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Collapse of DNA in ac electric fields
Chunda Zhou1, Walter W Reisner, Rory J Staunton
1North Carolina State University, Department of Physics, Raleigh, North Carolina 27695, USA.
Physical Review Letters
|July 21, 2011
Summary
Double-stranded DNA (dsDNA) collapses under AC electric fields, contrary to expectations of stretching. This unexpected behavior is attributed to counterion cloud dynamics, leading to DNA shortening.
Area of Science:
- Biophysics
- Physical Chemistry
- Molecular Biology
Background:
- Double-stranded DNA (dsDNA) is typically assumed to stretch in electric fields.
- Understanding DNA behavior in electric fields is crucial for applications in molecular manipulation and diagnostics.
Purpose of the Study:
- To investigate the behavior of dsDNA under AC electric fields.
- To challenge the conventional understanding of DNA stretching in electric fields.
Main Methods:
- Experimental application of AC electric fields at specific frequencies (hundreds of Hertz) to dsDNA.
- Observation and measurement of DNA length changes under these conditions.
Main Results:
- dsDNA was observed to collapse, not stretch, in AC electric fields.
- Confinement-stretched DNA significantly shortened to approximately one-quarter of its equilibrium length.
- The observed collapse is proposed to result from finite counterion cloud relaxation times.
Conclusions:
- Finite relaxation times of the counterion cloud drive DNA collapse in AC electric fields.
- This effect involves the partitioning of DNA into mutually attractive units.
- Alternative models for these attractive units warrant further investigation.
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