Nanoimpact Based Single-Entity Detection of Proteins using a Nanopore-Nanoelectrode Nanopipette

Abstract

Nanopores and nanoelectrodes are two promising electrochemical methods for single entities analysis. Combining these two methods in one nanopipette apex allows us to simultaneously monitor the signal changes at nanopore and nanoelectrode when a biomolecule enters the nanopore or collides at the nanoelectrode. Here, I present a facile electrical method of detecting proteins at the single-molecule level in the solution based on the nanoimpact events at the nanoelectrode. Proteins such as Horse Spleen Ferritin, Bovine Hemoglobin, and Lysozyme are used to test the method. Open circuit potential (OCP) changes are detected from the nanoimpact events due to the collision of individual proteins at or near the vicinity of the floating nanoelectrode. Compared to the commonly used amperometric method, the detected OCP changes are more sensitive showing a bigger detection range and a higher time resolution. The new nanopipette based potentiometric method provides new opportunities to study various biological entities at a single-entity level with close to physiological conditions.