Internally self-assembled particles entrapped in thermoreversible hydrogels

Abstract

The present study describes the development of thermogelling emulsions by the entrapment of internally self-assembled emulsion droplets (ISAsomes) within a thermoreversible hydrogel made of κ-carrageenan. The droplets are emulsified mesophases of cubic or hexagonal order, or emulsified micro-emulsions. Above 60 °C, the system was fluid and composed of a mixture of internally nanostructured small droplets and polymer chains dispersed in water. Below 60 °C, a physical gel with entrapped droplets was formed. A tuning of the temperature in order to switch between the gel and solution state did not affect the particles in terms of size. The thermoreversible behavior of the loaded polymer network and the effects on the internal structure of cubosomes, hexosomes and emulsified micro-emulsions was investigated by SAXS. We showed that the phase borders may be shifted due to the presence of the κ-carrageenan network, which alter the internal nanostructure of the droplets. This can induce a transformation from emulsified micro-emulsions to micellar cubosomes. In the hexagonal case, the lattice parameters of the hexosomes are slightly modified.