Different aggregation and shape characteristics of carbon materials affect biological responses in RAW264 cells

Abstract

IntroductionCarbon nanotubes (CNTs) have various shapes, including needle-like shapes and curled shapes, and the cytotoxicity and carcinogenicity of CNTs differ depending on their shapes and surface modifications. However, the biological responses induced by CNTs and related mechanisms according to the dispersion state of CNTs have not been extensively studied.Materials and methodsWe prepared multiwalled CNTs (MWCNTs) showing different dispersions and evaluated these MWCNTs in RAW264 cells to determine cytotoxicity, cellular uptake, and immune responses. Furthermore, RAW264 cells were also used to compare the cellular uptake and cytotoxicity of fibrous MWCNTs and spherical carbon nanohorns (CNHs) exhibiting the same degree of dispersion.ResultsOur analysis showed that the cellular uptake, localization, and inflammatory responses of MWCNTs differed depending on the dispersion state. Moreover, there were differences in uptake between MWCNTs and CNHs, even showing the same degree of dispersion. These findings suggested that receptors related to cytotoxicity and immune responses differed depending on the aggregated state of MWCNTs and surface modification with a dispersant. Furthermore, our results suggested that the receptors recognized by the cells differed depending on the particle shape.ConclusionTherefore, to apply MWCNTs as a biomaterial, it is important to determine the carcinogenicity and toxicity of the CNTs and to examine different biological responses induced by varying shapes, dispersion states, and surface modifications of particles.

Carbon Nanotubes: Smart Drug/Gene Delivery Carriers

“…This highuptake and low-toxicity of CNT agglomerates can facilitate drug/gene delivery through regulating agglomeration of CNTs in some delivery systems. Kuroda et al 65…”

Influence of Oxygen-Containing Functional Groups on the Environmental Properties, Transformations, and Toxicity of Carbon Nanotubes

“…Considered collectively, the various and often conflicting studies describing the effects of oxidation on CNT toxicity can be understood by the differential interaction of CNTs with cells based on aggregation state and the specific mechanism of toxicity, both of which vary depending on the organism of interest . Surface oxidation can promote toxic effects which manifest through certain pathways (e.g., DNA damage) but reduce toxic effects which emerge via others (e.g., membrane disruption) by virtue of the changes in dispersibility and membrane interactions produced by the addition of surface oxygen groups.…”

Cellular Responses of Human Lymphatic Endothelial Cells to Carbon Nanomaterials

“…Of the CNMs used in this study, the uptake weight of MWCNT was the highest at both time points. We previously compared the uptake of well-dispersed MWCNTs and CNHs by macrophage-like Raw264 cells, and reported that CNH was taken up but MWCNT was hardly taken up [30]. These results indicate that the cellular uptake mechanism of fibrous and spherical CNMs varies depending on the cell type.…”

“…We have already reported that the dispersion state of CNMs affects some cell lines differently [29,30]; accordingly, we first examined the dispersion state of the CNMs used in the aqueous solution. The sonicated CNMs were measured with a Zetasizer Nano ZS first (Table 1), and their shapes were observed with a TEM (Figure 1).…”