Physical Society Colloquium

Interview for Faculty Position

Nanostructures for Single-Molecule Biophysics

Derek Stein

Kavli Institute, Delft University of Technology

Biomolecules such as deoxyribonucleic acids (DNAs), ribonucleic acids (RNAs) and proteins are the fundamental machinery of life. Thanks to advances in nanofabrication techniques, it is now possible to create devices that can be used to directly probe individual biomolecules at their natural, molecular length scales in their native aqueous environment. This talk will focus on two classes of such nanofluidic structures, nanochannels and solid-state nanopores, that both illustrate how the dominant physics can change at the nanoscale, and how these effects can be exploited in the study of biomolecules.

Nanofluidic channels confine and transport tiny amounts of fluid and are used to manipulate single molecules. In sufficiently small nanochannels, charge transport is dominated by surface properties of the channel, rather than bulk properties of the fluid. Also, the pressure-driven transport of DNA in nanochannels depends on its length in a manner that reflects the dynamical and statistical properties of DNA coils. These effects may be used to realize an ionic "transistor" or a DNA length separation device, respectively. Solid-state nanopores, whose diameters are commensurate with the diameter of the DNA molecule, can be used to detect the presence and conformation of a single molecule. This exquisite sensitivity can be applied to the study of DNA structure, dynamics, and interactions, and may ultimately lead to a high-speed, single-molecule sequencing technology.