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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.


Cross section of the interdigitated electrodes. Each aluminium electrode (A, B) consists of 35 fingers of 800 μm length. The shading of the DNA solution is meant to illustrate the possible DNA attraction during dielectrophoresis.
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Figure 1: Cross section of the interdigitated electrodes. Each aluminium electrode (A, B) consists of 35 fingers of 800 μm length. The shading of the DNA solution is meant to illustrate the possible DNA attraction during dielectrophoresis.

Mentions: The electrode chamber has been prepared from commercially available surface acoustic wave resonators (R2633, Siemens/Matsushita). Their characteristic frequency of 433.6 MHz lies far away from the frequencies chosen in this study. Therefore the influence of surface waves can be neglected here. A quartz substrate of 4 mm length, 1 mm width and 0.5 mm height carries two pairs of 300 nm thick interdigitated aluminium electrodes. Each electrode consists of 35 fingers of 800 μm length and 2.3 μm width leaving an interelectrode gap of 1.7 μm (Fig. 1) [22]. A silicon rubber gasket of 0.5 mm thickness was trimmed using a CO2 laser plotter (Epilog Laser Legend 24TT) and mounted around the substrate with double-sided adhesive tape. It was sealed with a cover glass and immersion oil. Fluid samples of 12 μL volume were pipetted onto the electrodes leaving an air-filled space between fluid and gasket. Thus the sample only came into contact with the electrodes, the quartz substrate and the cover glass. This helped to minimise contaminations which can easily occur due to the sample's high surface-to-volume ratio.


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

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

Cross section of the interdigitated electrodes. Each aluminium electrode (A, B) consists of 35 fingers of 800 μm length. The shading of the DNA solution is meant to illustrate the possible DNA attraction during dielectrophoresis.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 1: Cross section of the interdigitated electrodes. Each aluminium electrode (A, B) consists of 35 fingers of 800 μm length. The shading of the DNA solution is meant to illustrate the possible DNA attraction during dielectrophoresis.
Mentions: The electrode chamber has been prepared from commercially available surface acoustic wave resonators (R2633, Siemens/Matsushita). Their characteristic frequency of 433.6 MHz lies far away from the frequencies chosen in this study. Therefore the influence of surface waves can be neglected here. A quartz substrate of 4 mm length, 1 mm width and 0.5 mm height carries two pairs of 300 nm thick interdigitated aluminium electrodes. Each electrode consists of 35 fingers of 800 μm length and 2.3 μm width leaving an interelectrode gap of 1.7 μm (Fig. 1) [22]. A silicon rubber gasket of 0.5 mm thickness was trimmed using a CO2 laser plotter (Epilog Laser Legend 24TT) and mounted around the substrate with double-sided adhesive tape. It was sealed with a cover glass and immersion oil. Fluid samples of 12 μL volume were pipetted onto the electrodes leaving an air-filled space between fluid and gasket. Thus the sample only came into contact with the electrodes, the quartz substrate and the cover glass. This helped to minimise contaminations which can easily occur due to the sample's high surface-to-volume ratio.

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.