Functional wound dressings hydrogels

Temporary replacement skins have also been studied by using velour fabrics (usually a nylon or Dacron) backed by a polymeric film (silicone or protein) (36). synthetic polypeptides (37). collagen (38). and dextran hydrogels (39). These replacement materials are only for short term use and could be classed as wound dressings. Although they do prevent gross infection and body fluid loss, they do not duplicate any of the other functions of the skin. A true artificial skin does not yet exist. 

Nanofibrillar chitin hydrogels are biodegradable, biocompatible, and nontoxic, and thus show promise for biomedical applications. The protonation of amino groups on the surface of chitin allows its application in wound dressings due to the antimicrobial properties of cationic gels [130]. Polymeric fibers that mimic the structure and function of the extracellular matrix are also of interest in tissue engineering and cell culture. Chitin nanofibers can promote cell attachment and show potential as extracellular matrix mimics [29, 125]. 

The applications of hydrogels in the production of medical items, resulting materials must have several features, which recommends them non-toxicity, functionability, sterilizability, biocompatibUity [115]. These characteristics are requires for wound dressings, drug delivery systems, transdermal systems, injectable polymers, implants, dental and ophthalmic applications, stimuli-responsive systems, hydrogel hybrid-type organs. 

A, 0-carboxymethyl chitosan (N,0-CC) is a chitosan derivative that has carboxymethyl substituents at some of both the amine and the 6-hydroxyl sites of its glucosamine units. It can be easily prepared using chitosan, sodium hydroxide, and isopropanol with chloroacetic acid [65]. N,0-CC as a wound dressing can stimulate the extracellular lysozyme activity of fibroblasts and considerably promote the proliferation of skin fibroblasts. N,0-CC is also used in the development of various functional hydrogels, including superporous or pH-sensitive hydrogels, which are used for protein drug delivery [66-69]. 

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