Free-flow electrophoresis techniques have been applied for separations in various areas of chemistry and biochemistry. Here we focus on the generation of a free-flow electrophoresis chip and direct monitoring of the separation of different molecules in the separation bed of the miniaturized chip. We demonstrate a fast and efficient way to generate a low-cost micro-free-flow electrophoresis (μFFE) chip with a filling capacity of 9.5 μL based on a multi-lamination technique. Separating webs realized by two transfer-adhesive tapes avoid the problem of gas bubbles entering the separation area. The chip is characterized by isoelectric focusing markers (IEF markers). The functionality of the chip is demonstrated by free-flow isoelectric focusing (FFIEF) of the proteins BSA (bovine serum albumin) and avidin and a single-stranded DNA (ssDNA) fragment in the pH range 3 to 10. The separation voltage ranges between 167 V cm(-1) and 422 V cm(-1), depending on the application.
The fabrication of substrates for surfaceenhanced Raman spectroscopy (SERS), which offer high enhancement factors as well as spatially homogeneous distribution of the enhancement, plays an important role for expanding the surface-enhanced Raman spectroscopy to a powerful quantitative and non-invasive measurement technique. In this paper, a method for the fabrication of capable SERS-active substrates by laser treatment of gold films supported on glass with single 351 nm UV-laser pulses is presented. Resulting nanometer scaled structures show enhancement factors of up to 10 6 with very high spatial reproducibility for a monolayer of benzenethiol. A method for integration of these substrates into PDMS microchannels is shown. A technique for the generation of a simple mold master for PDMS replication is presented. Rhodamine 6G is used as model system to demonstrate continuous measurements on a solid SERS-active substrate in a microchannel. The label-free detection of the biological molecule albumin is improved by an order of magnitude.
A setup was developed at Laser-Laboratorium that allows determination of LIDT data under simultaneous 1064nm, 532nm and 355nm irradiation (3l), in order to investigate the influence of combined irradiation of specific elements with multiple wavelengths. Utilizing a fully characterized test laser beam and a well defined sample environment, 10.000-on-1 LIDT data of high-reflecting mirrors (AOI 45°) in vacuum were determined both at multiple wavelengths (3l) and at 355nm alone. In addition, a test optics (HR355, 45°, ambient conditions) was irradiated for 150 million pulses at (3l) at a fixed fluence of 2 J/cm 2 as a certification test.
In this work we present the first approach towards low-cost free-flow electrophoresis (FFE) devices utilizing injection molding as a microfabrication process which has the potential to manufacture FFE chips at a cost which make their use commercially viable. This is achieved by realizing a new straightforward micro free-flow electrophoresis (FFE) design ensuring both, bubble free electrophoretic separation and effective electrical connection by implementing miniaturized partitioning bars. This creates a defined open gap of 20 µm in height and 500 µm in width between separation zone and electrode channels. The thermoplastic FFE chips are ready to use, there is no need for a subsequent labor-intensive implementation of membranes or salt bridges to separate the electrode channels from the separation zone
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