Stacked Graphene-Al₂O₃ Nanopore Sensors for Sensitive Detection of DNA and DNA–Protein Complexes

Abstract

We report the development of a multilayered graphene-Al₂O₃ nanopore platform for the sensitive detection of DNA and DNA–protein complexes. Graphene-Al₂O₃ nanolaminate membranes are formed by sequentially depositing layers of graphene and Al₂O₃, with nanopores being formed in these membranes using an electron-beam sculpting process. The resulting nanopores are highly robust, exhibit low electrical noise (significantly lower than nanopores in pure graphene), are highly sensitive to electrolyte pH at low KCl concentrations (attributed to the high buffer capacity of Al₂O₃), and permit the electrical biasing of the embedded graphene electrode, thereby allowing for three terminal nanopore measurements. In proof-of-principle biomolecule sensing experiments, the folded and unfolded transport of single DNA molecules and RecA-coated DNA complexes could be discerned with high temporal resolution. The process described here also enables nanopore integration with new graphene-based structures, including nanoribbons and nanogaps, for single-molecule DNA sequencing and medical diagnostic applications