“Synthesis of Nanostructured Metal-Chitosan Hybrids by Laser Ablation in Liquid”

The growing focus on environmental sustainability, coupled with the need to enhance technological performance across various industrial sectors, has led to an increasing interest in the development of innovative materials. In this scenario, composite materials are emerging as key players, owing to their ability to combine superior properties through the synergistic interaction of different components. Among composites, biopolymers stand out as a particularly promising class, as they merge biodegradability and biocompatibility characteristics with a reduced environmental impact compared to traditional materials. Specifically, chitosan, a polysaccharide derived from chitin, is renowned for its exceptional biological and chemical properties, making it an ideal candidate for applications ranging from biomedical to agri-food, environmental, and industrial fields. Concurrently, nanomaterial production techniques have rapidly evolved in recent decades, with a particular emphasis on sustainable and non-toxic methods. Among these techniques, laser ablation in liquids (LAL) has garnered interest as a versatile and eco-friendly approach for nanomaterial synthesis. LAL enables the control of the properties of the nanoparticles produced without the use of harmful chemicals, thereby minimizing waste and environmental emissions. This study explores the innovative potential of composite materials, focusing on the synergy between metallic nanoparticles (AgNPs and CuNPs) and chitosan. The research primarily centres on the synthesis and characterization of these materials through laser ablation in liquids (LAL), a technique that offers fine and precise control over the properties of the obtained nanoparticles, allowing for the modulation of their size, morphology, and chemical composition. A significant aspect of this study is the utilization of chitosan derived from Hermetia illucens, an alternative and sustainable source compared to traditional marine sources, thus promoting a more ecological and responsible approach in biomaterial production. The in-depth analysis of LAL process parameters has enabled a detailed understanding of their influence on the morphological and physicochemical characteristics of metal-chitosan composites. In particular, the crucial role of chitosan in modulating the formation, growth, and stability of metallic nanoparticles has been highlighted, significantly affecting their final properties. The experimental results obtained have demonstrated the antimicrobial efficacy of the silver composites, with a particular focus on their biocompatibility with fibroblast cell lines, representative of connective tissue. Furthermore, the ability of these composites to inhibit the growth of common and clinically relevant pathogens, such as Staphylococcus aureus and Escherichia coli, has been evaluated, paving the way for potential applications in infection prevention. An additional area of investigation has been the application of these materials as coatings for bone implants, using the electrophoretic deposition (EPD) technique. This method has proven its effectiveness in producing thin and uniform films on implant surfaces, imparting enhanced antibacterial and biocompatible properties, which are fundamental for promoting osseointegration and reducing the risk of implant failure. The investigation has also extended to the environmental domain, evaluating the efficacy of silver-chitosan nanocomposites in the photocatalytic degradation of organic dyes, such as methylene blue, present in industrial wastewater. The results obtained have highlighted their potential as efficient catalysts for the removal of organic pollutants, under both UV and visible light irradiation, suggesting their possible application in water purification processes. In conclusion, this study underscores the crucial importance of integrating sustainable technologies, such as LAL and the use of alternative chitosan sources, with biocompatible materials to develop innovative and sustainable solutions across various sectors, including biomedicine and the environment.