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Dietrich J, Enke A, Wilharm N, Konieczny R, Lotnyk A, Anders A, Mayr SG. Energetic Electron-Assisted Synthesis of Tailored Magnetite (Fe 3O 4) and Maghemite (γ-Fe 2O 3) Nanoparticles: Structure and Magnetic Properties. Nanomaterials (Basel) 2023; 13:786. [PMID: 36903665 PMCID: PMC10005483 DOI: 10.3390/nano13050786] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/27/2023] [Revised: 02/10/2023] [Accepted: 02/17/2023] [Indexed: 06/18/2023]
Abstract
Iron oxide nanoparticles with a mean size of approximately 5 nm were synthesized by irradiating micro-emulsions containing iron salts with energetic electrons. The properties of the nanoparticles were investigated using scanning electron microscopy, high-resolution transmission electron microscopy, selective area diffraction and vibrating sample magnetometry. It was found that formation of superparamagnetic nanoparticles begins at a dose of 50 kGy, though these particles show low crystallinity, and a higher portion is amorphous. With increasing doses, an increasing crystallinity and yield could be observed, which is reflected in an increasing saturation magnetization. The blocking temperature and effective anisotropy constant were determined via zero-field cooling and field cooling measurements. The particles tend to form clusters with a size of 34 nm to 73 nm. Magnetite/maghemite nanoparticles could be identified via selective area electron diffraction patterns. Additionally, goethite nanowires could be observed.
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Affiliation(s)
- Johannes Dietrich
- Leibniz Institute of Surface Engineering (IOM), Permoserstraße 15, 04318 Leipzig, Germany
- Division of Surface Physics, Faculty of Physics and Earth Science, Leipzig University, Linnéstraße 5, 04103 Leipzig, Germany
| | - Alexius Enke
- Leibniz Institute of Surface Engineering (IOM), Permoserstraße 15, 04318 Leipzig, Germany
- Division of Surface Physics, Faculty of Physics and Earth Science, Leipzig University, Linnéstraße 5, 04103 Leipzig, Germany
| | - Nils Wilharm
- Leibniz Institute of Surface Engineering (IOM), Permoserstraße 15, 04318 Leipzig, Germany
- Division of Surface Physics, Faculty of Physics and Earth Science, Leipzig University, Linnéstraße 5, 04103 Leipzig, Germany
| | - Robert Konieczny
- Leibniz Institute of Surface Engineering (IOM), Permoserstraße 15, 04318 Leipzig, Germany
| | - Andriy Lotnyk
- Leibniz Institute of Surface Engineering (IOM), Permoserstraße 15, 04318 Leipzig, Germany
| | - André Anders
- Leibniz Institute of Surface Engineering (IOM), Permoserstraße 15, 04318 Leipzig, Germany
- Division of Applied Physics, Faculty of Physics and Earth Science, Leipzig University, Linnéstraße 5, 04103 Leipzig, Germany
| | - Stefan G. Mayr
- Leibniz Institute of Surface Engineering (IOM), Permoserstraße 15, 04318 Leipzig, Germany
- Division of Surface Physics, Faculty of Physics and Earth Science, Leipzig University, Linnéstraße 5, 04103 Leipzig, Germany
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Wilharm N, Bertmer M, Knolle W, Griebel J, Elsner C, Mayr SG. Biomimetic crosslinking of collagen gels by energetic electrons: The role of L-lysine. Acta Biomater 2022; 140:219-232. [PMID: 34551331 DOI: 10.1016/j.actbio.2021.09.025] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2021] [Revised: 09/13/2021] [Accepted: 09/14/2021] [Indexed: 11/19/2022]
Abstract
Energetic electrons have recently evolved as a powerful tool for crosslinking bio-derived hydrogels without the need for adding potentially hazardous reagents. Application of this approach allows for synthesis of biomimetic collagen-derived networks of highly tunable properties and functionalization. Yet, the underlying reaction kinetics are still not sufficiently established at this point. While hydroxyl radicals are generated by energetic electron-induced hydrolysis of water and play a key role in introducing covalent bonds between network fibers, a detailed mechanistic understanding would significantly increase applicability. We present a comprehensive analysis of central aspects of the reactivity between the hydroxyl radical (•OH) and collagen, elastin, glycine (Gly) and l-lysine (Lys). Pulse radiolysis (PR), solid state nuclear magnetic resonance (NMR), ultraviolet-visible absorption spectroscopy (UV/VIS) and electron spray ionization mass spectrometry (ESI-MS) shine light on distinct features of the crosslinking process. These highlight retained protein backbone integrity in collagen and elastin whilst Lys's ability to form several imine bonded Lys-Lys-species suggests striking similarities to crosslinking via lysyl oxidase catalysis in vivo. Thus, energetic electron based crosslinking opens the venue for customized hybrid gels of outstanding biomimicry and -compatibility. STATEMENT OF SIGNIFICANCE: Energetic electron beam treatment constitutes a highly attractive approach to establish chemical bonds between (bio) molecules. Although a convincing number of publications showed the versatility regarding crosslinking of bioderived hydrogels, insights into the underlying chemistry are still unestablished at this point. The present work unravels the mechanistics of energetic electron induced processes in collagen and elastin hydrogels as well as several abundant amino acids in aqueous solution. As key finding we demonstrate, that i) the connection between polymer chains is dominated by amino acid side chain interaction and ii) two single l-lysine molecules form an imine bond between the terminal amino group of one molecule and the delta carbon of the second molecule. We also consider the formation of H-bonds as a second crosslinking pathway. These findings open up for advanced, optionally spatially resolved biomaterials design.
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Affiliation(s)
- Nils Wilharm
- Leibniz-Institut für Oberflächenmodifizierung e.V. (IOM), Permoserstr. 15, 04318 Leipzig, Germany; Division of Surface Physics, Department of Physics and Earth Sciences, University of Leipzig, Linnéstraße 5, 04103 Leipzig, Germany.
| | - Marko Bertmer
- Leipzig University, Felix-Bloch-Institute for Solid State Physics, Linnéstraße 5, 04103, Leipzig, Germany
| | - Wolfgang Knolle
- Leibniz-Institut für Oberflächenmodifizierung e.V. (IOM), Permoserstr. 15, 04318 Leipzig, Germany
| | - Jan Griebel
- Leibniz-Institut für Oberflächenmodifizierung e.V. (IOM), Permoserstr. 15, 04318 Leipzig, Germany
| | - Christian Elsner
- Leibniz-Institut für Oberflächenmodifizierung e.V. (IOM), Permoserstr. 15, 04318 Leipzig, Germany
| | - Stefan G Mayr
- Leibniz-Institut für Oberflächenmodifizierung e.V. (IOM), Permoserstr. 15, 04318 Leipzig, Germany; Division of Surface Physics, Department of Physics and Earth Sciences, University of Leipzig, Linnéstraße 5, 04103 Leipzig, Germany.
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Elbalasy I, Wilharm N, Herchenhahn E, Konieczny R, Mayr SG, Schnauß J. From Strain Stiffening to Softening—Rheological Characterization of Keratins 8 and 18 Networks Crosslinked via Electron Irradiation. Polymers (Basel) 2022; 14:polym14030614. [PMID: 35160604 PMCID: PMC8838340 DOI: 10.3390/polym14030614] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2021] [Revised: 01/21/2022] [Accepted: 01/28/2022] [Indexed: 02/01/2023] Open
Abstract
Networks of crosslinked keratin filaments are abundant in epithelial cells and tissues, providing resilience against mechanical forces and ensuring cellular integrity. Although studies of in vitro models of reconstituted keratin networks have revealed important mechanical aspects, the mechanical properties of crosslinked keratin structures remain poorly understood. Here, we exploited the power of electron beam irradiation (EBI) to crosslink in vitro networks of soft epithelial keratins 8 and 18 (k8–k18) filaments with different irradiation doses (30 kGy, 50 kGy, 80 kGy, 100 kGy, and 150 kGy). We combined bulk shear rheology with confocal microscopy to investigate the impact of crosslinking on the mechanical and structural properties of the resultant keratin gels. We found that irradiated keratin gels display higher linear elastic modulus than the unirradiated, entangled networks at all doses tested. However, at the high doses (80 kGy, 100 kGy, and 150 kGy), we observed a remarkable drop in the elastic modulus compared to 50 kGy. Intriguingly, the irradiation drastically changed the behavior for large, nonlinear deformations. While untreated keratin networks displayed a strong strain stiffening, increasing irradiation doses shifted the system to a strain softening behavior. In agreement with the rheological behavior in the linear regime, the confocal microscopy images revealed fully isotropic networks with high percolation in 30 kGy and 50 kGy-treated keratin samples, while irradiation with 100 kGy induced the formation of thick bundles and clusters. Our results demonstrate the impact of permanent crosslinking on k8–k18 mechanics and provide new insights into the potential contribution of intracellular covalent crosslinking to the loss of mechanical resilience in some human keratin diseases. These insights will also provide inspiration for the synthesis of new keratin-based biomaterials.
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Affiliation(s)
- Iman Elbalasy
- Peter-Debye Institute for Soft Matter Physics, Leipzig University, Linnéstraße 5, 04103 Leipzig, Germany;
- Faculty of Science, Cairo University, Giza 12613, Egypt
- Correspondence: (I.E.); (S.G.M.); (J.S.)
| | - Nils Wilharm
- Leibniz-Institut für Oberflächenmodifizierung e.V. (IOM), Permoserstr. 15, 04318 Leipzig, Germany; (N.W.); (R.K.)
- Division of Surface Physics, Department of Physics and Earth Sciences, Leipzig University, Linnéstraße 5, 04103 Leipzig, Germany
| | - Erik Herchenhahn
- Peter-Debye Institute for Soft Matter Physics, Leipzig University, Linnéstraße 5, 04103 Leipzig, Germany;
| | - Robert Konieczny
- Leibniz-Institut für Oberflächenmodifizierung e.V. (IOM), Permoserstr. 15, 04318 Leipzig, Germany; (N.W.); (R.K.)
| | - Stefan G. Mayr
- Leibniz-Institut für Oberflächenmodifizierung e.V. (IOM), Permoserstr. 15, 04318 Leipzig, Germany; (N.W.); (R.K.)
- Division of Surface Physics, Department of Physics and Earth Sciences, Leipzig University, Linnéstraße 5, 04103 Leipzig, Germany
- Correspondence: (I.E.); (S.G.M.); (J.S.)
| | - Jörg Schnauß
- Peter-Debye Institute for Soft Matter Physics, Leipzig University, Linnéstraße 5, 04103 Leipzig, Germany;
- Fraunhofer Institute for Cell Therapy and Immunology, Perlickstraße 1, 04103 Leipzig, Germany
- Unconventional Computing Lab, Department of Computer Science and Creative Technologies, UWE, Bristol BS16 1QY, UK
- Correspondence: (I.E.); (S.G.M.); (J.S.)
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Deuflhard M, Eberbeck D, Hietschold P, Wilharm N, Mühlberger M, Friedrich RP, Alexiou C, Mayr SG. Magnetically responsive composites: electron beam assisted magnetic nanoparticle arrest in gelatin hydrogels for bioactuation. Phys Chem Chem Phys 2019; 21:14654-14662. [DOI: 10.1039/c9cp02910a] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Tailored ferrogel bioactuators are feasible by arresting nanoparticles in simple gelatin gels with the help of electron beam treatment.
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Affiliation(s)
- Marie Deuflhard
- Leibniz Institute of Surface Engineering (IOM)
- 04318 Leipzig
- Germany
- Division of Surface Physics
- Department of Physics and Earth Sciences
| | - Dietmar Eberbeck
- Department 8.2 Biosignals
- Physikalisch-Technische Bundesanstalt Braunschweig und Berlin
- 10587 Berlin
- Germany
| | - Philine Hietschold
- Leibniz Institute of Surface Engineering (IOM)
- 04318 Leipzig
- Germany
- Division of Surface Physics
- Department of Physics and Earth Sciences
| | - Nils Wilharm
- Leibniz Institute of Surface Engineering (IOM)
- 04318 Leipzig
- Germany
- Division of Surface Physics
- Department of Physics and Earth Sciences
| | - Marina Mühlberger
- Department of Otorhinolaryngology
- Head and Neck Surgery
- Section of Experimental Oncology and Nanomedicine (SEON)
- Else Kröner-Fresenius-Stiftung-Professorship
- Universitätsklinikum Erlangen
| | - Ralf P. Friedrich
- Department of Otorhinolaryngology
- Head and Neck Surgery
- Section of Experimental Oncology and Nanomedicine (SEON)
- Else Kröner-Fresenius-Stiftung-Professorship
- Universitätsklinikum Erlangen
| | - Christoph Alexiou
- Department of Otorhinolaryngology
- Head and Neck Surgery
- Section of Experimental Oncology and Nanomedicine (SEON)
- Else Kröner-Fresenius-Stiftung-Professorship
- Universitätsklinikum Erlangen
| | - Stefan G. Mayr
- Leibniz Institute of Surface Engineering (IOM)
- 04318 Leipzig
- Germany
- Division of Surface Physics
- Department of Physics and Earth Sciences
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Fischer T, Wilharm N, Hayn A, Mierke CT. Matrix and cellular mechanical properties are the driving factors for facilitating human cancer cell motility into 3D engineered matrices. Converg Sci Phys Oncol 2017. [DOI: 10.1088/2057-1739/aa8bbb] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Kunschmann T, Puder S, Fischer T, Perez J, Wilharm N, Mierke CT. Integrin-linked kinase regulates cellular mechanics facilitating the motility in 3D extracellular matrices. Biochim Biophys Acta Mol Cell Res 2016; 1864:580-593. [PMID: 28011283 DOI: 10.1016/j.bbamcr.2016.12.019] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/18/2016] [Revised: 12/12/2016] [Accepted: 12/19/2016] [Indexed: 12/12/2022]
Abstract
The motility of cells plays an important role for many processes such as wound healing and malignant progression of cancer. The efficiency of cell motility is affected by the microenvironment. The connection between the cell and its microenvironment is facilitated by cell-matrix adhesion receptors and upon their activation focal adhesion proteins such as integrin-linked kinase (ILK) are recruited to sites of focal adhesion formation. In particular, ILK connects cell-matrix receptors to the actomyosin cytoskeleton. However, ILK's role in cell mechanics regulating cellular motility in 3D collagen matrices is still not well understood. We suggest that ILK facilitates 3D motility by regulating cellular mechanical properties such as stiffness and force transmission. Thus, ILK wild-type and knock-out cells are analyzed for their ability to migrate on 2D substrates serving as control and in dense 3D extracellular matrices. Indeed, ILK wild-type cells migrated faster on 2D substrates and migrated more numerous and deeper in 3D matrices. Hence, we analyzed cellular deformability, Young's modulus (stiffness) and adhesion forces. We found that ILK wild-type cells are less deformable (stiffer) and produce higher cell-matrix adhesion forces compared to ILK knock-out cells. Finally, ILK is essential for providing cellular mechanical stiffness regulating 3D motility.
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Affiliation(s)
- Tom Kunschmann
- University of Leipzig, Faculty of Physics and Earth Science, Institute for Experimental Physics I, Biological Physics Division, Linnestrasse 5, 04103 Leipzig, Germany
| | - Stefanie Puder
- University of Leipzig, Faculty of Physics and Earth Science, Institute for Experimental Physics I, Biological Physics Division, Linnestrasse 5, 04103 Leipzig, Germany
| | - Tony Fischer
- University of Leipzig, Faculty of Physics and Earth Science, Institute for Experimental Physics I, Biological Physics Division, Linnestrasse 5, 04103 Leipzig, Germany
| | - Jeremy Perez
- University of Leipzig, Faculty of Physics and Earth Science, Institute for Experimental Physics I, Biological Physics Division, Linnestrasse 5, 04103 Leipzig, Germany
| | - Nils Wilharm
- University of Leipzig, Faculty of Physics and Earth Science, Institute for Experimental Physics I, Biological Physics Division, Linnestrasse 5, 04103 Leipzig, Germany
| | - Claudia Tanja Mierke
- University of Leipzig, Faculty of Physics and Earth Science, Institute for Experimental Physics I, Biological Physics Division, Linnestrasse 5, 04103 Leipzig, Germany.
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