Diseño de un hidrogel autoreparable y antimicrobiano para la ingeniería de tejidos cutáneos.
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Date
2026
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Universidad de Concepción
Abstract
La ingeniería de tejidos requiere biomateriales capaces de reproducir las propiedades estructurales, mecánicas y biológicas de la matriz extracelular, manteniendo simultáneamente estabilidad, biocompatibilidad y capacidad de adaptación frente a estímulos fisiológicos. Es fundamental señalar que las propiedades mecánicas de los tejidos vivos varían significativamente, desde la rigidez del cartílago hasta la notable suavidad del tejido cerebral. En este contexto, el presente trabajo desarrolló una estrategia para la obtención de hidrogeles de red dual basados en gelatina modificada químicamente, mediante la combinación de entrecruzamientos covalentes permanentes, enlaces covalentes dinámicos e interacciones de coordinación metal-ligando.
Para ello, la gelatina fue funcionalizada independientemente con anhídrido metacrílico y ácido tióctico, obteniéndose gelatina metacrilada (GelMA) y gelatina modificada con ácido tióctico (GelTA), respectivamente. La funcionalización fue confirmada mediante espectroscopía infra-rojo (ATR-FTIR), resonancia magnética nuclear (RMN) y cuantificación de grupos amino mediante el ensayo de o-ftalaldehído (OPA) obteniendo grados de modificación aproximadamente de un 60%. Posteriormente, ambas gelatinas modificadas fueron combinadas en distintas proporciones y fotopolimerizadas para formar hidrogeles de red dual, donde la red primaria se estableció mediante la fotopolimerización de los grupos metacrilato de GelMA y la red secundaria mediante la reorganización de enlaces disulfuro provenientes de los grupos 1,2-ditiolano de GelTA. Adicionalmente, se incorporó Cu(II) como agente de coordinación con el propósito de generar puntos de entrecruzamiento físicos reversibles y potenciar tanto las propiedades mecánicas como la funcionalidad biológica del material.
Los hidrogeles fueron caracterizados mediante estudios reológicos, ensayos de compresión, análisis de hinchamiento, determinación de densidad de entrecruzamiento, microscopía electrónica de barrido, espectroscopía de energía dispersiva de rayos X, análisis termogravimétrico, estudios de absorción y liberación de Cu(II), así como ensayos biológicos de citocompatibilidad y actividad antimicrobiana.
Los resultados demostraron que la incorporación de GelTA favoreció la formación de una red dinámica capaz de reorganizarse mediante enlaces disulfuro, mientras que la presencia de Cu(II) incrementó la densidad efectiva de entrecruzamiento a través de interacciones de coordinación metal-ligando, lo que se establecen con los sitios de coordinación de la gelatina natural y los que resultan de la modificación química con ácido tióctico. La acción sinérgica de ambos mecanismos permitió mejorar la estabilidad estructural, el comportamiento viscoelástico, la resistencia mecánica y la capacidad de disipación de energía de los hidrogeles, sin afectar significativamente su estabilidad térmica. Asimismo, los materiales desarrollados presentaron una estructura porosa e interconectada, adecuada citocompatibilidad y actividad antibacteriana frente a las cepas evaluadas, evidenciando el efecto bioactivo de la incorporación del cobre.
En conjunto, esta investigación demuestra que la integración de una red covalente permanente basada en GelMA, una red covalente dinámica formada por GelTA y un sistema adicional de coordinación con Cu(II) constituye una estrategia eficaz para el diseño de hidrogeles multifuncionales con propiedades mecánicas y biológicas mejoradas. La arquitectura propuesta representa una plataforma prometedora para el desarrollo de andamios destinados a aplicaciones en ingeniería de tejidos y medicina regenerativa, proporcionando una nueva aproximación para el diseño de biomateriales inspirados en la organización dinámica.
Tissue engineering requires biomaterials capable of reproducing the structural, mechanical and biological properties of the extracellular matrix, while maintaining stability, biocompatibility and adaptability to physiological stimuli. It is critical to note that the mechanical properties of living tissues vary significantly, from the stiffness of the cartilage to the remarkable softness of the brain tissue. In this context, the present work developed a strategy for obtaining dual-lattice hydrogels based on chemically modified gelatin, by combining permanent covalent crosslinks, dynamic covalent bonds and metal-ligand coordination interactions. To this end, gelatin was independently functionalized with methacrylic anhydride and thioctic acid, obtaining methacrylate gelatin (GelMA) and gelatin modified with thioctic acid (GelTA), respectively. Functionalization was confirmed by infra-red spectroscopy (ATR-FTIR), nuclear magnetic resonance (NMR) and amino group quantification by o-phthalaldehyde (OPA) assay, obtaining degrees of modification of approximately 60%. Subsequently, both modified gelatins were combined in different proportions and photopolymerized to form dual-lattice hydrogels, where the primary lattice was established by photopolymerization of the methacrylate groups of GelMA and the secondary lattice by the reorganization of disulfide bonds from the 1,2-dithiolane groups of GelTA. Additionally, Cu(II) was incorporated as a coordination agent with the purpose of generating reversible physical cross-linking points and enhancing both the mechanical properties and the biological functionality of the material. The hydrogels were characterized by rheological studies, compression assays, swelling analysis, crosslinking density determination, scanning electron microscopy, X-ray energy dispersive spectroscopy, thermogravimetric analysis, Cu(II) absorption and release studies, as well as biological assays of cytocompatibility and antimicrobial activity. The results showed that the incorporation of GelTA favored the formation of a dynamic network capable of reorganizing itself by disulfide bonds, while the presence of Cu(II) increased the effective crosslinking density through metal-ligand coordination interactions, which are established with the coordination sites of natural gelatin and those resulting from chemical modification with thioctic acid. The synergistic action of both mechanisms allowed to improve the structural stability, viscoelastic behavior, mechanical resistance and energy dissipation capacity of the hydrogels, without significantly affecting their thermal stability. Likewise, the materials developed presented a porous and interconnected structure, adequate cytocompatibility and antibacterial activity against the evaluated strains, evidencing the bioactive effect of the incorporation of copper. Overall, this research demonstrates that the integration of a permanent covalent network based on GelMA, a dynamic covalent network formed by GelTA and an additional coordination system with Cu(II) constitutes an effective strategy for the design of multifunctional hydrogels with improved mechanical and biological properties. The proposed architecture represents a promising platform for the development of scaffolds for applications in tissue engineering and regenerative medicine, providing a new approach for the design of biomaterials inspired by dynamic organization.
Tissue engineering requires biomaterials capable of reproducing the structural, mechanical and biological properties of the extracellular matrix, while maintaining stability, biocompatibility and adaptability to physiological stimuli. It is critical to note that the mechanical properties of living tissues vary significantly, from the stiffness of the cartilage to the remarkable softness of the brain tissue. In this context, the present work developed a strategy for obtaining dual-lattice hydrogels based on chemically modified gelatin, by combining permanent covalent crosslinks, dynamic covalent bonds and metal-ligand coordination interactions. To this end, gelatin was independently functionalized with methacrylic anhydride and thioctic acid, obtaining methacrylate gelatin (GelMA) and gelatin modified with thioctic acid (GelTA), respectively. Functionalization was confirmed by infra-red spectroscopy (ATR-FTIR), nuclear magnetic resonance (NMR) and amino group quantification by o-phthalaldehyde (OPA) assay, obtaining degrees of modification of approximately 60%. Subsequently, both modified gelatins were combined in different proportions and photopolymerized to form dual-lattice hydrogels, where the primary lattice was established by photopolymerization of the methacrylate groups of GelMA and the secondary lattice by the reorganization of disulfide bonds from the 1,2-dithiolane groups of GelTA. Additionally, Cu(II) was incorporated as a coordination agent with the purpose of generating reversible physical cross-linking points and enhancing both the mechanical properties and the biological functionality of the material. The hydrogels were characterized by rheological studies, compression assays, swelling analysis, crosslinking density determination, scanning electron microscopy, X-ray energy dispersive spectroscopy, thermogravimetric analysis, Cu(II) absorption and release studies, as well as biological assays of cytocompatibility and antimicrobial activity. The results showed that the incorporation of GelTA favored the formation of a dynamic network capable of reorganizing itself by disulfide bonds, while the presence of Cu(II) increased the effective crosslinking density through metal-ligand coordination interactions, which are established with the coordination sites of natural gelatin and those resulting from chemical modification with thioctic acid. The synergistic action of both mechanisms allowed to improve the structural stability, viscoelastic behavior, mechanical resistance and energy dissipation capacity of the hydrogels, without significantly affecting their thermal stability. Likewise, the materials developed presented a porous and interconnected structure, adequate cytocompatibility and antibacterial activity against the evaluated strains, evidencing the bioactive effect of the incorporation of copper. Overall, this research demonstrates that the integration of a permanent covalent network based on GelMA, a dynamic covalent network formed by GelTA and an additional coordination system with Cu(II) constitutes an effective strategy for the design of multifunctional hydrogels with improved mechanical and biological properties. The proposed architecture represents a promising platform for the development of scaffolds for applications in tissue engineering and regenerative medicine, providing a new approach for the design of biomaterials inspired by dynamic organization.
Description
Tesis presentada para optar al grado de Doctor/a en Ciencias con mención en Química.
Keywords
Ingeniería de tejidos, Agentes anti-infecciosos, Materiales biocompatibles, Dermatitis