Lee, Tae-RinChoi, MyunghwanKopacz, Adrian M.Yun, Seok-HyunLiu, Wing KamDecuzzi, Paolo2014-02-132013Lee, Tae-Rin, Myunghwan Choi, Adrian M. Kopacz, Seok-Hyun Yun, Wing Kam Liu, and Paolo Decuzzi. 2013. “On the near-wall accumulation of injectable particles in the microcirculation: smaller is not better.” Scientific Reports 3 (1): 2079. doi:10.1038/srep02079. http://dx.doi.org/10.1038/srep02079.2045-2322http://nrs.harvard.edu/urn-3:HUL.InstRepos:11708641Although most nanofabrication techniques can control nano/micro particle (NMP) size over a wide range, the majority of NMPs for biomedical applications exhibits a diameter of ~100 nm. Here, the vascular distribution of spherical particles, from 10 to 1,000 nm in diameter, is studied using intravital microscopy and computational modeling. Small NMPs (≤100 nm) are observed to move with Red Blood Cells (RBCs), presenting an uniform radial distribution and limited near-wall accumulation. Larger NMPs tend to preferentially accumulate next to the vessel walls, in a size-dependent manner (~70% for 1,000 nm NMPs). RBC-NMP geometrical interference only is responsible for this behavior. In a capillary flow, the effective radial dispersion coefficient of 1,000 nm particles is ~3-fold larger than Brownian diffusion. This suggests that sub-micron particles could deposit within diseased vascular districts more efficiently than conventional nanoparticles.en-USJournal Article2014-02-1310.1038/srep02079