Table 1.

Analysis of physicochemical and biological properties of chitosan used for delivery of biotechnology drugs [73].

PROS	CONS
Natural polymer	Low solubility at physiological pH (7.4) or higher pH values because it is a weak base (pKa 6.2–7)
Readily available	High viscosity
Biodegradable and biocompatible	Contradicting data about its immuno-stimulating properties
Safe (low toxicity profile)	-
Forms salts with organic and inorganic acids	-
When protonated, adheres to negatively charged surfaces (bio/mucoadhesive), and forms gels with polyanions	-
Transmucosal absorption enhancer with minimal and reversible membrane damage	-
Amenable to chemical modifications	-