Research

The team of Prof. Belder is engaged in the development and application of microfluidic Lab-On-a-Chip devices for Analytical Chemistry. Our focus is the miniaturization of analytical separation techniques, such as microchip electrophoresis. Besides profound work on surface chemistry and contributions to instrumental developments further main aspects are applications for classical chemistry, sensors and bioanalytics.

Microchip Chromatography

Microchip chromatography offers a wide range of separation modes. The use of particulate material seems to have the greatest potential of exhausting this variability and knowledge. But the immobilization of loose particulate material within a microfluidic channel inheres great demand on the column preparation strategy. We developed a method to implement frits with high spatial resolution in a separation channel of a microfluidic network. Thus we are able to build particulate columns on demand. Another topic is the world-to-chip-interface. Here we designed a technical demanding interface allowing working pressures of several hundreds of bars. Together with a unique injection technique we gain high efficient and fast chromatographic separations.

Selected Publications

Seamless combination of high pressure chip-HPLC and droplet microfluidics on an integrated microfluidic glass chip
R. Gerhardt, A. J. Peretzki, S. K. Piendl, D. Belder, Anal. Chem. 2017, 89, 13030-13037

Temperature gradient elution and superheated eluents in chip-HPLC
J. J. Heiland, C. Lotter, V. Stein, L. Mauritz, D. Belder, Anal. Chem. 2017, 89, 3266–3271

Evaluation of Pressure Stable Chip-to-Tube Fittings Enabling High-Speed Chip-HPLC with Mass Spectrometric Detection
C. Lotter, J. J. Heiland, V. Stein, M. Klimkait, M. Queisser, D. Belder, Anal. Chem. 2016, 88, 7481–7486

Chip-based electrochromatography coupled to ESI-MS detection
C. Dietze, C. Hackl, R. Gerhardt, S. Seim, D. Belder, Electrophoresis 2016, 37, 1345-1352

Chip-Based High-Performance Liquid Chromatography for High-Speed Enantioseparations
S. Thürmann, C. Lotter, J. J. Heiland, B. Chankvetadze, D. Belder, Anal. Chem. 2015, 87, 5568-5576

High-performance liquid chromatography on glass chips using precisely defined porous polymer monoliths as particle retaining elements
S. Thürmann, L. Mauritz, C. Heck, D. Belder, J. Chromatogr. A 2014,
1370, 33-39

Phase-optimized chip-based liquid chromatography
S. Thürmann, D. Belder, Anal. Bioanal. Chem. 2014, 406, 6599-6606

A low pressure on-chip injection strategy for high-performance chip-based chromatography
S. Thurmann, A. Dittmar, D. Belder, J. Chromatogr. A 2014, 1340, 59–67

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Microchip Electrophoresis

Microchip electrophoresis (MCE) is a further miniaturized version of Capillary Electrophoresis (CE). MCE is a powerful analytical technique, which is characterized by high-speed separations, small sample and reagent requirements and high-throughput. Core of a MCE-system is a small glass or polymer microchip with integrated microfluidic channels of a few micrometers in size. By means of electric fields a tiny sample plug can be injected and separated, using different classical CE separation modes. One of the most fascinating features of MCE is the unsurpassed speed of separation. This allows for analysis in seconds or even microseconds, with the prospects of developing fast, portable systems for point-of-care-diagnostics. In numerous projects we have demonstrated the feasibility of MCE for real analytical problems in chemical synthesis, bioanalysis and diagnostics. Even demanding subsecond chiral separations could be performed.

Selected Publications

Rapid quantitative determination of ephedra alkaloids in tablet formulations and human urine by microchip electrophoresis
D. Belder*, K. Tolba, S. Nagl, Electrophoresis 2011, 32, 440-447

Chip electrophoresis of active banana ingredients with label-free detection utilizing deep UV native fluorescence and mass spectrometry
S. Ohla, P.Schulze, S. Fritzsche and D. Belder*, Analytical and Bioanalytical Chemistry 2011, 399, 1853-1857

Subsecond chiral separations on a microchip
N. Piehl, M. Ludwig. D. Belder, Electrophoresis 2004, 25, 3848–3852

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Chip-MS-Coupling

Mass Spectrometry (MS) offers an attractive alternative approach to sensitive fluorescence detection in microchip electrophoresis (MCE). It allows for identification of compounds on the basis of mass spectrum, avoiding troublesome fluorescence tagging.

For this purpose we developed the first microfluidic glass chips with monolithically integrated nanospray emitters. This new nanospray glass chips were successfully applied for coupling of MCE with MS. A patent application has been filed only recently.

Selected Publications

A. Kiontke, F. Holzer, D. Belder, C. Birkemeyer
The requirements for low-temperature plasma ionization support miniaturization of the ion source
Anal. Bioanal. Chem.
2018, DOI: 10.1007/s00216-018-1033-7

Liquid beam desorption mass spectrometry for the investigation of continuous flow reactions in microfluidic chips
S. Schulze, M. Pahl, F. Stolz, J. Appun, B. Abel, C. Schneider, D. Belder, Anal. Chem. 2017, 89, 6175–6181

Integrated on-chip mass spectrometry reaction monitoring in microfluidic devices containing porous polymer monolithic columns
C. Dietze, S. Schulze, S. Ohla, K. Gilmore, P. Seeberger, D. Belder, Analyst 2016, 141, 5412-5416

HPLC-MS with Glass Chips Featuring Monolithically Integrated Electrospray Emitters of Different Geometries
C. Lotter, J. J. Heiland, S. Thurmann, L. Mauritz, D. Belder, Anal. Chem. 2016, 88, 2856–2863

Improving sensitivity in microchip electrophoresis coupled to ESI-MS/MS on the example of a cardiac drug mixture
F. Schwarzkopf, T. Scholl, S. Ohla, D. Belder, Electrophoresis 2014, 35, 1880-1886

Chip-based separation devices coupled to mass spectrometry 
S. Ohla, D, Belder*, Current Opinion in Chemical Biology 2012, 16, 453–459

Chipelectrophoresis with mass spectrometric detection in record speed
S. Fritzsche, P. Hoffmann, D. Belder, Lab Chip  2010, 10, 1227-1230

Microfluidic glass chips with an integrated nanospray emitter for coupling to a mass spectrometer
P. Hoffmann, U. Häusig, P. Schulze, D. Belder, Angew. Chem. Int. Ed. 2007, 46, 4913-4916

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Micro Free Flow Electrophoresis

Free-flow electrophoresis (FFE) is a continuous separation technique which can be applied for prefractionation and separation of chemical and biological samples. Compared to classical large-scale devices, the chip-based miniaturized FFE has a much higher time and substance efficiency, i.e. shorter separation times and lower chemical consumption. Additionally, its continuous mode of operation allows a combination with an online monitoring system for real time surveillance. Our research in the field of microfluidic FFE includes development, fabrication and testing of a variety of microchip designs. We concentrate our efforts especially on the improvement of field injection and flow behaviour, and exploitation of new applications. Additional topics include the implementation of alternative detection strategies and the coupling of FFE chips to orthogonal analytical techniques.

Selected Publications

Continuous purification of reaction products by micro free-flow electrophoresis enabled by large area deep-UV fluorescence imaging
S. A. Pfeiffer, B. M. Rudisch, P. Glaeser, M. Spanka, F. Nitschke, A. A. Robitzki, C. Schneider, S. Nagl, D. Belder, Anal. Bioanal. Chem. 2018, 410, 853-862

Microfluidic Free-Flow Electrophoresis Based Solvent Exchanger for Continuously Operating Lab-on-Chip Applications
F. D. Zitzmann, H. G. Jahnke, S. A. Pfeiffer, R. Frank, F. Nitschke, L. Mauritz, B. Abel, D. Belder, A. A. Robitzki, Anal. Chem. 2017, 89, 13550–13558

Chip-Based Free-Flow Electrophoresis with Integrated Nanospray Mass-Spectrometry
C. Benz, M. Boomhoff, J. Appun, C. Schneider, D. Belder, Angew. Chem. Int. Ed. 2015, 54, 2766-2770

Towards an integrated device that utilizes adherent cells in a micro-free-flow electrophoresis chip to achieve separation and biosensing 
S. Jezierski, A. S. Klein, C. Benz, M. Schaefer, S. Nagl,  D. Belder, Anal. Bioanal. Chem. 2013,  5381-5386

Micro free-flow electrophoresis with injection molded chips
S. Köhler, C. Benz, H. Becker, E. Beckert, V. Beushausen, D. Belder;   RSC Adv. 2012, 520-525

Label-free real-time imaging in microchip free-flow electrophoresis applying high speed deep UV fluorescence scanning
S. Köhler, S. Nagl, S. Fritzsche, D. Belder, Lab Chip 2012, 12, 458-463

Multistep liquid-phase lithography for fast prototyping of microfluidic free-flow-electrophoresis chips
S. Jezierski, L. Gitlin, S. Nagl, D. Belder, Anal. Bioanal. Chem. 2011, 401, 2651-2656

PDMS free-flow electrophoresis chips with integrated partitioning bars for bubble segregation
S. Köhler, C. Weilbeer, S. Howitz, H. Becker, V. Beushausen, D. Belder, Lab Chip 2011, 11, 309-314

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Microreactions

One goal of miniaturization of analytical systems is the integration of all parts of the chemical process to a so-called lab-on-a-chip or micro total analysis system. This also includes the incorporation of reaction and detection.

In a highlighted paper we presented the first approach of the integration of a chemical reactor as well as an electrophoretic separation system on a microchip. This first truly integrated lab-on-a-chip device can be used for screening of enantioselective catalysts and respective mutants.



 

Selected Publications

A Highly Stereoselective Synthesis of Tetrahydrofurans
J. Appun, M. Boomhoff, P. Hoffmeyer, I. Kallweit, M. Pahl, D. Belder, C. Schneider, Angew. Chem. Int. Ed. 2017, 24, 6862-6865

On-chip integration of organic synthesis and HPLC/MS analysis for monitoring stereoselective transformations at the micro-scale
J. J. Heiland , R. Warias , C. Lotter , P. Fuchs , L. Mauritz , K. Zeitler , S. Ohla, D. Belder, Lab Chip 2017, 17, 76 - 81

Enantioselective reaction monitoring utilizing two-dimensional heart-cut liquid chromatography on an integrated microfluidic chip
C. Lotter, E. Poehler, J. J. Heiland, L. Mauritz, D. Belder, Lab Chip 2016, 16, 4648-4652

Analysis of Enantioselective Biotransformations Using a Few Hundred Cells on an Integrated Microfluidic Chip
K. M. Krone, R. Warias, C. Ritter, A. Li, C. G. Acevedo-Rocha, M. T. Reetz, D. Belder, JACS 2016, 138, 2102–2105

Monitoring on-Chip Pictet-Spengler Reactions by Integrated Analytical Separation and Label-Free Time-Resolved Fluorescence
S. Ohla,  R. Beyreiss, S. Fritzsche, P. Glaser, S. Nagl, K. Stockhausen, C. Schneider,  D. Belder, Chem. Eur. J. 201218, 1240 – 1246

Asymmetric Organocatalysis and Analysis on a Single Microfluidic Nanospray Chip
S. Fritzsche, S. Ohla, P. Glaser, D. S. Giera, M. Sickert, C. Schneider, and D. Belder*, Angew. Chem. Int. Ed. 2011, 50, 9467 –9470

Enantioselective catalysis and analysis on a chip
D. Belder, M. Ludwig, L.-W. Wang, M. T. Reetz, Angew. Chem. Int. Ed. 2006, 45, 2463-2466

Integrating chemical synthesis and analysis on a chip
D. Belder, Anal. Bioanal. Chem. 2006, 385, 416-418.

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Fluorescence Lifetime Imaging Microscopy

Fluorescence is a major readout method in microfluidic chip analysis due to ist sensitivity, selectivity and versatility. The fluorescence signal contains intensity, spectral, lifetime and in some formats anisotropy information.
Fluorescence lifetime is an attractive parameter since it is specific for each molecule, sensitive to the environment and insensitive to a lot of sources of noise in common fluorescence measurements such as variations in excitation intensity and detector efficiency, straylight and other optical background.
We develop fluorescence lifetime-based readout methods in microchip reaction, separation and analysis formats in order to differentiate between different dyes, obtain information about their microscopic environment and for referencing schemes in the time domain.

Selected Publications

Protein–protein interaction analysis in single microfluidic droplets using FRET and fluorescence lifetime detection
C. Benz, H. Retzbach, S. Nagl,  D. Belder, Lab Chip 2013, 13, 2808-2814

Monitoring on-Chip Pictet-Spengler Reactions by Integrated Analytical Separation and Label-Free Time-Resolved Fluorescence
S. Ohla,  R. Beyreiss, S. Fritzsche, P. Glaser, S. Nagl, K. Stockhausen, C. Schneider,  D. Belder, Chem. Eur. J. 201218, 1240 – 1246

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Chemical Sensor Miniaturization

We investigate the integration of sensing components in microfluidic analytical systems for continuous on-line recording of chemical and biological species on the microscale. For fabrication of microchips with optical sensing function layers of a few micrometers in thickness are immobilized that contain appropriate probe molecules and display analyte presence visually. Further research is directed towards hyphenation of microfluidic chemical sensing with other chip-integrated procedures such as chemical syntheses, analytical separations and biological applications.

Selected Publications

A chip-integrated optical microfluidic pressure sensor
C. Hoera, A. Kiontke, M. Pahl, D. Belder, Sensors and Actuators B: Chemical 2018, 255, 2407-2415

A chip-integrated highly variable thermal flow rate sensor
C. Hoera, M. M. Skadell, S. A. Pfeiffer, M. Pahl, Z. Shu, E. Beckert, D. Belder, Sensors and Actuators B: Chemical 2016, 225, 42-49

High-performance liquid chromatography on glass chips using precisely defined porous polymer monoliths as particle retaining elements
S. Thürmann, L. Mauritz, C. Heck, D. Belder, J. Chromatogr. A 2014,
1370, 33-39

Micro flow reactor chips with integrated luminescent chemosensors for spatially resolved on-line chemical reaction monitoring
L. Gitlin, C. Hoera, R. J. Meier, S. Nagl, D. Belder, Lab Chip2013, 13, 4134-4141

Microfluidic free-flow electrophoresis chips with an integrated fluorescent sensor layer for real time pH imaging in isoelectric focusing
S. Jezierski, D. Belder, S. Nagl, Chem. Commun., 2013, 49, 904-906

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Surface Chemistry

In order to separate complex protein mixtures such as in proteomics, chemical surface modification of microfluidic channels is absolutely necessary.

For this purpose our group develops and validates a host of techniques for surface modification. By means of a coating method for glass substrates with PVA, we could demonstrate the highly efficient separation of chicken white egg proteins in less than 2 min.

Selected Publications

Surface modification of PDMS microfluidic devices by controlled sulfuric acid treatment and the application in chip electrophoresis
L. Gitlin, P. Schulze, S. Ohla, H.J. Bongard, D. Belder, Electrophoresis 2015, 36, 449-456

Poly(ethylene glycol)-coated microfluidic devices for chip electrophoresis
M. Schulze, D. Belder, Electrophoresis 2012, 33, 370–378

Coating of powder–blasted channels for high performance microchip electrophoresis
D. Belder, F. Kohler, M. Ludwig, K. Tolba, N. Piehl, Electrophoresis 2006, 27, 3277–3283

Separation of fluorescein isothiocyanate-labeled amines by microchip electrophoresis in uncoated and polyvinyl alcohol-coated glass chips using water and dimethyl sulfoxide as solvents of background electrolyte
S.J.O. Varjo, M. Ludwig, D. Belder*, M.L. Riekkola*, Electrophoresis 2004, 25, 1901–1906

Surface modification in microchip electrophoresis
D. Belder*, M. Ludwig, Electrophoresis 2003, 24, 3595-3606

Electrokinetic Effects in poly(ethylene glycol)-coated capillaries induced by specific adsorption of cations
D. Belder*, J. Warnke, Langmuir 2001, 17, 4962-4966

Directed control of electroosmotic flow in nonaqueous electrolytes using poly(ethylene glycol) coated capillaries
D. Belder*, H. Husmann, J. Warnke, Electrophoresis 2001, 22, 666-672.

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Deep UV Fluorescence Detection

Fluorescence measurements enable to detect even tiny amounts of a substance in microchip channels of only a few µm optical path length. By means of deep UV induced native fluorescence troublesome fluorescence tagging can be avoided.

For this purpose, our group developed a MCE system based on quartz optical components. This system allowed the first label-free detection of separeted proteins or small molecules on a quartz chip. In addition, the application of 2-photon-excitation made the use of expensive quartz components dispensable.

Selected Publications

Continuous purification of reaction products by micro free-flow electrophoresis enabled by large area deep-UV fluorescence imaging
S. A. Pfeiffer, B. M. Rudisch, P. Glaeser, M. Spanka, F. Nitschke, A. A. Robitzki, C. Schneider, S. Nagl, D. Belder, Anal. Bioanal. Chem. 2018, 410, 853-862

Microfluidic Free-Flow Electrophoresis Based Solvent Exchanger for Continuously Operating Lab-on-Chip Applications
F. D. Zitzmann, H. G. Jahnke, S. A. Pfeiffer, R. Frank, F. Nitschke, L. Mauritz, B. Abel, D. Belder, A. A. Robitzki, Anal. Chem. 2017, 89, 13550–13558

Two-photon excitation in chip electrophoresis enabling label-free fluorescence detection in non-UV transparent full-body polymer chips
D. Geissler, D. Belder, Electrophoresis 2015, 36, 2976-2982

Label-free fluorescence detection of aromatic compounds in chip electrophoresis applying two photon excitation and time-correlated single photon counting
R. Beyreiss, D. Geißler, S. Ohla, S. Nagl, T. N. Posch, D. Belder, Anal. Chem. 2013, 85, 8150-8157

Crossing the Border towards Deep UV Time-Resolved Microscopy of Native Fluophores
M. Koenig, S.Tannert, T. Schoenau, K. Lauritsen, F. Koberling, R. Erdmann, R. Beyreiss, S. Nagel, D. Belder, Biophysical Journal  2013, 104, 667A-667A

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Microfabrication

For miniaturization of chemical systems the economical and fast production of microfluidic chips with specific properties is essential. Soft lithography is a very attractive technique for rapid prototyping of microfluidic systems made of polymer, glass and hybrid materials. Depending on material used, different microfabrication techniques like photo- or soft lithography can be applied. Regardless of the technique, fabrication on a microscopic level is a unique challenge. This is especially true for the integration of additional functionalities, such as reaction and separation channels, membranes, pumps, sensor layers or coupling with instrumental analytical methods like mass spectrometry.

Selected Publications

Rapid prototyping of microfluidic chips for dead-volume-free MS coupling
C. Dietze, T. Scholl, S. Ohla, J. Appun, C. Schneider, D. Belder
Anal. Bioanal. Chem. 2015, 407, 8735-8743

Rapid Prototyping of Electrochromatography Chips for Improved Two-Photon Excited Fluorescence Detection
C. Hackl , R. Beyreiss , D. Geissler , S. Jezierski, D. Belder, Anal. Chem. 2014, 86, 3773–3779

Multistep liquid-phase lithography for fast prototyping of microfluidic free-flow-electrophoresis chips
S. Jezierski, L. Gitlin, S.Nagl, D. Belder*, Anal Bioanal Chem. 2011, 401, 2651–2656

Rapid replication of master structures by double casting with PDMS
L. Gitlin, P. Schulze, D. Belder*, Lab Chip 2009, 9 (20), 3000-3002

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Microfluidic Dropletsystems

Microfluidic droplets are a versatile tool in synthesis and analytical high-throughput-screening (HTS) on a microfluidic scale. Droplets are encapsulated micro reaction vessels in an immiscible fluid, with volumes in the nano- or picoliter range. We use the combination of time-resolve-fluorescence-detection and microdroplet technology for bioanalytical assays, such as determination of protein contents in aqueous matrices by Förster-Resonance-Energy-Transfer (FRET).

Selected Publications

A droplet-chip / mass spectrometry approach to study organic synthesis at nanoliter scale
J. R. Beulig, R. Warias, J. J. Heiland, S. Ohla, K. Zeitler, D. Belder, Lab Chip 2017, 17, 1996-2002

Protein–protein interaction analysis in single microfluidic droplets using FRET and fluorescence lifetime detection
C. Benz, H. Retzbach, S. Nagl,  D. Belder,  Lab Chip 2013, 13, 2808-2814

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Raman Spectroscopy

Surface enhanced Raman Spectroscopy (SERS) is an attractive tool to label-free detection of even traces of molecules. It thus provides a good alternative to fluorescence spectroscopy, especially for those substances that do not show native fluorescence. Furthermore, similar to Infrared Spectroscopy, it yields structural information about probed substances. It therefore functions as a favourable tool for high throughput screening or can be used as a method for detecting various separation tools, especially in microfluidics.

Selected Publications

A. Tycova, R. F. Gerhardt, D. Belder
Surface enhanced Raman spectroscopy in microchip electrophoresis
J. Chromatogr. A 2018, 1541, 39-46.

Z. Zhang, U. Gernert, R. Gerhardt, E.-M. Höhn, D. Belder J. Kneipp
Catalysis by Metal Nanoparticles in a Plug-in Optofluidic Platform: Redox Reactions of p-Nitrobenzenethiol and p-Aminothiophenol
ACS Catal. 2018, 8, 2443-2449.

D. Geissler, J. J. Heiland, C. Lotter, D. Belder
Microchip HPLC separations monitored simultaneously by coherent anti-Stokes Raman scattering and fluorescence detection
Microchim Acta 2017, 184, 315-321.

T. A. Meier, E. Poehler, F. Kemper, O. Pabst, H. G. Jahnke, E. Beckert, A. Robitzki, D. Belder
Fast electrically assisted regeneration of on chip SERS substrates
Lab Chip 2015, 15, 2923-2927.

T. A. Meier, R. J. Beulig, E. Klinge, M. Fuss, S. Ohla, D. Belder
On-chip monitoring of chemical syntheses in microdroplets via surface-enhanced Raman spectroscopy
Chem. Commun. 2015, 51, 8588-8591.


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last modified: 09.05.2018