Shedding Light on Metal-Based Nanoparticles in Zebrafish by Computed Tomography with Micrometer Resolution

Supplementary 3D image stacks of microtomography data. 100 layer xy, xz, and yz image stacks Publication included as PDF file (open access, DOI: 10.1002/smll.202000746) ******************************************** Metal-based nanoparticles are clinically used for diagnostic and therapeutic<br> applications. After parenteral administration, they will distribute throughout<br> different organs. Quantification of their distribution within tissues in the 3D<br> space, however, remains a challenge owing to the small particle diameter.<br> In this study, synchrotron radiation-based hard X-ray tomography (SRμCT)<br> in absorption and phase contrast modes is evaluated for the localization of<br> superparamagnetic iron oxide nanoparticles (SPIONs) in soft tissues based<br> on their electron density and X-ray attenuation. Biodistribution of SPIONs<br> is studied using zebrafish embryos as a vertebrate screening model. This<br> label-free approach gives rise to an isotropic, 3D, direct space visualization<br> of the entire 2.5 mm-long animal with a spatial resolution of around 2<br> μm. High resolution image stacks are available on a dedicated internet<br> page (http://zebrafish.pharma-te.ch). X-ray tomography is combined with<br> physico-chemical characterization and cellular uptake studies to confirm the<br> safety and effectiveness of protective SPION coatings. It is demonstrated<br> that SRμCT provides unprecedented insights into the zebrafish embryo<br> anatomy and tissue distribution of label-free metal oxide nanoparticles.