Variation in the diffusion and release of ribonuclease through and from esterified hyaluronic acid membranes: Effect of changes in matrix characteristics

Investigations were conducted using membranes composed of esterified hyaluronic acid to determine the effect of the physical matrix properties on protein diffusion and release. Hyaluronate membranes prepared by a solvent evaporation method formed two visually distinct regions, one transparent and the other translucent. Each of the two regions were characterized by differential scanning calorimetry, Fourier transform infrared spectroscopy, and Karl Fisher titration for water content. The transparent region exhibited a higher endothermic transition temperature and lower water content than observed for the translucent region. For the transparent region, significant lag times (>50 h) were detected for the transport and release of a model protein (ribonuclease A) compared with that for the translucent region which showed no lag time. The results highlight the importance of carefully controlling matrix formation to ensure reproducible transport and release characteristics from polymer matrices. Copyright (C) 1999 Elsevier Science B.V.