Tailoring the hydrophobicity of graphene for its use as nanopores for DNA translocation.

Graphene nanopores are potential successors to biological and silicon-based nanopores. For sensing applications, it is however crucial to understand and block the strong nonspecific hydrophobic interactions between DNA and graphene. Here we demonstrate a novel scheme to prevent DNA-graphene interactions, based on a tailored self-assembled monolayer. For bare graphene, we encounter a paradox: whereas contaminated graphene nanopores facilitated DNA translocation well, clean crystalline graphene pores very quickly exhibit clogging of the pore. We attribute this to strong interactions between DNA nucleotides and graphene, yielding sticking and irreversible pore closure. We develop a general strategy to noncovalently tailor the hydrophobic surface of graphene by designing a dedicated self-assembled monolayer of pyrene ethylene glycol, which renders the surface hydrophilic. We demonstrate that this prevents DNA to adsorb on graphene and show that single-stranded DNA can now be detected in graphene nanopores with excellent nanopore durability and reproducibility.