Breathable Microgel Colloidosome: Gas-Switchable Microcapsules with O2 and CO2 Tunable Shell Permeability for Hierarchical Size-Selective Control Release

Microcapsules enabling precise delivery and controlled release are highly desirable. However, it is still challenging to control the release profile by regulating the microcapsule shell permeability. In this work, gas-switchable microgel colloidosome (MGC) with oxygen (O₂) and carbon dioxide (CO₂) dual gas-tunable shell permeability has been developed and tested for control release of water-soluble cargo molecules, based on the size exclusion mechanism. The O₂ and CO₂ dual gas-switchable poly(2-(diethylamino)ethyl methacrylate-co-2,3,4,5,6-pentafluorostyrene), P(DEA-co-FS), microgels having surface modified with amino group (-NH₂) were synthesized and used to stabilize oil-in-water (O/W) Pickering emulsions. The oil-soluble poly(propylene glycol) diglycidyl ether (PPGDGE) was added as an intermicrogel cross-linker. The cross-linking between adjacent microgel particles at the water-oil interface was achieved through the amine-epoxy reaction of PPGDGE with the amine groups at the particle surface. Fluorescent-labeled dextran model cargo molecules of 10 kDa (D₁) and 2000 kDa (D₂) were uploaded under CO₂ treatment and locked inside the MGC with N₂ treatment. The O₂ and CO₂ dual-gas switchable properties offered the MGC with tunable shell permeability, which allowed the hierarchical release of D₁ and D₂ based on size exclusive mechanism. This work provides a robust method for preparation of gas-switchable microcapsules with tunable permeability and size-exclusive hierarchical release profile, promising for multiple ingredient controllable release, separation, and reaction.