Regenerated cellulose capsules for controlled drug delivery: Part I. Physiological characteristics of membrane formation and the influence of thermal annealing

摘要

Formation of regenerated cellulose (RC) membranes from dimethyl sulfoxide and paraformaldehyde solvent system is described. These membranes were cast. on cylindrical molds using the dip coating approach. After dip coating, the molds were immersed in water, acetone and several short chain 1-alkanols to precipitate cellulose. The wet cast. membranes were then thermally treated to obtain rigid, solvent and non-solvent free membranes. The formation process of these membranes was examined under the microscope. Physiochemical characteristics of these membranes were analyzed using infrared spectroscopy and X-ray diffraction analysis. The effect of membrane hydration on solute permeability in side-by-side diffusion cells was examined under controlled hydration conditions. The effect of thermal treatment was investigated by measuring methylene blue dye adsorption on membranes prior to and after thermal treatment. Cellulose is in amorphous state in these membranes. The RC membranes poses a unique self-pore forming feature when they are exposed to aqueous environment. Solvent uptake is critical to solute diffusion through them. The pore forming capability is reversible by introducing organic solvents in the diffusion medium. Membrane formation is not influenced by the type of non-solvent used, but affects the amount of cellulose aggregation during thermal treatment. Thermal treatment can also reduce the permeability of the solute through them.