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| 15. |
- Johansson, Fredrik, et al.
(författare)
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Guidance of neurons on porous patterned silicon: is pore size important?
- 2005
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Ingår i: Physica Status Solidi. C, Current Topics in Solid State Physics. - : Wiley. - 1610-1634. ; 2:9, s. 3258-3262
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Tidskriftsartikel (refereegranskat)abstract
- The paper studies the conditions optimum for the proliferation of neural cells at the surface of porous silicon. The results of this study show that the best results are achieved with meso-porous silicon. Geometrical properties of the wafers are also important through charge distribution at mask edges, change of hydrophobicity, degree of oxidation, the release of adhesion proteins from regenerating axons, etc
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| 16. |
- Johansson, Fredrik I, et al.
(författare)
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Axonal outgrowth on nano-imprinted patterns
- 2006
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Ingår i: Biomaterials. - : Elsevier BV. - 1878-5905 .- 0142-9612. ; 27:8, s. 1251-1258
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Tidskriftsartikel (refereegranskat)abstract
- Nanotechnology has provided methods to fabricate surface patterns with features down to a few rim. If cells or cell processes exhibit contact guidance in response to such small patterns is an interesting question and could be pertinent for many applications. In the present study we investigated if axonal outgrowth was affected by nano-printed patterns in polymethylmethacrylate (PMMA)-covered silicon chips. To this end adult mouse sympathetic and sensory ganglia were mounted in Matrigel (R) on the chips close to the nano-patterns. The patterns consisted of parallel grooves with depths of 300 nm and varying widths of 100-400 nm. The distance between two adjacent grooves was 100-1600 nm. The chips were cultured in medium containing 25 ng/ml of nerve growth factor to stimulate axonal outgrowth. After 1 week of incubation. axonal outgrowth was investigated by immunocytochemistry or scanning electron microscopy. Axons displayed contact guidance on all patterns. Furthermore, we found that the nerve cell processes preferred to grow on ridge edges and elevations in the patterns rather than in grooves, a seemingly claustrophobic behavior. We conclude that axons of peripheral neurons might be guided by nanopatterns on PMMA when the lateral features are 100 nm or larger. The present results can be utilized for nerve regenerating scaffolds or the construction of a stable, high-resolution electronic interface to neurons, which is required for future brain machine interfaces. (c) 2005 Elsevier Ltd. All rights reserved.
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| 17. |
- Johansson, Fredrik, et al.
(författare)
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Nanomodified surfaces and guidance of nerve cell processes
- 2008
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Ingår i: Journal of Vacuum Science and Technology B. - : American Vacuum Society. - 1520-8567 .- 1071-1023. ; 26:6, s. 2558-2561
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Konferensbidrag (refereegranskat)abstract
- Axonal growth and guidance were studied on different micro- and nanostructured surfaces. Nanoimprinted grooves in a polymer, epitaxial III/V nanowires, porous silicon patterns, and chemically altered surfaces were all shown to induce axonal guidance. Neurons were also found to be able to attach and grow on gallium phosphide nanowires without compromising cell survival. The results are important for the construction of a new generation of neuroelectrical interfaces, including high spatial resolution electrodes. The advantages of the different nanostructured surfaces are discussed.
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| 18. |
- Johansson, Fredrik, et al.
(författare)
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Porous silicon as a potential electrode material in a nerve repair setting: Tissue reactions.
- 2009
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Ingår i: Acta Biomaterialia. - : Elsevier BV. - 1878-7568 .- 1742-7061. ; 5, s. 2230-2237
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Tidskriftsartikel (refereegranskat)abstract
- We compared porous silicon (pSi) with smooth Si as chip-implant surfaces in a nerve regeneration setting. Silicon chips can be used for recording neural activity and are potential nerve interface devices. A silicon chip with one smooth and one porous side inserted into a tube was used to bridge a 5 mm defect in rat sciatic nerve. Six or 12 weeks later, new nerve structures surrounded by a perineurium-like capsule had formed on each side of the chip. The number of regenerated nerve fibers did not differ on either side of the chip as shown by immunostaining for neurofilaments. However, the capsule that had formed in contact with the chip was significantly thinner on the porous side than on the smooth side. Cellular protrusions had formed on the pSi side and the regenerated nerve tissue was found to attach firmly to this surface, while the tissue was hardly attached to the smooth silicon surface. We conclude that a pSi surface, due to its large surface area, diminished inflammatory response and firm adhesion to the tissue, should be a good material for the development of new implantable electronic nerve devices.
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| 19. |
- Johansson, Fredrik, et al.
(författare)
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The influence of porous silicon on axonal outgrowth in vitro.
- 2008
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Ingår i: IEEE Transactions on Biomedical Engineering. - 1558-2531. ; 55:4, s. 1447-1449
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Tidskriftsartikel (refereegranskat)abstract
- Axonal outgrowth on smooth and porous silicon surfaces was studied in organ culture. The pore size of the silicon substrata varied between 100 and 1500 nm. We found that axons preferred to grow and elongate on porous silicon surfaces only when pores of (150-500 nm) are available.
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| 20. |
- Kataoka, Kazuya |, et al.
(författare)
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Induction of activating transcription factor 3 after different sciatic nerve injuries in adult rats
- 2007
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Ingår i: Scandinavian Journal of Plastic and Reconstructive Surgery and Hand Surgery. - : Informa UK Limited. - 1651-2073 .- 0284-4311. ; 41:4, s. 158-166
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Tidskriftsartikel (refereegranskat)abstract
- Staining by activating transcription factor 3 (ATF3), a neuronal marker of nerve injury, was examined by immunocytochemistry in neurons and Schwann cells after crush or transection (regeneration inhibited) of rat sciatic nerve. ATF3 immunoreactivity peaked in neurons after three days and then gradually subsided to normal within 12 weeks after the crush. The response lasted somewhat longer and declined over time in spinal cord neurons but not in those of dorsal root ganglia (DRG) after transection, indicating a differential regulation of sensory and motor neurons. ATF3 expression was more pronounced in Schwann cells, and remained longer after transection, implying that to some extent regenerating axons produce signals that reduce ATF3 expression in Schwann cells. However, even after transection without repair (no contact with regenerating axons), ATF3 expression in Schwann cells in the distal segment decreased over time suggesting that regenerating axons are not entirely responsible for the down-regulation. These findings have clinical implications on when it is worthwhile to reconstruct nerve injuries.
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