Hyaluronic acid-based materials

Hyaluronic acid is a linear polysaccharide formed from disaccharide units containing N-acetyl-D-glucosamine and glucuronic acid. Since it is present in almost all biological fluids and tissues, hyaluronic acid-based materials are very useful in biomedical applications. After cellulose, chitin is the second most abundant natural polysaccharide resource on earth. Chitin and its de-acetylated derivative chitosan are natural polymers composed of N-acetylglucosamine and glucosamine. Both chitin and chitosan have excellent properties such as biodegradability, biocompatibility, non-toxicity, hemostatic activity and antimicrobial activity. Chitin and its derivatives are widely used in various fields of medicine. 

Ballore L, Orru F, Nicolini F, Contini SA, Galletti G, Gherli T. Experimental results of the use of hyaluronic acid-based materials (CV Seprafilm and CV Sepracoat) in postoperative pericardial adhesions. Acta Biomed Ateneo Parmense 2000 71 159-166. 

Cloyd JM et al (2007) Material properties in unconfined compression of human nucleus pulposus, injectable hyaluronic acid-based hydrogels and tissue engineering scaffolds. Eur Spine J 16(11) 1892-1898... 

Besides the previously mentioned collagen, a wide variety of natural polymers have been involved in the synthesis of bio-nanohybrid materials with potential application in bone repair and dental prostheses. For instance, some recent examples refer to bionanocomposites based on the combination of HAP with alginate [96,97], chitosan [98,99], bovine serum albumin (BSA) [100], sodium caseinate [101], hyaluronic acid [102], silk fibroin [103,104], silk sericin [105], or polylactic add (PLA) [106,107]. These examples illustrate the increasing interest in the subject of HAP-based biohybrid materials, which has led to almost 400 articles appeared in scientific journals in 2006 alone. 

Recent studies show that powder dosage forms of peptide and protein drugs, based on materials such as microcrystalline cellulose, starch, and hyaluronic acid, can offer advantages over solution formulations. 

In addition to PEG-based materials, other materials such as polyphosphoester, polyanhydrides, poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (Pluronic), oUgo(poly(ethylene glycol) fumarate) and hyaluronic acid... 

Hyaluronic acid is an alternating copolymer of D-glucuronic acid and JV-acetyl glucosamine. It occurs in the lubricating fluid (sinuvial fluid) of the joints and the lachrymatory fluid of the eyes, and acts as a kind of cement for the extracellular base material of connective tissue. 

Aliphatic polyesters, copolyesters, and natural macromolecules (mainly collagen, elastin, fibrin, chitosan, and hyaluronic acid (HA)), as well as their blends, have also been used to prepare polymeric-based vascular grafts with tuned mechanical properties. Couet et al. reported a comprehensive overview of materials that have been explored as scaffolds for vascular tissue engineering [59]. The analysis of the mechanical behavior of non-PU-based vascular grafts is beyond the scope of this chapter. 

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