Shear-induced solvent release from gel particles: application to drug-delivery systems.

ABSTRACT

The behaviour of a swollen-in-water hydrogel particle and of a chitosan-alginate micro-capsule immersed in a silicon oil under shear is studied by the rheo-optical method. Both gel and capsule quantitatively behave in a same way. Shear stress leads to a solvent release from a particle and a further increase of shear stress induces the solvent detachment from the released areas. Particle deformation and solvent release are reversible when stopping the shear, the particle recovers its initial shape and volume. But when some solvent is detached, it flows separately as would do low-viscosity droplets immersed in a high-viscosity matrix.