Atomic force microscope-based methods for the nano-mechanical characterisation of hydrogels and other viscoelastic polymeric materials for biomedical applications
<p>Hydrogels, porous hydrated polymeric materials, are being increasingly used in biomedical applications. The mechanical properties of hydrogels play an important role in the success of many of these applications (e.g. tissue engineering and drug delivery), and can be modulated by external st...
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| Format: | Thesis |
| Language: | English |
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2020
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| _version_ | 1817932130349481984 |
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| author | Piacenti, AR |
| author2 | Antoranz Contera, S |
| author_facet | Antoranz Contera, S Piacenti, AR |
| author_sort | Piacenti, AR |
| collection | OXFORD |
| description | <p>Hydrogels, porous hydrated polymeric materials, are being increasingly used in biomedical applications. The mechanical properties of hydrogels play an important role in the success of many of these applications (e.g. tissue engineering and drug delivery), and can be modulated by external stimuli and/or by changing hydrogel structure and composition. Therefore, it is important to measure and understand these mechanical properties at cellular length scales (nano/micro-scale) to improve the efficacy of hydrogels in biomedical applications. </p>
<p>Hydrogels are often studied in terms of their elasticity. In this thesis, elastic properties of hydrogels were studied in terms of their elasticity via Atomic Force Microscopy (AFM) quasi-static micro-indentations. It is important to consider that hydrogels are not just elastic, but exhibit viscoelasticity, a time-dependent mechanical behaviour typical of hydrogels and polymeric materials in general. In this thesis, a novel AFM-based technique was developed to measure nano/micro-scale viscoelasticity.</p>
<p>First, changes in the local elastic properties of chitosan (a biopolymer) hydrogels in response to an external magnetic field were measured, demonstrating magneto-mechanical coupling. Second, this coupling was further explored by incorporating magnetic nanowires into the hydrogels. Both experiments suggest this coupling could be exploited to control hydrogel mechanics. Third, elasticity of hydrogels based on fullerenes was measured, and depended on the size of the fullerene used. Hydrogel elasticity in all three experiments matched that of biological tissues, suggesting biomechanical compatibility. The possibility of controlling hydrogel properties either by external stimuli or by composition, opens the door for all three of these materials to be used for therapeutic applications. Lastly, a novel technique based on photothermal excitation of the AFM cantilever was developed and proved to quantify viscoelasticity of polymeric materials over a frequency range up to five orders of magnitude (0.2 Hz to 20200 Hz), in good agreement with macroscopic data, revealing a promising tool for the viscoelastic characterisation of hydrogels.</p> |
| first_indexed | 2024-03-07T07:04:16Z |
| format | Thesis |
| id | oxford-uuid:1b7e8bf9-22e7-46c8-82b0-05953a5a5f17 |
| institution | University of Oxford |
| language | English |
| last_indexed | 2024-12-09T03:33:01Z |
| publishDate | 2020 |
| record_format | dspace |
| spelling | oxford-uuid:1b7e8bf9-22e7-46c8-82b0-05953a5a5f172024-12-01T16:10:14ZAtomic force microscope-based methods for the nano-mechanical characterisation of hydrogels and other viscoelastic polymeric materials for biomedical applicationsThesishttp://purl.org/coar/resource_type/c_db06uuid:1b7e8bf9-22e7-46c8-82b0-05953a5a5f17Polymers--Mechanical propertiesEnglishHyrax Deposit2020Piacenti, ARAntoranz Contera, S<p>Hydrogels, porous hydrated polymeric materials, are being increasingly used in biomedical applications. The mechanical properties of hydrogels play an important role in the success of many of these applications (e.g. tissue engineering and drug delivery), and can be modulated by external stimuli and/or by changing hydrogel structure and composition. Therefore, it is important to measure and understand these mechanical properties at cellular length scales (nano/micro-scale) to improve the efficacy of hydrogels in biomedical applications. </p> <p>Hydrogels are often studied in terms of their elasticity. In this thesis, elastic properties of hydrogels were studied in terms of their elasticity via Atomic Force Microscopy (AFM) quasi-static micro-indentations. It is important to consider that hydrogels are not just elastic, but exhibit viscoelasticity, a time-dependent mechanical behaviour typical of hydrogels and polymeric materials in general. In this thesis, a novel AFM-based technique was developed to measure nano/micro-scale viscoelasticity.</p> <p>First, changes in the local elastic properties of chitosan (a biopolymer) hydrogels in response to an external magnetic field were measured, demonstrating magneto-mechanical coupling. Second, this coupling was further explored by incorporating magnetic nanowires into the hydrogels. Both experiments suggest this coupling could be exploited to control hydrogel mechanics. Third, elasticity of hydrogels based on fullerenes was measured, and depended on the size of the fullerene used. Hydrogel elasticity in all three experiments matched that of biological tissues, suggesting biomechanical compatibility. The possibility of controlling hydrogel properties either by external stimuli or by composition, opens the door for all three of these materials to be used for therapeutic applications. Lastly, a novel technique based on photothermal excitation of the AFM cantilever was developed and proved to quantify viscoelasticity of polymeric materials over a frequency range up to five orders of magnitude (0.2 Hz to 20200 Hz), in good agreement with macroscopic data, revealing a promising tool for the viscoelastic characterisation of hydrogels.</p> |
| spellingShingle | Polymers--Mechanical properties Piacenti, AR Atomic force microscope-based methods for the nano-mechanical characterisation of hydrogels and other viscoelastic polymeric materials for biomedical applications |
| title | Atomic force microscope-based methods for the nano-mechanical characterisation of hydrogels and other viscoelastic polymeric materials for biomedical applications |
| title_full | Atomic force microscope-based methods for the nano-mechanical characterisation of hydrogels and other viscoelastic polymeric materials for biomedical applications |
| title_fullStr | Atomic force microscope-based methods for the nano-mechanical characterisation of hydrogels and other viscoelastic polymeric materials for biomedical applications |
| title_full_unstemmed | Atomic force microscope-based methods for the nano-mechanical characterisation of hydrogels and other viscoelastic polymeric materials for biomedical applications |
| title_short | Atomic force microscope-based methods for the nano-mechanical characterisation of hydrogels and other viscoelastic polymeric materials for biomedical applications |
| title_sort | atomic force microscope based methods for the nano mechanical characterisation of hydrogels and other viscoelastic polymeric materials for biomedical applications |
| topic | Polymers--Mechanical properties |
| work_keys_str_mv | AT piacentiar atomicforcemicroscopebasedmethodsforthenanomechanicalcharacterisationofhydrogelsandotherviscoelasticpolymericmaterialsforbiomedicalapplications |