Single Molecule Protein Segments Sequencing by a Plasmonic Nanopore

Obtaining sequential and conformational informa-tion on proteins is vital to understand their functions. Although the nanopore-based electrical detection can sense single molecule (SM) protein and distinguish among different amino acids, this approach still faces difficulties in slowing down protein trans -location and improving ionic current signal-to-noise ratio. Here, we observe the unfolding and multistep sequential translocation of SM cytochrome c (cyt c) through a surface enhanced Raman scattering (SERS) active conical gold nanopore. High bias voltage unfolds SM protein causing more exposure of amino acid residues to the nanopore, which slows down the protein translocation. Specific SERS traces of different SM cyt c segments are then recorded sequentially when they pass through the hotspot inside the gold nanopore. This study shows that the combination of SM SERS with a nanopore can provide a direct insight into protein segments and expedite the development of nanopore toward SM protein sequencing.

Automated summary

Obtaining sequential and conformational information on proteins is important for understanding their functions. This study combines surface enhanced Raman scattering (SERS) with a nanopore to observe the unfolding and multistep sequential translocation of single molecule (SM) cytochrome c (cyt c). The high bias voltage unfolds the SM protein, slowing down the translocation and allowing specific SERS traces of different SM cyt c segments to be recorded. This research provides insight into protein segments and accelerates the development of nanopore-based SM protein sequencing.