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Label-free electrical quantification of the dielectrophoretic response of DNA.

Henning A, Henkel J, Bier FF, Hölzel R - PMC Biophys (2008)

Bottom Line: The method has been applied to the characterisation of the dielectrophoretic response of DNA without the need for any chemical modifications.The results are in good agreement with data from dielectrophoretic studies on fluorescently labelled DNA.Extension of the method down to the single molecule level appears feasible.PACS: 87.50.ch, 87.80.Fe, 87.85.fK.

View Article: PubMed Central - HTML - PubMed

Affiliation: Fraunhofer Institute for Biomedical Engineering, Am Mühlenberg 13, 14476 Potsdam-Golm, Germany. ralph.hoelzel@ibmt.fraunhofer.de.

ABSTRACT
A purely electrical sensing scheme is presented that determines the concentration of macromolecules in solution by measuring the capacitance between planar microelectrodes. Concentrations of DNA in the ng/mL range have been used in samples of 1 muL volume. The method has been applied to the characterisation of the dielectrophoretic response of DNA without the need for any chemical modifications. The influence of electrical parameters like duty cycle, voltage and frequency has been investigated. The results are in good agreement with data from dielectrophoretic studies on fluorescently labelled DNA. Extension of the method down to the single molecule level appears feasible.PACS: 87.50.ch, 87.80.Fe, 87.85.fK.

No MeSH data available.


Time course of capacitance for a typical DEP experiment. Capacitance of an aqueous solution of 18 nM pBluescript DNA with a DEP excitation of 1 MHz and 4VRMS. The duty cycle of the modulated signal was varied from 0.1% ("0") to 100% ("1.0"). The magnified view shows the change between 8 s DEP ("d") application and 2 s measurement ("m").
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Figure 3: Time course of capacitance for a typical DEP experiment. Capacitance of an aqueous solution of 18 nM pBluescript DNA with a DEP excitation of 1 MHz and 4VRMS. The duty cycle of the modulated signal was varied from 0.1% ("0") to 100% ("1.0"). The magnified view shows the change between 8 s DEP ("d") application and 2 s measurement ("m").

Mentions: For the quantification of molecular DEP response the dielectrophoresis field was applied to the electrodes for 8 s followed by a measuring period of 2 s. As a measure of DEP response the increase in capacitance during DEP was taken. In order to examine whether this is a suitable measure, DEP frequency and amplitude were kept constant at 1 MHz and 4 VRMS, resp., and the field was 100% square modulated, that means it was switched on and off, at a rate of 1 kHz. The modulation's duty cycle was varied from 0.1% to 100% (Fig. 3). This should result in dielectrophoretic action onto the DNA being proportional to the duty cycle.


Label-free electrical quantification of the dielectrophoretic response of DNA.

Henning A, Henkel J, Bier FF, Hölzel R - PMC Biophys (2008)

Time course of capacitance for a typical DEP experiment. Capacitance of an aqueous solution of 18 nM pBluescript DNA with a DEP excitation of 1 MHz and 4VRMS. The duty cycle of the modulated signal was varied from 0.1% ("0") to 100% ("1.0"). The magnified view shows the change between 8 s DEP ("d") application and 2 s measurement ("m").
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2666632&req=5

Figure 3: Time course of capacitance for a typical DEP experiment. Capacitance of an aqueous solution of 18 nM pBluescript DNA with a DEP excitation of 1 MHz and 4VRMS. The duty cycle of the modulated signal was varied from 0.1% ("0") to 100% ("1.0"). The magnified view shows the change between 8 s DEP ("d") application and 2 s measurement ("m").
Mentions: For the quantification of molecular DEP response the dielectrophoresis field was applied to the electrodes for 8 s followed by a measuring period of 2 s. As a measure of DEP response the increase in capacitance during DEP was taken. In order to examine whether this is a suitable measure, DEP frequency and amplitude were kept constant at 1 MHz and 4 VRMS, resp., and the field was 100% square modulated, that means it was switched on and off, at a rate of 1 kHz. The modulation's duty cycle was varied from 0.1% to 100% (Fig. 3). This should result in dielectrophoretic action onto the DNA being proportional to the duty cycle.

Bottom Line: The method has been applied to the characterisation of the dielectrophoretic response of DNA without the need for any chemical modifications.The results are in good agreement with data from dielectrophoretic studies on fluorescently labelled DNA.Extension of the method down to the single molecule level appears feasible.PACS: 87.50.ch, 87.80.Fe, 87.85.fK.

View Article: PubMed Central - HTML - PubMed

Affiliation: Fraunhofer Institute for Biomedical Engineering, Am Mühlenberg 13, 14476 Potsdam-Golm, Germany. ralph.hoelzel@ibmt.fraunhofer.de.

ABSTRACT
A purely electrical sensing scheme is presented that determines the concentration of macromolecules in solution by measuring the capacitance between planar microelectrodes. Concentrations of DNA in the ng/mL range have been used in samples of 1 muL volume. The method has been applied to the characterisation of the dielectrophoretic response of DNA without the need for any chemical modifications. The influence of electrical parameters like duty cycle, voltage and frequency has been investigated. The results are in good agreement with data from dielectrophoretic studies on fluorescently labelled DNA. Extension of the method down to the single molecule level appears feasible.PACS: 87.50.ch, 87.80.Fe, 87.85.fK.

No MeSH data available.