Identification of Spherical and Nonspherical Proteins by a Solid-State Nanopore.

The three-dimensional structure of a protein plays an important role in protein dynamics in the biological system of human. By now, it remains a challenge to characterize and quantify the shape of a protein at the single-molecule level. The nanopores, as a novel single-molecule sensor, has been widely applied in many fields such as DNA sequencing and human diseases diagnosis. In this paper, we investigated the translocation of spherelike con.A and the prolate bovine serum albumin (BSA) under an electric field by a solid-state nanopore. By analyzing the ionic current, the con.A and the BSA could be characterized and differentiated due to their intrinsic shape difference. Because the prolate BSA will have the preferred orientations for a higher electric field, when it is residing inside the nanopore, multiple ionic current blockade levels will be observed. While for the spherical con.A, there is only one ionic current blockade level. The method presented here will be potentially applied to fingerprint a single protein as a new method having the features of low cost and high throughput in the near future.