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| 2. |
- Bengtsson, Martin, et al.
(författare)
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Improved performance in silicon enzyme microreactors obtained by homogeneous porous silicon carrier matrix
- 2002
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Ingår i: Talanta. - 1873-3573. ; 56:2, s. 341-353
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Tidskriftsartikel (refereegranskat)abstract
- The catalytic performance of porous silicon (PS) micro enzyme reactors (muIMER) is strongly dependent on the PS matrix morphology for enzyme immobilisation. PS was achieved in the muIMER by anodisation in a HF-ethanol mixture. PS etching of structured silicon surfaces commonly results in an inhomogeneous pore formation. The deep channel microreactors described herein have previously suffered from these phenomena, yielding non-optimised muIMERs. In order to obtain a homogeneous PS layer on the deep microreactor channel walls, different reactor geometries (channel wall thicknesses of 50 and 75 mum) were anodised at 10 and 50 mA cm(-2) for anodisation times ranging between 0 and 50 min. The muIMERs were evaluated by immobilising two types of enzymes, glucose oxidase (GOx) and trypsin, and the resulting catalytic turnover was monitored by a colorimetric assay. It was found that reactors with a homogeneous PS matrix displayed improved performance. The trypsin muIMERs were used to digest a protein, beta-casein, in an on-line format and the digest was analysed by MALDI-TOF MS. The importance of tailoring the muIMER geometry and the PS-matrix is crucial for the protein digestion. Successful protein identification after only 12 s. digestion was demonstrated for the best reactor, 75 mum channel wall, 25 mum channel width, anodised at 50 mA cm(-2) for 10 min. (C) 2002 Elsevier Science B.V. All rights reserved.
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| 3. |
- Bergkvist, Jonas, et al.
(författare)
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Improved chip design for integrated solid-phase microextraction in on-line proteomic sample preparation
- 2002
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Ingår i: Proteomics. - 1615-9861. ; 2:4, s. 422-429
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Tidskriftsartikel (refereegranskat)abstract
- A recently introduced silicon microextraction chip (SMEC), used for on-line proteomic sample preparation, has proved to facilitate the process of protein identification by sample clean up and enrichment of peptides. It is demonstrated that a novel grid-SMEC design improves the operating characteristics for solid-phase microextraction, by reducing dispersion effects and thereby improving the sample preparation conditions. The structures investigated in this paper are treated both numerically and experimentally. The numerical approach is based on finite element analysis of the micro-fluidic flow in the microchip. The analysis is accomplished by use of the computational fluid dynamics-module FLOTRAN in the ANSYS(R) software package. The modeling and analysis of the previously reported weir-SMEC design indicates some severe drawbacks, that can be reduced by changing the microextraction chip geometry to the grid-SMEC design. The overall analytical performance was thereby improved and also verified by experimental work. Matrix-assisted laser desorption/ionization mass spectra of model peptides extracted from both the weir-SMEC and the new grid-SMEC support the numerical analysis results. Further use of numerical modeling and analysis of the SMEC structures is also discussed and suggested in this work.
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| 7. |
- Ekström, Simon, et al.
(författare)
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Integrated microanalytical technology enabling rapid and automated protein identification
- 2000
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Ingår i: Analytical Chemistry. - : American Chemical Society (ACS). - 0003-2700 .- 1520-6882. ; 72:2, s. 286-293
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Tidskriftsartikel (refereegranskat)abstract
- Protein identification through peptide mass mapping by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) has become a standard technique, used in many laboratories around the world. The traditional methodology often includes long incubations (6-24 h) and extensive manual steps. In an effort to address this, an integrated microanalytical platform has been developed for automated identification of proteins. The silicon micromachined analytical tools, i.e., the microchip immobilized enzyme reactor (μ-chip IMER), the piezoelectric microdispenser, and the high-density nanovial target plates, are the cornerstones in the system. The μ-chip IMER provides on-line enzymatic digestion of protein samples (1 μL) within 1-3 min, and the microdispenser enables subsequent on- line picoliter sample preparation in a high-density format. Interfaced to automated MALDI-TOF MS, these tools compose a highly efficient platform that can analyze 100 protein samples in 3.5 h. Kinetic studies on the microreactors are reported as well as the operation of this microanalytical platform for protein identification, wherein lysozyme, myoglobin, ribonuclease A, and cytochrome c have been identified with a high sequence coverage (50-100%).
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| 8. |
- Ekström, Simon, et al.
(författare)
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Integrated selective enrichment target - a microtechnology platform for matrix-assisted laser desorption/ionization-mass spectrometry applied on protein biomarkers in prostate diseases
- 2004
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Ingår i: Electrophoresis. - : Wiley. - 0173-0835. ; 25:21-22, s. 3769-3777
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Tidskriftsartikel (refereegranskat)abstract
- The performance of a miniaturized sample processing platform for matrix-assisted laser desorption/ionization-mass spectrometry (MALDI-MS), manufactured by silicon microfabrication, called integrated selective enrichment target (ISET) technology was evaluated in a biological context. The ISET serves as both sample treatment device and MALDI-MS target, and contains an array of 96 perforated nanovials, which each can be filled with 40 nL of reversed-phase beads. This methodology minimizes the number of sample transfers and the total surface area available for undesired adsorption of the analytes in order to provide high-sensitivity analysis. ISET technology was successfully applied for characterization of proteins coisolated by affinity chromatography of prostate-specific antigen (PSA) from human seminal fluid. The application of ISET sample preparation enabled multiple analyses to be performed on a limited sample volume, which resulted in the discovery that prolactin inducible protein (PIP) was coisolated from the samples.
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| 9. |
- Ekström, Simon, et al.
(författare)
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On-chip microextraction for proteomic sample preparation of in-gel digests
- 2002
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Ingår i: Proteomics. - 1615-9861. ; 2:4, s. 413-421
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Tidskriftsartikel (refereegranskat)abstract
- Despite the high sensitivity and relatively high tolerance for contaminants of matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS) there is often a need to purify and concentrate the sample solution, especially after in-gel digestion of proteins separated by two-dimensional gel electrophoresis (2-DE). A silicon microextraction chip (SMEC) for sample clean-up and trace enrichment of peptides was manufactured and investigated. The microchip structure was used to trap reversed-phase chromatography media (POROS R2 beads) that facilitates sample purification/enrichment of contaminated and dilute samples prior to the MALDI-TOF MS analysis. The validity of the SMEC sample preparation technique was successfully investigated by performing analysis on a 10 nM peptide mixture containing 2 m urea in 0.1 m phosphate-buffered saline with MALDI-TOF MS. It is demonstrated that the microchip sample clean-up and enrichment of peptides can facilitate identification of proteins from 2-DE separations. The microchip structure was also used to trap beads immobilized with trypsin, thereby effectively becoming a microreactor for enzymatic digestion of proteins. This microreactor was used to generate a peptide map from a 100 nM bovine serum albumin sample.
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