Nanopore-Based Protein Sequencing Using Biopores: Current Achievements and Open Challenges

The synergy of life sciences discoveries, biomolecular and protein engineering advances, and groundbreaking nanofabrication technologies, has introduced over the past years the wide use of the nanopore-based investigations of matter at the molecular level. This review focuses on the fundamental principles of alpha-hemolysin (alpha-HL) protein-based nanopores, as sensitive investigative tools that combine single-molecule detection with the ability to simultaneously manipulate single molecules, in otherwise complex samples. Herein, there are presented some of the efforts directed to control the capture dynamics and translocation speed of tailored polypeptides through the alpha-HL nanopore, by harnessing the electro-osmotic flow and nanopore-tweezing influence on individual molecules, which are engineered to resemble macrodipoles. The reported applications of this approach suggest a solution to enhance the temporal resolution of nanopore detection, prove the capability of the system in distinguishing between groups of distinct amino acids from the studied polypeptides, and propose a strategy to translate such single-molecule sensors in devices suitable for polypeptide sequencing at unimolecular level.