Amphiphilic derivatives of sodium alginate and hyaluronate for cartilage repair: Rheological properties

Various amphiphilic derivatives of sodium alginate and hyaluronate were pre pared by covalent fixation of long alkyl chains (dodecyl and octadecyl) wit h various ratios on the polysaccharide backbones via ester functions. In th e semidilute regime, aqueous solutions of the resulting compounds exhibited the typical rheological properties of hydrophobically associating polymers : tremendous enhancement of zero shear rate Newtonian viscosity, steep shea r-thinning behavior, and formation of physically crosslinked gel-like netwo rks. The influence of the alkyl chain length, its content on the polysaccha ride and of the polymer concentration in the solution was well identified. All obtained results are discussed with respect to the schedule of conditio ns related to materials, which could be used for cartilage repair, such as in synovial fluid viscosupplementation as well as in cartilage replacement. In particular, it is seen that HA-C-12-5 (hyaluronate substituted with 5% of dodecyl chains) and HA-C-18-1 (hyaluronate substituted with 1% of octade cyl chains) in a 0.15N NaCl solution at 8 g/L have rheological properties q uite similar to those of healthy synovial fluid. On the other hand, the rhe ological parameters of solutions at 8 g/L in 0.15N NaCl of some of derivati ves, such as, for example, AA-C-12-8 (alginate substituted with 8% of dodec yl chains) or HA-C-18-2 are well fitted for a use in cartilage repair. (C) 2000 John Wiley & Sons, Inc.