The Interactions Between Graphene Oxide And Supported Lipid Bilayers Based On AFM

Understanding the interaction between graphene oxide(GO)and lipid membranes is of great importance for its various applications in biotechnology.In this thesis,we investigated the interaction between GO and charged supported lipid bilayers(SLBs)by in situ atomic force microscope(AFM)imaging.SLBs studied in the experiments included DOPC/DOTAP(4:1),DPPC/DOTAP(4:1),DOPC/DPTAP(4:1),DPPC/DPTAP(4:1)which were positively charged and DOPC/DOPS(7:3),DOPC/DPPG(4:1)and DPPC/DOPG(4:1)which were negatively charged.The influence of solid substrates on the interactions between GO and SLBs was also studied.In addition,the interaction between hydroxyl-functionalized graphene and SLBs was explored.It was found that GO could peel off a single layer of positively-charged SLBs and deposited on the hydrophobic part of the remaining sublayer.Then free lipid molecules would assemble on GO surface.For negatively-charged lipid bilayers,however,GO deposited to the SLBs only when its concentration was very high.These results indicate that,in addition to electrostatic interaction,the hydrophobic interaction plays an important role when GO sheets deposit onto the charged lipid bilayers,and should be helpful to understand possible cytotoxicity and antibiosis of graphene-related nanomaterials.