Transport properties of EVAl-starch-alpha amylase membranes.

We investigated the influence of various physicochemical parameters on the morphology and time-porosity formation of membranes composed of ethylene-vinyl alcohol, starch, and alpha-amylase. In particular, we determined that (1) it is possible to obtain a membrane with desired porosity by phase inversion in an appropriate water-ethanol mixture and (2) the enzymatic bioerosion is controlled by the amount of alpha-amylase present in the blend. Although no experiments involving drugs were carried out, the delivery properties of the film were determined by measuring the Darcy permeability, the effective diffusivity, and the mean reaction rate of the membranes, relating them to the modality of membrane preparation, the amount of enzyme present within the membrane, and the incubation time of the samples in a buffer solution. Simple theoretical models of the delivery properties of the membranes were developed, leading to predictions that were in good agreement with the experimental results.