@article{LauxErmilovaPannwitzetal.2018, author = {Laux, Eva-Maria and Ermilova, Elena and Pannwitz, Daniel and Gibbons, Jessica and H{\"o}lzel, Ralph and Bier, Frank Fabian}, title = {Dielectric Spectroscopy of Biomolecules up to 110 GHz}, series = {Frequenz}, volume = {72}, journal = {Frequenz}, number = {3-4}, publisher = {De Gruyter}, address = {Berlin}, issn = {0016-1136}, doi = {10.1515/freq-2018-0010}, pages = {135 -- 140}, year = {2018}, abstract = {Radio-frequency fields in the GHz range are increasingly applied in biotechnology and medicine. In order to fully exploit both their potential and their risks detailed information about the dielectric properties of biological material is needed. For this purpose a measuring system is presented that allows the acquisition of complex dielectric spectra over 4 frequency decade up to 110 GHz. Routines for calibration and for data evaluation according to physicochemical interaction models have been developed. The frequency dependent permittivity and dielectric loss of some proteins and nucleic acids, the main classes of biomolecules, and of their sub-units have been determined. Dielectric spectra are presented for the amino acid alanine, the proteins lysozyme and haemoglobin, the nucleotides AMP and ATP, and for the plasmid pET-21, which has been produced by bacterial culture. Characterisation of a variety of biomolecules is envisaged, as is the application to studies on protein structure and function.}, language = {en} } @article{LauxBierHoelzel2018, author = {Laux, Eva-Maria and Bier, Frank Fabian and H{\"o}lzel, Ralph}, title = {Dielectrophoretic Stretching of DNA}, series = {DNA Nanotechnology}, journal = {DNA Nanotechnology}, edition = {2}, publisher = {Humana Press Inc.}, address = {New York}, isbn = {978-1-4939-8582-1}, issn = {1064-3745}, doi = {10.1007/978-1-4939-8582-1_14}, pages = {199 -- 208}, year = {2018}, abstract = {The spatial control of DNA and of self-assembled DNA constructs is a prerequisite for the preparation of DNA-based nanostructures and microstructures and a useful tool for studies on single DNA molecules. Here we describe a protocol for the accumulation of dissolved lambda-DNA molecules between planar microelectrodes by the action of inhomogeneous radiofrequency electric fields. The resulting AC electrokinetic forces stretch the DNA molecules and align them parallel to the electric field. The electrode preparation from off-the-shelf electronic components is explained, and a detailed description of the electronic setup is given. The experimental procedure is controlled in real-time by fluorescence microscopy.}, language = {en} } @misc{LauxBierHoelzel2018, author = {Laux, Eva-Maria and Bier, Frank Fabian and H{\"o}lzel, Ralph}, title = {Electrode-based AC electrokinetics of proteins}, series = {Bioelectrochemistry : official journal of the Bioelectrochemical Society ; an international journal devoted to electrochemical aspects of biology and biological aspects of electrochemistry}, volume = {120}, journal = {Bioelectrochemistry : official journal of the Bioelectrochemical Society ; an international journal devoted to electrochemical aspects of biology and biological aspects of electrochemistry}, publisher = {Elsevier B.V.}, address = {Amsterdam}, issn = {1567-5394}, doi = {10.1016/j.bioelechem.2017.11.010}, pages = {76 -- 82}, year = {2018}, abstract = {Employing electric phenomena for the spatial manipulation of bioparticles from whole cells down to dissolved molecules has become a useful tool in biotechnology and analytics. AC electrokinetic effects like dielectrophoresis and AC electroosmosis are increasingly used to concentrate, separate and immobilize DNA and proteins. With the advance of photolithographical micro- and nanofabrication methods, novel or improved bioanalytical applications benefit from concentrating analytes, signal enhancement and locally controlled immobilization by AC electrokinetic effects. In this review of AC electrokinetics of proteins, the respective studies are classified according to their different electrode geometries: individual electrode pairs, interdigitated electrodes, quadrupole electrodes, and 3D configurations of electrode arrays. Known advantages and disadvantages of each layout are discussed.}, language = {en} }