| 1. |
- Beech, J. P., et al.
(författare)
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What do photons do to fluorescently stained DNA in confinement?
- 2013
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Ingår i: 17th International Conference on Miniaturized Systems for Chemistry and Life Sciences, MicroTAS 2013; Freiburg; Germany; 27 October 2013 through 31 October 2013. ; 1, s. 5-7
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Konferensbidrag (refereegranskat)abstract
- We have studied a selection of factors influencing the damage of DNA in nanochannels during fluorescence imaging. For cutting and nicking of DNA we show that the DNA is shortened during imaging. To avoid photodamage over the course of several hours of a typical experiment, we demonstrate the importance of an oxygen free gas to propel the buffer solution through the device. Finally, by varying the size of the channels, we show indications that higher DNA concentrations lead to higher rates of photodamage necessitating a balance between needs for highly stretched DNA and needs for long measurement times.
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| 2. |
- Deschout, H., et al.
(författare)
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Disposable microfluidic chip with integrated light sheet illumination enables diagnostics based on membrane vesicles
- 2014
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Ingår i: 17th International Conference on Miniaturized Systems for Chemistry and Life Sciences, MicroTAS 2013; Freiburg; Germany; 27 October 2013 through 31 October 2013. - 9781632666246
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Konferensbidrag (refereegranskat)abstract
- Cell-derived membrane vesicles that are released in body fluids are emerging as potential non-invasive biomarkers for diseases like cancer. Techniques capable of measuring the size and concentration of such membrane vesicles directly in body fluids are urgently needed. Here we report on a microfluidic chip with integrated light sheet illumination, and demonstrate accurate fluorescence Single Particle Tracking measurements of the size and concentration of membrane vesicles in cell culture medium and in interstitial fluid collected from primary human breast tumours.
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| 3. |
- Emilsson, Gustav, 1989, et al.
(författare)
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Identifying bacteria using DNA binding maps
- 2013
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Ingår i: 17th International Conference on Miniaturized Systems for Chemistry and Life Sciences, MicroTAS 2013; Freiburg; Germany; 27 October 2013 through 31 October 2013. - 9781632666246 ; 1, s. 473-475
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Konferensbidrag (refereegranskat)abstract
- We have developed an assay, based on nanofluidic channels and fluorescence microscopy, for optical mapping of DNA based on competitive binding between two molecules - one fluorescent and one sequence selective. From the experimental data we can extract binding constants for the two competing DNA binders, which may be subsequently used to calculate a theoretical reference map of any DNA with known sequence. The goal is to create a method for fast identification of bacteria from single DNA molecules without the need for additional cultivation or amplification. We here demonstrate a proof-of-principle experiment on phage DNA and furthermore show that the method can be used to distinguish between two strains of E. coli DNA and to map pieces of DNA onto the full genome.
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| 4. |
- Frykholm, Karolin, 1977, et al.
(författare)
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Probing physical properties of DNA-protein complexes using nanofluidic channels
- 2013
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Ingår i: 17th International Conference on Miniaturized Systems for Chemistry and Life Sciences, MicroTAS 2013; Freiburg; Germany; 27 October 2013 through 31 October 2013. - 9781632666246 ; 2, s. 1311-1313
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Konferensbidrag (refereegranskat)abstract
- We present the use of nanofluidic channels as a tool for determining physical properties of single DNA-protein complexes. By coating the nanochannels with a lipid bilayer we avoid sticking of proteins to the channel walls. RecA is a prokaryotic protein involved in recombination and DNA repair. We study filaments of RecA, bound to both double stranded (ds) and single stranded (ss) DNA. We determine the persistence length of RecA filaments on both dsDNA and ssDNA and obtain values in agreement with the literature. Neither the DNA nor the protein has to be attached to handles or surfaces, and the technique is directly transferable to Lab-on-a-Chip technologies for high throughput measurements in solution.
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| 5. |
- Holm, Stefan H., et al.
(författare)
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Combined density and size-based sorting in deterministic lateral displacement devices
- 2013
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Ingår i: 17th International Conference on Miniaturized Systems for Chemistry and Life Sciences, MicroTAS 2013. - 9781632666246 ; 2, s. 1224-1226
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Konferensbidrag (refereegranskat)abstract
- We present a deterministic-lateral-displacement (DLD) device that extends the capabilities of this traditionally sizebased particle separation technique to also be sensitive to density. By the use of T-shaped posts instead of the normally cylindrical posts the particle trajectory through the device will be a function of its vertical position which in turn is determined by the buoyancy of the particles. The potential lies in fast sorting of complex biological samples together with diagnosis and treatment-monitoring of diseases affecting cell-density, eg. cancer, sickle-cell anemia and malaria. We demonstrate proof-of-principle of combined size-and-density-based sorting, specifically particles of identical size but different density.
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| 6. |
- Iranmanesh, Ida, et al.
(författare)
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Magnitude and variance of acoustic energy density in microchannel acoustophoresis : Comparison between single-frequency and frequency-modulated actuation
- 2013
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Ingår i: 17th International Conference on Miniaturized Systems for Chemistry and Life Sciences, MicroTAS 2013. - 9781632666246 ; , s. 1400-1402
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Konferensbidrag (refereegranskat)abstract
- Using a novel light-intensity method, we quantify for the first time the magnitude and spatial variance in acoustic energy density along a microchannel during acoustophoretic focusing of particles with frequency-modulated ultrasound. We compare the distribution in energy density between single-frequency (SF) and frequency-modulation (FM) actuation along the microchannel. In addition, we analyze the field uniformity for the two actuation approaches (SF and FM) by measuring the deviation of the final particle pattern from an ideal straight line. We conclude that the magnitude of the energy density for FM actuation is of the same order of magnitude as for SF actuation, but with much less spatial variance.
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| 7. |
- Khorshidi, Mohammad Ali, et al.
(författare)
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Dynamic behavior analysis of single cells using droplet microfluidics
- 2013
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Ingår i: 17th International Conference on Miniaturized Systems for Chemistry and Life Sciences, MicroTAS 2013. - 9781632666246 ; , s. 1674-1676
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Konferensbidrag (refereegranskat)abstract
- We present a droplet microfluidic platform to automatically track and characterize the behavior of single cells over time. Time series analysis of single cells was enabled by encapsulating the cells in microdroplets followed by trapping microdroplets in static array of microwells that were fabricated on chip to make the droplets addressable by their position and imaging them over time. In this paper, we demonstrate the potential of automated time-lapse imaging and image analysis approach in droplet microfluidics by studying the viability of large number of single cells over time.
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| 8. |
- Ohlander, A., et al.
(författare)
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Foil-based DNA melting curve analysis platform for low-cost point-of-care molecular diagnostics
- 2013
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Ingår i: 17th International Conference on Miniaturized Systems for Chemistry and Life Sciences, MicroTAS 2013. - 9781632666246 ; , s. 1770-1772
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Konferensbidrag (refereegranskat)abstract
- We report on genotyping of single nucleotide polymorphisms (SNP) by melting curve analysis (MCA) on DNA microarrays in a plastic microfluidic system with integrated heaters using lamination foils. Thin-film micro-heaters were processed on polyethylene napthalate (PEN) foil in only one metallization step. DNA microarrays were prepared directly on the PEN surface without the need of surface pre-treatment via UV-mediated immobilization of the spotted DNA microarrays. MCA in microfluidic channels is demonstrated at a ramping rate of 60°C/min, enabling ultra-rapid (50 seconds) SNP analysis.
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| 9. |
- Ohlsson, P. D., et al.
(författare)
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Acoustophoresis separation of bacteria from blood cells for rapid sepsis diagnostics
- 2013
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Ingår i: 17th International Conference on Miniaturized Systems for Chemistry and Life Sciences, MicroTAS 2013. - 9781632666246 ; 2, s. 1320-1322
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Konferensbidrag (refereegranskat)abstract
- We present a significantly improved acoustophoresis method to separate bacteria from red and white blood cells. As much as 98% of the bacteria were recovered, while only 0.06 % of the red and white blood cells remained. This 1600-fold relative enrichment was achieved by adjusting the center medium density, tightly controlling the chip temperature and stabilizing the fluid flows. This is a crucial sample preparation step facilitating downstream bacteria identification for sepsis diagnostics.
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| 10. |
- Sjöström, Staffan, et al.
(författare)
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Droplet based directed evolution of yeast cell factories doubles production of industrial enzymes
- 2013
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Ingår i: 17th International Conference on Miniaturized Systems for Chemistry and Life Sciences, MicroTAS 2013. - : Chemical and Biological Microsystems Society. - 9781632666246 ; , s. 1270-1272
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Konferensbidrag (refereegranskat)abstract
- We present a high throughput micro-droplet based method for directed evolution of yeast cell factories for improved production of industrial enzymes. The workflow includes a fluorescently activated droplet sorter which was found to accurately sort droplets with a false positive rate of 0.0002 at 300 Hz. The workflow was used to screen a library of α-amylase expressing yeast mutants. A candidate yeast strain with a more than twofold increase in α-amylase production was isolated from a single round of directed evolution.
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| 11. |
- Wang, Jun, 1976, et al.
(författare)
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Spatial resolution of exocytosis across a single cell by a microwell-based individually addressable thin film ultra-microelectrode array
- 2013
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Ingår i: 17th International Conference on Miniaturized Systems for Chemistry and Life Sciences, MicroTAS 2013; Freiburg; Germany; 27 October 2013 through 31 October 2013. - 9781632666246 ; 1, s. 392-394
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Konferensbidrag (refereegranskat)abstract
- We report the fabrication and characterization of micro well-based individually addressable ultra-microelectrode arrays (MEAs) and their application to spatially and temporally resolved detection of neurotransmitter release across a single pheochromocytoma (PC 12) cell. The MEAs consist of sixteen 4-μm-width square microelectrodes, or twenty-five 3-μm-width square microelectrodes, or thirty-six 2-jim-width square microelectrodes. Each MEA is tightly defined in a 30×30 μm square area, which is further encased inside a 40×40 μm SU-8 microwell. We demonstrate the excellent stability and reproducibility of these microelectrodes by using cyclic voltammetry and we have performed recording of spatially resolution of single cell exocytosis with multiple ultra-microelectrodes in 2-μm resolution.
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