DIFFUSION OF MACROMOLECULES IN MEMBRANES OF HYALURONIC-ACID ESTERS

Permeability and partition coefficients were measured for a series of solutes in membranes formed from ethyl or benzyl esters of the polysac charide hyaluronic acid. The solutes were primarily peptides and prote ins, with molecular weights ranging from 108 to 66 000 Da. Logarithms of the apparent diffusion coefficients (log D-app), as calculated from the measured permeability and partition coefficients, were linearly r elated to the logarithm of solute molecular weight. In addition, log D -app was linearly related to the square of the solute radius, in keepi ng with Yasuda's free volume theory. As expected, measured partition c oefficients were not correlated to solute size. The results suggest th at these biocompatible and biodegradable hyaluronate esters may be use ful in peptide controlled release.