Bidirectional Peptide Translocation through Ultrasmall Solid-State Nanopores.

It is important to obtain the configuration of polypeptides and the sequence information on amino acids for understanding various life processes and many biological applications. Nanopores, as a newly developed single-molecule detection technology, exhibit unique advantages in real-time dynamics detection. Here, we designed a special peptide chain with 10 arginine in the head and achieved successful single-molecule detection by ultrasmall solid-state nanopores (2-3 nm). Unique bidirectional translocation signals were observed and explained under the framework of charge distribution of the peptide and interaction with the nanopore wall. Two natural peptide chains, histatin-5 and angiopep-2, were also explored by nanopore experiments to confirm our conjecture. Our designed peptide chain could realize multiple detections of the same peptide chain, offering possibilities for high-resolution peptide detection and fingerprinting by solid-state nanopores in the future.