| 1. |
- Adler, Belinda, et al.
(författare)
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Optimizing nanovial outlet designs for improved solid-phase extraction in the integrated selective enrichment target-ISET.
- 2012
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Ingår i: Electrophoresis. - : Wiley. - 0173-0835. ; 33:21, s. 3143-3150
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Tidskriftsartikel (refereegranskat)abstract
- The integrated selective enrichment target is a microfluidic platform for SPE sample preparation with integrated nanocolumns, which simultaneously offers direct MALDI MS read-out. Here, we present a study on the importance of different nanocolumn outlet hole geometries and hole areas in relation to MS signal intensity and reproducibility. A design solution that provides the flow characteristics required for robust sample preparation using automated liquid handling is reported.
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| 2. |
- Agaton, Charlotta, et al.
(författare)
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Genome-based proteomics
- 2004
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Ingår i: Electrophoresis. - : Wiley. - 0173-0835 .- 1522-2683. ; 25:9, s. 1280-1288
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Tidskriftsartikel (refereegranskat)abstract
- Protein-protein interactions play crucial roles in various biological pathways and functions. Therefore, the characterization of protein levels and also the network of interactions within an organism would contribute considerably to the understanding of life. The availability of the human genome sequence has created a range of new possibilities for biomedical research. A crucial challenge is to utilize the genetic information for better understanding of protein distribution and function in normal as well as in pathological biological processes. In this review, we have focused on different platforms used for systematic genome-based proteome analyses. These technologies are in many ways complementary and should be seen as various ways to elucidate different functions of the proteome.
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| 3. |
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| 4. |
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| 5. |
- Aldaeus, Fredrik, et al.
(författare)
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Superpositioned dielectrophoresis for enhanced trapping efficiency
- 2005
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Ingår i: Electrophoresis. - : Wiley. - 0173-0835 .- 1522-2683. ; 26:22, s. 4252-4259
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Tidskriftsartikel (refereegranskat)abstract
- One of the major applications for dielectrophoresis is selective trapping and fractionation of particles. If the surrounding medium is of low conductivity, the trapping force is high, but if the conductivity increases, the attraction decreases and may even become negative. However, high-conductivity media are essential when working with biological material such as living cells. In this paper, some basic calculations have been performed, and a model has been developed which employs both positive and negative dielectrophoresis in a channel with interdigitated electrodes. The finite element method was utilized to predict the trajectories of Escherichia coli bacteria in the superpositioned electrical fields. It is shown that a drastic improvement of trapping efficiency can be obtained in this way, when a high conductivity medium is employed.
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| 6. |
- Amini, Ahmad
(författare)
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Double-injection capillary electrophoresis for the identification of analytes
- 2014
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Ingår i: Electrophoresis. - : Wiley. - 0173-0835 .- 1522-2683. ; 35:20, s. 2915-2921
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents a new approach for identifying analytes by CE. The compound to be identified is analyzed together with the corresponding reference standard during a double injection capillary electrophoretic run. The inter-plug distance is regulated by applying an electrical field over the capillary for a predetermined time period (tPE). The migration time of an analyte being exposed to the partial electrophoresis was calculated from the partial migration time (tmig(p)) as described in this paper. The identification is based on the closeness of agreement between the calculated migration time (tmig(c)) and observed migration time (tmig) of the reference standard. The validity of the derived equations was checked by analyzing several substances such as caffeine, melamine, acetyl salicylic acid, paracetamol, ibuprofen, metoprolol, naproxen, somatropin, several insulin analogs, as well as different pharmaceutical and natural products. The migration time ratios for the identified solutes varied between 0.996 and 1.006 (i.e., 1.001 ± 0.005), indicating good agreement between the observed and calculated migration times.
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| 7. |
- Amini, Ahmad, et al.
(författare)
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Principles for different modes of multiple-injection CZE
- 2008
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Ingår i: Electrophoresis. - : Wiley. - 0173-0835 .- 1522-2683. ; 29:19, s. 3952-3958
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Tidskriftsartikel (refereegranskat)abstract
- This paper introduces four different modes of multiple-injection CZE (MICZE). The validity of these MICZE models was evaluated by the experimental data. Prior to the application of MICZE, the electrophoretic conditions are developed in the single-injection mode by adjusting different experimental parameters such as pH, type and concentration of buffer additives and temperature. Based on the migration time difference (tmig) between the analyte and the internal standard or injection marker, one or more MICZE modes can be employed. The injection marker is added to the sample to compensate for injection-volume fluctuations. The inter-plug distance is regulated by applying an electrical field over the capillary for a short period of time between each injection. After the final injection, the separation is completed by electrophoresis for a time period corresponding to that in the single-injection mode
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| 8. |
- Andersson, Helene, et al.
(författare)
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Micromachined filter-chamber array with passive valves for biochemical assays on beads
- 2001
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Ingår i: Electrophoresis. - 0173-0835 .- 1522-2683. ; 22:2, s. 249-257
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Tidskriftsartikel (refereegranskat)abstract
- The filter-chamber array presented here enables a real-time parallel analysis of three different samples on beads in a volume of 3 nL, on a 1 cm(2) chip. The filter-chamber array is a system containing three filter-chambers, three passive valves at the inlet channels and a common outlet. The design enables parallel sample handling and time-controlled analysis. The device is microfabricated in silicon and sealed with a Pyrex lid to enable real-time analysis. Single nucleotide polymorphism analysis by using pyrose-quencing has successfully been performed in single filter-chamber devices. The passive valves consist of plasma-deposited octafluorocyclobutane and show a much higher resistance towards water and surface-active solutions than previous hydrophobic patches. The device is not sensitive to gas bubbles, clogging is rare and reversible, and the filter-chamber array is reusable. More complex (bio)chemical reactions on beads can be performed in the devices with passive valves than in the devices without valves.
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| 9. |
- Andersson, Helene, et al.
(författare)
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Patterned self-assembled beads in silicon channels
- 2001
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Ingår i: Electrophoresis. - 0173-0835 .- 1522-2683. ; 22:18, s. 3876-3882
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Tidskriftsartikel (refereegranskat)abstract
- A novel technique enabling selective bead trapping in microfluidic devices without the use of physical barriers is presented in this paper. It is a fast, convenient and simple method, involving microcontact printing and self-assembly, that can be applied to silicon, quartz or plastic substrates. In the first step, channels are etched in the substrate. The surface chemistry of the internal walls of the channels is then modified by microcontact printing. The chip is submerged in a bead slurry where beads self-assemble based on surface chemistry and immobilize on the internal walls of the channels. Silicon channels (100 mum wide and 50 mum deep) have been covered with monolayers of streptavidin-, amino- and hydroxy-functionalized microspheres and resulted in good surface coverage of beads on the channel walls. A high-resolution pattern of lines of self-assembled streptavidin beads, as narrow as 5 mum, has also been generated on the bottom of a 500 mum wide and 50 mum deep channel. Flow tests were performed in sealed channels with the different immobilized beads to confirm that the immobilized beads could withstand the forces generated by water flowing in the channels. The presented results indicate that single beads can be precisely positioned within microfluidic devices based on self-assembly which is useful as screening and analysis tools within the field of biochemistry and organic chemistry.
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| 10. |
- Axén, Jakob, et al.
(författare)
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An investigation of peak-broadening effects arising when combining CE with MS.
- 2007
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Ingår i: Electrophoresis. - : Wiley. - 0173-0835 .- 1522-2683. ; 28:18, s. 3207-3213
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Tidskriftsartikel (refereegranskat)abstract
- In this study, peak-broadening effects caused by nebulizing gas flow and lack of temperature control have been investigated for separation capillaries with three different inner diameters. The study was performed with serial UV/ESI-MS detection in an effort to distinguish between peak broadening arising in the separation and peak broadening arising in the ion source. The nebulizing gas was found to significantly affect both migration time and separation efficiency when using capillaries with 50 and 75 µm id. If the nebulizing gas is on during injection, the injection volume increases to such an extent that significant peak broadening is induced. Reducing the id to 25 µm minimizes the parabolic flow induced by the nebulizing gas. Results indicate that the nebulizing gas pressure can be optimized to minimize peak broadening in the ion source. A decrease in detection sensitivity, possibly related to the orthogonal design of the interface, was observed when the nebulizing gas pressure was increased. A tapered capillary tip was found to provide superior separation efficiency as well as sensitivity.
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