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Chemical characterisation and fabrication of chitosan–silica hybrid scaffolds with 3-glycidoxypropyl trimethoxysilane

Chemical characterisation and fabrication of chitosan–silica hybrid scaffolds with 3-glycidoxypropyl trimethoxysilane
Chemical characterisation and fabrication of chitosan–silica hybrid scaffolds with 3-glycidoxypropyl trimethoxysilane
Chitosan has been explored as a potential component of biomaterials and scaffolds for many tissue engineering applications. Hybrid materials, where organic and inorganic networks interpenetrate at the molecular level, have been a particular focus of interest using 3-glycidoxypropyl trimethoxysilane (GPTMS) as a covalent crosslinker between the networks in a sol–gel process. GPTMS contains both an epoxide ring that can undergo a ring opening reaction with the primary amine of chitosan and a trimethoxysilane group that can co-condense with silica precursors to form a silica network. While many researchers have exploited this ring-opening reaction, it is not yet fully understood and thus the final product is still a matter of some dispute. Here, a detailed study of the reaction of GPTMS with chitosan under different pH conditions was carried out using a combination of solution state and solid state MAS NMR techniques. The reaction of GPTMS with chitosan at the primary amine to form a secondary amine was confirmed and the rate was found to increase at lower pH. However, a side-reaction was identified between GPTMS and water producing a diol species. The relative amounts of diol and chitosan–GPTMS species were 80 and 20% respectively and this ratio did not vary with pH. The functionalisation pH had an effect on the mechanical properties of 65 wt% organic monoliths where the properties of the organic component became more dominant. Scaffolds were fabricated by freeze drying and had pore diameters in excess of 140 μm, and tailorable by altering freezing temperature, which were suitable for tissue engineering applications. In both monoliths and scaffolds, increasing the organic content disrupted the inorganic network, leading to an increase in silica dissolution in SBF. However, the dissolution of silica and chitosan was congruent up to 4 weeks in SBF, illustrating the true hybrid nature resulting from covalent bonding between the networks.
2050-750X
668-680
Connell, Louise S.
21c91c43-81b7-44b2-8305-b7f374cc1d7f
Romer, Frederik
78473760-5d63-472a-ab97-2e5ca3645a98
Suárez, Marta
97e7395d-57e2-470e-84b8-4191e02826c1
Valliant, Esther M.
13fc7358-07b0-43e5-9934-7f5a3f46f977
Zhang, Ziyu
9fe21730-2c8f-4868-bec6-fd55260e1f40
Lee, Peter D.
38d06919-c96f-472b-8796-d3f11321e3a7
Smith, Mark E.
abd04fbf-5f56-459d-89ec-e51ab2598c09
Hanna, John V.
20ab8960-4ac0-41c7-bc4a-a40195717a51
Jones, Julian R.
be62105e-98fc-40ff-95cb-16afc9f3b512
Connell, Louise S.
21c91c43-81b7-44b2-8305-b7f374cc1d7f
Romer, Frederik
78473760-5d63-472a-ab97-2e5ca3645a98
Suárez, Marta
97e7395d-57e2-470e-84b8-4191e02826c1
Valliant, Esther M.
13fc7358-07b0-43e5-9934-7f5a3f46f977
Zhang, Ziyu
9fe21730-2c8f-4868-bec6-fd55260e1f40
Lee, Peter D.
38d06919-c96f-472b-8796-d3f11321e3a7
Smith, Mark E.
abd04fbf-5f56-459d-89ec-e51ab2598c09
Hanna, John V.
20ab8960-4ac0-41c7-bc4a-a40195717a51
Jones, Julian R.
be62105e-98fc-40ff-95cb-16afc9f3b512

Connell, Louise S., Romer, Frederik, Suárez, Marta, Valliant, Esther M., Zhang, Ziyu, Lee, Peter D., Smith, Mark E., Hanna, John V. and Jones, Julian R. (2014) Chemical characterisation and fabrication of chitosan–silica hybrid scaffolds with 3-glycidoxypropyl trimethoxysilane. Journal of Materials Chemistry B, 2 (6), 668-680. (doi:10.1039/C3TB21507E).

Record type: Article

Abstract

Chitosan has been explored as a potential component of biomaterials and scaffolds for many tissue engineering applications. Hybrid materials, where organic and inorganic networks interpenetrate at the molecular level, have been a particular focus of interest using 3-glycidoxypropyl trimethoxysilane (GPTMS) as a covalent crosslinker between the networks in a sol–gel process. GPTMS contains both an epoxide ring that can undergo a ring opening reaction with the primary amine of chitosan and a trimethoxysilane group that can co-condense with silica precursors to form a silica network. While many researchers have exploited this ring-opening reaction, it is not yet fully understood and thus the final product is still a matter of some dispute. Here, a detailed study of the reaction of GPTMS with chitosan under different pH conditions was carried out using a combination of solution state and solid state MAS NMR techniques. The reaction of GPTMS with chitosan at the primary amine to form a secondary amine was confirmed and the rate was found to increase at lower pH. However, a side-reaction was identified between GPTMS and water producing a diol species. The relative amounts of diol and chitosan–GPTMS species were 80 and 20% respectively and this ratio did not vary with pH. The functionalisation pH had an effect on the mechanical properties of 65 wt% organic monoliths where the properties of the organic component became more dominant. Scaffolds were fabricated by freeze drying and had pore diameters in excess of 140 μm, and tailorable by altering freezing temperature, which were suitable for tissue engineering applications. In both monoliths and scaffolds, increasing the organic content disrupted the inorganic network, leading to an increase in silica dissolution in SBF. However, the dissolution of silica and chitosan was congruent up to 4 weeks in SBF, illustrating the true hybrid nature resulting from covalent bonding between the networks.

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More information

Accepted/In Press date: 2 December 2013
e-pub ahead of print date: 3 December 2013
Published date: 14 February 2014

Identifiers

Local EPrints ID: 440901
URI: http://eprints.soton.ac.uk/id/eprint/440901
ISSN: 2050-750X
PURE UUID: a9102566-5b49-4359-b30b-4a14da374a5c

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Date deposited: 22 May 2020 16:37
Last modified: 16 Mar 2021 17:40

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Contributors

Author: Louise S. Connell
Author: Frederik Romer
Author: Marta Suárez
Author: Esther M. Valliant
Author: Ziyu Zhang
Author: Peter D. Lee
Author: Mark E. Smith
Author: John V. Hanna
Author: Julian R. Jones

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