Molecular Dynamics Simulation Study Of Electrostatic Potentia Polarization In The Translocation Of Graphene Quantum Dots Across Membranes

Graphene quantum dots(GQDs)have shown promising potential applications in the field of biomedicine.To date,understanding the GQDs-cell membrane interactions remains a key issue to develop their biomedical applications,such as target drug delivery and bio-imaging.In this study,we mainly shed light on the mechanism of how to control the interactions between GQD and membrane by tuning the electrostatic potential(EP)of GQD.Charge distributions at the edge sites were adjusted to mimic the modified EP of GQD,given the fact that the physicochemical properties of GQD are usually regulated and determined by the grafted groups and doped atoms at edges.We found that,the dynamics of GQD in the GQD-membrane system can be regulated effectively by modulating the EP of GQD.Both the direct GQD-cell interactionsand the GQD-water interactions were found very crucial in the process.GQD with non-or less-polarized EP is hydrophobic,and it can easily translocates into the inner membrane from the bulk water,because of the decreased GQD-POPC van der Waals interactions and the favorable dehydration process.In the case of GQD with more polarized EP,the nanomaterial prefers to adsorb onto the membrane surface due to the strong electrostatic attraction between GQD and lipid headgroup,and especially,the high dehydration free energy of GQD can even lead to transient detachment from the surface.These findings would be helpful to understand the interactions between GQD-based nanomaterials and cell membranes,facilitating the rational design of GQDs-related biomedicines.