Sustainable Supramolecular Polymers.

Polymer waste is a pressing issue that requires innovative solutions from the scientific community. As a beacon of hope in addressing this challenge, the concept of sustainable supramolecular polymers (SSPs) emerges. This article discusses challenges and efforts in fabricating SSPs. Addressing the trade-offs between mechanical performance and sustainability, the ultra-tough and multi-recyclable supramolecular polymers are fabricated via tailoring mismatched supramolecular interactions. Additionally, the healing of kinetically inert polymer materials is realized through transient regulation of the interfacial reactivity. Furthermore, a possible development trajectory for SSPs is proposed, and the transient materials can be regarded as the next generation in this field. The evolution of SSPs promises to be a pivotal stride towards a regenerative economy, sparking further exploration and innovation in the realm of sustainable materials.

The effect of the contact angle on particle stabilization and bridging in water-in-water emulsions.

HYPOTHESIS: Water-in-water (W/W) emulsions formed by mixing incompatible polymers in aqueous solution can in some cases be stabilized by adding particles that adsorb spontaneously at the W/W interface. The importance of the contact angle of the particles with the interface on the stability of W/W emulsions is still an outstanding issue. We hypothesize that if the contact angle with the continuous phase is smaller than 90°, particles can bridge dispersed droplets, which enhances the stability of the emulsion. EXPERIMENTS: The W/W emulsions consisted of a dispersed poly(ethylene oxide) (PEO) phase in a continuous dextran phase or vice versa. Gelatin microgels were added and their contact angle was varied by varying the pH. The morphology during aging was observed by microscopy. FINDINGS: The contact angle of the microgels with the PEO phase varied between 110° close to neutral pH and 0° at pH 3 and pH 11. The W/W emulsions were stable only when the contact angle with the continuous phase was smaller than 90°. In this case, microgels could form bridges between dispersed droplets creating a network of droplets.

Poly(ethylene oxide)/Gelatin-Based Biphasic Photocrosslinkable Hydrogels of Tunable Morphology for Hepatic Progenitor Cell Encapsulation.

Macroporous hydrogels have great potential for biomedical applications. Liquid or gel-like pores were created in a photopolymerizable hydrogel by forming water-in-water emulsions upon mixing aqueous solutions of gelatin and a poly(ethylene oxide) (PEO)-based triblock copolymer. The copolymer constituted the continuous matrix, which dominated the mechanical properties of the hydrogel once photopolymerized. The gelatin constituted the dispersed phase, which created macropores in the hydrogel. The microstructures of the porous hydrogel were determined by the volume fraction of the gelatin phase. When volume fractions were close to 50 v%, free-standing hydrogels with interpenetrated morphology can be obtained thanks to the addition of a small amount of xanthan. The hydrogels displayed Young's moduli ranging from 5 to 30 kPa. They have been found to be non-swellable and non-degradable in physiological conditions. Preliminary viability tests with hepatic progenitor cells embedded in monophasic PEO-based hydrogels showed rapid mortality of the cells, whereas encouraging viability was observed in PEO-based triblock copolymer/gelatin macroporous hydrogels. The latter has the potential to be used in cell therapy.

Exploiting multiple phase separation to stabilize water in water emulsions and form stable microcapsules.

HYPOTHESIS: Water in water (W/W) emulsions are formed by mixing aqueous solutions of incompatible polymers. It is possible to add a third polymer solution that forms at the right conditions a phase that completely covers the dispersed droplets as a thin layer. Our hypothesis is that by gelling the third phase, W/W emulsions can be stabilized and that microcapsules can be formed that are stable against dilution. EXPERIMENTS: W/W emulsions were formed by mixing aqueous solutions of poly(ethylene oxide) (PEO) and dextran. Gelatin was added to form the third phase, gelation of which was induced by cooling. The morphology was observed by microscopy, and the rheological properties were investigated. FINDINGS: The compatibility of gelatin and PEO can be fine-tuned by the pH such that a continuous layer of the gelatin phase forms around the droplets of the dextran phase, with a thickness that can be varied. After cooling, the gelatin layer forms a gel and provides stabilization against coalescence. The gelatin microcapsule was found to be stable to dilution. The generality of the method was demonstrated by applying it to another, fully food-grade, W/W emulsion formed by mixing amylopectin and xyloglucan.

Utilization of xanthan to stabilize water in water emulsions and modulate their viscosity.

Water in water emulsions were prepared by mixing aqueous solutions of dextran and poly(ethylene oxide) at three volume fractions. The xanthan was added to the emulsions up to 0.5 wt%. The stability of the emulsions was probed by measuring the time dependence of the transmission profiles at different centrifugal forces. At lower concentrations, xanthan partitioned to the dextran phase and strong shear-thinning was observed at higher concentrations. At lower concentrations, destabilization was caused by a combination of coalescence and creaming or sedimentation. Above 0.1 wt%, xanthan strongly increased the viscosity of the emulsions and stabilized them under gravity for at least one week. The time evolution of the emulsion microstructure was observed using confocal scanning laser microscopy. The effect of shear on the microstructure was investigated using a specific rheo-optical device. It showed the formation of thin strands that broke up into small drops after stopping the flow.

RNA m6A methyltransferase METTL3 promotes colorectal cancer cell proliferation and invasion by regulating Snail expression.

Nitrogen 6-methyladenosine (m6A) is the result of methylation of nitrogen-6 on adenosine, and is the most abundant chemical modification of eukaryotic mRNA. Dysregulation of m6A methylation has been implicated in cancer development and progression through various mechanisms. This type of methylation is primarily regulated by methyltransferase-like 3 (METTL3). However, the molecular mechanisms underlying the role of METTL3 in colorectal cancer (CRC) have not been extensively elucidated. The present study explored m6A modification and the underlying mechanism of m6A, which serve regulatory roles in the development of CRC. It was found that METTL3 is upregulated in CRC cell lines and tissues, and its expression positively correlated with poor overall survival (OS). Mechanistically, the present study demonstrated that METTL3 methylates Snail mRNA, thus stabilizing it to promote CRC malignancy. The present findings indicate that m6A modification is involved in CRC tumorigenesis, and highlight its potential as a therapeutic target against CRC.