A nanopore is a small orifice with a diameter
ranging from 2 to 100nm. It can be extracted
from a biological organism (i.e. a protein channel)
or fabricated by drilling in a wafer using an
electron or ion beam (solid-state nanopore).
The generality of the detection principle and the
ease of single biomolecule detection suggest
many potential applications of the nanopore
technology in biosensing and diagnostics.
Nanopores operate on a basic principle: a
nanoscale hole is made on an impermeable membrane between two electrolytic fluid chambers. A steady “baseline” ion flux current across the pore can be observed when voltage is applied across the membrane. Monitoring the current across the pore enables molecular sensing, as transient changes in the ion flux across the pore can result from occupation of a macromolecule in the pore. Addition of charged biomolecules (e.g., DNA, proteins/peptides) to one of the fluid chambers results in continuous passing of biomolecules through the pore, which temporarily blocks the pore and produces a series of discrete fluctuations in the ion flux current. These current fluctuations communicate many properties of the sample, including the biomolecular size, concentration, and structure.