Magnetic nanoparticles (MNPs) attract much attention due to their unique magnetic properties and have a wide range of applications; from data storage media to cancer treatment hyperthermia. Iron oxide magnetite (Fe3O4) is a group of MNPs that exhibits high magnetic anisotropy and magnetization as well as biocompatibility making them a great tool to study magnetic properties at the nanoscale. When the length scale is reduced to a few nanometers, remarkable phenomena such as Superparamagnetism, Exchange Bias and Giant Magnetoresistance occur. The magnetic properties of individual particles depend on their size, shape, and their intrinsic magnetic characteristics. However, as the concentration of the particles increases, the magnetic properties of the particles become dependent on the interparticle interactions and collective magnetic behaviors are observed. The strength of the interaction depends on the length of the distance between adjacent particles and their environment. Modulating these interparticle interactions leads to different collective behaviors such as; superparamagnetism (SPM), superspin glass (SSG) and superferromagnetism (SFM). The current self-assembly methods used to make ordered structures of MNPs are limited to closed packed morphologies that are not capable of modulating the regularity and the interparticle spacing. Therefore, fail to efficiently tune MNP’s collective properties. We introduce a DNA-Assisted self-assembly technique which allows controlling the regularity and the distance between the nanoparticles with precision. First, Monodispersed MNPs are synthesized by thermal decomposition and then coated with gold followed by functionalization with thiol-modified oligonucleotides. DNA Functionalized MNPs are then pinned on the DNA origami surface, used as the building block to assemble MNPs, by hybridization of the complementary strands on the particles and the origami.

Study of collective magnetic behavior of iron oxide at nanoscale interparticle distances through DNA-assisted self-assembly

2019 Fall National Meeting

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