Hyaluronan cross-linked gels

The introduction of cross-linked, water-insoluble gels of hyaluronan for tissue aug-... 

The first cross-linked hyaluronan gel developed and clinically tested for dermal augmentation was produced by cross-linking with divinyl sulfone (DVS hylan B)... 

Hallen L, Johannson C, Laurent C. Cross-linked hyaluronan (Hylan B gel) a new injectable remedy for treatment of vocal fold insufficiency—an animal study. Acta Otolaryngol (Stockh) 1999 119 107-111. 

Since polysaccharides have polar groups as well as some hydrophobic features, there can be inter residue interactions in a polysaccharide as well, but these attractions are expressed as interactions between different chains giving rise to such phenomena as crystallization which is prominently expressed in chitin and in cellulose. Other types of polysaccharides exhibit multistrand helix formation as in the case of sceleroglucan whose tendency for triple helix formation leads to unusual physical properties. Still other types of polysaccharides can form cross links in a more random way leading to gel formation as in the case of pectin, agarose and alginates. Chain interactions in other polysaccharides such as hyaluronan, chondroitin or... 

These relationships used in the theory of elasticity and developed for ideal networks make it possible to determine the degree of polysaccharide reticulation and establish the maximal degree of cross-linking in the hyaluronan gel, after which its injection into derma becomes technically impossible. Specifically, this determines comparatively short (up to half a year) times of the correction of the skin volume changes by intradermal administration of the cross-linked HA-based monophase (homogeneons) fillers. The solution to the problem of increasing the duration of correction lies in the field of biphase (heterogeneous) micro-implant administration. 

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