The properties and potential applications of chitosan have attracted a lot of interest
each year, the number of publications and patents based on this polymer increases. A significant obstacle to the application of chitosan is its limited solubility in basic and neutral solutions. The fact that chitosan is a series of molecules with variations in size, content, and monomer distribution rather than a single polymer with a well-defined structure and a natural origin is another significant barrier. Some of the claimed biological qualities are distinct, and these characteristics have a fundamental effect on the polymer's technological and biological performance. The poor solubility of the polymer can be improved by chitosan chemistry, and in this assessment, we discuss the changes made to make chitosan more soluble and its possible uses. We concentrate on a few of the primary biological characteristics of chitosan and how they relate to the physicochemical characteristics of the polymer. The use of chitosan in the environmentally friendly manufacture of metallic nanoparticles as well as its usage as a booster for biocatalysts are two further applications of polymers that are linked to green processes that we revisit. This study also presents information about utilizing chitosan's technological advantages.