title: Real time observation and kinetic modeling of the cellular uptake and removal of silicon quantum dots.
abstract: The time courses of uptake and removal of silicon quantum dots (Si-QDs) by human umbilical endothelial cells (HUVECs) were observed via confocal laser scanning microscope. Si-QDs were internalized via endocytosis and transported to late endosomes/lysosomes. The number of internalized Si-QDs increased with time and gradually reached a plateau value. When Si-QD-internalized HUVECs were subsequently washed and exposed to fresh culture medium, HUVECs removed internalized Si-QDs via exocytosis. The number of internalized Si-QDs decreased with time and gradually reached a plateau value. Not all internalized Si-QDs were removed from the cell interior but large numbers of internalized Si-QDs remained accumulated inside cells. A kinetic model based on the mass balance of Si-QDs and receptors in a cell was proposed to describe the cellular uptake and removal of Si-QDs. Model calculation fitted well with experimental results. Using this model, the dissociation constant between receptors and Si-QDs in the endosome, K(d,in), was found to be a determinant factor for Si-QD accumulation in cells after the removal process.
authors.affiliation: Department of Chemical System Engineering, Graduate School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan. s-ohta@chemsys.t.u-tokyo.ac.jp
authors.forename: Seiichi
authors.initials: S
authors.lastname: Ohta
authors.forename: Susumu
authors.initials: S
authors.lastname: Inasawa
authors.forename: Yukio
authors.initials: Y
authors.lastname: Yamaguchi
mesh_terms: D002460:Cell Line; D006801:Humans; D007700:Kinetics; D018613:Microscopy, Confocal; D008954:Models, Biological; D045663:Quantum Dots; D012825:Silicon
chemical_list: D012825:Silicon