石墨烯和氧化石墨烯对细胞脂膜破坏作用研究

Destructive extraction of phospholipids from cell membranes by graphene and graphene oxide nanosheets

石墨烯作为一种新型材料不断受到关注,如何与生物分子(如蛋白质、细胞脂膜等)发生作用是其生物相容性方面的重要问题之一.石墨烯以sp2杂化的碳为主的成键方式,形成独特的二维结构,具有显著的疏水特征.细胞脂膜主要是由双亲的磷脂分子在水环境中自组装而成.早期实验组观察到石墨烯的抗菌现象,认为锋利的侧边可能会以类似于刀片的方式插入、切割细胞膜.在理论上,我们阐述了一种可能的石墨烯的细胞毒性的分子机理:石墨烯不仅会通过主动插入、切割细胞脂膜,而且会将大量的磷脂分子抽离细胞脂膜,从而破坏细胞膜的完整性导致细胞死亡;尽管氧化石墨烯表面分布着大量的亲水氧化基团,但氧化基团高关联分布特点致使氧化石墨烯有着类似的破坏细胞脂膜的能力.本文综述了石墨烯、氧化石墨烯纳米片与细胞脂膜相互作用的理论研究进展,着重阐述石墨烯和氧化石墨烯从细胞脂膜中大量地抽取磷脂分子的过程以及在此过程中环境水分子所起的关键作用.在石墨烯、氧化石墨烯和细胞脂膜的相互作用中所表现出的特点有可能是一种共性,也会出现在其他疏水特性的纳米材料(如纳米碳管、碳纳米线和大面积的富勒烯等)与细胞脂膜的相互作用过程中.

While graphene has attracted wide interests, the emergence of its relevant nanomaterials represents an increase in the potential hazard to human health. Consequently, there is currently an urgent need to understand the interaction between graphene and biomolecules, such as proteins and cell membranes. Experimentally, graphene and graphene-oxide nanosheets have shown strong antibacterial activity, and its cytotoxicity was hypothesized to arise from direct interactions between graphene and bacteria cell membranes. In theory, we revealed an important molecular mechanism that underlies the interaction between lipid membranes and graphene/graphene oxide, to understand the strong antibacterial activity of graphene/graphene-oxide nanosheets, i.e., the graphene could penetrate/cut into and destructively extract out large amounts of phospholipids from lipid membranes, inducing the degradation of cell membranes; although there exist hydrophilic oxidized-groups on graphene oxide nanosheets, the high correlation between oxidation loci ensures the similar ability of graphene oxide nanosheets to damage cell membranes. In this paper, we review the recent theoretical progress on graphene/graphene-oxide nanosheets and their interactions with lipid membranes. In particular, we focus on the destructive extraction of lipid molecules from cell membranes by graphene and graphene oxide and the significance of water molecules during the extracting processes. The water-mediated interactions of graphene and graphene oxide with lipid membranes presented here are expected to be common for the interaction between nanomaterials with hydrophobic characteristics and cell membranes.