Emulsion‐Templated Preparation of Protein‐Encapsulated Hydrophilic Polymeric Nanocapsules

Abstract Encapsulation of biomacromolecules, such as proteins, enzymes, and nucleic acids, is of great interest for applications in drug delivery systems and nanobioreactors, because it protects biomacromolecules from degradation by protease. This paper describes the facile preparation of protein‐encapsulated hydrophilic polymeric nanocapsules using an emulsion‐templated approach. A water‐soluble block copolymer emulsifier, poly(2‐methacryloyloxyethyl phosphorylcholine)‐ b ‐poly[oligo(ethylene glycol)methacrylate] (PMPC‐ b ‐POEGMA), is synthesized via reversible addition fragmentation chain transfer polymerization. The PMPC‐ b ‐POEGMA emulsifier stabilizes the water‐chloroform interface in water‐in‐oil emulsions. Nanocapsules are prepared by cross‐linking the POEGMA blocks of the emulsifier located on the surface of the water droplets using divinyl sulfone (DVS). The resulting nanocapsules have a cross‐linked POEGMA membrane and are stably dispersed in aqueous media without further modification. Peroxidase is encapsulated in nanocapsules by dissolving it in the water phase prior to emulsification and cross‐linking. The cross‐linking density of the capsule membrane can be tuned by varying the DVS to hydroxy group ratio, which affects the encapsulation efficiency. The nearly complete encapsulation of peroxidase is achieved when the DVS to hydroxy group ratio ranges from 0.1 to 1.0. This emulsion‐templated strategy provides a facile route to protein‐loaded hydrophilic nanocapsules, which have potential applications in nanobioreactors, drug delivery systems, and diagnostic systems.