Recent studies suggest the great promise of functionalized nanosized graphene in biomedical applications, but the transmembrane translocation mechanisms of this two-dimensional nanomaterial have remained poorly understood. Understanding how graphene interacts with cell membrane is related to the fundamental biological responses and cytotoxicity, and is thereby one critical issue to be resolved before further applications of graphene in nanomedicine. Here, by using computer simulations, we explore the translocation of graphene nanosheet (GN) across lipid bilayer membrane and the roles of size and edge of GN in the process. We discover the permeation of small GN into bilayer center through insertion and rotation driven by transbilayer lateral pressure. For large GNs, the translocation undergoes a vesiculation process driven by complicated energetic contributions. Circular GNs with smooth edge show faster translocation but similar mechanisms with square GNs. Our results are fundamentally essential for optimized design of GNs towards extensively biological and biomedical applications.
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