An official website of the United States government
Here’s how you know
Official websites use .gov
A .gov website belongs to an official government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.
Optical Spectroscopy and Single-Molecule Microscopy Combined to Study the Conformation of Confined Polymers
Published
Author(s)
B. Akerman, Kenneth D. Cole
Abstract
Optical microscopy is a powerful tool to study the global behavior of individual polymers, which we here combine with optical spectroscopy to study the conformation of confined polymers also at sub-optical length scales. Circular DNA molecules (52 and 220 kbp) are impaled on single gel fibers in agarose gels and stretched by an electric field ( 75 V/cm). Combined fluorescence microscopy and polarised UV-spectroscopy data on the coil-deformation show that the DNA-helix is less field-aligned than theoretically predicted for an unconfined polymer at the same apparent coil extension. This observation suggests that the gel obstacles deflect the DNA-path through the gel at sub-optical length scales. An analysis based on the reptation model indicate that the DNA chains are fully stretched along the path at all fields, while the average degree of field-alignment of the path itself increases with increasing field in agreement with biased reptation. The effective DNA-charge is evaluated to be (0.25 0.05)e per base-pair, in agreement with previous measurements in agarose gels. These conclusions are supported by studies of linear DNA-molecules which instead are anchored by covalent end-tethering to the gel fibers through a streptavidin-biotin bridge. The results demonstrate a microscopy-spectroscopy approach to characterize confined polymers at all length scales.
Akerman, B.
and Cole, K.
(2021),
Optical Spectroscopy and Single-Molecule Microscopy Combined to Study the Conformation of Confined Polymers, Macromolecules
(Accessed December 4, 2024)