(186p) pH-Responsive Nanoparticles, Colloidosomes and Hybrid Microcapsules: Triggerable Release and Tunable Permeability | AIChE

(186p) pH-Responsive Nanoparticles, Colloidosomes and Hybrid Microcapsules: Triggerable Release and Tunable Permeability

Authors 

San Miguel, A. - Presenter, Georgia Institute of Technology
Behrens, S. H. - Presenter, Georgia Institute of Technology


Microencapsulation techniques have become increasingly important as an advanced formulation tool with widespread applications in the preparation of functional materials, chemically or biologically active agents, pharmaceuticals, cosmetics, food, and especially as drug delivery agents and cell carriers. One novel technique for encapsulation relies on solid-stabilized emulsions, so-called ?Pickering emulsions?, as a template for capsule formation: colloidal particles adsorbed to emulsion droplets are connected into a solid shell enclosing the droplet. The resulting microcapsules, whose shell is composed of solid particles, are known as colloidosomes. Ideally, such capsules should retain and protect an encapsulated agent until delivery conditions are reached in the target environment. Release could be triggered by an external disruption of the system or ideally by a change in the inherent conditions of the delivery medium, such as its temperature, pH, or salinity. We have developed Pickering emulsion-based microcapsules that dissolve rapidly upon a pH change under mild solution conditions. These capsules combine the sturdiness and pore size control of colloidosomes with the option of triggered disassembly known from stimulus-responsive Pickering emulsions. This work reports the assembly of pH-responsive microcapsules from double Pickering emulsions. The double emulsions are stabilized with nanoparticles, which have been prepared by nanoprecipitation (?Ouzo Effect?). The microcapsules dissolve upon a slight pH change at mild solution conditions. Evidence of this triggered response is provided in micrographs demonstrating a fast and complete dissolution of the microcapsules. The permeability of the capsule shell is quantified using Fluorescence Recovery After Photobleaching (FRAP). Capsules with switchable permeability have also been achieved by including an additional polymer in the middle phase and are currently under development.