Programmable Assembly of Iron Oxide Nanoparticles Using DNA Origami.

Magnetic iron oxide nanoparticles (IONPs) have received significant interest for the use in biomedical applications. The assembly of IONPs into larger superstructures has been used to modify the properties and functionality of these particles. For example, the clustering of IONPs can lead to improvements in MRI contrast generation, changes in heat generation during magnetic fluid hyperthermia, and alterations to pharmacokinetics and biodistribution. Nevertheless, the IONP clustering leads to significant heterogeneity in the assembly. Here, we demonstrate a method for using DNA origami to precisely control the number and positions of IONPs. We also showed how this technique can be used to module the functionality of IONP clusters by showing how MRI contrast generation efficiency can be tuned by altering the number and spacing of IONPs. Finally, we show that these property changes can be dynamically regulated, demonstrating the possibility for this technology to be used in biosensing applications.