Assembly of graphene oxide multilayer film for stable and sustained release of nitric oxide gas

Achieving slow release of gas molecules from a thin solid film is challenging because of the high release rates of gas molecules. Graphene oxide (GO) is a well-known material in the field of gas barriers and separation and is the best choice for long-term gas-release applications. To generate the release of nitric oxide (NO) gas from GO, N-diazeniumdiolate (NONOate)-an NO donor source-is conjugated to a GO sheet, and a multilayer film is fabricated via layer-by-layer (LbL) assembly. Two strategies are used in this study. First, the gas permeability is reduced owing to the two-dimensional structure of GO, which generates a physical barrier. This increases the length of the diffusion path. Second, the intra-H bonding of neighboring cation amines and intercalated water molecule between GO layers stabilizes the NO gas. When these two strategies are applied, the multilayer film exhibits release times 2 and 15 times longer than those for the solution and monolayer film, respectively. The sustained and highly controllable release of NO gas from the multilayer GO film is applied for cell-migration tests. The results indicate excellent cell migration-which is related to the surface modification-suitable for wound-healing applications.