Chitosan is a biodegradable and biocompatible natural polymer that has been extensively explored in recent decades. The Food and Drug Administration has approved chitosan for wound treatment and nutritional use. Furthermore, chitosan has paved the way for advancements in different biomedical applications including as a nanocarrier and tissue-engineering scaffold. Its antibacterial, antioxidant, and haemostatic properties make it an excellent option for wound dressings. Because of its hydrophilic nature, chitosan is an ideal starting material for biocompatible and biodegradable hydrogels. To suit specific application demands, chitosan can be combined with fillers, such as hydroxyapatite, to modify the mechanical characteristics of pH-sensitive hydrogels. Furthermore, the cationic characteristics of chitosan have made it a popular choice for gene delivery and cancer therapy. Thus, the use of chitosan nanoparticles in developing novel drug delivery systems has received special attention. This review aims to provide an overview of chitosan-based nanoparticles, focusing on their versatile properties and different applications in biomedical sciences and engineering.

Graphene oxide (GO) and nanohydroxyapatite (nHAp) proved to be a potential material for bone tissue-regeneration applications. Therefore, GO and nHAp reinforced porous polymeric nanocomposite scaffolds have been gaining significant research thrust. In this study, GO and nHAp based nanocomposite was synthesized and used as a reinforcing agent to develop gelatin-alginate (GA)-based three-dimensional porous polymeric nanocomposite scaffold. The polymeric nanocomposite scaffold (nHAp-GO/GA) was fabricated by using freeze-drying process, which may show a synergistic effect of each of the components for tissue regeneration. The scaffold demonstrates good physico-chemical properties. The porous microstructure of the scaffold is evidenced by Field emission scanning electron microscopy (FESEM). High swelling of the scaffold in presence water, indicates that the scaffold is highly hydrophilic, which implies the suitability of the scaffold for tissue regeneration. Further, the incorporation of nHAp-GO enhances the compressive strength of the scaffold while reduces the rate of biodegradation, which is good for bone tissue engineering. The scaffold is biocompatible. In vitro cell study with MG-63 bone cells demonstrates the synergistic effect of each of the components of the scaffold, on mineral deposition. Therefore, it can be concluded that nHAp-GO/GA polymeric nanocomposite scaffold can be a potential candidate for bone tissue regeneration.