Abstract
The unbelievable features of chitosan (CS) put it at the forefront of the interest of a huge number of researchers worldwide. CS is the deacetylated product of chitin and mainly extracted several natural resources. The value of CS is in its 'tunable' characteristics due to the prevalence of reactive hydroxyl and amine groups, on its surface, which can be easily modified to produce templates with the necessary qualities for specific applications. Amongst numerous documented CS modification approaches in the literature, Schiff base condensation, crosslinking, and thiolation were selected as the subject of this review owing to the amazing physicochemical characteristics and potentials as well as multidisciplinary applications of their outcomes. To date, there is no exclusive review that has focused on thiolated and crosslinked chitosan as well as CSBs combined. The findings of most of the previous studies revealed that these modifications strategies have significantly upgraded the potentials of chitosan and enabled it to invade various recent application fields.