title: The effect of sedimentation and diffusion on cellular uptake of gold nanoparticles.
abstract: In vitro experiments typically measure the uptake of nanoparticles by exposing cells at the bottom of a culture plate to a suspension of nanoparticles, and it is generally assumed that this suspension is well-dispersed. However, nanoparticles can sediment, which means that the concentration of nanoparticles on the cell surface may be higher than the initial bulk concentration, and this could lead to increased uptake by cells. Here, we use upright and inverted cell culture configurations to show that cellular uptake of gold nanoparticles depends on the sedimentation and diffusion velocities of the nanoparticles and is independent of size, shape, density, surface coating and initial concentration of the nanoparticles. Generally, more nanoparticles are taken up in the upright configuration than in the inverted one, and nanoparticles with faster sedimentation rates showed greater differences in uptake between the two configurations. Our results suggest that sedimentation needs to be considered when performing in vitro studies for large and/or heavy nanoparticles.
authors.affiliation: Department of Biomedical Engineering, Washington University, St. Louis, Missouri 63130, USA.
authors.forename: Eun Chul
authors.initials: EC
authors.lastname: Cho
authors.forename: Qiang
authors.initials: Q
authors.lastname: Zhang
authors.forename: Younan
authors.initials: Y
authors.lastname: Xia
mesh_terms: D018929:Cell Culture Techniques; D002470:Cell Survival; D002477:Cells / Q000378:metabolism*; D011232:Chemical Precipitation; D004058:Diffusion; D006046:Gold / Q000493:pharmacokinetics*; D053758:Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D010316:Particle Size; D013499:Surface Properties
chemical_list: D006046:Gold