Publicação
Chitosan scaffolds with cork-derivatives to promote bone tissue regeneration
| Resumo: | Bone is a key structure in the human body, essential for support and many other functions. Unfortunately, various bone diseases that reduce bone density can lead to fractures and mobility issues. This has led to growing research in bone regeneration, focusing on the development of scaffolds, temporary artificial three-dimensional biomaterial structures that provide a specific environment and architecture for bone growth and development. Natural polymers like chitosan have similar properties to the organic components of bone extracellular matrix, with exceptional properties including biodegradability, non-toxicity, antimicrobial, nonimmunogenic, mucoadhesive, ease of modification, and osteoconductivity. Hydroxyapatite is one of the main components of the bone matrix, being a biodegradable material, biocompatible, non-toxic, non-immunogenic agent, osteoconductive, and has a high specific surface area. And cork, due to its unique 3D structure, is a promising material to be used as template agent for bone scaffolds. Chitosan/hydroxyapatite composites are well-studied for bone regeneration, while cork biochar combined with natural polymers and calcium phosphates shows promise for biomedical applications but remains in early research stages. Given that, this work focused on developing a new scaffold for bone tissue engineering combining cork-derived hydroxyapatite filler with chitosan prepared by freeze-drying. Cork pyrolyzed at 500 °C was successfully converted to calcium carbonate using calcium acetate impregnation. The best results obtained from the optimization of hydroxyapatite synthesis using commercial reagents using the precipitation method at 100 °C for 16 h, producing a mixture of 53% hydroxyapatite and 47% calcium carbonate, confirmed by X-ray diffraction analysis. Using the same conditions (100 °C, 16 h), cork-derived hydroxyapatite was also obtained from cork-derived calcium carbonate. Five porous structures were prepared: one with 2.5% (m/v) chitosan and four others with different fillers, including cork-derived calcium carbonate, cork-derived hydroxyapatite, optimized HA, and a mix of commercial HA with cork-derived calcium carbonate. Overall, the scaffolds presented interconnected pores ranging from 100 to 700 μm, with some around 2000 μm. Cork-derived hydroxyapatite scaffolds had the highest proportion of pores under 100 μm. They also presented high porosities between 88 and 98%, swelling capacities over 600% suggesting hydrophilicity, and biocompatibilities above 85%. However, the mechanical properties were well below real bone capacity, with compressive modulus between 0.58 and 2.18 MPa and compressive strengths in the range of 0.09-0.19 MPa, where the material with cork-derived hydroxyapatite presented the highest mechanical properties, doubling the values of the material composed of just chitosan, The cork-derived hydroxyapatite construct showed favorable properties to bone tissue engineering compared to the chitosan material, while exhibiting significantly better mechanical properties and maintaining strong cell viability. These promising results open new avenues for further exploration of potential applications for these materials. |
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| Autores principais: | Fernandes, Ana Beatriz Dinis |
| Assunto: | Bone Bone regeneration Chitosan Cork Hydroxyapatite Scaffold |
| Ano: | 2024 |
| País: | Portugal |
| Tipo de documento: | dissertação de mestrado |
| Tipo de acesso: | acesso embargado |
| Instituição associada: | Universidade de Aveiro |
| Idioma: | inglês |
| Origem: | RIA - Repositório Institucional da Universidade de Aveiro |
| Resumo: | Bone is a key structure in the human body, essential for support and many other functions. Unfortunately, various bone diseases that reduce bone density can lead to fractures and mobility issues. This has led to growing research in bone regeneration, focusing on the development of scaffolds, temporary artificial three-dimensional biomaterial structures that provide a specific environment and architecture for bone growth and development. Natural polymers like chitosan have similar properties to the organic components of bone extracellular matrix, with exceptional properties including biodegradability, non-toxicity, antimicrobial, nonimmunogenic, mucoadhesive, ease of modification, and osteoconductivity. Hydroxyapatite is one of the main components of the bone matrix, being a biodegradable material, biocompatible, non-toxic, non-immunogenic agent, osteoconductive, and has a high specific surface area. And cork, due to its unique 3D structure, is a promising material to be used as template agent for bone scaffolds. Chitosan/hydroxyapatite composites are well-studied for bone regeneration, while cork biochar combined with natural polymers and calcium phosphates shows promise for biomedical applications but remains in early research stages. Given that, this work focused on developing a new scaffold for bone tissue engineering combining cork-derived hydroxyapatite filler with chitosan prepared by freeze-drying. Cork pyrolyzed at 500 °C was successfully converted to calcium carbonate using calcium acetate impregnation. The best results obtained from the optimization of hydroxyapatite synthesis using commercial reagents using the precipitation method at 100 °C for 16 h, producing a mixture of 53% hydroxyapatite and 47% calcium carbonate, confirmed by X-ray diffraction analysis. Using the same conditions (100 °C, 16 h), cork-derived hydroxyapatite was also obtained from cork-derived calcium carbonate. Five porous structures were prepared: one with 2.5% (m/v) chitosan and four others with different fillers, including cork-derived calcium carbonate, cork-derived hydroxyapatite, optimized HA, and a mix of commercial HA with cork-derived calcium carbonate. Overall, the scaffolds presented interconnected pores ranging from 100 to 700 μm, with some around 2000 μm. Cork-derived hydroxyapatite scaffolds had the highest proportion of pores under 100 μm. They also presented high porosities between 88 and 98%, swelling capacities over 600% suggesting hydrophilicity, and biocompatibilities above 85%. However, the mechanical properties were well below real bone capacity, with compressive modulus between 0.58 and 2.18 MPa and compressive strengths in the range of 0.09-0.19 MPa, where the material with cork-derived hydroxyapatite presented the highest mechanical properties, doubling the values of the material composed of just chitosan, The cork-derived hydroxyapatite construct showed favorable properties to bone tissue engineering compared to the chitosan material, while exhibiting significantly better mechanical properties and maintaining strong cell viability. These promising results open new avenues for further exploration of potential applications for these materials. |
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