Scientists at National Institute of Standards and Technology (NIST) are using nanopores (membrane gates less than 2 nanometers wide) to identify the type of molecules that are passing through the openings. The method measures the electrical change of the ionic fluid that is pumped through the nanopores along with the molecules in question. Because each molecule reduces the amount of the ionic fluid passing through based on its size and shape, the electrical measurements reveal which molecule is traversing the gate. Once developed, nanopore based technology may allow for all kinds of new diagnostic devices that can identify pathogens, proteins, and other reagents.
Nanopores are not new themselves; for more than a decade, scientists have sought to use a nanopore-based electrical detector to characterize single-stranded DNA for genetic sequencing applications. More recently, NIST scientists turned their attention to using nanopores to identify, quantify and characterize each of the more than 20,000 proteins the body produces—a capability that would provide a snapshot of a patient’s overall health at a given moment. But while nanopores permit molecules to enter into them one at a time, determining what specific individual molecule has just passed through has not been easy.
To address this problem, members of the NIST team that previously developed a method to distinguish both the size and concentration of each type of molecule the nanopore admits have now answered the question of just how these single molecules interact with the nanopore. Their new theoretical model describes the physics and chemistry of how the nanopore, in effect, parses a molecule, an understanding that will advance the use of nanopores in the medical field.