Surface permeability of membrane and catalytic performance based on redox-responsive of hybrid hollow polymeric microcapsules

“Smart” polymeric microcapsules with excellent permeability of membranes have drawn considerable attention in scientific and industrial research such as drug delivery carriers, microreac-tors, and artificial organelles. In this work, hybrid hollow polymeric microcapsules (HPs) containing redox-active gold-sulfide bond were prepared with bovine serum albumin, inorganic metal cluster (AuNCs), and poly(N-isopropylacrylamide) conjugates by using Pickering emulsion method. HPs were transferred from water-in-oil to water-in-water by adding PEGbis(N-succinimidylsuccinate). To achieve redox-responsive membrane, the Au-S bond units incorporated into the microcapsules’ membranes, allowed us to explore the effects of a new stimuli, that is, the redox Au-S bond breaking on the microcapsules’ membranes. The permeability of these hybrid hollow polymeric microcapsules could be sensitively tuned via adding environment-friendly hydrogen peroxide (H₂ O₂ ), resulting from a fast fracture of Au-S bond. Meanwhile, AuNCs and conjugates could depart from the micro-capsules, and enhance the permeability of the membrane. Based on the excellent permeability of the membrane, phosphatase was encapsuled into HPs and p-nitrophenyl phosphate as a substrate. After adding 1 × 10⁻² and 1 × 10⁻⁴ M H₂ O₂, the catalytic efficiency was nearly 4.06 and 2.22 times higher than that of HPs in the absence of H₂ O₂, respectively. Hence, the unique redox-responsive HPs have potential applications in biocatalytic reaction, drug delivery, and materials as well as in bioscience.