Interaction of nanoparticles at the DEP microelectrode interface under high conductance conditions

This was a first work, where Biological Dynamic's founders were able to demonstrate possibility of isolation of nanoparticles from a high conductivity solution using hydrogel over-coated microelectrodes.

Krishnan, R., Dehlinger, D.A., Gemmen, G.J., Mifflin, R.L., Esener, S.C., and Heller, M.J. (2009), Interaction of nanoparticles at the DEP microelectrode interface under high conductance conditions. Electrochem commun., 11: 1661–1666. doi: 10.1016/j.elecom.2009.06.033

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ABSTRACT

The separation of nanoparticles from micron size particles in high conductance buffers was achieved using an AC dielectrophoretic (DEP) microarray device with hydrogel over-coated microelectrodes. While nanoparticles could be selectively concentrated into high field regions directly over the platinum microelectrodes, micro-bubbling and electrode darkening was also observed. For similar experiments using un-coated microelectrodes, SEM analysis showed severe erosion of the platinum microelectrodes and fusion of nanoparticles due to the aggressive electrochemistry.

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An AC Electrokinetic Method for Enhanced Detection of DNA Nanoparticles

This was a first work, where Biological Dynamic's founder were able to demonstrate possibility of no-dilution isolation of nanoparticles from a high conductivity solution using special conditions applied to DEP field.

Krishnan, R. and Heller, M. J. (2009), An AC Electrokinetic Method for Enhanced Detection of DNA Nanoparticles. J. Biophoton., 2: 253–261. doi: 10.1002/jbio.200910007

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ABSTRACT

In biomedical research and diagnostics it is a challenge to isolate and detect low levels of nanoparticles and nanoscale biomarkers in blood and other biological samples. While highly sensitive epifluorescent microscope systems are available for ultra low level detection, the isolation of the specific entities from large sample volumes is often the bigger limitation.

AC electrokinetic techniques like dielectrophoresis (DEP) offer an attractive mechanism for specifically concentrating nanoparticles into microscopic locations. Unfortunately, DEP requires significant sample dilution thus making the technology unsuitable for biological applications. Using a microelectrode array device, special conditions have been found for the separation of hmw-DNA and nanoparticles under high conductance (ionic strength) conditions. At AC frequencies in the 3000-10 000 Hz range, 10 mum microspheres and human T lymphocytes can be isolated into the DEP low field regions, while hmw-DNA and nanoparticles can be concentrated into microscopic high field regions for subsequent detection using an epifluorescent system.

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