Multi-Stimuli-Responsive Microcapsules for Adjustable Controlled-Release

Novel multi‐stimuli‐responsive microcapsules with adjustable controlled‐release characteristics are prepared by a microfluidic technique. The proposed microcapsules are composed of crosslinked chitosan acting as pH‐responsive capsule membrane, embedded magnetic nanoparticles to realize “site‐specific targeting”, and embedded temperature‐responsive sub‐microspheres serving as “micro‐valves”. By applying an external magnetic field, the prepared smart microcapsules can achieve targeting aggregation at specific sites. Due to acid‐induced swelling of the capsule membranes, the microcapsules exhibit higher release rate at specific acidic sites compared to that at normal sites with physiological pH. More importantly, through controlling the hydrodynamic size of sub‐microsphere “micro‐valves” by regulating the environment temperature, the release rate of drug molecules from the microcapsules can be flexibly adjusted. This kind of multi‐stimuli‐responsive microcapsules with site‐specific targeting and adjustable controlled‐release characteristics provides a new mode for designing “intelligent” controlled‐release systems and is expected to realize more rational drug administration. Multi‐stimuli‐responsive microcapsules with adjustable controlled‐release chara­cteristics are successfully prepared by embedding magnetic nanoparticles and temperature‐responsive sub‐microspheres into pH‐responsive chitosan microcapsule membranes. This kind of microcapsules can simultaneously achieve targeted delivery by applying an external magnetic field, self‐regulated drug release according to pH difference at pathological sites, and adjustable controlled‐release depending on temperature regulation.