Stimuli-Responsive Aggregation of High Molar Mass Poly(N,N-Diethylacrylamide)-b-Poly(4-Acryloylmorpholine) in Tetrahydrofuran.

The self-assembly of block copolymers constitutes a timely research area in polymer science with implications for applications like sensing or drug-delivery. Here, the unprecedented aggregation behavior of high molar mass block copolymer poly(N,N-diethylacrylamide)-b-poly(4-acryloylmorpholine) (PDEA-b-PAM) (Mn >400 kg mol-1 ) in organic solvent tetrahydrofuran (THF) is investigated. To elucidate the aggregation, dynamic light scattering, cryo-transmission electron microscopy, and turbidimetry are employed. The aggregate formation is assigned to the unprecedented upper critical solution temperature behavior of PAM in THF at elevated concentrations (> 6 wt.%) and high molar masses. Various future directions for this new thermo-responsive block copolymer are envisioned, for example, in the areas of photonics or templating of inorganic structures.

Cascade Kinetics in an Enzyme-Loaded Aqueous Two-Phase System.

Macromolecular crowding plays a critical role in the kinetics of enzymatic reactions. Dynamic compartmentalization of biological components in living cells due to liquid-liquid phase separation represents an important cell regulatory mechanism that can increase enzyme concentration locally and influence the diffusion of substrates. In the present study, we probed partitioning of two enzymes (horseradish-peroxidase and urate-oxidase) in a poly(ethylene glycol)-dextran aqueous two-phase system (ATPS) as a function of salt concentration and ion position in the Hofmeister series. Moreover, we investigated enzymatic cascade reactions and their kinetics within the ATPS, which revealed a strong influence of the ion hydration stemming from the background electrolyte on the partitioning coefficients of proteins following the Hofmeister series. As a result, we were able to realize cross-partitioning of two enzymes because of different protein net charges at a chosen pH. Our study reveals a strong dependency of the enzyme activity on the substrate type and crowding agent interaction on the final kinetics of enzymatic reactions in the ATPS and therefore provides substantial implications en route toward dynamic regulation of reactivity in synthetic protocells.

Polysaccharide nanoparticles: from fabrication to applications.

Polysaccharides have attracted considerable attention in a broad range of applications in recent years, which is due to their remarkable features such as biocompatibility, biodegradability, renewable origin, and facile modification. Considerable research efforts have been focused on developing polysaccharide nanoparticles and to promote their applications in various areas and biomedicine in particular. The present review highlights the properties of common polysaccharides used in nanoparticle formation as well as strategies to fabricate polysaccharide nanoparticles. Furthermore, the combination of polysaccharide nanoparticles and polymers is presented and brought into the context of applications. Finally, applications of polysaccharide nanoparticles as nano-delivery system, Pickering emulsion stabilisers, and material reinforcing agent in the fields of nanomedicine, cosmetics, and food system are highlighted. Moreover, this review describes and critically discusses present limitations and drawbacks in the preparation and use of polysaccharide nanoparticles, revealing directions to develop polysaccharide nanoparticles for further utilisation in various applications in the future.

Temperature sensitive water-in-water emulsions.

A novel approach for a temperature-sensitive stabilization of water-in-water (W/W) emulsions is described. Specifically, we leveraged the thermal induced conformation change of tailored thermoresponsive block copolymers to reversibly stabilize and destabilize water-water interfaces. In addition, we investigated our approach to reversibly tune the reaction kinetics of enzymes compartmentalized within aqueous two-phase systems.