The influence of patterned magnetic beads on the self-assembly of magnetic nanoparticles

The assembly of nanostructures has critical importance for construction of higher structures to utilize the unique properties of nanoparticles (NPs). The future applications of nanotechnology mostly depend on directing the NPs on desired location or orientation in the proposed structure. Therefore, there is a need to understand the forces governing their self-assembly and approaches to control them. The magnetic nanoparticles (MNPs) also show unique properties and can be manipulated under the influence of a magnetic field. However, there is limited information on how to control their behavior in a well-controlled manner. In this study, the influence of the presence of magnetic layer of particles and their template structure on the controlled assembly of MNPs is investigated. Several unpatterned and patterned, hydrophobic and hydrophilic surfaces are prepared to assemble the magnetic beads (MBs) on these surfaces to investigate their influences on the assembly of MNPs that are composed of iron oxide (Fe3O4). Different surfaces with different patterns are successfully used and tested. It is found that the presence of a patterned surface between a magnetic field and the substrate that the MNPs are assembled on has an influence on the finally formed structure. It is also found that the assembly of the MNPs on surfaces is influenced by the solvent that the MNPs are dispersed in. This work may offer a new and simple approach for preparation of patterned and renewable surfaces, constructed from MNPs, which find use in many fields of science and technology.