The elastic properties of single double-stranded DNA chains of different lengths as measured with optical tweezers
Colloid Polym Sci, (2006)DOI: 10.1007/s00396-006-1517-4
Abstract
Optical tweezers are microscopic tools with extraordinary precision in the determination of the position (±2 nm) of a colloid (diameter: ∼2.0 μm) in 3D-space and in the measurement of small forces in the range between 0.1 and 100 pN (pN=10(-12) N). Experiments are reported in which single double-stranded (ds)-DNA chains of different length 2,000 base pairs (bp), 3,000, 4,000, and 6,000 bp are spanned between two colloidal particles by use of appropriate molecular linkers. For the forces applied (≤40 pN) a fully reversible and well reproducible force-extension dependence is found. The data can be well described by both the worm-like chain model or by an approach developed by R. G. Winkler. For the resulting persistence length, a pronounced dependence on the ionic concentration in the surrounding medium is found.
Description
The elastic properties of single double-st... [Colloid Polym Sci. 2006] - PubMed - NCBI