Hyaluronate-alginate gel as a novel biomaterial: Mechanical properties andformation mechanism

With the aim of producing a biomaterial for surgical applications, the algi nate-hyaluronate association has been investigated to combine the gel-formi ng properties of alginate with the healing properties of hyaluronate. Gels were prepared by diffusion of calcium into alginate-hyaluronate mixtures, w ith an alginate content of 20 mg/mL, The hyaluronate source was shown to ha ve significant effect on the aspect and the properties of the gels. The gel s have viscoelastic behaviour and the transient measurements carried out in creep mode could be interpreted through a Kelvin-Voigt generalised model: experimental data led to the steady state hardness and a characteristic vis cosity of the gel. Gels prepared from Na rooster comb hyaluronate with weig ht ratio up to 0.50 have satisfactory mechanical properties, and fully stab le gels are obtained after a few days; on the contrary, use of lower molecu lar weight hyaluronate led to loose gels for hyaluronate contents over 0.25 . Gel formation was investigated by measurements of the exchange fluxes bet ween the calcium chloride solution and the forming gel, which allowed thoro ugh investigations of the occuring diffusion phenomena of water, calcium io n and hyaluronate. Strong interactions of water with hyaluronate reduce sig nificantly the rate of weight loss from the gel beads and allows higher wat er content in steady-state gels. Calcium content in the gel samples could b e correlated to the actual alginate concentration, whatever the nature and the weight ratio of hyaluronate. (C) 1999 John Wiley & Sons, Inc.