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· What does Dermaxgel™ do?
· High-Viscosity, Shear-Thinning Gels
· Hyaluronic acid&cross-linked hyaluronic acid
  Technology Home >>Technology  

  A high-viscosity, shear-thinning polymer solution or a slightly cross-linked gel may be injected

 through a relatively small gage needle. Upon removal of the injection shearing force, a thick gel is

 formed in situ. A good example of such a system are gels of hyaluronic acid. Hyaluronan is found

 in  the  extracellular  matrix of most tissues.  It  is  a linear, negatively  charged  polysaccharide

 comprised  of  alternating  repeating  units  of glucoronic acid and N-acetylglucosamine. The  first

 preparations  of    hyaluronan  were  derived  from  rooster combs. Hyaluronan  gels form  in  situ

 upon injection  of  a viscous (but still injectable) gel formulation. Viscoelastic  and  shear-thinning

 properties   of   hyaluronan  inspired  researchers to  use  it  as  a carrier   for drugs, protein, and

 peptide   delivery  (Drobnik, 1991), as  well  as   tissue  engineering  applications  such  as bone

 fracture   repair,   wound   healing (Goa   and  Benfield, 1994),  and   soft   tissue    augmentation

 procedures (Duranti et al., 1998).

  A  non-animal hyaluronic acid  may be produced in cultures of streptococci by fermentation

 in   the  presence of  sugar and modified subsequently by chemical cross-linking with epoxides.

 The resulting  transparent gel, suitable for intradermal injections, is no longer  water-soluble but

 retains  its  affinity for water. Viscosity of   hyaluronic acid solutions decreases  with  increasing

 temperature, which makes it suitable for injectable applications.

  Physicochemical   properties   of   hyaluronan   may   also   be   improved    by    chemical

 cross-linking   withdivinyl  sulfone. The  cross-linking  produces  insoluble,  hydrated  soft  gels,

 so-called  hylan  polymers. Animal  studies demonstrated  that   hylan  polymers  are   nontoxic,

 nonantigenic,  noninflammatory,  and    do   not   elicit   a  foreign   body   reaction  (Hallen et al.,

 1999).  Examples   of   how   different  hyaluronan   preparations  may   be   applied   in   tissue

 engineering will be described.

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