Brownian Relaxation Shakes and Breaks Magnetic Iron Oxide ‐Polymer Nanocomposites to Release Cargo

Iron oxide nanoparticles larger than ≈15 nm react to alternating magnetic fields by Brownian relaxation resulting in tumbling and shaking. It is shown that this shaking motion partially detaches and cleaves polymer coatings to release cargo molecules. As opposed to typical hyperthermia applications, this release mechanism is heat-fr ee hence broadening the application space of magnetic nanoparticles. AbstractMagnetic nanoparticles (NPs) are widely employed for remote controlled molecular release applications using alternating magnetic fields (AMF). Yet, they intrinsically generate heat in the process by N éel relaxation limiting their application scope. In contrast, iron oxide NPs larger than ≈15 nm react to AMF by Brownian relaxation resulting in tumbling and shaking. Here, such iron oxide NPs are combined with polymer shells where the shaking motion mechanically agitates and partially detaches the polymer chains, covalently cleaves a fraction of the polymers, and releases the prototypical cargo molecules doxorubicin and curcumin into solution. This heat-free release mechanism broadens the potential application space of polymer-functionalized magnetic NP composites.
Source: Small - Category: Nanotechnology Authors: Tags: Research Article Source Type: research