Study of Uptake and Loss of Silica Nanoparticles in Living Human Lung Epithelial Cells at the Single Cell Level


The toxicology of nanomaterials is a blooming field of study, yet it is difficult to keep pace with the innovations in new materials and material applications. Those applications are quickly being introduced in research, industrial, and consumer settings. Even though the cytotoxicity of many types of nanoparticles has been demonstrated, the behavior of those particles in a biological environment is not yet fully known. This work characterized the following over time: protein adsorption on silica particle surfaces, the internalization of particles in human lung carcinoma (A549) cells when coated with different specific proteins or no proteins at all, and the cellular loss of particles following the removal of extracellular particles. Proteins were shown to quickly saturate the particle surface, followed by a competitive process of particle agglomeration and protein adsorption. Uptake of particles peaked at 8-10 h, and it was determined that, in this system, the charge of the protein-coated particles changed the rate of uptake if the charge difference was great enough. Cells internalized particles lacking any adsorbed proteins with approximately 3 times the rate of protein-coated particles with the same charge. Although particles exited cells over time, the process was slower than uptake and did not near completion within 24 h. Finally, analysis at the single cell level afforded observations of particle agglomerates loosely associated with cell membranes when serum was present in the culture medium, but in the absence of serum, particles adhered to the dish floor and formed smaller agglomerates on cell surfaces. Although data trends were easily distinguished, all samples showed considerable variation from cell to cell.



Second Department

Biological Sciences


Missouri University of Science and Technology. Environmental Research Center
Missouri University of Science and Technology. Department of Chemistry


The authors want to acknowledge financial support from the Environmental Research Center and the Chemistry Department at Missouri University of Science and Technology.

Keywords and Phrases

Cell Uptake; Human Lung Epithelial Cells; Silica Nanoparticles; Single Cell Imaging

International Standard Serial Number (ISSN)

1618-2642; 1618-2650

Document Type

Article - Journal

Document Version


File Type





© 2009 Springer Verlag, All rights reserved.

Publication Date

01 Jul 2009

PubMed ID