Liangzhi Hong

One-step formation of w/o/w multiple emulsions stabilized by single amphiphilic block copolymers.

Multiple emulsions are complex polydispersed systems in which both oil-in-water (O/W) and water-in-oil (W/O) emulsion exists simultaneously. They are often prepared accroding to a two-step process and commonly stabilized using a combination of hydrophilic and hydrophobic surfactants. Recently, some reports have shown that multiple emulsions can also be produced through one-step method with simultaneous occurrence of catastrophic and transitional phase inversions. However, these reported multiple emulsions need surfactant blends and are usually described as transitory or temporary systems. Herein, we report a one-step phase inversion process to produce water-in-oil-in-water (W/O/W) multiple emulsions stabilized solely by a synthetic diblock copolymer. Unlike the use of small molecule surfactant combinations, block copolymer stabilized multiple emulsions are remarkably stable and show the ability to separately encapsulate both polar and nonpolar cargos. The importance of the conformation of the copolymer surfactant at the interfaces with regards to the stability of the multiple emulsions using the one-step method is discussed.

Investigation of the factors affecting the carbohydrate–lectin interaction by ITC and QCM-D

Although the carbohydrate–lectin interactions have been intensively investigated, there is little report concerning the factors that affect the carbohydrate–lectin interaction. The interactions between concanavalin A (Con A) and glycopolymers, namely poly(2-(methacrylamido)-glucopyranose) and poly(2-methacrylamido-2-deoxy-glucitol) containing pyranose ring form and open form of glucosamine, respectively, have been investigated by a combination of isothermal titration calorimetry and quartz crystal microbalance-dissipation. Our results show that not only the pyranose ring form of glucosamine but also the open form can bind to Con A. Moreover, we investigate the influence of temperature on the carbohydrate–lectin interaction. As the temperature increases, the carbohydrate–lectin interaction is enhanced.

Shear-Assisted Fabrication of Block Copolymer Agglomerates with Various Morphologies in Viscous Medium

In this work, we have investigated the effect of laminar flow shearing on the formation of block copolymer agglomerates in viscous medium. Under a laminar flow shearing, the block copolymer solution droplets were spontaneously emulsified and were then elongated into protofibers, which in turn transformed into particles with various morphologies. Besides micro-/nanorods, which were previously reported for homopolymers, sphere and sheetlike structures were unexpectedly fabricated from block copolymers depending on the solvent quality, solvent exchange rates, and the entanglement of the polymer chains. In particular, the sheet structure, fabricated from poly(ethylene glycol)-b-polystyrene (PEG-b-PS), can be fixed by UV irradiation when photo-crosslinkable azide groups were introduced onto the polystyrene block. Surprisingly, we found that the fixed sheetlike structures show demulsification capability in tens of seconds, which may have great potential application in the separation of oil from emulsions.

Submicron Inverse Pickering Emulsions for Highly Efficient and Recyclable Enzymatic Catalysis

Herein, we report the utilization of a submicron Pickering emulsion (SPE) for the encapsulation of enzymes (e.g., lipase from Candida sp.) in water droplets that were solely stabilized by hydrophobic solid or mesoporous silica nanoparticles in toluene for use in biphasic reactions. The catalytic performance of encapsulated lipase was evaluated in the esterification of 1-hexanol and hexanoic acid under stirring-free conditions, which was favorable for maintaining enzymatic activity. Remarkably, the SPE significantly increased the specific activity of encapsulated lipase, owing to the exceptionally high water/oil interfacial area and short diffusion distance of the reagents in the SPE. With mesoporous silica nanoparticles, the activity of lipase was approximately 25.5- and 2.8-times higher than that of free lipase and encapsulated lipase in the micron Pickering emulsion, respectively. The higher water/toluene interfacial area was attributed to the smaller submicron-scale water droplets and the increase in the mass transfer of enzymes or substrates was further improved by using mesoporous Pickering stabilizers. In addition, the encapsulated lipase in SPE also demonstrated excellent stability and could be recycled up to 15 times without significant loss of activity.

All‐Silica Submicrometer Colloidosomes for Cargo Protection and Tunable Release

Colloidosomes have received considerable attention for the controlled delivery of active ingredients in medicine, agrochemicals, and cosmetics. However, most reported colloidosomes are highly permeable and size is larger than 1 μm. All silica colloidosomes have now been prepared with adjustable size, compact shell and low permeability. Our approach is based on the formation of inverse water-in-oil (w/o) emulsions stabilized solely by hydrophobic silica nanoparticles and subsequent locking of the particle at the oil-water interface by a simple sol-gel reaction of silica precursor at room temperature. The colloidosomes obtained display a robust and closed shell, ensuring a long-term retention of small hydrophilic molecules such as Methylene Blue. Remarkably, unlike all other reported silica colloidosomes, a timely and stepwise release of the encapsulated cargo can be triggered by adding ethanol or surfactant without destroying the capsule shell.