Optical sensors and detection methods for miniaturized separation procedures
Microchip-based electrophoresis enable the separation of biological species within a few seconds only but methods are needed for on-line observation of separation parameters and analyte properties. One platform we work on is microfluidic free-flow electrophoresis (µFFE) that enables continuous spatial separation of compounds and is of particular use for protein separations and other cellular contents. In a recent work we have demonstrated a continuous separation of two proteins with micro-free flow isoelectric focusing (µFFIEF) with on-line monitoring of the pH gradient in the IEF procedure, allowing us to determine the isoelectric point (IEP) of these proteins instantly by read-out of a microchip-integrated pH sensor layer (Fig. 1). Currently we are extending this methodology towards improved fabrication procedures, more complex samples, optical sensors for other electrophoretic parameters and the implementation of optical sensors for other separation procedures. We have also contributed in the introduction of UV fluorescence detection and UV fluorescence lifetime detection on µFFE and microchip electrophoresis platforms.
Publications in this area
(11) C. Herzog, E. Poehler, A.J. Peretzki, S.M. Borisov, D. Aigner, T. Mayr, S. Nagl,
Continuous on-chip fluorescence labelling, free-flow isoelectric focusing and marker-free isoelectric point determination of proteins and peptides, Lab Chip 2016, 16, 1565-1572
(10) E. Poehler, C. Herzog, C. Lotter, S.A. Pfeiffer, D. Aigner, T. Mayr, S. Nagl, Label-free microfluidic free-flow isoelectric focusing, pH gradient sensing and near real-time isoelectric point determination of biomolecules and blood plasma fractions,
Analyst 2015, 140, 7496-7502
(9) C. Herzog, G.F.W. Jochem, P. Glaeser, S. Nagl, Gas removal in free-flow electrophoresis using an integrated nanoporous membrane, Microchim. Acta 2015, 182, 887-892
(8) E. Poehler, C. Herzog, M. Suendermann, S.A. Pfeiffer, S. Nagl, Development of microscopic time domain dual lifetime referencing luminescence detection for pH monitoring in microfluidic free-flow isoelectric focusing , Eng. Life Sci., in press
(7) C. Herzog, E. Beckert, S. Nagl, Rapid isoelectric point determination in a miniaturized preparative separation using jet-dispensed optical pH sensors and micro free-flow electrophoresis, Anal. Chem. 2014, 86, 9533–9539
(6) R. Beyreiss, D. Geißler, S. Ohla, S. Nagl, T.N. Posch, D. Belder, Label-free fluorescence detection of aromatic compounds in chip electrophoresis applying two photon excitation and time-correlated single photon counting, Anal. Chem. 2013, 85, 8150–8157
(5) S. Jezierski, A.S. Klein, C. Benz, M. Schaefer, S. Nagl, D. Belder, Towards an integrated device that utilizes adherent cells in a micro-free-flow electrophoresis chip to achieve separation and biosensing, Anal. Bioanal. Chem. 2013, 405, 5381-5386
(4) S. Jezierski, D. Belder, S. Nagl, Microfluidic free-flow electrophoresis chips with an integrated fluorescent sensor layer for real time pH imaging in isoelectric focusing, Chem. Commun. 2013, 49, 904-906
(3) S. Köhler, S. Nagl, S. Fritzsche, D. Belder, Label-free Detection in Microchip Free-Flow Electrophoresis using Deep UV Laser Scanning Fluorescence Detection, Lab Chip 2012, 12, 458-463
(2) S. Jezierski, L. Gitlin, S. Nagl, D. Belder, Multistep Liquid Phase Lithography for Fast Prototyping of Microfluidic Free-Flow-Electrophoresis Chips, Anal. Bioanal. Chem. 2011, 401, 2651-2656
(1) R. Beyreiss, S. Ohla, S. Nagl, D. Belder, Label-Free Analysis in Chip Electrophoresis Applying Deep UV Fluorescence Lifetime Detection, Electrophoresis 2011, 32, 3108-3114
