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Item Síntesis de hidrogeles sensibles a pH para la liberación de nanopartículas de óxido de cobre contra escherichia coli y pseudomonas aeruginosaAutores: Jara Moya, Cristóbal; Vásquez Saa, KrislerAutor Institucional: Universidad de TalcaProfesor Guía: Durán Lara, EstebanLos hidrogeles son estructuras poliméricas porosas con la capacidad de absorber grandes cantidades de agua y ser cargados de otras moléculas dentro de sí como fármacos, antibióticos o nanopartículas, entre otros. Estos son una prometedora opción de tratamiento a las infecciones bacterianas, las cuales suponen una creciente preocupación en materia de salud pública debido al aumento de cepas bacterianas multirresistentes y el fracaso en el tratamiento de estas. Este estudio se enfocó en la síntesis de hidrogeles de goma guar sensibles al pH con el objetivo de liberar nanopartículas de óxido de cobre para combatir cepas ATCC de Escherichia coli y Pseudomonas aeruginosa. Los hidrogeles fueron diseñados y sintetizados mediante química verde para responder a cambios en el pH del entorno y liberar las nanopartículas de óxido de cobre de manera controlada. Los resultados obtenidos mostraron que los hidrogeles sintetizados poseían buenas características de gelificación y absorción de líquido. Sin embargo, respecto a las nanopartículas, no se observó actividad antimicrobiana significativa in vitro usando nanopartículas de óxido de cobre contra las cepas ATCC de Escherichia coli y Pseudomonas aeruginosa evaluadas.Item Stimuli-Responsive Hydrogels for Cancer Treatment: The Role of pH, Light, Ionic Strength and Magnetic FieldAutores: Andrade, Fernanda; Roca Melendres, María Merce; Durán Lara, Esteban F.; Rafael, Diana; Schwartz, Simo, Jr.Cancer remains as the world second leading cause of death. The severe side effects associated to high doses of chemotherapy and the development of drug resistance are major drawbacks for a successful cancer treatment. Therefore, new formulations that promote localized therapy at tumor sites are needed to improve the therapeutic outcomes and patient welfare. The use of hydrogels is a very promising alternative, since they can be composed by smart materials able to respond to external factors, changing their properties accordingly and promoting a localized drug delivery. As a result, a more specific, efficient, and less toxic local cancer treatment can be accomplished. In this context, the most important characteristics of hydrogels recent studies regarding the application of pH-, light-, ionic strength-, and magnetic-responsive hydrogels in cancer treatment are here presented.Item Rational Design of Hydrogels for Cationic Antimicrobial Peptide Delivery: A Molecular Modeling ApproachAutores: Pereira, Alfredo; Valdés-Muñoz, Elizabeth; Marican, Adolfo; Cabrera-Barjas, Gustavo; Vijayakumar, Sekar; Valdés, Óscar; Rafael, Diana; Andrade, Fernanda; Abaca, Paulina; Bustos, Daniel; Durán-Lara, Esteban F.In light of the growing bacterial resistance to antibiotics and in the absence of the development of new antimicrobial agents, numerous antimicrobial delivery systems over the past decades have been developed with the aim to provide new alternatives to the antimicrobial treatment of infections. However, there are few studies that focus on the development of a rational design that is accurate based on a set of theoretical-computational methods that permit the prediction and the understanding of hydrogels regarding their interaction with cationic antimicrobial peptides (cAMPs) as potential sustained and localized delivery nanoplatforms of cAMP. To this aim, we employed docking and Molecular Dynamics simulations (MDs) that allowed us to propose a rational selection of hydrogel candidates based on the propensity to form intermolecular interactions with two types of cAMPs (MP-L and NCP-3a). For the design of the hydrogels, specific building blocks were considered, named monomers (MN), co-monomers (CM), and cross-linkers (CL). These building blocks were ranked by considering the interaction with two peptides (MP-L and NCP-3a) as receptors. The better proposed hydrogel candidates were composed of MN3-CM7-CL1 and MN4-CM5-CL1 termed HG1 and HG2, respectively. The results obtained by MDs show that the biggest differences between the hydrogels are in the CM, where HG2 has two carboxylic acids that allow the forming of greater amounts of hydrogen bonds (HBs) and salt bridges (SBs) with both cAMPs. Therefore, using theoretical-computational methods allowed for the obtaining of the best virtual hydrogel candidates according to affinity with the specific cAMP. In conclusion, this study showed that HG2 is the better candidate for future in vitro or in vivo experiments due to its possible capacity as a depot system and its potential sustained and localized delivery system of cAMP.Item Biopolymer-Based Composite Hydrogels Embedding Small Silver Nanoparticles for Advanced Antimicrobial Applications: Experimental and Theoretical InsightsAutores: Rojas, Moisés A.; Amalraj, John; Santos, Leonardo S.In this work, we report a two-step methodology for the synthesis of small silver nanoparticles embedded into hydrogels based on chitosan (CS) and hydroxypropyl methylcellulose (HPMC) biopolymers. This method uses d-glucose as an external green reducing agent and purified water as a solvent, leading to an eco-friendly, cost-effective, and biocompatible process for the synthesis of silver nanocomposite hydrogels. Their characterization comprises ultraviolet-visible spectroscopy, Fourier-transform infrared spectra, differential scanning calorimetry, scanning electron microscopy with energy-dispersive spectroscopy, and transmission electron microscopy assays. Moreover, the structural stability of the hydrogels was investigated through sequential swelling–deswelling cycles. The nanomaterials showed good mechanical properties in terms of their structural stability and revealed prominent antibacterial properties due to the reduced-size particles that promote their use as new advanced antimicrobial agents, an advantage compared to conventional particles in aqueous suspension that lose stability and effectiveness. Finally, theoretical analyses provided insights into the possible interactions, charge transfer, and stabilization process of nanoclusters mediated by the high-electron-density groups belonging to CS and HPMC, revealing their unique structural properties in the preparation of nano-scaled materials.
