A recent study of controlled release of a model small-molecule drug from poly(lactide-co-glycolide) microspheres prepared by the single-emulsion method found that the diffusion constant of the drug through the polymer was best related to the polymers molecular weight according
1. Two hydrogels are prepared from two different candidate polymers for controlled release of a protein drug, interleukin-2(IL-2). The gels exhibit the same swelling ratio at equilibrium, but gel A(formed by cross-linked polymer A, repeat unit molecular weight Mo= 100 g/mole)has