Rim-Based Binding of Perfluorinated Acids to Pillararenes Purifies Water.

Per- and polyfluoroalkyl substances (PFAS) pose a rapidly increasing global problem as their widespread use and high stability lead worldwide to water contamination, with significant detrimental health effects.[1] Supramolecular chemistry has been invoked to develop materials geared towards the specific capture of PFAS from water,[2] to reduce the concentration below advisory safety limits (e.g., 70 ng/L for the sum of perfluorooctane sulfonic acid, PFOS and perfluorooctanoic acid, PFOA). Scale-up and use in natural waters with high PFAS concentrations has hitherto posed a problem. Here we report a new type of host-guest interaction between deca-ammonium-functionalized pillar[5]arenes (DAF-P5s) and perfluoroalkyl acids. DAF-P5 complexes show an unprecedented 1 : 10 stoichiometry, as confirmed by isothermal calorimetry and X-ray crystallographic studies, and high binding constants (up to 106 M-1) to various polyfluoroalkyl acids. In addition, non-fluorinated acids do not hamper this process significantly. Immobilization of DAF-P5s allows a simple single-time filtration of PFAS-contaminated water to reduce the PFOS/PFOA concentration 106 times to 15-50 ng/L level. The effective and fast (<5 min) orthogonal binding to organic molecules without involvement of fluorinated supramolecular hosts, high breakthrough capacity (90 mg/g), and robust performance (>10 regeneration cycles without decrease in performance) set a new benchmark in PFAS-absorbing materials.

The mechanism of encapsulating curcumin into oleosomes (Lipid Droplets).

Organisms have evolved intracellular micron-sized lipid droplets to carry and protect lipids and hydrophobic minor compounds in the hydrophilic environment of cells. These droplets can be utilized as carriers of hydrophobic therapeutics by taking advantage of their biological functions. Here, we focus on the potential of plant-derived lipid droplets, known as oleosomes, as carriers for hydrophobic therapeutics, such as curcumin. By spectroscopy and confocal microscopy, we demonstrate that the oleosome membrane is permeable to hydrophobic curcumin molecules. Fluorescence recovery after photobleaching shows rapid curcumin diffusion towards oleosomes, with a diffusion time in the range of seconds. Following this, quenching probes and dilatational rheology reveal that part of the loaded curcumin molecules can accumulate at the oleosome interface, and the rest settle in the inner core. Our findings shed light on the loading mechanism of the plant-derived lipid droplets and underscore the significance of molecular localization for understanding the mechanism. This work not only enhances the understanding of the loading process but also shows potential for oleosomes use as lipid carriers.

Presence of digestible starch impacts in vitro fermentation of resistant starch.

Starch is an important energy source for humans. Starch escaping digestion in the small intestine will transit to the colon to be fermented by gut microbes. Many gut microbes express α-amylases that can degrade soluble starch, but only a few are able to degrade intrinsic resistant starch (RS), which is insoluble and highly resistant to digestion (≥80% RS). We studied the in vitro fermentability of eight retrograded starches (RS-3 preparations) differing in rapidly digestible starch content (≥70%, 35-50%, ≤15%) by a pooled adult faecal inoculum and found that fermentability depends on the digestible starch fraction. Digestible starch was readily fermented yielding acetate and lactate, whereas resistant starch was fermented much slower generating acetate and butyrate. Primarily Bifidobacterium increased in relative abundance upon digestible starch fermentation, whereas resistant starch fermentation also increased relative abundance of Ruminococcus and Lachnospiraceae. The presence of small fractions of total digestible starch (±25%) within RS-3 preparations influenced the fermentation rate and microbiota composition, after which the resistant starch fraction was hardly fermented. By short-chain fatty acid quantification, we observed that six individual faecal inocula obtained from infants and adults were able to ferment digestible starch, whereas only one adult faecal inoculum was fermenting intrinsic RS-3. This suggests that, in contrast to digestible starch, intrinsic RS-3 is only fermentable when specific microbes are present. Our data illustrates that awareness is required for the presence of digestible starch during in vitro fermentation of resistant starch, since such digestible fraction might influence and overrule the evalution of the prebiotic potential of resistant starches.

The dilatable membrane of oleosomes (lipid droplets) allows their in vitro resizing and triggered release of lipids.

It has been reported that lipid droplets (LDs), called oleosomes, have an inherent ability to inflate or shrink when absorbing or fueling lipids in the cells, showing that their phospholipid/protein membrane is dilatable. This property is not that common for membranes stabilizing oil droplets and when well understood, it could be exploited for the design of responsive and metastable droplets. To investigate the nature of the dilatable properties of the oleosomes, we extracted them from rapeseeds to obtain an oil-in-water emulsion. Initially, we added an excess of rapeseed oil in the dispersion and applied high-pressure homogenization, resulting in a stable oil-in-water emulsion, showing the ability of the molecules on the oleosome membrane to rearrange and reach a new equilibrium when more surface was available. To confirm the rearrangement of the phospholipids on the droplet surface, we used molecular dynamics simulations and showed that the fatty acids of the phospholipids are solubilized in the oil core and are homogeneously spread on the liquid-like membrane, avoiding clustering with neighbouring phospholipids. The weak lateral interactions on the oleosome membrane were also confirmed experimentally, using interfacial rheology. Finally, to investigate whether the weak lateral interactions on the oleosome membrane can be used to have a triggered change of conformation by an external force, we placed the oleosomes on a solid hydrophobic surface and found that they destabilise, allowing the oil to leak out, probably due to a reorganisation of the membrane phospholipids after their interaction with the hydrophobic surface. The weak lateral interactions on the LD membrane and their triggered destabilisation present a unique property that can be used for a targeted release in foods, pharmaceuticals and cosmetics.

The emulsifying ability of oleosomes and their interfacial molecules.

Oleosomes are natural oil droplets, present in all organisms and abundant in oilseeds. After their aqueous extraction from oilseeds, they can be directly utilized as oil droplets in food, cosmetics and all types of oil-in-water emulsion systems. However, to expand the potential uses of oleosomes as green ingredients and to valorize oilseeds as efficient as possible, we explored their emulsifying ability. Oleosomes were extracted from rapeseeds, and 10.0 wt% oil-in-water emulsions were created after homogenization with 0.5-6.0 wt% oleosomes, and the droplet size of the emulsions and their structure was measured by laser diffraction and confocal laser scanning microscopy (CLSM), respectively. The emulsion with an oleosome concentration lower than 1.0 wt% gave unstable emulsions with visible free oil. At oleosome concentrations at 1.5 wt% or higher, we obtained stable emulsions with droplet sizes between 2.0 and 12.0 µm. To investigate the role of the oleosome interfacial molecules in stabilizing emulsions we also studied their emulsifying and interfacial properties (using drop tensiometry) after isolating them from the oleosome structure. Both oleosomes and their isolated interfacial molecules exhibited a similar behavior on the oil-water interfaces, forming predominantly elastic interfacial films, and also showed a similar emulsifying ability. Our results show that oleosomes are not stabilizing the oil-in-water emulsions as intact particles, but they provide their interfacial molecules, which are enough to stabilize an oil-water surface up to about 2 times bigger than the initial oleosome surface. The understanding of the behavior of oleosomes as emulsifiers, opens many possibilities to use oleosomes as alternative to synthetic emulsifiers in food and pharma applications.

Steering the Selectivity of Electrocatalytic Glucose Oxidation by the Pt Oxidation State.

Electrocatalytic glucose oxidation can produce high value chemicals, but selectivity needs to be improved. Here we elucidate the role of the Pt oxidation state on the activity and selectivity of electrocatalytic oxidation of glucose with a new analytical approach, using high-pressure liquid chromatography and high-pressure anion exchange chromatography. It was found that the type of oxidation, i.e. dehydrogenation of primary and secondary alcohol groups or oxygen transfer to aldehyde groups, strongly depends on the Pt oxidation state. Pt0 has a 7-fold higher activity for dehydrogenation reactions than for oxidation reactions, while PtOx is equally active for both reactions. Thus, Pt0 promotes glucose dialdehyde formation, while PtOx favors gluconate formation. The successive dehydrogenation of gluconate is achieved selectively at the primary alcohol group by Pt0 , while PtOx also promotes the dehydrogenation of secondary alcohol groups, resulting in more complex reaction mixtures.

Effect of ultrasound on keratin valorization from chicken feather waste: Process optimization and keratin characterization.

Chicken feather (CF) has been deemed as one of the main poultry byproducts with a large amount produced globally. However, the robust chemical nature of chicken feathers has been limiting in its wide-scale utilization and valorization. The study proposed a strategy of keratin regeneration from chicken feather combining ultrasound and Cysteine (Cys)-reduction for keratin regeneration. First, the ultrasonic effect on feather degradation and keratin properties was systematically explored based on Cys-reduction. Results showed that the feather dissolution was significantly improved by increasing both ultrasonic time and power, and the former had a greater impact on keratin yield. However, the treatment time over 4 h led to a decrease of keratin yield, producing more soluble peptides, > 9.7 % of which were < 0.5 kDa. Meanwhile, prolonging time decreased the thermal stability with weight loss at a lower temperature and amino acids content (e.g., Ser, Pro and Gly) of keratin. Conversely, no remarkable damage in chemical structure and thermal stability of regenerated keratin was observed by only increasing ultrasonic power, while the keratin solubility was notably promoted and reached 745.72 mg·g-1 in NaOH (0.1 M) solution (400 W, 4 h). The regenerated keratin under optimal conditions (130 W, 2.7 h, and 15 % of Cys) possessed better solubility while without obvious damage in chemical structure, thermal stability, and amino acids composition. The study illustrated that ultrasound physically improved CF degradation and keratin solubility without nature damage and provided an alternative for keratin regeneration involving no toxic reagent, probably holding promise in the utilization and valorization of feather waste.

Methodology for In Situ Microsensor Profiling of Hydrogen, pH, Oxidation-Reduction Potential, and Electric Potential throughout Three-Dimensional Porous Cathodes of (Bio)Electrochemical Systems.

We developed a technique based on the use of microsensors to measure pH and H2 gradients during microbial electrosynthesis. The use of 3D electrodes in (bio)electrochemical systems likely results in the occurrence of gradients from the bulk conditions into the electrode. Since these gradients, e.g., with respect to pH and reactant/product concentrations determine the performance of the electrode, it is essential to be able to accurately measure them. Apart from these parameters, also local oxidation-reduction potential and electric field potential were determined in the electrolyte and throughout the 3D porous electrodes. Key was the realization that the presence of an electric field disturbed the measurements obtained by the potentiometric type of microsensor. To overcome the interference on the pH measure, a method was validated where the signal was corrected for the local electric field measured with the electric potential microsensor. The developed method provides a useful tool for studies about electrode design, reactor engineering, measuring gradients in electroactive biofilms, and flow dynamics in and around 3D porous electrodes of (bio)electrochemical systems.

On the influence of protein aggregate sizes for the formation of solid and hollow protein microparticles.

Microparticles can function as carriers of e.g. pharmaceuticals and food ingredients. Hollow microparticles can enhance the capacitance due to their large interior void. For preparing microparticles, polymers have been assembled into spherical structures through the use of porous CaCO3 templates, followed by polymer cross-linking and selective template removal. However, this often results in the formation of microparticles with a solid core. Here we use proteins with different aggregate size distributions (<10 nm or >100 nm) to either form solid or hollow microparticles. Proteins were mixed with CaCl2 and Na2CO3 solutions, which from CaCO3 microcrystals (with 20-60 nm pores) with encapsulated proteins. Here it will be shown that small protein aggregates uniformly distributed into the CaCO3 templates. However, larger protein aggregates accumulated at the template edges. Au3+ ions were then added, which oxidize and cross-link proteins and are reduced to form gold nanoparticles (AuNPs). After removal of the templates, the small proteins formed solid microparticles and the larger protein aggregates hollow microparticles. This method of fabrication of solid and hollow protein microparticles, with embedded AuNPs, could be used for generating biomaterials with a broader range of applications, such as hosting molecules and multimodal imaging due to the presence of the AuNPs.

Fourier Transform Infrared Spectroscopy for Assessing Structural and Enzymatic Reactivity Changes Induced during Feather Hydrolysis.

Chicken feathers are major byproducts of the livestock processing industry with high potential in the feed sector. In this study, we present a new approach using Fourier transform infrared (FTIR) spectroscopy to detect the structural changes of feather keratin and its availability for enzymatic hydrolysis (AEH) induced by the thermal pressure hydrolysis (TPH) process. Compared to time-consuming in vitro measurement techniques, the proposed method provides rapid information about the structural changes during TPH which enables quick adaptation of TPH conditions as the quality of the incoming feather changes. By analyzing the FTIR spectra of raw and processed feathers, it was found that AEH negatively relates to the ß-sheet content (represented by two IR peaks centered at 1635 and 1689 cm-1), while it positively relates to a new series of peaks centered around 1700 cm-1 appearing after the TPH process. The proposed FTIR technique provides a reliable and rapid approach to determine the digestibility indicated by AEH of the processed feather and may be used in process control and optimization.

Phosphorus Tailors the d-Band Center of Copper Atomic Sites for Efficient CO2 Photoreduction under Visible-Light Irradiation.

Photoreduction of CO2 into solar fuels has received great interest, but suffers from low catalytic efficiency and poor selectivity. Herein, two single-Cu-atom catalysts with unique Cu configurations in phosphorus-doped carbon nitride (PCN), namely, Cu1 N3 @PCN and Cu1 P3 @PCN were fabricated via selective phosphidation, and tested in visible light-driven CO2 reduction by H2 O without sacrificial agents. Cu1 N3 @PCN was exclusively active for CO production with a rate of 49.8 µmolCO gcat -1 h-1 , outperforming most polymeric carbon nitride (C3 N4 ) based catalysts, while Cu1 P3 @PCN preferably yielded H2 . Experimental and theoretical analysis suggested that doping P in C3 N4 by replacing a corner C atom upshifted the d-band center of Cu in Cu1 N3 @PCN close to the Fermi level, which boosted the adsorption and activation of CO2 on Cu1 N3 , making Cu1 N3 @PCN efficiently convert CO2 to CO. In contrast, Cu1 P3 @PCN with a much lower Cu 3d electron energy exhibited negligible CO2 adsorption, thereby preferring H2 formation via photocatalytic H2 O splitting.

Hollow protein microparticles formed through cross-linking by an Au3+ initiated redox reaction.

Hollow microparticles (MPs) are of great relevance in the materials industry for a wide range of applications, such as catalysis, coatings, and delivery of theranostics. Here, we report the formation of hollow MPs through the assembly of lipoproteins in CaCO3 templates. Proteins interact in the pores of CaCO3 templates through attractive hydrophobic forces and form dense edges of hollow MPs. To further cross-link the proteins, Au3+ was added to initiate a redox reaction, where proteins were oxidized forming inter- and intramolecular covalent bonds, while Au3+ was reduced and gold nanoparticles (AuNPs) were formed. The obtained protein-based hollow MPs have a diameter of 6 µm and the AuNPs are embedded on their surface. Through this research, we suggest a new route to design biobased Au-protein hollow MPs in simple steps, which can allow new possibilities for carrying functional molecules and bioimaging.

Environmental Impact Evaluation for Heterogeneously Catalysed Starch Oxidation.

Oxidised starch is currently produced from native starch using sodium hypochlorite as an oxidising agent. The use of hypochlorite has undesired side reactions and produces stoichiometric amounts of waste (salt), thus alternative oxidation methods are desired. In this study, the potential of two catalysed starch oxidation methods to reduce the environmental impact (EI) of oxidised starch production are assessed. We compared the EI of oxidation with molecular oxygen (heterogeneously catalysed) and hydrogen peroxide (homogeneously catalysed) to hypochlorite oxidation through life cycle assessment (LCA). The results confirm that hypochlorite oxidation is the main environmental hotspot in the current process of oxidised starch production, and that both hydroperoxide oxidation and molecular oxygen oxidation can significantly lower the EI of the process. The impact reduction is most significant in the categories of freshwater eutrophication (∼67 %), ozone depletion (∼66 %), climate change (35-60 %) and resource use (40 %-78 %) for peroxide and molecular oxygen oxidation, respectively.

Au3+-Induced gel network formation of proteins.

The formation of protein gel networks in aqueous systems is a result of protein intermolecular interactions after an energy input, like heating. In this research, we report that a redox reaction between Au3+ ions and proteins can also lead to the formation of a protein gel network. Amino acids, like cysteine and tyrosine, get oxidized and form covalent bonds with neighboring protein molecules, while Au3+ ions get reduced to Au+ and Au0, nucleate and form gold nanoparticles. The protein gel network formation occurs within 2 h at room temperature and can be tuned by varying Au3+/protein ratio and accelerated by increasing the incubation temperature. The proposed Au3+-induced gel network formation was applied to different proteins, like egg yolk high-density lipoprotein, bovine serum albumin and whey protein. This research opens new insights for the investigation of the metal-protein interactions and may aid in the design of novel hybrid-soft nanocomposite materials.

Phosphorus Induced Electron Localization of Single Iron Sites for Boosted CO2 Electroreduction Reaction.

Electrochemical reduction of carbon dioxide (CO2 ) into chemicals and fuels has recently attracted much interest, but normally suffers from a high overpotential and low selectivity. In this work, single P atoms were introduced into a N-doped carbon supported single Fe atom catalyst (Fe-SAC/NPC) mainly in the form of P-C bonds for CO2 electroreduction to CO in an aqueous solution. This catalyst exhibited a CO Faradaic efficiency of ≈97 % at a low overpotential of 320 mV, and a Tafel slope of only 59 mV dec-1 , comparable to state-of-the-art gold catalysts. Experimental analysis combined with DFT calculations suggested that single P atom in high coordination shells (n≥3), in particular the third coordination shell of Fe center enhanced the electronic localization of Fe, which improved the stabilization of the key *COOH intermediate on Fe, leading to superior CO2 electrochemical reduction performance at low overpotentials.

Adsorption of rapeseed proteins at oil/water interfaces. Janus-like napins dominate the interface.

Plants offer a vast variety of protein extracts, typically containing multiple species of proteins that can serve as building blocks of soft materials, like emulsions. However, the role of each protein species concerning the formation of emulsions and interfaces with diverse rheological properties is still unknown. Therefore, deciphering the role of the individual proteins in an extract is highly relevant, since it determines the optimal level of purification, and hence the sustainability aspects of the extract. Here, we will show that when oil/water emulsions were prepared with a rapeseed protein extract containing napins and cruciferins (in a mass ratio of 1:1), only napins adsorbed at the interface exhibiting a soft solid-like rheological behavior. The dominance of napins at the interface was ascribed to their small size (radius r = 1.7 nm) and its unique Janus-like structure, as 45% of the amino acids are hydrophobic and primarily located at one side of the protein. Cruciferins with a bigger size (r = 4.4 nm) and a more homogeneous distribution of the hydrophobic domains couldn't reach the interface, but they appear to just weakly interact with the adsorbed layer of napins.

On the Emulsifying Properties of Self-Assembled Pea Protein Particles.

Pea proteins are promising oil-in-water emulsifying agents at both neutral and acidic conditions. In an acidic environment, pea proteins associate to form submicrometer-sized particles. Previous studies suggested that the emulsions at acidic pH were stabilized due to a Pickering mechanism. However, protein particles can be in equilibrium with protein molecules, which could play a significant role in the stabilization of emulsion droplets. Therefore, we revisited the emulsion stabilization mechanism of pea proteins at pH 3 and investigated whether the protein particles or the protein molecules are the major emulsifying agent. The theoretical and experimental surface load of dispersed oil droplets were compared, and we found that protein particles can cover only 3.2% of the total oil droplet surface, which is not enough to stabilize the droplets, whereas protein molecules can cover 47% of the total oil droplet surface. Moreover, through removing protein particles from the mixture and emulsifying with only protein molecules, the contributions of pea protein molecules to the emulsifying properties of pea proteins at pH 3 were evaluated. The results proved that the protein molecules were the primary stabilizers of the oil droplets at pH 3.

Exploring the Treasure of Plant Molecules With Integrated Biorefineries.

Despite significant progress toward the commercialization of biobased products, today's biorefineries are far from achieving their intended goal of total biomass valorization and effective product diversification. The problem is conceptual. Modern biorefineries were built around well-optimized, cost-effective chemical synthesis routes, like those used in petroleum refineries for the synthesis of fuels, plastics, and solvents. However, these were designed for the conversion of fossil resources and are far from optimal for the processing of biomass, which has unique chemical characteristics. Accordingly, existing biomass commodities were never intended for modern biorefineries as they were bred to meet the needs of conventional agriculture. In this perspective paper, we propose a new path toward the design of efficient biorefineries, which capitalizes on a cross-disciplinary synergy between plant, physical, and catalysis science. In our view, the best opportunity to advance profitable and sustainable biorefineries requires the parallel development of novel feedstocks, conversion protocols and synthesis routes specifically tailored for total biomass valorization. Above all, we believe that plant biologists and process technologists can jointly explore the natural diversity of plants to synchronously develop both, biobased crops with designer chemistries and compatible conversion protocols that enable maximal biomass valorization with minimum input utilization. By building biorefineries from the bottom-up (i.e., starting with the crop), the envisioned partnership promises to develop cost-effective, biomass-dedicated routes which can be effectively scaled-up to deliver profitable and resource-use efficient biorefineries.

The effect of me-substituents of 1,4-butanediol analogues on the thermal properties of biobased polyesters.

Biobased 1,4-butanediol analogues are used to tune the glass transition temperature and crystallization in a series of polyesters and allow for the formation of stereocomplexes.

High Rate Biomethanation of Carbon Monoxide-Rich Gases via a Thermophilic Synthetic Coculture.

Carbon monoxide-fermenting microorganisms can be used for the production of a wide range of commodity chemicals and fuels from syngas (generated by gasification of, e.g., wastes or biomass) or industrial off-gases (e.g., from steel industry). Microorganisms are normally more resistant to contaminants in the gas (e.g., hydrogen sulfide) than chemical catalysts, less expensive and self-regenerating. However, some carboxydotrophs are sensitive to high concentrations of CO, resulting in low growth rates and productivities. We hypothesize that cultivation of synthetic cocultures can be used to improve overall rates of CO bioconversion. As a case study, a thermophilic microbial coculture, consisting of Carboxydothermus hydrogenoformans and Methanothermobacter thermoautotrophicus was constructed to study the effect of cocultivation on conversion of CO-rich gases to methane. In contrast to the methanogenic monoculture, the coculture was able to efficiently utilize CO or mixtures of H2/CO/CO2 to produce methane at high efficiency and high rates. In CSTR-bioreactors operated in continuous mode, the coculture converted artificial syngas (66.6% H2:33.3% CO) to an outflow gas with a methane content of 72%, approaching the 75% theoretical maximum. CO conversion efficiencies of 93% and volumetric production rates of 4 m3methane/m3liquid/day were achieved. This case shows that microbial cocultivation can result in a significant improvement of gas-fermentation of CO-rich gases.