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Resolution of multiple ssDNA structures in free solution electrophoresis
Eve F Fabrizio1, Ali Nadim, James D Sterling
1Keck Graduate Institute of Applied Life Sciences, Claremont, California 91711, USA.
Analytical Chemistry
|January 8, 2004
Summary
High electric fields in microfluidic chips enable rapid DNA separation. However, single-stranded DNA (ssDNA) can form secondary structures, leading to multiple peaks during electrophoresis.
Area of Science:
- Analytical Chemistry
- Molecular Biology
- Microfluidics
Background:
- Microfluidic chips offer efficient heat dissipation for high-field electrophoresis.
- Free solution electrophoresis is a method for separating DNA molecules.
- Uncoated channels with high buffer concentrations minimize electroosmotic flow.
Purpose of the Study:
- To investigate the electrophoretic separation of DNA in microfluidic channels at high electric fields.
- To understand the factors causing multiple peaks during single-stranded DNA (ssDNA) separation.
Main Methods:
- Utilized microfluidic chips with uncoated channels and high buffer concentrations.
- Applied high electric field strengths (up to 600 V/cm) for DNA electrophoresis.
- Analyzed the electrophoretic behavior of both double-stranded DNA (dsDNA) and ssDNA labeled with Texas Red.
Main Results:
- Achieved rapid DNA separations (minutes) in an 8-cm channel due to high field strengths and efficient heat dissipation.
- Observed multiple peaks for ssDNA (<22 bases) but a single peak for dsDNA under high electric fields.
- Demonstrated that ssDNA secondary structures, influenced by base sequence, fluorophore, and G-quadruplex formation, cause peak multiplicity.
Conclusions:
- High electric field free solution electrophoresis in microfluidics is effective for DNA separation.
- The observed multiple peaks for ssDNA are attributed to sequence-dependent secondary structure formation.
- Fluorophore interactions and G-quadruplexes contribute to the complex electrophoretic behavior of ssDNA.