This means that the micelle-templated nanoparticles are acting as intended: as a contrast agent. Individual nanoparticles are clearly far smaller than the voxel size, and are not resolved: rather each voxel of the aqueous phase contains many nanoparticle that raise its average electron attenuation level. No aggregates are visible, so the colloidal stability of the nanoparticles is intact at least to the extent necessary for this application, which is expected given their very high stability in electrolyte solutions (see above). Furthermore, the nanoparticles do not accumulate or deposit at the edges of the mineral particles, as the mineral phase particles do not exhibit bright edges. Again this is an indication that the stabilizing PEGMA-bottlebrush corona is functioning as intended. Indeed, this is a potentially more challenging requirement than the avoidance of flocculation, as mineral phases can present both positive and negative charges. Furthermore, the stabilization of nanoparticles not be possible to characterize water transport. Hence the diffusion rate provides a lower limit on the flow rates to be investigated. In principle a nanoparticle system should be superior to a small-molecule or ionic contrast agent, because in general larger objects diffuse more slowly. Here we test that for the micelle-templated nanoparticle system.