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Nanomaterials have shown promise for a variety of medical applications due to their unique properties and form factors compared to their bulk counterparts. Several novel medical technologies leveraging these properties are in various stages of development for applications including drug delivery, anti-microbial, diagnostic, or therapy technologies. A subset of these technologies, namely radiation therapy applications, require the nanoparticles to retain their structure and properties in radiation environments. It has been demonstrated that nanoparticle irradiation response can vary greatly from bulk materials response, as damage effects become dominated by sputtering and surface effects. As such, the stability, or rather the resistance of these materials towards radiation-induced degradation needs to be well understood to gauge the efficacy of candidate nanoparticles for these applications. This presentation details ongoing efforts at the In-situ Ion Irradiation Transmission Electron Microscopy (I3TEM) facility at Sandia National Laboratories to study and characterize the structural evolution of nanoparticles utilizing both in-situ and ex-situ ion beam irradiation techniques. Materials systems of interest include CeO2 nanoparticles, used for protecting healthy cells from radiation damage, and Au and HfO2 nanoparticles, used to increase local dose from proton therapies. Observed nanoparticle responses were varied and included stability, coalescence, ablation, cratering, sputtering, and swelling, depending on particle species, morphology, and irradiation condition. This diversity in nanoparticle irradiation response demonstrates the need for additional systematic study to determine the ultimate usefulness of various nanoparticle species for radiation therapy applications.
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