Chitosan/Gold Nanoparticle Hydrogels for Drug Delivery and Tissue Engineering Applications

In recent years, materials for biomedical applications have taken on great relevance, including applications related to drug-controlled release and tissue regeneration. Hydrogels stand out among the various options that can be worked on since they can be designed to imitate the biomechanical properties and composition of different soft tissues. Furthermore, hydrogels possess adequate biocompatibility, biodegradability, and non-toxicity. Hydrogels can be manufactured from natural and synthetic polymers. In the case of natural polymers, chitosan stands out, the second most abundant natural polymer, obtained from the deacetylation of chitin. Chitosan hydrogels are widely investigated for their use in biomedical applications. Among the advantages that chitosan presents, it can be mentioned that it is the only natural polysaccharide with a positive charge capable of interacting with negative biological molecules. Multiple options have been explored to improve the physicochemical, biological, and mechanical properties of chitosan hydrogels. Different polymers and inorganic nanoparticles from chemical and physical modifications can be added to chitosan hydrogels. In the case of inorganic nanoparticles, gold nanoparticles (AuNPs) possess properties that make them potentially useful for biomedical applications and these properties can be easily modified by changing the shape, size, and aspect ratio of the AuNPs. This chapter will present the main properties of chitosan hydrogels and AuNPs and their main synthesis techniques. In addition, we will analyze the most relevant and recent biomedical applications of chitosan–AuNPs systems, focusing on drug delivery devices and tissue engineering applications.