Magnetic nanoparticles of magnetite (Fe3O4) are an exciting class of nanomaterials with application in medical imaging and drug delivery. However, the clustering behaviour of these nanoparticles is not well understood, and has direct implications on their application.
Pictured below is a dark-field image of a cluster of magnetic nanoparticles. High-Angle Annular Dark-Field Scanning Transmission Electron Microscopy (HAADF-STEM) images have enhanced mass contrast, and heavier iron-based nanoparticles stand out from the supporting carbon film.
A cluster of magnetite nanoparticles imaged using HAADF-STEM. (Particles from Haw Choon Yian)
Understanding this clustering behaviour is important as it can affect the performance of the magnetic nanoparticles in the body. Magnetic clusters are formed predominantly through a combination of magnetic and van der waal interactions. An added complication is the introduced structure from sample preparation which introduces capillary forces that draw the particles together as the solvent evaporates. Eliminating this will be one of the goals in my PhD, and will enable better understanding and application of magnetic nanoparticles.
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