Artificial magnetosomes: Molecularly restructured SPIONs with enhanced potential for magnetic imaging

Abstract

Magnetosomes represent an elegant example of ultrastable nanomaterials that nature produces by encapsulating magnetic nanoparticles in liposomal sub-compartments of magnetotactic bacteria. Materials chemists continue to strive for ways to mimic the performance of natural systems, but the artificial synthesis of magnetosomes remains unrealized. Here, we report molecular restructuring of the surface of oleic-acid-capped superparamagnetic iron oxide nanoparticles (SPIONs) to produce magnetosomes. Our strategy involves the use of triethylamine as an amphiphilic surfactant that through a combination of ligand exchange and rearrangement mechanisms, facilitates an organic-to-aqueous phase transfer of SPIONs while turning them into magnetosomes. These liposome-encapsulated SPIONs showed dynamic aqueous stability alongside noticeably improved magnetic properties. This improved their performance as contrast agents for magnetic resonance imaging (MRI) and magnetic particle imaging (MPI), the latter revealing a 33.5 % improvement in signal sensitivity over the original SPIONs. The presented strategy is extendable to prepare liposomal dispersions of other biomedically important nanomaterials.