Formation and characterization of pH-responsive liquid core microcapsules.

A protocol for making microcapsules with either organic or aqueous cores and various polymers for the shell is established. Release profiles are obtained, with the effect of complete and incomplete shell formation investigated. Triggered release due to environmental pH is evaluated as a method for release targeting. Results from microcapsules with poly(4-vinylpyridine) shells showed a release of methylene blue dye when the pH was below 3.5, due to swelling of the polymer. This behavior was also observed for poly(lactide-co-glycolide) microcapsules due to cleavage of ester bonds. Both polymers showed complete release after 6 h. Various active ingredients such as polyacrylamide and hydroxypropylcellulose are also encapsulated using the established protocol.