Complex and non-sequential current signatures of a β-hairpin peptide confined in a nanopore

Nanopore sensing is widely used for single-molecule detection, originally applied to nucleic acids and now extended to protein sensing. Our study focuses on the complex conformational changes of peptides in nanopores, which may have implications for peptide fingerprinting and protein identification. Specifically, we investigated the interaction of a β-hairpin peptide (SV28) within an α-hemolysin (αHL) nanopore. Our experiments revealed that SV28 is captured via dielectrophoresis and exhibits long dwell times within the nanopore, leading to multiple current blockade levels. Unlike DNA hairpins, the peptide showed non-sequential transitions among four distinct blockade levels. This complex behavior indicates that the peptide dynamics in nanopores cannot be simply modeled along a single reaction coordinate. Our findings provide insights into peptide-nanopore interactions, which are potentially useful for developing nanopore-based peptide identification technologies.