Related Experiment Video
Updated: Jul 5, 2026
08:48
Stretching Short Sequences of DNA with Constant Force Axial Optical Tweezers
Published on: October 13, 2011
Sizing of single globular DNA molecules by using a circular acceleration technique with laser trapping
Ken Hirano1, Hideya Nagata, Tomomi Ishido
1Health Technology Research Center, National Institute of Advanced Industrial Science and Technology, 2217-14, Hayashi-cho, Takamatsu, Kagawa, 761-0395, Japan. hirano-ken@aist.go.jp
Analytical Chemistry
|May 21, 2008
Summary
We developed a laser trapping method to size large DNA molecules by condensing them into nanoparticles. This technique accurately measures DNA size without prior conformational data and preserves DNA integrity for downstream applications like PCR.
Area of Science:
- Molecular Biology
- Biophysics
- Nanotechnology
Background:
- Accurate sizing of large DNA molecules is crucial for genomics and molecular biology.
- Existing methods often involve mechanical fragmentation or require prior knowledge of DNA conformation.
- Developing non-destructive, in situ sizing techniques for individual DNA molecules is highly desirable.
Purpose of the Study:
- To establish a novel method for in situ sizing of individual large DNA molecules using laser trapping.
- To demonstrate that DNA size can be determined by measuring the critical velocity of condensed DNA nanoparticles.
- To assess the compatibility of the condensation agents with downstream Polymerase Chain Reaction (PCR).
Main Methods:
- Reversible condensation of single DNA molecules into globular nanoparticles using poly(ethylene glycol) (PEG) and Mg(2+).
- In situ sizing of condensed DNA molecules using laser trapping and measurement of critical velocity during circular acceleration.
- Calibration of the sizing method using known DNA sizes (lambda, T4, and yeast chromosomes).
Main Results:
- The critical velocity of condensed DNA nanoparticles was found to be directly proportional to DNA size.
- Accurate sizing of a yeast chromosome III (285 kbp) was achieved (281 +/- 40 kbp) using the established calibration curve.
- Condensed DNA molecules retained their integrity and functionality, showing no significant deterioration in PCR efficiency.
Conclusions:
- Laser trapping of condensed DNA nanoparticles offers a robust method for sizing individual large DNA molecules without prior conformational information.
- The critical velocity serves as a reliable parameter for DNA sizing, enabling nanoparticle manipulation.
- The condensation process using PEG and Mg(2+) is compatible with PCR, allowing for subsequent molecular analysis.
