Stimuli-Responsive Capsules Prepared from Regenerated Silk Fibroin Microspheres

Microcapsules are synthesized via the self-assembly of silk-fibroin microspheres with polycaprolactone in a colliodosome preparation procedure. The microsphere building blocks with controlled diameter are prepared from the naturally occurring biopolymer, silk fibroin, and then act as stabilizers for oil-in-water (O/W) emulsion and organized themselves on the surface of chloroform droplets to form the capsules. The concentration of the protein-based microspheres and the binding polycacrolactone is used to tailor the size, as well as the permeability of the resultant capsules. Furthermore, microencapsulation of fluorescently labeled macromolecules (20–2000 KDa) is demonstrated. The permeability of the capsules is observed to be stimuli responsive, making it possible to incorporate a pH-triggered payload release from the capsules. The relatively simple preparation of capsules with controlled dimensions and tunable permeability, alongside the biocompatibility and biodegradability of both polymer components makes these promising materials for potential use in smart drug-delivery systems.