation.