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.

No abstract

Background The COVID‐19 pandemic has demanded effective therapeutic protocol from researchers and clinicians across the world. Currently, a large amount of primary data have been generated from several preclinical studies. At least 300 clinical trials are underway for drug repurposing against COVID‐19; the clinician needs objective evidence‐based medication to treat COVID‐19. Observations Single‐stranded RNA viral genome of SARS‐CoV‐2 encodes structural proteins (spike protein), non‐structural enzymatic proteins (RNA‐dependent RNA polymerase, helicase, papain‐like protease, 3‐chymotrypsin‐like protease) and other accessory proteins. These four enzymatic proteins on spike protein are rate‐limiting steps in viral replications and, therefore, an attractive target for drug development against SARS‐CoV‐2. In silico and in vitro studies have identified various potential epitomes as candidate sequences for vaccine development. These studies have also revealed potential targets for drug development and drug repurposing against COVID‐19. Clinical trials utilizing antiviral drugs and other drugs have given inconclusive results regarding their clinical efficacy and side effects. The need for angiotensin‐converting enzyme (ACE‐2) inhibitors/angiotensin receptor blockers and corticosteroids has been recommended. Western countries have adopted telemedicine as an alternative to prevent transmission of infection in the population. Currently, no proven, evidence‐based therapeutic regimen exists for COVID‐19. Conclusion The COVID‐19 pandemic has put tremendous pressure on researchers to evaluate and approve drugs effective against the disease. Well‐controlled randomized trials should assess medicines that are not marketed with substantial evidence of safety and efficacy and more emphasis on time tested approaches for drug evaluation.

No abstract