A Robust Oil-in-Oil Emulsion for the Nonaqueous Encapsulation of Hydrophilic Payloads

Compartmentalized structures widely exist in cellular systems (organelles) and perform essential functions in smart composite materials (microcapsules, vasculatures, and micelles) to provide localized functionality and enhance materials’ compatibility. An entirely water-free compartmentalization system is of significant value to the materials community as nonaqueous conditions are critical to packaging microcapsules with water-free hydrophilic payloads while avoiding energy-intensive drying steps. Few nonaqueous encapsulation techniques are known, especially when considering just the scalable processes that operate in batch mode. Herein, we report a robust oil-in-oil Pickering emulsion system that is compatible with nonaqueous interfacial reactions as required for encapsulation of hydrophilic payloads. A major conceptual advance of this work is the notion of the partitioning inhibitora chemical agent that greatly reduces the payload’s distribution between the emulsion’s two phases, thus providing appropriate conditions for emulsion-templated interfacial polymerization. As a specific example, an immiscible hydrocarbon–amine pair of liquids is emulsified by the incorporation of guanidinium chloride (GuHCl) as a partitioning inhibitor into the dispersed phase. Polyisobutylene (PIB) is added into the continuous phase as a viscosity modifier for suitable modification of interfacial polymerization kinetics. The combination of GuHCl and PIB is necessary to yield a robust emulsion with stable morphology for 3 weeks. Shell wall formation was accomplished by interfacial polymerization of isocyanates delivered through the continuous phase and polyamines from the droplet core. Diethylenetriamine (DETA)-loaded microcapsules were isolated in good yield, exhibiting high thermal and chemical stabilities with extended shelf-lives even when dispersed into a reactive epoxy resin. The polyamine phase is compatible with a variety of basic and hydrophilic actives, suggesting that this encapsulation technology is applicable to other hydrophilic payloads such as polyols, aromatic amines, and aromatic heterocyclic bases. Such payloads are important for the development of extended pot or shelf life systems and responsive coatings that report, protect, modify, and heal themselves without intervention

Preparation of Surfactant-Resistant Polymersomes with Ultrathick Membranes through RAFT Dispersion Polymerization

Surfactant-resistant polymersomes have substantial potential to be used as delivery vehicles in industrial applications. Herein, we report the preparation of poly­(ethylene oxide)-<i>block</i>-polystyrene copolymers with ultrahigh hydrophobic-block molecular weights through RAFT dispersion polymerization, which allows the polymerization-induced self-assembly into well-defined polymersomes with ultrathick membranes up to ∼47 nm. These ultrathick membranes significantly enhance the resistance against surfactant solubilization of the vesicles, improving the vesicles’ potential for use in industrial encapsulations. Vesicle-encapsulated actives are well retained in the presence of up to 40 wt % of various anionic and nonionic surfactants, with less than 7% active leakage being observed after 30 days

Amino-Acid-Incorporating Nonionic Surfactants for Stabilization of Protein Pharmaceuticals

With the rapid development of protein-based pharmaceutical products over the past decade, one of the biggest challenges in product development is maintaining the structural stability of proteins during purification, processing, and storage. In this work, the design of a new class of surfactants, polyether-modified N-acyl amino acids, is presented. One surfactant from this series, containing a phenylalanine moiety, demonstrated remarkable stabilization against aggregation of several model protein drugs. Dynamic light scattering, size exclusion chromatography, and circular dichroism all show the rate of thermally accelerated protein aggregation slowed. IgG aggregation was reduced by 3-fold compared to polysorbate controls. Testing of Orencia, a prescription biologic drug for rheumatoid arthritis, demonstrated a 36% improvement in monomer retention upon heat-aging