Effects of biomolecules on the electrokinetics of colloidal nanoparticles in liquid suspension

Midelet, C., Lin, J.-Y., Tsang, S., Sun, C.-I., Midelet, J., Kanaras, A.G., Le Pioufle, B., Francais, O. and Werts, M.H.V. (2017) Effects of biomolecules on the electrokinetics of colloidal nanoparticles in liquid suspension. Osinski, Marek, Parak, Wolfgang J. and Liang, Xing-Jie (eds.) In Colloidal Nanoparticles for Biomedical Applications XII. vol. 1007801, SPIE: the International Society for Optics and Photonics.. (doi:10.1117/12.2252470).

Abstract

Electric fields can induce various types of motion in liquid suspensions of colloidal nanoparticles. These electrokinetic phenomena depend on the parameters of the electric field (frequency, amplitude, 3D topology), the particles (size, shape,composition) and the suspending liquid (polarizability, ionic strength, pH). In particular, the dielectrophoretic force onsubmicron colloidal particles is dependent on the properties of the electric double layer (the "ion cloud") around theseparticles. This dependence provides a mechanism for detecting and quantifying interactions between biomolecules andthese nanoparticles, which can be combined with optical and spectroscopic measurements. Here, we report onfunctionalized plasmonic nanoparticles that are tracked inside microfluidic systems by dark-field video-microscopy. Ahigh-gradient AC electric field is set up using transparent micro-electrodes. Electrohydrodynamic motion of the entirefluid and dielectrophoretic trapping of individual particles can be analyzed quantitatively by numerical methods. Byswitching the electric field synchronously with the video acquisition, the effect of biomolecules on the electrokinetictrapping can be quantified. The electromicrofluidic devices allow also for rapid measurement of diffusion coefficients.

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Contributors

Author: A.G. Kanaras

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