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Xue W, Shi W, Kong Y, Kuss M, Duan B. Anisotropic scaffolds for peripheral nerve and spinal cord regeneration. Bioact Mater 2021; 6:4141-4160. [PMID: 33997498 PMCID: PMC8099454 DOI: 10.1016/j.bioactmat.2021.04.019] [Citation(s) in RCA: 52] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Revised: 04/05/2021] [Accepted: 04/13/2021] [Indexed: 12/12/2022] Open
Abstract
The treatment of long-gap (>10 mm) peripheral nerve injury (PNI) and spinal cord injury (SCI) remains a continuous challenge due to limited native tissue regeneration capabilities. The current clinical strategy of using autografts for PNI suffers from a source shortage, while the pharmacological treatment for SCI presents dissatisfactory results. Tissue engineering, as an alternative, is a promising approach for regenerating peripheral nerves and spinal cords. Through providing a beneficial environment, a scaffold is the primary element in tissue engineering. In particular, scaffolds with anisotropic structures resembling the native extracellular matrix (ECM) can effectively guide neural outgrowth and reconnection. In this review, the anatomy of peripheral nerves and spinal cords, as well as current clinical treatments for PNI and SCI, is first summarized. An overview of the critical components in peripheral nerve and spinal cord tissue engineering and the current status of regeneration approaches are also discussed. Recent advances in the fabrication of anisotropic surface patterns, aligned fibrous substrates, and 3D hydrogel scaffolds, as well as their in vitro and in vivo effects are highlighted. Finally, we summarize potential mechanisms underlying the anisotropic architectures in orienting axonal and glial cell growth, along with their challenges and prospects.
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Affiliation(s)
- Wen Xue
- Mary & Dick Holland Regenerative Medicine Program, University of Nebraska Medical Center, Omaha, NE, USA
- Division of Cardiology, Department of Internal Medicine, University of Nebraska Medical Center, Omaha, NE, USA
| | - Wen Shi
- Mary & Dick Holland Regenerative Medicine Program, University of Nebraska Medical Center, Omaha, NE, USA
- Division of Cardiology, Department of Internal Medicine, University of Nebraska Medical Center, Omaha, NE, USA
| | - Yunfan Kong
- Mary & Dick Holland Regenerative Medicine Program, University of Nebraska Medical Center, Omaha, NE, USA
- Division of Cardiology, Department of Internal Medicine, University of Nebraska Medical Center, Omaha, NE, USA
| | - Mitchell Kuss
- Mary & Dick Holland Regenerative Medicine Program, University of Nebraska Medical Center, Omaha, NE, USA
- Division of Cardiology, Department of Internal Medicine, University of Nebraska Medical Center, Omaha, NE, USA
| | - Bin Duan
- Mary & Dick Holland Regenerative Medicine Program, University of Nebraska Medical Center, Omaha, NE, USA
- Division of Cardiology, Department of Internal Medicine, University of Nebraska Medical Center, Omaha, NE, USA
- Department of Surgery, University of Nebraska Medical Center, Omaha, NE, USA
- Department of Mechanical Engineering, University of Nebraska-Lincoln, Lincoln, NE, USA
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Fabrication and Characterization of Single-Crystal Diamond Membranes for Quantum Photonics with Tunable Microcavities. MICROMACHINES 2020; 11:mi11121080. [PMID: 33291795 PMCID: PMC7762039 DOI: 10.3390/mi11121080] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/11/2020] [Revised: 11/27/2020] [Accepted: 12/02/2020] [Indexed: 11/17/2022]
Abstract
The development of quantum technologies is one of the big challenges in modern research. A crucial component for many applications is an efficient, coherent spin-photon interface, and coupling single-color centers in thin diamond membranes to a microcavity is a promising approach. To structure such micrometer thin single-crystal diamond (SCD) membranes with a good quality, it is important to minimize defects originating from polishing or etching procedures. Here, we report on the fabrication of SCD membranes, with various diameters, exhibiting a low surface roughness down to 0.4 nm on a small area scale, by etching through a diamond bulk mask with angled holes. A significant reduction in pits induced by micromasking and polishing damages was accomplished by the application of alternating Ar/Cl2 + O2 dry etching steps. By a variation of etching parameters regarding the Ar/Cl2 step, an enhanced planarization of the surface was obtained, in particular, for surfaces with a higher initial surface roughness of several nanometers. Furthermore, we present the successful bonding of an SCD membrane via van der Waals forces on a cavity mirror and perform finesse measurements which yielded values between 500 and 5000, depending on the position and hence on the membrane thickness. Our results are promising for, e.g., an efficient spin-photon interface.
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Hicks ML, Pakpour-Tabrizi AC, Jackman RB. Diamond Etching Beyond 10 μm with Near-Zero Micromasking. Sci Rep 2019; 9:15619. [PMID: 31666585 PMCID: PMC6821859 DOI: 10.1038/s41598-019-51970-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2019] [Accepted: 09/23/2019] [Indexed: 12/13/2022] Open
Abstract
To exploit the exceptional properties of diamond, new high quality fabrication techniques are needed to produce high performing devices. Etching and patterning diamond to depths beyond one micron has proven challenging due to the hardness and chemical resistance of diamond. A new cyclic Ar/O2 - Ar/Cl2 ICP RIE process has been developed to address micromasking issues from the aluminium mask by optimising the proportion of O2 in the plasma and introducing a preferential “cleaning” step. High quality smooth features up to, but not limited to, 10.6 μm were produced with an average etched surface roughness of 0.47 nm at a diamond etch rate of 45 nm/min and 16.9:1 selectivity.
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Affiliation(s)
- Marie-Laure Hicks
- London Centre for Nanotechnology & Department of Electronic and Electrical Engineering, University College London, 17-19 Gordon Street, WC1H 0AH, London, UK
| | - Alexander C Pakpour-Tabrizi
- London Centre for Nanotechnology & Department of Electronic and Electrical Engineering, University College London, 17-19 Gordon Street, WC1H 0AH, London, UK
| | - Richard B Jackman
- London Centre for Nanotechnology & Department of Electronic and Electrical Engineering, University College London, 17-19 Gordon Street, WC1H 0AH, London, UK.
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Liu XQ, Yang SN, Sun YL, Yu L, Bai BF, Chen QD, Sun HB. Ultra-smooth micro-optical components of various geometries. OPTICS LETTERS 2019; 44:2454-2457. [PMID: 31090705 DOI: 10.1364/ol.44.002454] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2019] [Accepted: 04/21/2019] [Indexed: 06/09/2023]
Abstract
A dry-etching-assisted femtosecond laser lithography technology is proposed to in-site fabricate micro-optical components with an ultra-smooth three-dimensional continuous profile on a non-planar substrate. Owing to the nanometric resolution of femtosecond laser multi-photon polymerization and dry etching, smooth micro-optical components can be realized on hard materials with surface roughness of approximately 1.5 nm. With flexible and arbitrary designability of femtosecond laser lithography, various high-quality micro-optical components are realized on sapphire. These results indicate that dry-etching-assisted femtosecond laser lithography has promising potential for versatile fabrication of arbitrary ultra-smooth micro/nanostructures on hard materials.
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