Given the tremendous potential for graphene quantum dots (QDs) in biomedical applications, a thorough understanding of the interaction of these materials with macrophages is essential because macrophages are one of the most important barriers against exogenous particles. Although the cytotoxicity and cellular uptake of graphene QDs were reported in previous studies, the interaction between nuclei and the internalized graphene QDs is not well understood. We thus systematically studied the nuclear uptake and related nuclear response associated with aminated graphene QDs (AG-QDs) exposure. AG-QDs showed modest 24-h inhibition to rat alveolar macrophages (NR8383), with a minimum inhibitory concentration (MIC) of 200 μg/mL. Early apoptosis was significantly increased by AG-QDs (100 and 200 μg/mL) exposure and played a major role in cell death. The internalization of AG-QDs was mainly via energy-dependent endocytosis, phagocytosis and caveolae-mediated endocytosis. After a 48-h clearance period, more than half of the internalized AG-QDs remained in the cellular cytoplasm and nucleus. Moreover, AG-QDs were effectively accumulated in nucleus and were likely regulated by two nuclear pore complexes genes (Kapβ2 and Nup98). AG-QDs were shown to alter the morphology, area, viability and nuclear components of exposed cells. Significant cleavage and cross-linking of DNA chains after AG-QDs exposure were confirmed by atomic force microscopy investigation. Molecular docking simulations showed that H-bonding and π-π stacking were the dominant forces mediating the interactions between AG-QDs and DNA, and were the important mechanisms resulting in DNA chain cleavage. In addition, the generation of reactive oxygen species (ROS) (e.g., •OH), and the up-regulation of caspase genes also contributed to DNA cleavage. AG-QDs were internalized by macrophages and accumulated in nuclei, which further resulted in nuclear damage and DNA cleavage. It is demonstrated that oxidative damage, direct contact via H-bonding and π-π stacking, and the up-regulation of caspase genes are the primary mechanisms for the observed DNA cleavage by AG-QDs.

中文翻译：

---

肺泡巨噬细胞中的石墨烯量子点：摄取-胞吐作用、细胞核中的积累、核反应和 DNA 裂解

鉴于石墨烯量子点（QD）在生物医学应用中的巨大潜力，彻底了解这些材料与巨噬细胞的相互作用至关重要，因为巨噬细胞是抵御外源颗粒的最重要屏障之一。尽管之前的研究报道了石墨烯量子点的细胞毒性和细胞摄取，但细胞核与内化石墨烯量子点之间的相互作用尚不清楚。因此，我们系统地研究了与胺化石墨烯量子点（AG-QD）暴露相关的核摄取和相关核反应。AG-QD 对大鼠肺泡巨噬细胞 (NR8383) 表现出适度的 24 小时抑制作用，最低抑制浓度 (MIC) 为 200 μg/mL。AG-QD（100 和 200 μg/mL）暴露显着增加早期细胞凋亡，并在细胞死亡中发挥重要作用。AG-QDs 的内化主要通过能量依赖性内吞作用、吞噬作用和小窝介导的内吞作用。经过 48 小时的清除期后，超过一半的内化 AG-QD 保留在细胞质和细胞核中。此外，AG-QDs在细胞核中有效积累，并且可能受到两个核孔复合物基因（Kapβ2和Nup98）的调节。AG-QD 被证明可以改变暴露细胞的形态、面积、活力和核成分。原子力显微镜研究证实了 AG-QD 暴露后 DNA 链的显着断裂和交联。分子对接模拟表明，氢键和π-π堆积是介导AG-QD与DNA相互作用的主导力，也是导致DNA链断裂的重要机制。此外，活性氧（ROS）（例如·OH）的产生和半胱天冬酶基因的上调也有助于DNA切割。AG-QDs被巨噬细胞内化并积累在细胞核中，进一步导致核损伤和DNA裂解。结果表明，氧化损伤、通过氢键和 π-π 堆积的直接接触以及 caspase 基因的上调是观察到的 AG-QD 切割 DNA 的主要机制。