Studies on the permeability and molecular weight cut off of HEMA-MMA microcapsules

The mass transfer characteristics of the HEMA-MMA microcapsules were evaluated under a variety of conditions. Several production parameters were reviewed for their effect on the mass transfer coefficient of albumin: (1) polymer solution to core solution flowrate ratios; (2) two core suspensions and incubation temperature. The mass transfer coefficient for BSA did not change as a function of these parameters. This analysis indicated that the permeability decreased with increasing molecular weight as expected. The mass transfer coefficient for BSA was calculated capsules aged for 1, 3, and 8 weeks. It was determined that the mass transfer coefficient and thus the permeability of HEMA-MMA microcapsules did not change during this time period. Gel electrophoresis analysis of the composition of the core contents of capsules incubated in Fetal calf serum to determine a molecular weight cut off that was very close to 69 kD.