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- Zhao, Qing, et al.
(författare)
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Rat sciatic nerve regeneration through a micromachined silicon chip
- 1997
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Ingår i: Biomaterials. - 1878-5905. ; 18:1, s. 75-80
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Tidskriftsartikel (refereegranskat)abstract
- The capacity of regenerating nerve fibres to grow through a perforated silicon chip was tested using the silicone chamber model for nerve regeneration. The chips were fabricated as circular membranes, 4 mm in diameter, thickness 60 microns, with a perforated area, 2 mm in diameter, in the centre. Three types of chips were fabricated utilizing anisotropic etching. The chips were glued with silicone adhesive between two halves of silicone rubber tubing (total length 8 mm, inner diameter 1.8 mm, outer diameter 3.0 mm) which was used to bridge a 4 mm gap between the proximal and distal nerve stumps of a transected rat sciatic nerve. The capacity of regenerating nerve fibres to grow through the holes of the chip was analysed by light and scanning electron microscopy after 4 or 16 weeks of regeneration. Furthermore, the muscle contractility force of the gastrocnemius muscle was measured after 16 weeks of regeneration and compared as a percentage of the contralateral uninjured side. Nerves generated through chips with hole diameters of 10 or 50 microns were morphological and functional failures. The nerve structures distal to chips with hole diameters of 100 microns contained many myelinated nerve fibres in a minifascicular pattern after both 4 and 16 weeks of regeneration. The muscle contractility force was 56% of that of contralateral control muscles.
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| 2. |
- Önnerfjord, Patrik, et al.
(författare)
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Picoliter sample preparation in MALDI-TOF MS using a micromachined silicon flow-through dispenser
- 1998
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Ingår i: Analytical Chemistry. - : American Chemical Society (ACS). - 0003-2700 .- 1520-6882. ; 70:22, s. 4755-4760
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents a picoliter sample preparation technique utilizing the flow-through principle, allowing on-line coupling of chromatographic systems to be made. The work was performed in order to investigate the characteristics and the physicochemical properties of the sample preparation using typical mobile phase conditions from μ-CLC (column liquid chromatography) separations. The device presented here is a pressure pulse- driven dispenser, formed by two silicon structures processed by conventional micromachining. The pressure pulse is generated in the flow-through channel by a piezoceramic element. Depending on the orifice size, the droplets ejected range between 30 and 200 pL. The maximum ejection frequency is 500 Hz, limited by resonances within the unit. A pyramid-shaped nozzle improves the directivity of the droplets since it reduces the wetting of the orifice front surface area. The risk of particles sticking close to the orifice is also minimized. The analyses of the deposited sample spots were carried out on a matrix-assisted laser desorption/ionization time-of-flight mass spectrometer with delayed extraction. It was possible to detect attomole amounts (159-248 amol) of various proteins (cytochrome c, ribonuclease A, lysozyme, and myoglobin) from a single droplet of matrix:analyte 1:1 (drop volume ≃ 110 pL). Additionally, it was found that sample enrichment could be carried out using multiple depositions on the same spot; i.e., 31 nM of insulin was easily detected when more than four depositions were made on the same spot, while no detection was possible without sample enrichment. Size optimization of the MALDI sample spot gave target zones of 100-500-μm diameter that matched the size of the laser focal point and resulted in a considerably increased sample throughput.
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