Single-molecule detection of proteins using nanopores

Abstract

Recently, protein and synthetic nanopores have been employed extensively as single-molecule probes to illuminate the functional features of proteins, including their binding affinity to different ligands, backbone flexibility, enzymatic activity and folding state. In this chapter, I present a brief overview in this emerging area of biosensing. The underlying principle of detection is that the device is based upon a single nanopore drilled into an insulating membrane, which is immersed in a symmetric chamber containing electrolyte solution. The application of a transmembrane potential across the membrane will enable the recording of a well-defined electric current due to the flow of ions crossing the nanopore. The partitioning of single proteins into the interior of the nanopore is detected by discrete current fluctuations that depend upon the interaction between the proteins and the nanopore. The detection mechanisms include chemical modification and genetic engineering of protein nanopores, electrophoretic capture of proteins via movable nucleic acid arms, and functionalization of the inner surface of synthetic nanopores. This approach holds promise for the exploration of proteins at high temporal and spatial resolution. Moreover, nanopore probe techniques can be employed in high-throughput devices used in biomedical molecular diagnosis and environmental monitoring.