Modulated deformation of lipid membrane to vesicles and tubes due to reduction of graphene oxide substrate under laser irradiation

Biomembrane transformations are closely related to many biological processes including endo/exocytosis and the cellular response to the local physical environment. In this work, we investigated the transformation between lipid membranes and lipid vesicles/tubes modulated by the solid substrate of graphene oxide (GO) aggregates under laser irradiation. We firstly fabricate a novel type of lipid@GO composite consisting of micrometer-sized GO aggregates surrounded by lamellar lipid membranes. Upon laser irradiation, lipid protrusion occurs and leads to the formation of vesicles adsorbed on the GO aggregate surface, with an average size as 0.43 times of the radius of GO aggregate. Both the location and the dynamic formation process of vesicles can be modulated. The arising of vesicles prefers to occur at edges of the GO planes rather than on surface of individual GO sheets within the GO aggregate. Furthermore, at a reduced laser power density, the lipid protrusion mainly grows to tubes instead of vesicles. Such transformations from lipid membrane to vesicles and tubes is ascribed to the reduction of GO to reduced-GO (rGO) under laser irradiation, probably along with the release of gases leading to the deformation of lipid membrane surrounding the GO surface.