Quantitative Evaluation of Cellular Uptake and Trafficking of Plain and Polyethylene Glycol‐Coated Gold Nanoparticles

Abstract

This study addresses the cellular uptake and intracellular trafficking of 15-nm gold nanoparticles (NPs), either plain (i.e., stabilized with citrate) or coated with polyethylene glycol (PEG), exposed to human alveolar epithelial cells (A549) at the air-liquid interface for 1, 4, and 24 h. Quantitative analysis by stereology on transmission electron microscopy images reveals a significant, nonrandom intracellular distribution for both NP types. No particles are observed in the nucleus, mitochondria, endoplasmic reticulum, or golgi. The cytosol is not a preferred cellular compartment for both NP types, although significantly more PEG-coated than citrate-stabilized NPs are present there. The preferred particle localizations are vesicles of different sizes (<150, 150-1000, >1000 nm). This is observed for both NP types and indicates a predominant uptake by endocytosis. Subsequent inhibition of caveolin- and clathrin-mediated endocytosis by methyl-beta-cyclodextrin (MbetaCD) results in a significant reduction of intracellular NPs. The inhibition, however, is more pronounced for PEG-coated than citrate-stabilized NPs. The latter are mostly found in larger vesicles; therefore, they are potentially taken up by macropinocytosis, which is not inhibited by MbetaCD. With prolonged exposure times, both NPs are preferentially localized in larger-sized intracellular vesicles such as lysosomes, thus indicating intracellular particle trafficking. This quantitative evaluation reveals that NP surface coatings modulate endocytotic uptake pathways and cellular NP trafficking. Other nonendocytotic entry mechanisms are found to be involved as well, as indicated by localization of a minority of PEG-coated NPs in the cytosol.

The effect of nanoparticle degradation on poly(methacrylic acid)-coated quantum dot toxicity: The importance of particle functionality assessment in toxicology

“…Additionally, the QDots themselves were only allowed to be taken up by the cells for 30 min, resulting in relatively low uptake values compared to data obtained after longer incubations (see, for instance, Figure 4). Note that due to the resolution limit of optical microscopy no individual QDots inside the endosomes can be resolved, and that the fluorescence signals originate from clusters of QDots within the same endosomal vesicles [35]. In order to obtain more quantitative information, the level of cellassociated Cd 2+ was determined using a previously validated spectrophotometric technique [36], as described in the supporting information.…”

Investigating the Interaction of Cellulose Nanofibers Derived from Cotton with a Sophisticated 3D Human Lung Cell Coculture

“…Fluorescent latex, nontoxic micrometer-sized and nanosized spherical nano-objects have been used to study the entry mechanism and intracellular fate that these micrometer/nano-objects may take following suspension exposure. 21 In addition, Fe 2 O 3 and Au core nano-objects with an ATTO polymer shell, 27 as well as "naked" (i.e., no shell) citrate stabilized Au NPs and Au with a polyethylene glycol polymer shell NPs 28 have been shown to localize within lysosomes, but not the mitochondria, when exposed to the triple cell coculture model by either aerosol or suspension methods. Numerous studies have also investigated the potential adverse effects that nano-objects may elicit following their interaction with the epithelial airway barrier in vitro.…”

Nanoparticle Adhesion to the Cell Membrane and Its Effect on Nanoparticle Uptake Efficiency

“…8,9 Previous studies have shown that the uptake of NPs by living cells is affected by NP properties such as size [10][11][12][13] and surface. [14][15][16] However, NPs dispersed in a biological fluid are rapidly covered by biomolecules, such as proteins and lipids, forming a biomolecular 'corona' that effectively screens the bare NP surface. [17][18][19][20][21][22] When cells are exposed to NPs it is therefore, in realistic circumstances, typically not the bare NP surface that interacts with the cell but the NP-biomolecular corona complex.…”