Chitosan-based hydrogels: Preparation, properties and applications.

Chitosan (CS), the second most plentiful natural polysaccharide next to cellulose, has valuable characteristics including biocompatibility, nontoxicity and biodegradability. CS is broken down in the human body to innocuous products (amino sugars). Hydrogels are polymeric materials with three dimensional networks retaining a huge quantity of water within their structures which are of great interest in biomedical/environmental applications. Usually, injectable hydrogels have functional groups which are sensitive to pH, temperature or irradiation stimuli. Injectable scaffolds can be formed in situ through stimuli-responsive effect and they can overcome the drawback of traditional scaffolds which require surgery in order to be placed on the desired tissue. The antibacterial/antifungal activities of chitosan-based hydrogels and their applications in controlled drug delivery/release systems, tissue engineering, preparation of injectable hydrogels and water treatment (removal of heavy/toxic metals and dyes) will be described. Moreover, the molecular dynamics (MD) simulation were performed on the delivery of the anticancer chlorambucil (CB) drug using three silica filled polymeric nanocomposites based on chitosan (CS), polylactic acid (PLA) and polyethylene glycol (PEG) and it was illustrated that among three drug delivery systems (DDSs), the CS nanocomposite was the most efficient DDS due to the lowest drug diffusion was measured for the CS system that could lead to the most sustained/controlled drug delivery.