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The process of liquid–liquid crystalline phase separation (LLCPS) in filamentous colloids is at the very core of multiple biological, physical and technological processes of broad significance. However, the complete theoretical understanding of the process is still missing. LLCPS involves the nucleation, growth and up-concentration of anisotropic droplets from a continuous isotropic phase, until a state of equilibrium is reached. Herein, by combining the thermodynamic extremum principle with the Onsager theory, we describe the nucleation and growth of liquid crystalline droplets, and the evolution of their size and concentration during phase separation, eventually leading to a multitude of order–order phase transitions. Furthermore, a decreasing pitch behaviour can be predicted using this combined theory during tactoid growth, already observed experimentally but not yet explained by present theories. The results of this study are compared with the experimental data of cholesteric pitch, observed in three different systems of biological chiral liquid crystals. These findings give an important framework for predicting the formation, growth and phase behaviour of biological filamentous colloids undergoing LLCPS, advancing our understanding of liquid–liquid phase separation and self-assembly mechanisms in biological systems, and provide a valuable rationale for developing nanomaterials and applications in nanotechnology., The process of liquid–liquid crystalline phase separation (LLCPS) in filamentous colloids is described for the first time via a theory predicting the evolution of binodal lines and the evolution of the cholesteric pitch in chiral nematic droplets.

We introduce a green and efficient approach for removing per- and polyfluoroalkyl substances (PFASs) based on the beta-lactoglobulin amyloid fibril membrane. The membrane exhibits superior adsorption capability for long-chain PFASs. At low pH, the membrane efficiency improved significantly due to enhanced electrostatic interactions between positively charged fibrils and negatively charged PFASs. Furthermore, intermolecular adhesion force measurements confirm the hydrophobic-hydrophobic interaction at the nanoscale with PFOS and PFOA representing perfluoroalkyl sulfonic acids (PFSAs) and perfluoroalkyl carboxylic acids (PFCAs), respectively. For real PFAS-contaminated water from the Xiaoqing River basin and under single-step filtration mode, the membrane exhibits high efficiency for removing both high (>mu g L-1) and trace (ng L-1) levels of the compounds. To demonstrate the scalability and generality, a commercial amyloid-carbon-based hybrid membrane is applied for removal of a range of long-chain and short-chain PFASs as well as their replacement compounds, offering complete removal of PFASs with >= 4 perfluorinated carbon atoms in the molecular structure and a removal efficiency of low molecular weight PFBA (3 perfluorinated carbon atoms) exceeding 96%. Analysis of the sustainability footprint reveals the superiority of the amyloid-carbon hybrid membrane for PFAS removal. Altogether, these results demonstrate a high potential of amyloid fibril membrane technology for the sustainable removal of PFASs from water., Environmental Science: Water Research & Technology, 7 (10), ISSN:2053-1400, ISSN:2053-1419

β-Lactoglobulin amyloid fibrils are bio-colloids of high interest in many fields (e.g. water purification, cell growth, drug delivery and sensing). While the mechanical properties of pure amyloid fibril gels meet the needs of some applications, mechanical fragility often hinders a wider usage basin. In this work, we present a simple and sustainable approach for reinforcing amyloid fibril hydrogels and aerogels, upon the diffusion of polysaccharides (low-acetylated Gellan Gum and κ-carrageenan) inside their mesh. The formed hybrid materials show enhanced resistance upon compression, without any loss of the exquisite surface reactivity of the amyloid fibrils. The proposed approach can pave the way for designing composite materials that are both highly functional and environmentally friendly.

The linear polysaccharide λ-carrageenan is the only one among the carrageenans not forming secondary, tertiary, and quaternary structures in the presence of inorganic ions. Chloroquine (CQ) is a well-established antimalaria drug also recently discussed in therapeutics against the COVID-19 pandemic. The interaction of this polysaccharide-ionic drug pair was investigated by combining UV-vis spectrophotometry and atomic force microscopy (AFM) imaging. A decrease of the UV peak assigned to free CQ and the occurrence of isosbestic points indicate the formation of complexes. High-resolution AFM height images revealed an increasing height of the single polysaccharide chains in the random coil state upon addition of CQ, indicating the formation of a secondary structure, followed by higher hierarchical aggregates. The disappearance of higher-ordered structures and the recovery of polysaccharide chains with primary structure were observed by introducing inorganic cations (Na

Mesh size is a crucial parameter that governs the behavior of gels made of semiflexible polymers. We show that the average mesh size of amyloid fibril gels can be extracted from simple dynamic ligh...

With the rapid worldwide industrial development, large amounts of pollutants such as heavy metals are discharged into the water sources, causing a huge threat to living beings. To mitigate this issue, there is an urgent need for new water treatment strategies. Inspired by a natural shell nacre structure and a multidimensional hybrid concept, we demonstrate multilayered inorganic-organic hybrid membranes using metallic molybdenum disulfide (MoS2) as two-dimensional transition metal dichalcogenide nanosheets and one-dimensional silk nanofibrils for water purification. Because of its possessing negatively charged layers and interaction sites, the hybrid film could adsorb metal ions and dyes from water. The separation performance can be tuned by changing the component ratios of these two nanomaterials. During filtration, due to the reducing effect of the MoS2 nanosheets, precious metal ions are reduced to their nanoparticle form without any further thermal or chemical treatments. In addition to the one-step removal and recovery of metal ions, the hybrid membranes exhibit excellent potential for the determination and removal of different dyes from water. The results of this research can open up an effective and green avenue for water purification and recovery of metal ions dissolved in water.

Lipidic mesophases are versatile bioorganic materials that have been effectively employed as nanoscale matrices for membrane protein crystallization, drug delivery and as food emulsifiers over the last 30 years. In this review, the focus is upon studies that have employed non-lamellar lipid mesophases as matrices for organic, inorganic and enzymatic reactions. The ability of lipidic mesophases to incorporate hydrophilic, amphiphilic and hydrophobic molecules, together with the high interfacial area of the lipidic cubic and inverse hexagonal phases has been exploited in heterogeneous catalysis as well as for enzyme immobilization. The unique nanostructure of these mesophases is the driving force behind their ability to act as templates for synthesis, resulting in the creation of highly ordered polymeric and inorganic materials with complex geometries.

Water scarcity and contamination by biological pollutants are global challenges that significantly affect public health. Reverse osmosis, nanofiltration and ultrafiltration technologies are very effective for the elimination of pathogens and most contaminants but associated with considerable capital and operating costs, high energy consumption and the use of chlorinated chemicals to suppress membrane fouling. Additionally, the pressure needed by these techniques may disrupt the pathogenic microbial cell membranes, causing the release of genetic material (fragments of DNA, RNA and plasmids) into the water. Here, we introduce the simultaneous removal of both bacteria and associated genetic material using amyloid hybrid membranes, via a combined adsorption and size exclusion mechanism. Amyloid hybrid membranes can remove upto and beyond 99% of the genetic material by adsorption, where amyloid fibrils act as the primary adsorbing material. When the same membranes are surface-modified using chitosan, the anti-biofouling performance of the membranes improved significantly, with a bacterial removal efficiency exceeding 6 log. © 2020 The Royal Society of Chemistry., Nanoscale Advances, 2 (10), ISSN:2516-0230

Nuclear medicine uses various radioactive compounds for the administration into patients to diagnose and treat diseases, which generates large amounts of radioactively contaminated water. Currently, radioactively contaminated hospital wastewater has to be stored until the contained radionuclides have sufficiently decayed because cost-effective and efficient removal technologies are not available. Similar considerations apply in the nuclear power industry, with, however, decay times of the radionuclides several orders of magnitude higher. Previously, we reported hybrid membranes composed of amyloid fibrils produced from cheap and readily available proteins and activated carbon, which efficiently removed heavy metal ions and radioactive compounds from water. Here, we show that these membranes are highly efficient in the adsorption & removal of diverse, clinically relevant radioactive compounds from hospital wastewater by single-step filtration. The radionuclides technetium (Tc-99m), iodine (I-123) and gallium (Ga-68) can be removed from water with efficiencies above 99.8% in one single step. We also demonstrate the purification of a real clinical wastewater sample from a Swiss hospital containing iodine (I-131) and lutetium (Lu-177). With the use of single-photon emission computed tomography (SPECT) and positron emission tomography (PET), we were able to visualize the accumulation of the radioactive compounds within the membrane and demonstrate its outstanding performance. By converting large volumes of radioactive wastewater into low volumes of solid radioactive waste, the present technology emerges as a possible game-changer in the treatment of nuclear wastewater., Environmental Science: Water Research & Technology, 6 (12), ISSN:2053-1400, ISSN:2053-1419

Substance P neuropeptide is here reported to self-assemble into well-defined semi-flexible nanotubes. Using a blend of synchrotron small angle X-ray scattering, atomic force microscopy and other biophysical techniques, the natural peptide is shown to self-assemble into monodisperse 6 nm wide nanotubes, which can closely associate into nano-arrays with nematic properties. Using simple protocols, the nanotubes could be precipitated or mineralised while conserving their dimensions and core-shell morphology. Our discovery expands the small number of available monodisperse peptide nanotube systems for nanotechnology, beyond direct relevance to biologically functional peptide nanostructures since the substance P nanotubes are fundamentally different from typical amyloid fibrils.

Design and fabrication of versatile adsorbents for universal water purification following green chemistry principles remain challenging. Here, it is shown that amyloid fibrils from protein waste can be used as a functional scaffold for metal organic framework (MOF) biomimetic mineralization. The resulting amyloid fibrils/ZIF-8 hybrid aerogels can effectively remove nine different heavy metal ions from water due to their hierarchical porous structure. Importantly, amyloid fibrils/ZIF-8 hybrid aerogels can efficiently remove Hg2+ and Pb2+ from water over five consecutive adsorption-regeneration cycles. Furthermore, a dual removal pathway of adsorption and catalytic degradation is observed in the synthetic dyes, indicating that the aerogel preserves its porous nature and maintains the integrity of versatile functional ligands within ZIF-8. Finally, it is shown that these hybrid aerogels can also perform successfully in oil-water separation. Considering the facile synthesis procedure, high removal efficiency, affordable cost, and regeneration possibilities, the amyloid fibrils/ZIF-8 hybrid aerogel stands as an ideal candidate for addressing open challenges in wastewater treatment and water purification., Small, 18 (4), ISSN:1613-6810, ISSN:1613-6829

Water purification from per- and poly-fluoroalkyl substances (PFASs), as a group of persistent and mobile fluoro-organic contaminants, is receiving increasing attention worldwide due to the ubiquitous presence of these highly toxic compounds. To reduce the risk of exposure of human life to PFASs and their dispersion in the environment, various techniques, primarily based on membrane technologies, have been rapidly developed. Here we critically review and analyze the current state-of-the-art of membrane-based techniques for PFASs removal, including direct membrane filtrations, adsorption-based membranes, and hybrid membrane processes. Membranes performance, treatment efficiencies, characteristic parameters and mechanisms for PFASs removal are discussed in detail. We highlight and discuss advantages and limitations, as well as challenges and prospects of individual membrane-based PFASs treatments, pointing towards the practical and sustainable application of these technologies., Environment International, 157, ISSN:0160-4120, ISSN:1873-6750

The tap water quality in Peru fails to meet the World Health Organization (WHO) drinking water standards; consequently, the local population in Peru has been exposed over the last few years to harmful arsenic levels through water consumption. A field study was conducted in Peru between 2019 and 2020 using granular adsorbers and hybrid membranes based on the technology using milk protein nanofibril–carbon hybrid materials previously introduced in the literature by us (S. Bolisetty and R. Mezzenga, Nat. Nanotechnol., 2016, 11, 365). The performance was analyzed across 28 households as well as 3 community-based water treatment plants in some of the Peruvian arsenic burdened regions, covering a range of groundwater arsenic concentrations between 11 μg L−1 and 1.1 mg L−1. Three different kinds of filtration units were installed including the combined granular media and hybrid membrane (type I), hybrid membrane alone (type II), and granular media (type III), to determine the effectiveness of different filtration setups for arsenic removal in different regions. The arsenic removal by household filtration units and community filtration units shows a removal efficiency exceeding 99% at various initial arsenic concentrations for a duration up to nine months. In addition, it is shown that an aqueous NaOH solution can be used to regenerate the adsorbent, extending its operational lifetime and the overall capacity for As removal. High purification efficiency, very low cost, safety, little to no energy requirement, possibility of regeneration and simplicity of operation make this technology suitable for arsenic removal from drinking water in a broad range of urban and rural areas., Environmental Science: Water Research & Technology, 7 (12), ISSN:2053-1400, ISSN:2053-1419

The billion tons of synthetic-polymer-based materials (i.e. plastics) produced yearly are a great challenge for humanity. Nature produces even more natural polymers, yet they are sustainable. Proteins are sequence-defined natural polymers that are constantly recycled when living systems feed. Digestion is the protein depolymerization into amino acids (the monomers) followed by their re-assembly into new proteins of arbitrarily different sequence and function. This breaks a common recycling paradigm where a material is recycled into itself. Organisms feed off of random protein mixtures that are "recycled" into new proteins whose identity depends on the cell's specific needs. In this study, mixtures of several peptides and/or proteins are depolymerized into their amino acid constituents, and these amino acids are used to synthesize new fluorescent, and bioactive proteins extracellularly by using an amino-acid-free, cell-free transcription-translation (TX-TL) system. Specifically, three peptides (magainin II, glucagon, and somatostatin 28) are digested using thermolysin first and then using leucine aminopeptidase. The amino acids so produced are added to a commercial TX-TL system to produce fluorescent proteins. Furthermore, proteins with high relevance in materials engineering (beta-lactoglobulin films, used for water filtration, or silk fibroin solutions) are successfully recycled into biotechnologically relevant proteins (fluorescent proteins, catechol 2,3-dioxygenase)., Advanced Materials, 33 (44), ISSN:0935-9648, ISSN:1521-4095

Minimizing the spread of viruses in the environment is the first defense line when fighting outbreaks and pandemics, but the current SARS-CoV-2 pandemic demonstrates how difficult this is on global scale, particularly in a sustainable and environmental-friendly way. Here we introduce and develop a sustainable and bio-degradable anti-viral filtration membrane composed of amyloid nanofibrils made from food-grade milk proteins and iron oxyhydroxide nanoparticles synthesized in-situ from iron salts by simple pH-tuning. Thus, all the membrane components are made of environmentally friendly, non-toxic and widely available materials. The membrane has outstanding efficacy against a broad range of viruses, including enveloped, non-enveloped, airborne and waterborne viruses, such as SARS-CoV-2, H1N1 (the influenza A virus strain responsible for the swine flu pandemic in 2009), and enterovirus 71 (EV71; a non-enveloped virus resistant to harsh conditions such as highly acidic pH), highlighting a possible role in fighting the current and future viral outbreaks and pandemics., Nature Nanotechnology, 16, ISSN:1748-3387, ISSN:1748-3395

The billion tons of synthetic polymer-based materials (i.e. plastics) produced every year are one of the greatest challenges that humanity has to face. Nature produces even more natural polymers, yet they are sustainable. For example, proteins are sequence-defined natural polymers, that are constantly recycled when living systems feed. Indeed, digestion is the protein depolymerization into amino acids (i.e. the monomers) followed by their re-assembly into new proteins of arbitrarily different sequence and function. This process breaks a common recycling paradigm where a material is recycled into itself. Organisms feed of random protein mixtures that are ‘recycled’ into new proteins whose identity depends on the cell’s needs at the time of protein synthesis. Currently, advanced materials are increasingly made of proteins, but the abovementioned ideal recyclability of such materials has yet to be recognized and established. In this study mixtures of several (up to >30) peptides and/or proteins were depolymerized into their amino acid constituents, and these amino acids were used to synthesize new fluorescent, and bio-active proteins extra-cellularly by using an amino acid-free cell-free transcription-translation system. Proteins with high relevance in materials engineering (β-lactoglobulin films, used for water filtration, or silk fibroin solutions) were successfully recycled into biotechnologically relevant proteins (green, and red fluorescent proteins, catechol 2,3-dioxygenase). The potential long-term impact of this approach to recycling lies in its compatibility with circular-economy models where raw materials remain in use as long as possible, thus reducing the burden on the planet.

The propensity to self-assemble into amyloid fibrils with a shared cross-β architecture is a generic feature of proteins. Amyloid-related diseases affect millions of people worldwide, yet they are incurable and cannot be effectively prevented, largely due to the irreversible assembly and extraordinary stability of amyloid fibrils. Recent studies suggest that labile amyloids may be possible in certain proteins containing low-complexity domains often involved in the formation of subcellular membraneless organelles. Although the fundamental understanding of this reversible amyloid folding process is completely missing, the current view is that a given protein sequence will result in either irreversible, as in most of the cases, or reversible amyloid fibrils, as in few exceptions. Here we show that two common globular proteins, human lysozyme and its homologue from hen egg white, can self-assemble into both reversible and irreversible amyloid fibrils depending on the folding path followed by the protein. In both folding states, the amyloid nature of the fibrils is demonstrated at the molecular level by its cross-β structure, yet with substantial differences on the mesoscopic polymorphism and the labile nature of the amyloid state. Structural analysis shows that reversible and irreversible amyloid fibrils possess the same full-length protein sequence but different fibril core structures and β-sheet arrangements. These results illuminate a mechanistic link between the reversible and irreversible nature of amyloids and highlight the central role of protein folding states in regulating the lability and reversibility of amyloids.

The efficient removal of the long-lived fission product 137Cs from radioactive water by a filter material based on whey protein fibrils and activated carbon.

Cryo-enzymology provides the possibility to develop unconventional biological reactions and detect intermediates in ultrafast enzymatic catalysis processes, but also illuminates the understanding of life principles in extremely cold environments. The scarcity of biological or biomimetic host systems that provide liquid water at subzero temperatures inhibits the prosperity of cryo-enzymology. Here we introduce cryo-enzymatic reactions in subzero water nanoconfined within lipid mesophases formed by conventional lipids. We show that the enzymatic reactions that ensue outperform the homologue catalytic processes run at standard temperatures. We use phytantriol-based lipidic mesophases (LMPs), within which water remains in the liquid state down to −120 °C, and combine crystallization and dynamic studies of the confined water to provide a fundamental understanding of the physical status of water at subzero temperatures, which sets the stage for cryo-enzymatic reactions in these environments. In the model horseradish peroxidase oxidization, the cation free-radical product is stabilized in LMPs at −20 °C, in contrast to the fast-consuming reactions at temperatures above 0 °C. Furthermore, the LMP system also supports the cascade reaction and lipase reaction at subzero temperatures, at which enzymatic reactions with both hydrophilic and hydrophobic substrates are successfully carried out. Our designed LMP system opens access to the nature of confined water in the biomimetic environment and provides a platform for low-temperature biomacromolecule reconstitution and the cryogenic control of enzymatic reactions in bionanotechnology. By employing the nanoconfinement in the mesophase formed by conventional lipids, cryo-enzymatic reactions are performed in subzero liquid water.

Particles of biological origin are of increasing interest for the Pickering stabilization of biocompatible and environmentally friendly foams and emulsions. Cellulose nanofibrils (CNFs) are readily employed in that respect; however, the underlying mechanisms of interfacial stabilization remain widely unknown. For instance, it has not been resolved why CNFs are unable to stabilize foams while efficiently stabilizing emulsions. Here, we produce CNFs with varying contour lengths and charge densities to investigate their behavior at the air-water phase boundary. CNFs adsorbing at the air-water interface reduce surface tension and form interfacial layers with high viscoelasticity, which are attributed to the thermodynamic and kinetic stability of CNF-stabilized colloids, respectively. CNF adsorption is accelerated and higher surface pressures are attained at lower charge densities, indicating that CNF surface charges limit both adsorption and surface coverage. CNFs form monolayers with ∼40% coverage and are primarily wetted by the aqueous phase indicating a contact angle90°, as demonstrated by neutron reflectometry. The low contact angle at the air-water interface is energetically unfavorable for adsorbed CNFs, which is proposed as a potential explanation why CNFs show poor foaming capacity.

This study provides insights into dynamic nanostructural changes in phospholipid systems during hydrolysis with phospholipase C, the fate of the hydrolysis products, and the kinetics of lipolysis. The effect of lipid restructuring of the vesicle was investigated using small-angle X-ray scattering and cryogenic scanning electron microscopy. The rate and extent of phospholipid hydrolysis were quantified using nuclear magnetic resonance. Hydrolysis of two phospholipids, phosphatidylethanolamine (PE) and phosphatidylcholine (PC), results in the cleavage of the molecular headgroup, causing two strikingly different changes in lipid self-assembly. The diacylglycerol product of PC escapes the lipid bilayer, whereas the diacylglycerol product adopts a different configuration within the lipid bilayer of the PE vesicles. These results are then discussed concerning the change of the lipid configuration upon the lipid membrane and its potential implications in vivo, which is of significant importance for the detailed understanding of the fate of lipidic particles and the rational design of enzyme-responsive lipid-based drug delivery systems.

We report a new strategy for efficient removal of F- from contaminated water streams, and it relies on carbon hybrid membranes made of amyloid fibril/ZrO2 nanoparticles (

Horseradish peroxidase isoenzyme C (HRP) and Engyodontium album proteinase K (proK) were immobilized inside macro- and mesoporous silica monoliths. Stable immobilization was achieved through simple noncovalent adsorption of conjugates, which were prepared from a polycationic, water-soluble second generation dendronized polymer (denpol) and the enzymes. Conjugates prepared from three denpols with the same type of repeating unit (r.u.), but different average lengths were compared. It was shown that there is no obvious advantage of using denpols with very long chains. Excellent results were achieved with denpols having on average 750 or 1000 r.u. The enzyme-loaded monoliths were tested as flow reactors. Comparison was made with microscopy glass coverslips onto which the conjugates were immobilized and with glass micropipettes containing adsorbed conjugates. High enzyme loading was achieved using the monoliths. Monoliths containing immobilized denpol–HRP conjugates exhibited good operational stability at 25 °C (for at least several hours), and good storage stability at 4 °C (at least for weeks) was demonstrated. Such HRP-containing monoliths were applied as continuous flow reactors for the quantitative determination of hydrogen peroxide in aqueous solution between 1 μM (34 ng/mL) and 50 μM (1.7 μg/mL). Although many methods for immobilizing enzymes on silica surfaces exist, there are only a few approaches with porous silica materials for the development of flow reactors. The work presented is a promising contribution to this field of research toward bioanalytical and biosynthetic applications., ACS Omega, 4 (4), ISSN:2470-1343

The present work addresses the effect of partial equilibration and molecular partitioning on the interpretation of release experiments. In this regard, it is shown how release profiles and the values of extracted transport parameters are affected by the time protocol chosen for sample collection by considering a series of experiments where the latter is systematically varied. Caffeine is investigated as a main model drug because of its similar affinity for water and lipids, while monolinolein-based lipid cubic phases are chosen as host matrices because of their wide employment in release studies. Our findings point to a progressive decline in diffusion rate upon increasing the time step, that is, the gap in time between two consecutive pickups, which is a signature of increasing equilibration of caffeine concentration between the lipidic mesophase and the water phase. Furthermore, the amount of released molecules at the first pickup displays negligible changes for large time steps, indicating complete equilibration in such cases. A model is introduced based on Fick’s diffusion which goes beyond the assumption of perfect-sink conditions, a common feature of the typical theoretical approaches hitherto developed. The model is shown to account quantitatively for the experimental data and is subsequently employed to clarify the interplay of the adopted release protocol with the various transport parameters in determining the final outcome of the release process. Particularly, two additional molecular drugs are considered, namely glucose and proflavine, which are, respectively, more hydrophilic and hydrophobic than caffeine, thus allowing elucidating the role of molecular partitioning. ISSN:0743-7463 ISSN:1520-5827

Polysaccharides are ubiquitous in nature and represent an essential class of biopolymers with multiple levels of conformation and structural hierarchy. However, a standardized structural nomenclature, as in the case of proteins, is still lacking due to uncertainty on their hierarchical organization. In this work we use carrageenans as model polysaccharides to demonstrate that several structural levels exist and can be unambiguously resolved by statistical analysis on high resolution Atomic Force Microscopy images, supported by spectroscopic, X-ray scattering and rheological techniques. In direct analogy with proteins, we identify primary, secondary, tertiary and quaternary structures. The structure-property relationship induced by monovalent ions for κ-, ι- and the non-gelling control λ-carrageenan is established from the single chain regime to the occurrence of hydrogels at higher concentrations. For κ-carrageenan in the presence of potassium, a disorder-order transition from random coil to single helix is first observed (secondary structure), followed by intrachain supercoiling events (tertiary structure) and macroscopic anisotropic domains which are parts of a network (quaternary structure) with tunable elasticity up to ∼10

Water contamination is a global threat due to its damaging effects on the environment and human health. Water pollution by microplastics (MPs), dissolved natural organic matter (NOM), and other turbid particles is ubiquitous in water treatment. Here, we introduce lysozyme amyloid fibrils as a novel natural bio-flocculant and explore their ability to flocculate and precipitate the abovementioned undesired colloidal objects. Thanks to their positively charged surface in a very broad range of pH, lysozyme amyloid fibrils show an excellent turbidity removal efficiency of 98.2 and 97.9% for dispersed polystyrene MPs and humic acid (HA), respectively. Additionally, total organic carbon measurements confirm these results by exhibiting removal efficiencies of 93.4 and 61.9% for purifying water from dispersed MPs and dissolved HA, respectively. The comparison among amyloid fibrils, commercial flocculants (FeCl3 and polyaluminumchloride), and native lysozyme monomers points to the superiority of amyloid fibrils at the same dosage and sedimentation time. Furthermore, the turbidity of pristine and MP-spiked wastewater and lake water decreased after the treatment by amyloid fibrils, validating their coagulation-flocculation performance under natural conditions. All these results demonstrate lysozyme amyloid fibrils as an appropriate natural bio-flocculant for removing dispersed MPs, NOM, and turbid particles from water.

Phytantriol-based lipidic mesophases (LMs) are introduced as a platform for cryoenzymology, which relies on the presence of liquid water in LMs at subzero temperatures. After incorporation into LMs, the model enzyme Benzaldehyde lyase (BAL) shows high cryogenic stability and activity. In contrast, BAL in bulk solution undergoes significant secondary structural transitions caused by low temperatures (cold denaturation), demonstrating the potential of this approach to enablein mesocryoenzymology., Chemical Communications, 57 (46), ISSN:1359-7345, ISSN:1364-548X

We present the optimization of experimental conditions to yield long, rigid apoferritin protein amyloid fibrils, as well as the corresponding fibrillation pathway. Fibril growth kinetics was followed using atomic force microscopy (AFM), transmission electron microscopy (TEM), dynamic light scattering (DLS), circular dichroism (CD), fourier-transform infrared spectroscopy (FTIR), and sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). Among the morphologies identified, we show that the conditions result in small aggregates, as well as medium and long fibrils. Extended incubation times led to progressive unfolding and hydrolysis of the proteins into very short peptide fragments. AFM, SDS-PAGE, and CD support a universal common fibrillation mechanism in which hydrolyzed fragments play the central role. These collective results provide convincing evidence that protein unfolding and complete hydrolysis of the proteins into very short peptide sequences are essential for the formation of the final apoferritin amyloid-like fibrils., Junta de Andalucia P11-FQM-8136 P18-RT-1373, Ministry of Science and Innovation, Spain (MICINN), Instituto de Salud Carlos III, Spanish Government PID2019-111461GB-I00, Boehringer Ingelheim

Glycosylation is a crucial post-translational modification for a wide range of functionalities. Adhesive protein-based biomaterials in nature rely on heavily glycosylated proteins such as spider silk and mussel adhesive proteins. Engineering protein-based biomaterials genetically enables desired functions and characteristics. Additionally, utilization of glycosylation for biomaterial engineering can expand possibilities by including saccharides to the inventory of building blocks. Here, de novo glycosylation of Bacillus subtilis amyloid-like biofilm protein TasA using a Campylobacter jejuni glycosylation circuit is proposed to be a novel biomaterial engineering method for increasing adhesiveness of TasA fibrils. A C. jejuni glycosylation motif is genetically incorporated to tasA gene and expressed in Escherichia coli containing the C. jejuni pgl protein glycosylation pathway. Glycosylated TasA fibrils indicate enhanced adsorption on the gold surface without disruption of fibril formation. Our findings suggest that N-linked glycosylation can be a promising tool for engineering protein-based biomaterials specifically regarding adhesion.

Metal-coordinated hydrogels are physical hydrogels entirely crosslinked by complexes between ligand decorated polymers and metal ions. The mechanical properties of these hydrogels strongly depend on the density and dynamics of metal-coordinated interactions. Most commonly, telechelic metal-coordinated hydrogels contain catechol or histidine ligands, although hydrogels containing a stronger complexation agent, nitrocatechol, have been reported. Here, we introduce a pyrogallol end-functionalized polymer that can be crosslinked with di-and trivalent ions, in contrast to previously reported metal-coordinated hydrogels. We can tune the mechanical properties of the hydrogels with the types of ions used and the density of crosslinking sites. Ions form nm-sized precipitates that bind to pyrogallols and impart distinct properties to the hydrogels: strong ion-pyrogallol interactions that form in the presence of Al3+, V3+, Mn2+, Fe3+, Co2+, Ni2+ and Cu2+ result in long relaxation times. The resulting hydrogels display solid-like yet reversible mechanical properties, such that they can be processed into macroscopic 3D structures that retain their shapes. Weak ion-pyrogallol interactions that form in the presence of Ca2+ or Zn2+ result in short relaxation times. The resulting hydrogels display a fast self-healing behavior, suited for underwater glues, for example. The flexibility of tuning the mechanical properties of hydrogels simply by selecting the adequate ion-pyrogallol pair broadens the mechanical properties of metal-coordinated hydrogels to suit a wide range of applications that require them to retain their shape for a given time to act as dampers. This journal is. © The Royal Society of Chemistry., Nanoscale, 13 (7), ISSN:2040-3364, ISSN:2040-3372

Biological liquid crystals, originating from the self-assembly of biological filamentous colloids, such as cellulose and amyloid fibrils, show a complex lyotropic behaviour that is extremely difficult to predict and characterize. Here we analyse the liquid crystalline phases of amyloid fibrils, and sulfated and carboxylated cellulose nanocrystals and measure their Frank-Oseen elastic constants K1, K2 and K3 by four different approaches. The first two approaches are based on the benchmark of the predictions of: (i) a scaling form and (ii) a variational form of the Frank-Oseen energy functional with the experimental critical volumes at order–order liquid crystalline transitions of the tactoids. The third and the fourth methods imply: (iii) the direct scaling equations of elastic constants and (iv) a molecular theory predicting the elastic constants from the experimentally accessible contour length distributions of the filamentous colloids. These three biological systems exhibit diverse liquid crystalline behaviour, governed by the distinct elastic constants characterizing each colloid. Differences and similarities among the three systems are highlighted and interpreted based on the present analysis, providing a general framework to study dispersed liquid crystalline systems., Soft Matter, 17 (8), ISSN:1744-683X, ISSN:1744-6848

Solar distillation is an appealing and facile technology for seawater desalination and water purification, but constructing stable, environmentally-friendly, and cost-effective solar evaporators often remain unfeasible. Here, amyloid hybrid aerogels are introduced for universal and renewable freshwater production by relying on the combination of sustainable materials and solar energy, thus making the process highly ecological and virtually costless. Amyloid fibrils obtained from whey, a byproduct of the dairy industry, are used as the main scaffold for the aerogels, whose solar energy harvesting properties of the top surface are enhanced by bioinspired dark polymers, such as polydopamine. Due to the fast water transport throughout the porous aerogels, the high-yielding photothermal conversion ability of the top surface, and efficient heat insulation at the bottom, the hybrid amyloid fibrils aerogel exhibits a water evaporation rate of 1.61 kg center dot m(-2) h(-1) with a solar-thermal conversion efficiency as high as 91.3% under 1 sun illumination. The process allows desalinating various seawater sources with different salinities to levels below the drinking water threshold recommended by the World Health Organization. Moreover, the same hybrid amyloid evaporator is highly efficient in removing heavy metals, organic pollutants, bacteria, and viruses from water, introducing a general, sustainable and energy-efficient solution for desalination and water purification., Advanced Sustainable Systems, 6 (1)

Physical interactions between vascular endothelial growth factor (VEGF), a central player in blood endothelial cell biology, and fibronectin, a major fibrillar protein of the extracellular matrix, are important determinants of angiogenic activity in health and disease. Conditions signaling the need for new blood vessel growth, such as hypoxia and low extracellular pH, increase VEGF–fibronectin interactions. These interactions can be further fine-tuned through changes in the availability of the VEGF-binding sites on fibronectin, regulated by conformational changes induced by heparin and heparan sulfate chains within the extracellular matrix. These interactions may alter VEGF bioavailability, generate gradients, or alter the way VEGF is recognized by and activates its cell-surface receptors. Here, using equilibrium and kinetic studies, we discovered that fibronectin can also interact with the extracellular domain of the VEGF receptor 2 (VEGFR2). The VEGFR2-binding sites on fibronectin show great similarity to the VEGF-binding sites, as they were also exposed upon heparin-induced conformational changes in fibronectin, and the interaction was enhanced at acidic pH. Kinetic parameters and affinities for VEGF and VEGFR2 binding to fibronectin were determined by surface plasmon resonance measurements, revealing two populations of fibronectin-binding sites for each molecule. Our data also suggest that a VEGF/VEGFR2/fibronectin triple complex may be formed by VEGF or VEGFR2 first binding to fibronectin and subsequently recruiting the third binding partner. The formation of such a complex may lead to the activation of distinct angiogenic signaling pathways, offering new possibilities for clinical applications that target angiogenesis., Journal of Biological Chemistry, 296, ISSN:0021-9258, ISSN:1083-351X

The manifold array of saccharide linkages leads to a great variety of polysaccharide architectures, comprising three conformations in aqueous solution: compact sphere, random coil, and rigid rod. This conformational variation limits the suitability of the commonly applied molecular weight cut-off (MWCO) as selection criteria for polysaccharide ultrafiltration membranes, as it is based on globular marker proteins with narrow Mw and hydrodynamic volume relation. Here we show the effect of conformation on ultrafiltration performance using randomly coiled pullulan and rigid rod-like scleroglucan as model polysaccharides for membrane rejection and molecular weight distribution. Ultrafiltration with a 10 kDa polyethersulfone membrane yielded significant different recoveries for pullulan and scleroglucan showing 1% and 71%, respectively. We found deviations greater than 77-fold between nominal MWCO and apparent Mw of pullulan and scleroglucan, while recovering over 90% polysaccharide with unchanged Mw. We anticipate our work as starting point towards an optimized membrane selection for polysaccharide applications., Carbohydrate Polymers, 260, ISSN:0144-8617, ISSN:1879-1344

Supramolecular attachment of mesogenic or non-mesogenic side chains to polymer backbones can result in the formation of liquid crystalline morphologies. The various parameters that can be tuned in order to achieve these morphologies, such as the type of non-covalent bonding chemistry (hydrogen bonding, ionic bonding, metal coordination, π–π interactions), the polymeric template architecture, and the side chain structure and properties, are reviewed in what follows, with emphasis placed on the role these parameters play in the determination of the final material morphologies and properties.

Niemann-Pick Disease Type C (NPC) is a severe neurovisceral disorder that is pathophysiologically characterized by intracellular transport abnormalities leading to cytoplasmic accumulation of lipids such as cholesterol and multiple sphingolipids, including sphingosine. The compound 2-hydroxypropyl-β-cyclodextrin (HPβCD) is a compound with high cholesterol complexation capacity and is currently under clinical investigation for the treatment of NPC. However, due to its short blood half-life, high doses are required to produce a therapeutic effect. It has been reported in mice that HPβCD’s circulation time and efficacy can be improved by increasing its size via polymerization, but the biodegradable nature of these systems did not allow the contribution of the macromolecule to the activity to be determined. In this work, stable forms of polymerized HPβCD were generated (via epichlorohydrin crosslinking) to investigate their in vitro mechanisms of action and in vivo effects. Crosslinked CDs (8-312 kDa) displayed a 10-fold greater complexation capacity towards cholesterol than monomeric HPβCD but were taken up by cells to a lower extent (in a size-dependent fashion), resulting in an overall comparable in vitro effect on intracellular cholesterol accumulation that was dependent on cholesterol complexation. When tested in vivo, the crosslinked 19.3 kDa HPβCD exhibited a longer terminal half-life than the monomeric HPβCD. However, it did not increase the life span of Npc1 mice, possibly due to reduced organ penetration and brain diffusion consequence of its large molecular weight. This could be circumvented by the application of magnetic resonance imaging-guided low intensity-pulsed focused ultrasound (MRIg-FUS), which increased the brain penetration of the CD. In conclusion, stable forms of polymerized HPβCD constitute valuable tools to elucidate CDs’ mechanism of action. Moreover, the use of MRIg-FUS to maximize CDs tissue penetration warrants further investigation, as it may be key to harnessing CDs full therapeutic potential in the treatment of NPC.Graphical abstractThe 2-hydroxypropyl-β-cyclodextrin (HPβCD) is a well-established pharmaceutical excipient that can complex cholesterol and is currently under clinical investigation to treat Niemann-Pick Disease Type C (NPC). However, high doses of the drug are needed to achieve a therapeutic effect. Using stable and long circulating crosslinked HPβCDs, this study attempts to further understand the mechanisms behind CDs’ activity.

As abundant and renewable materials with excellent mechanical and functional properties, cellulose nanomaterials are utilized in advanced structural, optical and electronic applications. However, in order to further improve and develop new cellulose nanomaterials, a better understanding of the interplay between the self-assembled materials and their building blocks is crucial. This paper describes the structure–property relationships between cellulose nanofibrils (CNFs) and their resulting self-assembled structures in the form of hydrogels and aerogels. Rheological experiments revealed that the transition from viscous to elastic state with the corresponding evolution of the properties of the CNF dispersion depends on the aspect ratio and can be described in terms of the dynamic overlap concentration. The elastic shear modulus was dependent on the aspect ratio at very low CNF concentrations, reaching a plateau, where only the concentration of CNFs was relevant. This transition point in shear modulus was exploited to determine the mesh size of the fibril network, which was found to be in excellent agreement with predictions from scaling arguments. These findings highlight the possibility to tune the self-assembled materials response directly from the bottom-up by the CNF particle structure and thus, suggest new assembly routes starting directly from the CNF design., Structure-property studies of cellulose nanofibril (CNF) gels revealed the influence of CNF morphology on the gel properties and a transition point in the shear modulus of the gels was exploited to determine the mesh size of the fibril network.

Several atomic structures have now been found for micrometer-scale amyloid fibrils or elongated microcrystals using a range of methods, including NMR, electron microscopy, and X-ray crystallography, with parallel β-sheet appearing as the most common secondary structure. The etiology of amyloid disease, however, indicates nanometer-scale assemblies of only tens of peptides as significant agents of cytotoxicity and contagion. By combining solution X-ray with molecular dynamics, we show that antiparallel structure dominates at the first stages of aggregation for a specific set of peptides, being replaced by parallel at large length scales only. This divergence in structure between small and large amyloid aggregates should inform future design of molecular therapeutics against nucleation or intercellular transmission of amyloid. Calculations and an overview from the literature argue that antiparallel order should be the first appearance of structure in many or most amyloid aggregation processes, regardless of the endpoint. Exceptions to this finding should exist, depending inevitably on the sequence and on solution conditions., Biophysical Journal, 118 (10), ISSN:0006-3495, ISSN:1542-0086

It is a desirable and powerful strategy to precisely fabricate functional soft matter through self-assembly of molecular building blocks across a range of length scales. Proteins, nucleic acids, and polyphenols are the self-assemblers ubiquitous in nature. Assembly of proteins into flexible biocolloids, amyloid fibrils with high aspect ratio, has emerged as an unchallenged templating strategy for high-end technological materials and bio-nanotechnologies. We demonstrate the ability of these fibrils to support the deposition and self-assembly of polyphenols into hybrid nanofilaments and functional macroscopic hydrogels made thereof. The length scale of the substance that amyloid fibrils can attach with acting as the building templates was extended from nanometer down to sub-nanometer. Significantly increased loading capacities of polyphenols (up to 4.0 wt %) compared to that of other delivery systems and improved stability were realized. After oral administration, the hydrogels could transport from the stomach to the small intestine and finally to the gut (cecum, colon, rectum), with a long retention time in the colon. Oral administration of the hydrogels significantly ameliorated colitis in a mouse model, promoted intestinal barrier function, suppressed the pro-inflammatory mRNA expression, and very significantly (P < 0.01) regulated gut microbial dysbiosis. Specifically, it reduced the abundance of normally enriched operational taxonomic units related to colitis, especially targeting facultative anaerobes of the phylum Proteobacteria, such as Aestuariispira and Escherichia. The short-chain fatty acid metabolites were enriched. Combined with their nontoxic nature observed in this long-term study in mice, the obtained amyloid-polyphenol gels have high application potentials for gastrointestinal diseases by "drugging the microbiome".

The problem of malnutrition and nutrition deficiency, as well as droughts that lead to reduction in food supply and starvation, is well documented for Sub-Saharan Africa. Reducing post-harvest losses of five species of African leafy vegetables (ALVs) by preservation through drying is studied herein. Energy efficient gentle drying conditions using superabsorbent polymers and a temperature of 40 °C were shown to preserve most leaf structures and vitamins. The microbial safe moisture content of the ALVs was found to be ≤14% dry basis. Dried Slender Leaf and Nightshade leaves could be rehydrated to the equilibrium moisture content of fresh leaves upon dry storage, while it was not possible for Jute Mallow, Cowpea and Amaranthus. This was attributed to different palisade parenchyma cell lengths. An increased amount of starch granules as observed in the microstructure of Cowpea and Nightshade leaves is suggested to explain their fibrous texture upon cooking. These results show that the ALVs can be effectively preserved using the same drying method and that this can be used to fight micro-nutrient deficiencies during droughts., Food & Function, 11 (1), ISSN:2042-6496, ISSN:2042-650X

The gut–brain axis has attracted increasing attention in recent years, fueled by accumulating symptomatic, physiological, and pathological findings. In this study, the aggregation and toxicity of amyloid beta (Aβ ), the pathogenic peptide associated with Alzheimer's disease (AD), seeded by FapC amyloid fragments (FapCS) of Pseudomonas aeruginosa that colonizes the gut microbiome through infections are examined. FapCS display favorable binding with Aβ and a catalytic capacity in seeding the peptide amyloidosis. Upon seeding, twisted Aβ fibrils assume a much‐shortened periodicity approximating that of FapC fibrils, accompanied by a 37% sharp rise in the fibrillar diameter, compared with the control. The robust seeding capacity for Aβ by FapCS and the biofilm fragments derived from P. aeruginosa entail abnormal behavior pathology and immunohistology, as well as impaired cognitive function of zebrafish. Together, the data offer the first concrete evidence of structural integration and inheritance in peptide cross‐seeding, a crucial knowledge gap in understanding the pathological correlations between different amyloid diseases. The catalytic role of infectious bacteria in promoting Aβ amyloidosis may be exploited as a potential therapeutic target, while the altered mesoscopic signatures of Aβ fibrils may serve as a prototype for molecular assembly and a biomarker for screening bacterial infections in AD., Advanced Science, 7 (18), ISSN:2198-3844

Polysaccharides are ubiquitous in nature; they serve fundamental roles in vivo and are used for a multitude of food, pharmaceutical, cosmetic biomaterials, and biomedical applications. Here, the structure-property function for low acetylated Gellan gum hydrogels induced by divalent ions was established by means of optical, rheological, and microscopic techniques. The hydrogels interacted with visible light as revealed by birefringence and multiple scattering, as a consequence of quaternary, supramolecular fibrillar structures. The molecular assembly and structure were elucidated by statistical analysis and polymer physics concepts applied to high-resolution AFM height images and further supported by FTIR. This revealed intramolecular coil-to-single helix transitions, followed by lateral aggregation of single helices into rigid, fibrillar quaternary structures, ultimately responsible for gelation of the system. Calcium and magnesium chloride were shown to lead to fibrils up to heights of 6.0 nm and persistence lengths of several micrometers. The change in molecular structure affected the macroscopic gel stiffness, with the plateau shear modulus reaching ∼10

Lipidic cubic phases (LCPs) can reduce Pd2+ salts to palladium nanoparticles (PdNPs) of ∼5 nm size in their confined water channels under mild conditions. The resulting PdNP-containing LCPs were used as nanoreactor scaffolds to catalyze Suzuki-Miyaura cross-coupling reactions in the aqueous channels of the mesophase. To turn on catalysis, PdNP-containing LCPs were activated by swelling the aqueous channels of the lipidic framework, thereby enabling diffusion of the water-soluble substrates to the catalysts. The mesophases play a threefold role: they act as reducing agents for Pd2+, as limiting templates for their growth, and as support. The system was characterized and investigated by small-angle X-ray scattering (SAXS), cryo-transmission electron microscopy, dynamic light scattering, and nuclear magnetic resonance. Bulk LCPs and three dispersed palladium/lipid hybrid nanoparticle types were applied in the catalysis. The latter-liposomes, hexosomes, and cubosomes-can be obtained by design through combination of lipids and additives. The Suzuki-Miyaura cross-coupling of 5-iodo-2'-deoxyuridine and phenylboronic acid was used as a model reaction to study these systems. Bulk Pd-LCPs deliver the Suzuki-Miyaura product in 24 h in conversions up to 98% at room temperature, whereas with palladium/lipid dispersions at 40 °C, 68% of the starting material was transformed to the product after 72 h.