Monodisperse core-shell chitosan microcapsules for pH-responsive burst release of hydrophobic drugs

Monodisperse core-shell microcapsules based on crosslinked chitosan membrane with acid-triggered burst release properties are successfully developed. The microcapsules are fabricated from double emulsion precursors that are prepared with a microfluidic approach. In neutral medium (pH 7.1), the microcapsules maintain a good spherical shape and structural integrity; while, in acidic medium (pH 1.5 ∼ 4.7), the microcapsules decompose rapidly and release the encapsulated contents completely in short periods varying from 39 s to 22 min. The acid-triggered burst release pattern from the proposed chitosan microcapsules may make them capable for stomach-specific drug delivery systems with quick and complete release characteristics in a controllable pH-responsive manner.