Multi‐Stimuli‐Responsive Microcapsules for Adjustable Controlled‐Release

Abstract

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.

pH‐Responsive Drug‐Delivery Systems

“…[118] and vitamin B12-loaded microcapsules composed of crosslinked chitosan that acts as a pH-responsive capsule membrane, embedded magnetic nanoparticles to realize site-specific targeting, and embedded temperature-responsive submicrospheres that serve as micro-valves. [119] From the above-discussed examples, one can see that inorganic/organic-nanocomposites-based pH-responsive drug-delivery systems have displayed interesting properties and promising applications. The nanostructured inorganic components of these pH-responsive drug-delivery systems can provide various novel structures with well-defined size, morphology, and multifunctionality.…”

Controllable microfluidic strategies for fabricating microparticles using emulsions as templates

“…This can create chitosan shells containing magnetic nanoparticles as navigators for targeted delivery and PNI-PAM nanogels as thermo-responsive micro-valves for controlled release of drugs ( Fig. 8(g)) (Wei et al, 2014). The chitosan networks comprising the shell can undergo reversible swelling/shrinking volume transitions in response to pH changes, thus showing a pH-dependent release behavior.…”

“…(f) Compartmental microparticles with shells consisting of a chitosan hydrogel . (g) Multi-stimuli-responsive hollow chitosan microparticles combined with PNIPAM nanogels and magnetic nanoparticles for advanced controlled release (Wei et al, 2014). (h) Magnetic core-shell PNIPAM microparticles for thermo-induced burst release (Wang et al, 2009).…”

Preparation and Characterization of Biocompatible Polymer Particles as Potential Nanocarriers for Inhalation Therapy

“…Typically, drug release is achieved due to polymer swelling or erosion [5]. In addition, the release rate can be "tuned" using the responsive systems; that is, it can be triggered by pH, temperature, radiation, magnetic field, and so forth [6,7]. In such cases polymerbased carriers become the specialized and effective tool of medical treatment.…”