Peptide bond detection via graphene nanogaps : a proof of principles study

In the context of the density functional theory atomistic modeling and non equilibrium Green function calculation, we show that, in the elastic regime of tunneling, glicyne based polypeptide chains translocating across a nano-gap between two semi-infinite graphene nano-ribbons leaves a specific transverse current signature for each peptide bond. Projected density of states and bond current analyses evidence that transmission occurs mainly through the closest ↵-carbons and side chains but a key role is also played by the partially resonant double bond of the peptide bond. The signal measured can be considered as a specific fingerprint of peptide bonds between small and neutral aminoacids with no polar/charge effects. On this basis, a newly conceived nano-device made of a graphene based array of nano-gap is proposed as a possible route to approach peptide sequencing with atomic resolution.