To understand the influence of carboxylation on the interaction of carbon nanotubes with cells, the amount of pristine multi-walled carbon nanotubes (P-MWNTs) or carboxylated multi-walled carbon nanotubes (C-MWNTs) coated with Pluronic® F-108 that were accumulated by macrophages was measured by quantifying CNTs extracted from cells. Mouse RAW 264.7 macrophages and differentiated human THP-1 (dTHP-1) macrophages accumulated 80-100 times more C-MWNTs than P-MWNTs during a 24-h exposure at 37 °C. The accumulation of C-MWNTs by RAW 264.7 cells was not lethal; however, phagocytosis was impaired as subsequent uptake of polystyrene beads was reduced after a 20-h exposure to C-MWNTs. The selective accumulation of C-MWNTs suggested that there might be receptors on macrophages that bind C-MWNTs. The binding of C-MWNTs to macrophages was measured as a function of concentration at 4 °C in the absence of serum to minimize the potential interference by serum proteins or temperature-dependent uptake processes. The result was that the cells bound 8.7 times more C-MWNTs than P-MWNTs, consistent with the selective accumulation of C-MWNTs at 37 °C. In addition, serum strongly antagonized the binding of C-MWTS to macrophages, suggesting that serum contained inhibitors of binding. Moreover, inhibitors of class A scavenger receptor (SR-As) reduced the binding of C-MWNTs by about 50%, suggesting that SR-As contribute to the binding and endocytosis of C-MWNTs in macrophages but that other receptors may also be involved. Altogether, the evidence supports the hypothesis that macrophages contain binding sites selective for C-MWNTs that facilitate the high accumulation of C-MWNTs compared to P-MWNTs.

中文翻译：

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细胞相关碳纳米管的定量：巨噬细胞对羧基化碳纳米管的选择性结合和积累。

要了解羧化对碳纳米管与细胞相互作用的影响，可以使用涂覆有Pluronic®F-108的原始多壁碳纳米管（P-MWNTs）或羧化多壁碳纳米管（C-MWNTs）的数量通过对从细胞中提取的CNT进行定量来测量巨噬细胞的累积积累。在37°C暴露24小时期间，小鼠RAW 264.7巨噬细胞和分化的人类THP-1（dTHP-1）巨噬细胞积累的C-MWNT比P-MWNT多80-100倍。RAW 264.7细胞对C-MWNT的积累没有致死性；但是，吞噬作用会受到损害，因为在暴露于C-MWNTs 20小时后，聚苯乙烯珠的吸收减少了。C-MWNTs的选择性积累表明巨噬细胞上可能有结合C-MWNTs的受体。在不存在血清的情况下，将C-MWNTs与巨噬细胞的结合作为4°C浓度的函数进行测量，以最大程度地降低血清蛋白或温度依赖性摄取过程的潜在干扰。结果是，细胞结合的C-MWNT数量是P-MWNT的8.7倍，这与C-MWNT在37°C下的选择性积累相一致。另外，血清强烈拮抗C-MWTS与巨噬细胞的结合，表明血清含有结合抑制剂。此外，A类清除剂受体（SR-As）的抑制剂使C-MWNTs的结合降低了约50％，这表明SR-As有助于巨噬细胞中C-MWNTs的结合和胞吞作用，但其他受体也可能参与其中。共，