Measuring single-bond rupture forces using high electric fields in micro-fluidic channels and DNA-oligomers as force tags
Stefanie Breisch 1, Julian Gonska 1, Helmut Deissler 2 and Martin Stelzle 1*
1 Naturwissenschaftliches und Medizinisches Institut
2 University Ulm
* To whom correspondence should be addressed. E-mail: stelzle{at}nmi.de.
Submitted on May 18, 2005
Revised on June 28, 2005
Accepted on 30 June 2005
 |
Abstract |
|---|
The disruption force of specific biotin-streptavidin bonds was determined using DNA-oligomers as force tags. Forces were generated by an electric field acting on a biotinylated fluorescently labeled DNA-oligomer. DNA-oligomers were immobilized via biotin-streptavidin bonds on the walls of micro-fluidic channels. Channel layout and fluid-based deposition process were designed to enable well-defined localized deposition of the oligomers in a narrow gap of the micro-channel. Electric fields of up to 400V/cm were applied and electric field induced desorption of DNA-oligomers was observed. At T = 30° C field induced desorption of both a 12mer as well as a 48mer yielded a streptavidin-biotin disruption force of 75fN. Streptavidin functionalized surfaces remained intact and could be reloaded with biotinylated oligomers. At approx. 20°C, however, no field induced unbinding of the oligomers was observed at electric field strength of up to 400V/cm, indicating a significant temperature dependence of the bond strength.
Key Words:
DNA oligomer, electric field, micro-channel, single-bond forces, streptavidin-biotin bond