C₆₀fullerene localization and membrane interactions in RAW 264.7 immortalized mouse macrophages

Abstract

There continues to be a significant increase in the number and complexity of hydrophobic nanomaterials that are engineered for a variety of commercial purposes making human exposure a significant health concern. This study uses a combination of biophysical, biochemical and computational methods to probe potential mechanisms for uptake of C60 nanoparticles into various compartments of living immune cells. Cultures of RAW 264.7 immortalized murine macrophage were used as a canonical model of immune-competent cells that are likely to provide the first line of defense following inhalation. Modes of entry studied were endocytosis/pinocytosis and passive permeation of cellular membranes. The evidence suggests marginal uptake of C60 clusters is achieved through endocytosis/pinocytosis, and that passive diffusion into membranes provides a significant source of biologically-available nanomaterial. Computational modeling of both a single molecule and a small cluster of fullerenes predicts that low concentrations of fullerenes enter the membrane individually and produce limited perturbation; however, at higher concentrations the clusters in the membrane causes deformation of the membrane. These findings are bolstered by nuclear magnetic resonance (NMR) of model membranes that reveal deformation of the cell membrane upon exposure to high concentrations of fullerenes. The atomistic and NMR models fail to explain escape of the particle out of biological membranes, but are limited to idealized systems that do not completely recapitulate the complexity of cell membranes. The surprising contribution of passive modes of cellular entry provides new avenues for toxicological research that go beyond the pharmacological inhibition of bulk transport systems such as pinocytosis.

Fullerene C60 Penetration into Leukemic Cells and Its Photoinduced Cytotoxic Effects

“…Our data are in agreement with studies where the uptake of pristine C 60 in nano-aggregated form by MCF10A normal breast epithelial cells [16], lung epithelial adenocarcinoma A549 cells [28], and leukemic monocyte macrophage RAW 264.7 cells [29] was demonstrated.…”

Oxygen driven soot formation

“…The formation of carbonaceous material from combustion, ranging from polycyclic aromatic hydrocarbons, to nanoparticles and eventually soot, is of prime importance for the environment and human health [1][2][3][4][5][6][7][8][9][10][11][12]. A large research effort has been focused on lowering the emission of hydrocarbons, nanoparticles and particulate matter.…”

A Multiparametric Study of Internalization of Fullerenol C60(OH)36 Nanoparticles into Peripheral Blood Mononuclear Cells: Cytotoxicity in Oxidative Stress Induced by Ionizing Radiation

“…The ability of NPs to assemble and interconnect strongly depends on their physical and chemical characteristics and their surface properties, including size, shape, ratio of electric charges and hydrophobicity, and last, but not least, on the concentration and the presence of functional groups [2,3]. These factors, as well as ability to interact with superficial cellular receptors also determine the rate and mechanism of entry of NMs into a cell [4].…”

“…Due to those bonds, it has a pseudo-aromatic structure resulting from delocalization of π-electrons over the carbon core. This structure allows easy reaction with oxygen free radicals [4][5][6]. It was shown that pristine C 60 fullerene was non-toxic at low concentrations, and it was able to penetrate cellular plasma membrane.…”