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Dielectrophoretic immobilization of proteins: Quantification by atomic force microscopy

: Laux, Eva-Maria; Knigge, Xenia; Bier, Frank F.; Wenger, Christian; Hölzel, Ralph


Electrophoresis 36 (2015), Nr.17, S.2094-2101
ISSN: 0173-0835
ISSN: 1522-2683
Fraunhofer IZI ()
atomic force microscopy; dielectrophoresis; electric field simulation; immobilization; protein

The combination of alternating electric fields with nanometer-sized electrodes allows the permanent immobilization of proteins by dielectrophoretic force. Here, atomic force microscopy is introduced as a quantification method, and results are compared with fluorescence microscopy. Experimental parameters, for example the applied voltage and duration of field application, are varied systematically, and the influence on the amount of immobilized proteins is investigated. A linear correlation to the duration of field application was found by atomic force microscopy, and both microscopical methods yield a square dependence of the amount of immobilized proteins on the applied voltage. While fluorescence microscopy allows real-time imaging, atomic force microscopy reveals immobilized proteins obscured in fluorescence images due to low S/N. Furthermore, the higher spatial resolution of the atomic force microscope enables the visualization of the protein distribution on single nanoelectrodes. The electric field distribution is calculated and compared to experimental results with very good agreement to atomic force microscopy measurements.