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.