Amyloid Fibrils Aerogel for Sustainable Removal of Organic Contaminants from Water

Anisotropic Chitosan-nanocellulose/Zeolite imidazolate frameworks-8 aerogel for sustainable dye removal

Assembling microscopic metal-organic frameworks into macroscopic polymeric scaffolds to develop highly renewable materials has been a promising yet challenging area of research. Herein, chitosan (CS) blended with nano-cellulose (NC) was unidirectionally transformed into an aerogel with oriented macropores and then biomineralized with zeolite imidazolate frameworks-8 (ZIF-8) to form a hierarchical structured chitosan-nanocellulose/zeolite imidazolate frameworks-8 (CS-NC-ZIF-8) hybrid aerogel. Incorporating ZIF-8 significantly increases the versatility and mechanical strength with a Young's modulus of 14.18 MPa of the CS-NC aerogel. The incorporation of ZIF-8 into the aerogel not only enhances its adsorption capacity for methylene blue, rhodamine B, acid fuchsin, and methyl orange, but also facilitates the generation of electrons from water that can be transferred to degrade > 90 % of malachite green within 90 min in each catalytic cycle, and this capability was maintained for at least 10 consecutive cycles. Remarkably, the hybrid aerogel was highly renewable after the adsorption of cationic dyes and catalytic removal of malachite green. With its facile production process, high removal efficiency, affordable and green nature, and excellent regeneration feasibility, the CS-NC-ZIF-8 aerogel stands as a promising solution for addressing challenges associated with dye-contaminated water treatment.

Sustainable protein/polysaccharide aerogel for the simultaneous and efficient removal of multiple organic contaminants: Insights from DFT calculations and phenomenological mass-transfer modeling

Wastewater contains various organic contaminants that pose great hazards to human health and the environment. A protein/polysaccharide-derived aerogel, namely, ICMA, was developed as a high-performance adsorbent for the simultaneous and efficient removal of diverse contaminants from wastewater, including melanoidin (MLE), Congo red (CR), and diclofenac (DIC). Metal organic framework (UiO-66-NH2), as a regulatory factor, significantly improved the porosity and pore volume of the ICMA to enhance the capture performance of contaminants. The ICMA exhibited outstanding adsorption efficiency owing to the incorporation of ample polyamine functional groups and its well-developed pore structure, large porosity and pore volume, and remarkable heat resistance. The equilibrium capture capacities of the ICMA were 1364, 2031, and 539 mg/g for MLE, CR, and DIC, respectively, with corresponding removal efficiencies all exceeding 90%. Furthermore, the ICMA can capture cationic dyes through MLE/CR/DIC-bridging interactions. After five cycles, the used ICMA can still maintain a high contaminant removal rate/amount, demonstrating good reusability. The classic adsorption model showed that the capture of contaminants by the ICMA is a double-layered and heterogeneous adsorption orientation. A brand new LWAMTM model demonstrated that the adsorption mass-transfer process is jointly determined by the external mass conveyance, pore diffusion, and adsorption on the active site. Multiple characterizations indicated that the contaminant adsorption onto the ICMA was mainly facilitated by charge interactions, with H-bonds playing a secondary role. Quantum chemical theory simulations further provide insights into the atomic-level mechanisms involved in the capture of contaminants. Hirshfeld surface analysis revealed that the ICMA functions as both an H-bond acceptor and a donor during contaminant adsorption. Scale-up and upgrade adsorption were performed to treat actual/simulated wastewater, establishing the groundwork for the industrial implementation of the ICMA.

Versatile Keratin Fibrous Adsorbents with Rapid-Response Shape-Memory Features for Sustainable Water Remediation

Biodegradable shape-memory polymers derived from protein substrates are attractive alternatives with strong potential for valorization, although their reconstruction remains a challenge due to the poor processability and inherent instability. Herein, based on Maillard reaction and immobilization, a feather keratin fibrous adsorbent featuring dual-response shape-memory is fabricated by co-spinning with pullulan, heating, and air-assisted spraying ZIF-8-NH2. Maillard reaction between the amino group of keratin and the carbonyl group of pullulan improves the mechanics and thermal performance of the adsorbent. ZIF-8-NH2 immobilization endows the adsorbent with outstanding multipollutant removal efficiency (over 90%), water stability, and photocatalytic degradation and sterilization performance. Furthermore, the adsorbent can be folded to 1/12 of its original size to save space for transportation and allow for rapid on-demand unfolding (12 s) upon exposure to water and ultraviolet irradiation to facilitate the adsorption and photocatalytic activity with a larger water contact area. This research provides new insight for further applications of keratin-based materials with rapid shape-memory features.

Nature-inspired recycling of a protein mixture into a green fluorescent protein-based hydrogel

Protein-based materials are biocompatible and have a variety of remarkable properties; consequently, they are finding more and more applications. Nature recycles proteins in multiple ways, ranging from bio-degradation (a slow approach) to fast recycling of protein metabolism. The latter is a wonderful example because a random mixture of proteins gets digested into amino acids (AAs), the fundamental building blocks of proteins. These AAs are then used by cells to produce whichever protein is needed at the time of synthesis. Seen through the lens of recycling, this process transforms a random mixture into something not necessarily present at the start but needed at the moment of recycling. We have recently shown that the process of protein recycling can be performed in vitro and called it NaCRe (Nature Inspired Circular Recycling). In a previous NaCRe proof-of-concept experiment, we started with various protein mixtures but were able to produce only small quantities of recycled protein, in the microgram scale. Here, we show that NaCRe can be used to convert milligrams of a protein mixture containing one of the most common protein materials (silk) into a milligram of an hydrogel made of green fluorescent protein (GFP). We show that in order for NaCRe to be efficient the starting protein mixture must contain a good balance of all AAs and discuss the challenges encountered when scaling up NaCRe.

Directed Assembly of Proteinaceous-Polysaccharide Nanofibrils to Fabricate Membranes for Emerging Contaminant Remediation

Emerging contaminants, including per- and polyfluoroalkyl substances and heavy metals, are threatening the health of humans and ecosystems. Their removal from the environment remains challenging. Here, we designed silk fibroin-cellulose nanocrystal (silk-CNC) nanofibrillar and nanoporous membranes for emerging contaminant remediation. The protein-polysaccharide nanofibrils were fabricated by templating the assembly of silk fibroin using CNCs. Silk fibroin polymorphic nature combined with surface charge modulation of CNCs produced cationic silk-CNC(+) and anionic silk-CNC(-) nanofibrils that can target a broad spectrum of contaminants. Silk-CNC(+) nanofibrils and membranes exhibited antimicrobial properties and captured both short-chain heptafluorobutyric acid, perfluorobutanesulfonic acid, and long-chain perfluorooctanoic acid by virtue of hydrophobic attraction from β-sheeted silk fibroin and electrostatic interactions with CNC(+). Silk-CNC(-) provided the opportunity to target cations such as heavy metal cocontaminants. The nanofabrication of biopolymer-based membranes combines high performance with environmentally benign and cost-effective removal of emerging contaminants for water purification, wastewater treatment, and remediation.

Amyloid peptide - synthetic polymer blends with enhanced mechanical and biological properties

Interest in utilizing amyloids to develop biomaterials is increasing due to their potential for biocompatibility, unique assembling morphology, mechanical stability, and biophysical properties. However, challenges include the complexity of peptide chemistry and the practical techniques required for processing amyloids into bulk materials. In this work, two decapeptides with fibrillar and globular morphologies were selected, blended with poly(ethylene oxide), and fabricated into composite mats via electrospinning. Notable enhancements in mechanical properties were observed, attributed to the uniform distribution of the decapeptide assemblies within the PEO matrix. Morphological differences, such as the production of thinner nanofibers, are attributed to the increased conductivity from the zwitterionic nature of the decapeptides. Blend rheology and post-processing analysis revealed how processing might affect the amyloid aggregation and secondary structure of the peptides. Both decapeptides demonstrated good biocompatibility and strong antioxidant activity, indicating their potential for safe and effective use as biomaterials. By evaluating these interdependencies, this research lays the foundation for understanding the structure-property-processing relationships of peptide-polymer blends and highlights the strong potential for developing applications in biotechnology.

Lanthanum-Integrated Porous Adsorbent for Effective Phosphorus Removal

In pursuit of accessing clean water, the phosphate removal is of great importance for preventing eutrophication toward sustainable ecology. However, effective adsorbents with high capacity, selectivity, and long-term stability for treating phosphate in water still remain desired, which requires further development. Herein, a type of porous La-based adsorbents, which are composed of highly dispersed La(OH)3 on amino-functionalized Caragana korshinskii (CK) nanowires, are designed and fabricated through simple amination and decoration of lemon bars. Specifically, the adsorption to phosphate can be quickly completed within 50 min, and an ultrahigh adsorption capacity of 173.3 mg of P g-1 is realized. Moreover, these composite adsorbents display excellent selectivity and anti-interference ability to phosphate in the presence of common anions (CO3 2-, NO3-, Cl-, and SO4 2-). After four regenerations, there is still a removal rate of 85%. This study underscores an integrated material model for designing advanced structures toward efficient wastewater treatment.

Renewable biomass-based aerogels: from structural design to functional regulation

Global population growth and industrialization have exacerbated the nonrenewable energy crises and environmental issues, thereby stimulating an enormous demand for producing environmentally friendly materials. Typically, biomass-based aerogels (BAs), which are mainly composed of biomass materials, show great application prospects in various fields because of their exceptional properties such as biocompatibility, degradability, and renewability. To improve the performance of BAs to meet the usage requirements of different scenarios, a large number of innovative works in the past few decades have emphasized the importance of micro-structural design in regulating macroscopic functions. Inspired by the ubiquitous random or regularly arranged structures of materials in nature ranging from micro to meso and macro scales, constructing different microstructures often corresponds to completely different functions even with similar biomolecular compositions. This review focuses on the preparation process, design concepts, regulation methods, and the synergistic combination of chemical compositions and microstructures of BAs with different porous structures from the perspective of gel skeleton and pore structure. It not only comprehensively introduces the effect of various microstructures on the physical properties of BAs, but also analyzes their potential applications in the corresponding fields of thermal management, water treatment, atmospheric water harvesting, CO2 absorption, energy storage and conversion, electromagnetic interference (EMI) shielding, biological applications, etc. Finally, we provide our perspectives regarding the challenges and future opportunities of BAs. Overall, our goal is to provide researchers with a thorough understanding of the relationship between the microstructures and properties of BAs, supported by a comprehensive analysis of the available data.

Food Protein Nanofibril Gels: From Conditions, Types and Properties to Applications

Many food proteins can be assembled into nanofibrils under pH conditions far from the isoelectric point and with a low ionic strength by heating them for a long period. These food protein nanofibrils (FPN) have outstanding functional and biological properties and are considered sustainable biomaterials in many fields. In this study, we review the recent developments in FPN gels and introduce the key factors in promoting food protein self-assembly in order to create functional gels. The major variables discussed are the morphology of nanofibrils, protein concentration, heating time, and the type and concentration of salts. We also highlight current advances in the formation and properties of different types of FPN gels. In addition, the various applications of FPN gels in bioactive and nutrient delivery, adsorbents for CO2 and toxic pollutants, cell scaffolding biomaterials, biosensors, and others are introduced and discussed.

Functional Amyloids: The Biomaterials of Tomorrow?

Functional amyloid (FAs), particularly the bacterial proteins CsgA and FapC, have many useful properties as biomaterials: high stability, efficient, and controllable formation of a single type of amyloid, easy availability as extracellular material in bacterial biofilm and flexible engineering to introduce new properties. CsgA in particular has already demonstrated its worth in hydrogels for stable gastrointestinal colonization and regenerative tissue engineering, cell-specific drug release, water-purification filters, and different biosensors. It also holds promise as catalytic amyloid; existing weak and unspecific activity can undoubtedly be improved by targeted engineering and benefit from the repetitive display of active sites on a surface. Unfortunately, FapC remains largely unexplored and no application is described so far. Since FapC shares many common features with CsgA, this opens the window to its development as a functional scaffold. The multiple imperfect repeats in CsgA and FapC form a platform to introduce novel properties, e.g., in connecting linkers of variable lengths. While exploitation of this potential is still at an early stage, particularly for FapC, a thorough understanding of their molecular properties will pave the way for multifunctional fibrils which can contribute toward solving many different societal challenges, ranging from CO2 fixation to hydrolysis of plastic nanoparticles.

Gold Recovery from E-Waste by Food-Waste Amyloid Aerogels

Demand for gold recovery from e-waste grows steadily due to its pervasive use in the most diverse technical applications. Current methods of gold recovery are resource-intensive, necessitating the development of more efficient extraction materials. This study explores protein amyloid nanofibrils (AF) derived from whey, a dairy industry side-stream, as a novel adsorbent for gold recovery from e-waste. To do so, AF aerogels are prepared and assessed against gold adsorption capacity and selectivity over other metals present in waste electrical and electronic equipment (e-waste). The results demonstrate that AF aerogel has a remarkable gold adsorption capacity (166.7 mg g-1) and selectivity, making it efficient and an adsorbent for gold recovery. Moreover, AF aerogels are efficient templates to convert gold ions into single crystalline flakes due to Au growth along the (111) plane. When used as templates to recover gold from e-waste solutions obtained by dissolving computer motherboards in suitable solvents, the process yields high-purity gold nuggets, constituted by ≈90.8 wt% gold (21-22 carats), with trace amounts of other metals. Life cycle assessment and techno-economic analysis of the process finally consolidate the potential of protein nanofibril aerogels from food side-streams as an environmentally friendly and economically viable approach for gold recovery from e-waste.

Using silver nanoparticle-decorated whey protein isolate amyloid fibrils to modify the electrode surface used for electrochemical detection of para-nitrophenol

Due to their organized structures, remarkable stiffness, and nice biocompatibility and biodegradability, amyloid fibrils serve as building blocks for versatile sustainable materials. Silver nanoparticles (AgNPs) are commonly used as the nano-catalysts for various electrochemical reactions. Given their large specific surface area and high surface energy, AgNPs exhibit high aggregation propensity, which hampers their electrocatalytic performance. Food protein wastes have been identified to be associated with climate change and environmental impacts, and a surplus of whey proteins in dairy industries causes high biological and chemical demands, and greenhouse gas emissions. This study is aimed at constructing sustainable electrode surface modifiers using AgNP-deposited whey protein amyloid fibrils (AgNP/WPI-AFs). AgNP/WPI-AFs were synthesized and characterized via spectroscopic techniques, electron microscopy, and X-ray diffraction. Next, the electrocatalytic performance of AgNP/WPI-AF modified electrode was assessed via para-nitrophenol (p-NP) reduction combined with various electrochemical analyses. Moreover, the reaction mechanism of p-NP electrocatalysis on the surface of AgNP/WPI-AF modified electrode was investigated. The detection range, limit of detection, sensitivity, and selectivity of the AgNP/WPI-AF modified electrode were evaluated accordingly. This work not only demonstrates an alternative for whey valorization but also highlights the feasibility of using amyloid-based hybrid materials as the electrode surface modifier for electrochemical sensing purposes.

Eliminating trade-offs between optical scattering and mechanical durability in aerogels as outdoor passive cooling metamaterials

Passive cooling is a promising approach for reducing the large energy consumption to achieve carbon neutrality. Foams/aerogels can be considered effective daytime cooling materials due to their good solar scattering and thermal insulation capacity. However, the contradiction between the desired high solar reflectivity and mechanical performance still limits their scalable production and real application. Herein, inspired by the "Floor-Pillar" concept in the building industry, a multi-structure assembly-induced ice templating technology was used to construct all-cellulosic aerogels with well-defined biomimetic structures. By using cellulose nanofibers (CNFs) as pillars and cellulose nanocrystals (CNCs) as floors and methyltrimethoxysilane (MTMS) as a crosslinking material, an all-cellulosic aerogel (NCA) exhibiting high mechanical strength (mechanical strength = 0.3 MPa at 80% compression ratio, Young's modulus = 1 MPa), ultralow thermal conductivity (28 mW m-1 K-1), ultrahigh solar reflectance (97.5%), high infrared emissivity (0.93), as well as excellent anti-weather function can be achieved, exceeding the performance of most reported cellulosic aerogels. Furthermore, the mechanisms of the improved mechanical strength and stimulated superior solar reflectance of NCA were studied in detail using finite element simulations and COMSOL Multiphysics. As a result, the NCA can achieve a cooling efficiency of 7.5 °C during the daytime. The building energy stimulus demonstrated that 44% of cooling energy can be saved in China annually if the NCA is applied. This work lays the foundation for the preparation of biomass aerogels for energy-saving applications.

Hybrid Amyloid-Chitin Nanofibrils for Magnetic and Catalytic Aerogels

In the quest for a sustainable and circular economy, it is essential to explore environmentally friendly alternatives to traditional petroleum-based materials. A promising pathway toward this goal lies in the leveraging of biopolymers derived from food waste, such as proteins and polysaccharides, to develop advanced sustainable materials. Here, we design versatile hybrid materials by hybridizing amyloid nanofibrils derived by self-assembly of whey, a dairy byproduct, with chitin nanofibrils exfoliated from the two distinct allomorphs of α-chitin and β-chitin, extracted from seafood waste. Various hydrogels and aerogels were developed via the hybridization and reassembly of these biopolymeric nanobuilding blocks, and they were further magnetized upon biomineralization with iron nanoparticles. The pH-phase diagram highlights the significant role of electrostatic interactions in gel formation, between positively charged amyloid fibrils and negatively charged chitin nanofibrils. Hybrid magnetic aerogels exhibit a ferromagnetic response characterized by a low coercivity (<50 Oe) and a high specific magnetization (>40 emu/g) at all temperatures, making them particularly suitable for superparamagnetic applications. Additionally, these aerogels exhibit a distinct magnetic transition, featuring a higher blocking temperature (200 K) compared to previously reported similar nanoparticles (160 K), indicating enhanced magnetic stability at elevated temperatures. Finally, we demonstrate the practical application of these hybrid magnetic materials as catalysts for carbon monoxide oxidation, showcasing their potential in environmental pollution control and highlighting their versatility as catalyst supports.

Wheat flour-derived amyloid fibrils for efficient removal of organic dyes from contaminated water

Amyloid fibrils derived from different proteins have been proved as a promising material for adsorption of various pollutants from wastewater, which showed advantages of low cost and eco-friendliness. However, most of the amyloid fibrils derived from animal-based proteins with high environmental footprint, while more sustainable amyloid fibrils derived from plant materials are desirable. In this study, a plant-derived amyloid fibril was extracted from the commonly used wheat flour with a simple and scalable protein purification and fibrillization process. Interestingly, the amyloid fibrils showed good adsorption capacity towards typical organic dyes (Eosin Y (EY) and Congo red (CR)) from contaminated water. Adsorption kinetic analysis indicated the adsorption process to EY or CR by wheat flour amyloid well fitted with a pseudo-second-order model. The adsorption also followed a Langmuir isothermal model with adsorption capacities of 333 mg/g and 138 mg/g towards CR and EY, respectively. This work demonstrated the feasibility to utilize the plant-based amyloid fibril for organic dyes removal from contaminated water, which provided an affordable, sustainable and scalable tool for organic dyes removal from wastewater.

Green Starch-Based Hydrogels with Excellent Injectability, Self-Healing, Adhesion, Photothermal Effect, and Antibacterial Activity for Promoting Wound Healing

Hydrogel materials have proven valuable in wound healing, but improving the safety of these hydrogels is still challenging. Therefore, designing multifunctional natural polymeric-based hydrogels with excellent mechanical properties to replace toxic or potentially risky, refractory chemical polymer-based hydrogels such as polyacrylamide and polyethylene glycol is of particular significance. Here, a green starch-based hydrogel (Starch@Ca/CGC hydrogel) with injectability, self-healing, and instant adhesion was constructed by coordination interaction, electrostatic interaction, and intramolecular and intermolecular hydrogen bonds. Therein, natural bioactive small molecules gallic acid (GA) and carvacrol (CA) were coordinated with metal ions by the ultrasonic-triggered self-assembly and ionic cross-linking codriven strategy to prepare Cu-gallic acid-carvacrol nanospheres (CGC NPs), which conferred the hydrogel with near-infrared light (NIR)-controlled CA release and photothermal synergistic sterilization properties, as well as antioxidant and anti-infection capabilities. More importantly, the multifunctional hydrogel platforms could completely cover an irregular wound shape to prevent secondary injury and significantly accelerate wound healing under NIR with more skin appendages like hair follicles and blood vessels appearing. Therefore, it is expected that this starch-based hydrogel could serve as a competitive multifunctional dressing in the biomedical field, including bacteria-derived wound infection and other tissue repair.

Bioinspired Amino Acid Based Materials in Bionanotechnology: From Minimalistic Building Blocks and Assembly Mechanism to Applications

Inspired by natural hierarchical self-assembly of proteins and peptides, amino acids, as the basic building units, have been shown to self-assemble to form highly ordered structures through supramolecular interactions. The fabrication of functional biomaterials comprised of extremely simple biomolecules has gained increasing interest due to the advantages of biocompatibility, easy functionalization, and structural modularity. In particular, amino acid based assemblies have shown attractive physical characteristics for various bionanotechnology applications. Herein, we propose a review paper to summarize the design strategies as well as research advances of amino acid based supramolecular assemblies as smart functional materials. We first briefly introduce bioinspired reductionist design strategies and assembly mechanism for amino acid based molecular assembly materials through noncovalent interactions in condensed states, including self-assembly, metal ion mediated coordination assembly, and coassembly. In the following part, we provide an overview of the properties and functions of amino acid based materials toward applications in nanotechnology and biomedicine. Finally, we give an overview of the remaining challenges and future perspectives on the fabrication of amino acid based supramolecular biomaterials with desired properties. We believe that this review will promote the prosperous development of innovative bioinspired functional materials formed by minimalistic building blocks.

Well-designed protein amyloid nanofibrils composites as versatile and sustainable materials for aquatic environment remediation: A review

Amyloid nanofibrils (ANFs) are supramolecular polymers originally classified as pathological markers in various human degenerative diseases. However, in recent years, ANFs have garnered greater interest and are regarded as nature-based sustainable biomaterials in environmental science, material engineering, and nanotechnology. On a laboratory scale, ANFs can be produced from food proteins via protein unfolding, misfolding, and hydrolysis. Furthermore, ANFs have specific structural characteristics such as a high aspect ratio, good rigidity, chemical stability, and a controllable sequence. These properties make them a promising functional material in water decontamination research. As a result, the fabrication and application of ANFs and their composites in water purification have recently gained considerable attention. Despite the large amount of literature in this field, there is a lack of systematic review to assess the gap in using ANFs and their composites to remove contaminants from water. This review discusses significant advancements in design techniques as well as the physicochemical properties of ANFs-based composites. We also emphasize the current progress in using ANFs-based composites to remove inorganic, organic, and biological contaminants. The interaction mechanisms between ANFs-based composites and contaminants are also highlighted. Finally, we illustrate the challenges and opportunities associated with the future preparation and application of ANFs-based composites. We anticipate that this review will shed new light on the future design and use of ANFs-based composites.

Effective removal of Cr(VI) in water by bulk-size polyaniline/polyvinyl alcohol/amyloid fibril composite beads

With the rapid expansion of industrial activities, chromium ions are discharged into the environment and cause water and soil pollution of various extents, which seriously endangers the natural ecological environment and human health. In this study, polyaniline/polyvinyl alcohol/amyloid fibril (PANI/PVA/AFL) composite gel beads (PPA) were prepared from polyaniline and amyloid fibrils with HCl as doping acid and PVA as a cross-linking agent. The results showed that PPA was an irregular composite bead with a diameter of 6 mm. The adsorption of Cr(VI) on the PPA gel beads followed the pseudo-second-order kinetics model, suggesting that chemical reactions were the controlling step in the Cr(VI) adsorption process. Though the Redlich-Peterson isotherm model had the best fit for the adsorption data, the isothermal adsorption process can be simplified using the Langmuir model. The maximum adsorption capacity for Cr(VI) in water was 51.5 mg g-1, comparable to or even higher than some PANI-based nanomaterials. Thermodynamic parameters showed that the adsorption process was a spontaneous, endothermic, and entropy-increasing process. Microscopic analysis revealed that the capture of Cr(VI) on PPA was mainly governed by electrostatic attraction, reduction, and complexation reactions. PPA can be used as a kind of effective remediation agent to remove Cr(VI) in water.

Green composite aerogel based on citrus peel/chitosan/bentonite for sustainable removal Cu(II) from water matrices

Here, we propose a green and sustainable 3D porous aerogel based on citrus peel (CP), chitosan (CS), and bentonite (BT). This aerogel is prepared through a simple sol-gel and freeze-drying process and is designed for efficient capture of Cu(II) ions from water matrices. CCBA-2, with its abundance of active binding sites, exhibits an impressive Cu(II) adsorption yield of 861.58 mg/g. The adsorption isotherm and kinetics follow the Freundlich and pseudo-second-order models, respectively. In the presence of coexisting mixed-metal ions, CCBA-2 demonstrates a significantly higher selectivity coefficient (KdCu = 1138.5) for removing Cu(II) ions compared to other toxic metal ions. Furthermore, the adsorption of Cu(II) ions by CCBA-2 is not significantly affected by coexisting cations/anions, ionic strength, organic matter, or different water matrices. Dynamic fixed-bed column experiments show that the adsorption capacity of Cu(II) ions reaches 377.4 mg/g, and the Yoon-Nelson model accurately describes the adsorption process and breakthrough curve. Through experiments, FTIR, and XPS analyses, we propose a reasonable binding mechanism between CCBA-2 and metal cations, involving electrostatic attraction and chemical chelation between Cu(II) and the functional groups of the aerogel. CCBA-2 saturated with Cu(II) ions can be successfully regenerated by elution with 1 M HNO3, with only a slight decrease in adsorption efficiency (5.3%) after 5 adsorption-desorption cycles. Therefore, CCBA-2 offers a cost-effective and environmentally friendly material that can be considered as a viable alternative for the green and efficient removal of toxic Cu(II) ions from wastewater.

Slice-layer COFs-aerogel: a regenerative dispersive solid-phase extraction adsorbent for determination of ultra-trace quinolone antibiotics

A novel type of three-dimensional network structure, covalent organic frameworks (COFs) aerogel, was fabricated and applied to dispersive solid-phase extraction (dSPE) of quinolone antibiotics (QAs). Density functional theory (DFT) was applied to investigate the possible interaction mechanism and results confirmed that the strong adsorption affinity is attributed to the intralayer hydrogen bonds and π-π interaction. Furthermore, a sensitive analytical method based on COFs-aerogel for determining quinolone antibiotics residues in water and honey samples was developed and HPLC-MS/MS was used for sample detection and quantification. Under the optimal conditions, COFs-aerogel exhibited a wide linearity (0.1-500 ng∙L-1), low limits of detection (0.02-0.06 ng∙L-1), and good precision (RSD ˂ 10%) for selected QAs. A preliminary practical application of the developed method was proved by the efficient detection of quinolone antibiotics in water and food samples with good recoveries (68.2-104% and 64.0-100% for water and honey samples, respectively). Combining the experimental data with theoretical calculation, results illustrated that COFs-aerogel holds a great potential to capture contaminants and address environmental and food safety issues.

N-Octadecane Encapsulated by Assembled BN/GO Aerogels for Highly Improved Thermal Conductivity and Energy Storage Capacity

The rapid development of industry has emphasized the importance of phase change materials (PCMs) with a high latent-heat storage capacity and good thermal stability in promoting sustainable energy solutions. However, the inherent low thermal conductivity and poor thermal-cycling stability of PCMs limit their application. In this study, we constructed three-dimensional (3D) hybrid graphene aerogels (GBA) based on synergistic assembly and cross-linking between GO and modified hexagonal boron nitride (h-BN). Highly thermally conductive GBA was utilized as the supporting optimal matrix for encapsulating OD, and further implied that composite matrix n-octadecane (OD)/GBA composite PCMs were further prepared by encapsulating OD within the GBA structure. Due to the highly thermally conductive network of GBA, the latent heat of the composite PCMs improved to 208.3 J/g, with negligible changes after 100 thermal cycles. In addition, the thermal conductivity of the composite PCMs was significantly enhanced to 1.444 W/(m·k), increasing by 738% compared to OD. These results sufficiently confirmed that the novel GBA with a well-defined porous structure served as PCMs with excellent comprehensive performance offer great potential for thermal energy storage applications.

Regulation mechanism of human insulin fibrillation by L-lysine carbon dots: low concentration accelerates but high concentration inhibits the fibrillation process

The fibrillation process of human insulin (HI) is closely related to the therapy for type II diabetes (T2D). Due to changes in the spatial structure of HI, the fibrillation process of HI takes place in the body, which leads to a significant decrease in normal insulin levels. L-Lysine CDs with a size of around 5 nm were synthesized and used to adjust and control the fibrillation process of HI. ThT fluorescence analysis and transmission electron microscopy (TEM) characterization of the CDs showed the role of HI fibrillation from the perspective of the kinetics of HI fibrillation and regulation. Isothermal titration calorimetry (ITC) was used to explore the regulatory mechanism of CDs at all stages of HI fibrillation from the perspective of thermodynamics. Contrary to common sense, when the concentration of CDs is less than 1/50 of the HI, CDs will promote the growth of fibres, while a high concentration of CDs will inhibit the growth of fibres. The experimental results of ITC clearly prove that different concentrations of CDs will correspond to different pathways of the combination between CDs and HI. CDs have a strong ability to combine with HI during the lag time, and the degree of combination has become the main factor influencing the fibrillation process.

Amyloidogenic and non-amyloidogenic molten globule conformation of β-lactoglobulin in self-crowded regime

Molecular insights on the β-lactoglobulin thermal unfolding and aggregation are derived from FTIR and UV Resonance Raman (UVRR) investigations. We propose an in situ and in real-time approach that thanks to the identification of specific spectroscopic markers can distinguish the two different unfolding pathways pursued by β-lactoglobulin during the conformational transition from the folded to the molten globule state, as triggered by the pH conditions. For both the investigated pH values (1.4 and 7.5) the greatest conformational variation of β-lactoglobulin occurs at 80 °C and a high degree of structural reversibility after cooling is observed. In acidic condition β-lactoglobulin exposes to the solvent its hydrophobic moieties in a much higher extent than in neutral solution, resulting on a highly open conformation. Moving from the diluted to the self-crowded regime, the solution pH and consequently the different molten globule conformation select the amyloid or non-amyloid aggregation pathway. At acidic condition the amyloid aggregates form during the heating cycle leading to the formation of transparent hydrogel. On the contrary, in neutral condition the amyloid aggregates never form. Information on the secondary structure conformational change of β-lactoglobulin and the formation of amyloid aggregates are obtained by FTIR spectroscopy and are related to the information of the structural changes localized around the aromatic amino acid sites by UVRR technique. Our results highlight a strong involvement of the chain portions where tryptophan is located on the formation of amyloid aggregates.

Sustainable soy protein microsponges for efficient removal of lead (II) from aqueous environments

Protein-based materials recently emerged as good candidates for water cleaning applications, due to the large availability of the constituent material, their biocompatibility and the ease of preparation. In this work, new adsorbent biomaterials were created from Soy Protein Isolate (SPI) in aqueous solution using a simple environmentally friendly procedure. Protein microsponge-like structures were produced and characterized by means of spectroscopy and fluorescence microscopy methods. The efficiency of these structures in removing lead (Pb²⁺) ions from aqueous solutions was evaluated by investigating the adsorption mechanisms. The molecular structure and, consequently, the physico-chemical properties of these aggregates can be readily tuned by selecting the pH of the solution during production. In particular, the presence of β-structures typical of amyloids as well as an environment characterized by a lower dielectric constant seem to enhance metal binding affinity revealing that hydrophobicity and water accessibility of the material are key features affecting the adsorption efficiency. Presented results provide new knowledge on how raw plant proteins can be valorised for the production of new biomaterials. This may offer extraordinary opportunities towards the design and production of new tailorable biosorbents which can also be exploited for several cycles of purification with minimal reduction in performance. SYNOPSIS: Innovative, sustainable plant-protein biomaterials with tunable properties are presented as green solution for water purification from lead (II) and the structure-function relationship is discussed.

Application of nanofibrous protein for the purification of contaminated water as a next generational sorption technology: a review

Globally, wastes from agricultural and industrial activities cause water pollution. Pollutants such as microbes, pesticides, and heavy metals in contaminated water bodies beyond their threshold limits result in several diseases like mutagenicity, cancer, gastrointestinal problems, and skin or dermal issues when bioaccumulated via ingestion and dermal contacts. Several technologies have been used in modern times to treat wastes or pollutants such as membrane purification technologies and ionic exchange methods. However, these methods have been recounted to be capital intensive, non-eco-friendly, and need deep technical know-how to operate thus, contributing to their inefficiencies and non-efficacies. This review work evaluated the application of Nanofibrils-protein for the purification of contaminated water. Findings from the study indicated that Nanofibrils protein is economically viable, green, and sustainable when used for water pollutant management or removal because they have outstanding recyclability of wastes without resulting in a secondary phase-pollutant. It is recommended to use residues from dairy industries, agriculture, cattle guano, and wastes from a kitchen in conjunction with nanomaterials to develop nanofibrils protein which has been recounted for the effective removal of micro and micropollutants from wastewater and water. The commercialization of nanofibrils protein for the purification of wastewater and water against pollutants has been tied to novel methods in nanoengineering technology, which depends strongly on the environmental impact in the aqueous ecosystem. So, there is a need to establish a legal framework for the establishment of a nano-based material for the effective purification of water against pollutants.

Turning Food Protein Waste into Sustainable Technologies

For each kilogram of food protein wasted, between 15 and 750 kg of CO2 end up in the atmosphere. With this alarming carbon footprint, food protein waste not only contributes to climate change but also significantly impacts other environmental boundaries, such as nitrogen and phosphorus cycles, global freshwater use, change in land composition, chemical pollution, and biodiversity loss. This contrasts sharply with both the high nutritional value of proteins, as well as their unique chemical and physical versatility, which enable their use in new materials and innovative technologies. In this review, we discuss how food protein waste can be efficiently valorized not only by reintroduction into the food chain supply but also as a template for the development of sustainable technologies by allowing it to exit the food-value chain, thus alleviating some of the most urgent global challenges. We showcase three technologies of immediate significance and environmental impact: biodegradable plastics, water purification, and renewable energy. We discuss, by carefully reviewing the current state of the art, how proteins extracted from food waste can be valorized into key players to facilitate these technologies. We furthermore support analysis of the extant literature by original life cycle assessment (LCA) examples run ad hoc on both plant and animal waste proteins in the context of the technologies considered, and against realistic benchmarks, to quantitatively demonstrate their efficacy and potential. We finally conclude the review with an outlook on how such a comprehensive management of food protein waste is anticipated to transform its carbon footprint from positive to negative and, more generally, have a favorable impact on several other important planetary boundaries.

The Rising Aerogel Fibers: Status, Challenges, and Opportunities

Aerogel fibers garner tremendous scientific interest due to their unique properties such as ultrahigh porosity, large specific surface area, and ultralow thermal conductivity, enabling diverse potential applications in textile, environment, energy conversion and storage, and high-tech areas. Here, the fabrication methodologies to construct the aerogel fibers starting from nanoscale building blocks are overviewed, and the spinning thermodynamics and spinning kinetics associated with each technology are revealed. The huge pool of material choices that can be assembled into aerogel fibers is discussed. Furthermore, the fascinating properties of aerogel fibers, including mechanical, thermal, sorptive, optical, and fire-retardant properties are elaborated on. Next, the nano-confining functionalization strategy for aerogel fibers is particularly highlighted, touching upon the driving force for liquid encapsulation, solid-liquid interface adhesion, and interfacial stability. In addition, emerging applications in thermal management, smart wearable fabrics, water harvest, shielding, heat transfer devices, artificial muscles, and information storage, are discussed. Last, the existing challenges in the development of aerogel fibers are pointed out and light is shed on the opportunities in this burgeoning field.

Amyloid Protein Cross-Seeding Provides a New Perspective on Multiple Diseases In Vivo

Amyloid protein cross-seeding is a peculiar phenomenon of cross-spreading among different diseases. Unlike traditional infectious ones, diseases caused by amyloid protein cross-seeding are spread by misfolded proteins instead of pathogens. As a consequence of the interactions among misfolded heterologous proteins or polypeptides, amyloid protein cross-seeding is considered to be the crucial cause of overlapping pathological transmission between various protein misfolding disorders (PMDs) in multiple tissues and cells. Here, we briefly review the phenomenon of cross-seeding among amyloid proteins. As an interesting example worth mentioning, the potential links between the novel coronavirus pneumonia (COVID-19) and some neurodegenerative diseases might be related to the amyloid protein cross-seeding, thus may cause an undesirable trend in the incidence of PMDs around the world. We then summarize the theoretical models as well as the experimental techniques for studying amyloid protein cross-seeding. Finally, we conclude with an outlook on the challenges and opportunities for basic research in this field. Cross-seeding of amyloid opens up a new perspective in our understanding of the process of amyloidogenesis, which is crucial for the development of new treatments for diseases. It is therefore valuable but still challenging to explore the cross-seeding system of amyloid protein as well as to reveal the structural basis and the intricate processes.

Biopolymeric Fibrous Aerogels: The Sustainable Alternative for Water Remediation

The increment in water pollution due to the massive development in the industrial sector is a worldwide concern due to its impact on the environment and human health. Therefore, the development of new and sustainable alternatives for water remediation is needed. In this context, aerogels present high porosity, low density, and a remarkable adsorption capacity, making them candidates for remediation applications demonstrating high efficiency in removing pollutants from the air, soil, and water. Specifically, polymer-based aerogels could be modified in their high surface area to integrate functional groups, decrease their hydrophilicity, or increase their lipophilicity, among other variations, expanding and enhancing their efficiency as adsorbents for the removal of various pollutants in water. The aerogels based on natural polymers such as cellulose, chitosan, or alginate processed by different techniques presented high adsorption capacities, efficacy in oil/water separation and dye removal, and excellent recyclability after several cycles. Although there are different reviews based on aerogels, this work gives an overview of just the natural biopolymers employed to elaborate aerogels as an eco-friendly and renewable alternative. In addition, here we show the synthesis methods and applications in water cleaning from pollutants such as dyes, oil, and pharmaceuticals, providing novel information for the future development of biopolymeric-based aerogel.

Protein nanofibrils as versatile and sustainable adsorbents for an effective removal of heavy metals from wastewater: A review

Water is a valuable natural resource, which plays a crucial role in ecological survival as well as economic progress. However, the water quality has deteriorated in recent years as a result of urbanization, industrialization and human activities due to the uncontrolled release of industrial wastes, which can be extremely carcinogenic and non-degradable, in air, water and soil bodies. Such wastes showed the presence of organic and inorganic pollutants in high dosages. Heavy metals are the most obstinate contaminants, and they can be harmful because of having a variety of detrimental consequences to the ecosystem. The existing water treatment methods in many situations may not be sustainable or effective because of their high energy requirements and ecological impacts. In this review, state-of-the-art water treatment methods for the elimination of heavy metals with the help of protein nanofibrils are covered featuring a discussion on the strategies and possibilities of developing protein nanofibrils for the active elimination of heavy metals using kitchen waste as well as residues from the cattle, agriculture, and dairy industries. Further, the emphasis has been given to their environmental sustainability and economical aspects are also discussed.

Fluorescent Microswimmers Based on Cross-β Amyloid Nanotubes and Divergent Cascade Networks

Shaped through millions of years of evolution, the spatial localization of multiple enzymes in living cells employs extensive cascade reactions to enable highly coordinated multimodal functions. Herein, by utilizing a complex divergent cascade, we exploit the catalytic potential as well as templating abilities of streamlined cross-β amyloid nanotubes to yield two orthogonal roles simultaneously. The short peptide based paracrystalline nanotube surfaces demonstrated the generation of fluorescence signals within entangled networks loaded with alcohol dehydrogenase (ADH). The nanotubular morphologies were further used to generate cascade-driven microscopic motility through surface entrapment of sarcosine oxidase (SOX) and catalase (Cat). Moreover, a divergent cascade network was initiated by upstream catalysis of the substrate molecules through the surface mutation of catalytic moieties. Notably, the resultant downstream products led to the generation of motile fluorescent microswimmers by utilizing the two sets of orthogonal properties and, thus, mimicked the complex cascade-mediated functionalities of extant biology.

Metal-Organic Framework Composite Photothermal Membrane for Removal of High-Concentration Volatile Organic Compounds from Water via Molecular Sieving

Water-soluble volatile organic compounds (VOCs) are among the most difficult-to-treat species during wastewater treatment. The current purification and removal of high-concentration VOCs still rely on the energy-consuming distillation and high-pressure driven reverse osmosis technology. There is an urgent need for an advanced technology that can effectively remove high-concentration VOCs from water. Here, we report a metal-organic framework (MOF)/polyaniline (PANI) nanofiber array composite photothermal membrane for removal of high-concentration VOCs from water via molecular sieving during a solar-driven evaporation process. The modified zeolitic imidazole framework-8 (ZIF-8) layer grown on a PANI nanofiber array acts as a molecular sieving layer to evaporate water but intercept VOCs. The composite membrane exhibits high VOCs rejection and a high-water evaporation rate for water containing different concentrations of VOCs. When treating water containing VOCs with a concentration of up to 400 mg L^-1, the VOCs rejection rate is up to 99% and the water evaporation rate is 1.0 kg m^-2 h^-1 under 1 sun irradiation (1 kW m^-2). Our work effectively combines the molecular sieve effect with a solar-driven evaporation process, which provides an effective strategy for the treatment of water containing VOCs.

Multicomponent Hydrogel Matrices of Fmoc-FF and Cationic Peptides for Application in Tissue Engineering

In the last years, peptide based hydrogels are being increasingly used as suitable matrices for biomedical and pharmaceutical applications, including drug delivery and tissue engineering. Recently, we decrived the synthesis and the gelation properties of a small library of cationic peptides, containing a Lys residue at the C-teminus and derivatized with a Fmoc group or with the Fmoc-diphenylalanine (FmocFF) at the N-terminus. Here, we demonstrate that the combination of these peptides with the well known hydrogelator FmocFF, in different weight/weight ratios, allows the achievement of seven novel self-sorted hydrogels, which share similar peptide organization of their supramolecular matrix. Rheological and relaxometric characterization highlighted a different mechanical rigidity and water mobility in the gels as demostrated by the storage modulus values (200 Pa<G'<35000 Pa) and by relaxometry, respectively. In vitro studied demonstrated that most of the tested mixed hydrogels do not disturb significantly the cell viability (>95%) over 72h of treatment. Moreover, in virtue to its capability to strongly favour adhesion, spreading and duplication of 3T3-L1 cells, one of the tested hydrogel may be eligible as sinthetic extracellular matrix. This article is protected by copyright. All rights reserved.

Biofiber waste derived zwitterionic and photocatalytic dye adsorbent: Switchable selectivity, in-situ degradation and multi-tasking application

Dye wastewater and discarded biofiber have brought huge pressure to sustainable developments of ecology and economy. By utilizing dopamine chemistry and benzophenone mediated "grafting onto" atom transfer radical polymerization (ATRP), this work reported a biomass adsorbent containing discarded wool substrate, photocatalytic PDA coating and zwitterionic polymer brushes for dyes removal. The grafted zwitterionic polymer brushes impart the material with not only high adsorption capacity and rapid adsorption rate, but also switchable adsorption selectivity and pH-controlled regeneration capability. Benefiting from such outstanding adsorption performance and excellent free-standing property, the adsorbent could fulfill diversified needs of both static and dynamic adsorptions. Under daylight, the constructed photocatalytic PDA coating could in-situ degrade the captured pollutant, thus achieving consecutive adsorption-degradation-regeneration utilization. Furthermore, through simple dip-coating and cleaner UV-irradiation techniques, the preparation process could be scaled up. This work contributes to both the upcycling of discarded biofiber waste and the development of advanced biomass adsorbent.

Amyloid fibril-UiO-66-NH2 aerogels for environmental remediation

A sustainable hybrid aerogel based on β-lactoglobulin amyloid fibril/UiO-66-NH₂ is developed for environmental remediation. The hybrid aerogel's CO₂ capture and water purification performances were investigated. The hybrid aerogel can achieve CO₂ capture and possesses excellent adsorption capacities for several heavy metals, dyes, and organic solvents.

Monolithic carbon aerogels within foam framework for high-temperature thermal insulation and organics absorption

Carbon aerogels exhibit high porosity, good electrical conductivity, and low thermal conductivity, but their practical applications are greatly hindered by their tedious preparation and inherent structure brittleness. Herein, monolithic carbon aerogels (MCAs) with low density and large size are prepared via a facile sol-gel polymerization of phenolic resin within melamine foam (MF), followed by ambient pressure drying and co-carbonization. During ambient pressure drying process, the MF matrix can deliver supporting force to counteract against the solvent evaporation surface tension, thus inhibiting volume shrinkage and shape deformation. Upon co-carbonization process, the MF matrix and organic aerogel could pyrolyze and shrink cooperatively, which could effectively prevent the brittle fracture of monolith. Therefore, large-sized MCAs (up to 250 × 250 × 20 mm) with low densities of 0.12-0.22 g·cm^-3 are obtained. The as-obtained MCAs possess high compressive strength (2.50 MPa), ultra-low thermal conductivity (0.051 W·m^-1·K^-1 at 25 °C and 0.111 W·m^-1·K^-1 at 800 °C), and high-volume organic absorption capability (77.3-88.0%, V/V). This facile and low-cost method for the fabrication of large-sized monolithic carbon aerogels with excellent properties could envision enormous potential for high-temperature thermal insulation and organics absorption.

Amyloid-Templated Palladium Nanoparticles for Water Purification by Electroreduction

Electrocatalysis offers great promise for water purification but is limited by low active area and high uncontrollability of electrocatalysts. To overcome these constraints, we propose hybrid bulk electrodes by synthesizing and binding a Pd nanocatalyst (nano-Pd) to the electrodes via amyloid fibrils (AFs). The AFs template is effective for controlling the nucleation, growth, and assembly of nano-Pd on the electrode. In addition, the three-dimensional hierarchically porous nanostructure of AFs is beneficial for loading high-density nano-Pd with a large active area. The novel hybrid cathodes exhibit superior electroreduction performance for the detoxification of hexavalent chromium (Cr6+ ), 4-chlorophenol, and trichloroacetic acid in wastewater and drinking water. This study provides a proof-of-concept design of an AFs-templated nano-Pd-based hybrid electrode, which constitutes a paradigm shift in electrocatalytic water purification, and broadens the horizon of its potential engineered applications.

Super Water-Extracting Gels for Solar-Powered Volatile Organic Compounds Management in the Hydrological Cycle

Water-soluble volatile organic compounds (VOCs) are widely spread in the natural hydrological cycle, contaminating potential water sources, and leading to unexpected ecological hazards. However, water-purification technologies toward VOCs are energy-intensive and present unsatisfactory purity of the obtained water. The fundamental challenge is to differentiate the motion of water and VOC molecules by separators. Here, the concept of a super water-extracting gel (SWEG) for VOC-management and water purification via direct solar distillation is proposed. The strong hydrogen bonding effect in the hypercrosslinked hydrophilic polymeric networks enables the SWEG to extract water from VOC-containing water, which rejects the VOC solutes while allowing water through for interfacial evaporation. The obtained SWEG achieves a VOCs removal ratio up to 99.99% by solar distillation under 1 sun. A solar water-purification system is also demonstrated to produce clean water, which surpasses other competitive technologies based on electricity.

Cationic microcrystalline cellulose - Montmorillonite composite aerogel for preconcentration of inorganic anions from dairy wastewater

Development of efficient adsorbents to inorganic anions as a solid phase extraction (SPE) material is highly desirable for chromatographic analysis and pollution control. In this work we developed a new hybrid cationic microcrystalline cellulose aerogel composite. Cationic cetylpyridinium imbedded montmorillonite (CPC-MT) was uniformly entrapped in microcrystalline cellulose (MCC) to enhance anionic adsorption efficiency and mechanical stability. The developed CPC-MT@MCC aerogel was used as an SPE adsorbent for anions from dairy wastewater by coupling with ion-column chromatography. Further quaternized CPC-MT@MCC aerogel (CPC-MT@QMCC) showed unique low density (10.6 mg cm^-3), large specific surface area (320 m² g^-1), porosity 70%, 800 mg g^-1 nitrate adsorption capacity within 60 min and ease of elution in alkaline solutions. The CPC-MT@QMCC aerogel showed efficient regeneration and reuse performances for up to 10 cycles. More importantly, a dynamic binding efficiency of 710 mg g^-1 highlights its excellent performance for practical applications. 96% of nitrate anion from environmental manure wastewater samples were adsorbed with 98.7% recovery. A good linear relationship was obtained in the range of 0.01-10 mg L^-1 and the limits of detection was 0.5 mg L^-1 using CPC-MT@QMCC aerogel as a preconcentration column. The successful synthesis of such intriguing and economic CPC-MT@QMCC aerogel may provide a promising matrix for high-performance and high efficiency chromatographic media.

Oat Plant Amyloids for Sustainable Functional Materials

Amyloid functional materials from amyloid fibril building blocks, produced in vitro from amyloidogenic natural proteins or synthetic peptides, show diverse functionalities ranging from environmental science and biomedicine, to nanotechnology and biomaterials. However, sustainable and affordable sources of amyloidogenic proteins remain the bottleneck for large-scale applications, and to date, interest remains essentially limited to fundamental studies. Plant-derived proteins would be an ideal source due to their natural abundance and low environmental impact. Hereby oat globulin, the primary protein of oat plant (Avena sativa), is utilized to yield high-quality amyloid fibrils and functional materials based thereof. These fibrils show a rich multistranded ribbon-like polymorphism and a fibrillization process with both irreversible and reversible pathways. The authors furthermore fabricate oat-amyloid aerogels, films, and membranes for possible use in water purification, sensors, and patterned electrodes. The sustainability footprint of oat-amyloids against other protein sources is demonstrated, anticipating an environmentally-efficient platform for advanced materials and technologies.

Biohybrid Nanocellulose-Lysozyme Amyloid Aerogels via Electrostatic Complexation

Modern science is increasingly turning to nature for inspiration to design sustainable biomaterials in a smart and effective way. Herein, we describe biohybrid aerogels based on electrostatic complexation between cellulose and proteins-two of the most abundant natural polymers on Earth. The effects of both particle surface charge and particle size are investigated with respect to aerogel properties including the morphology, surface area, stability, and mechanical strength. Specifically, negatively charged nanocellulose (cellulose nanocrystals and cellulose nanofibers) and positively charged lysozyme amyloid fibers (full-length and shortened via sonication) are investigated in the preparation of fibrillar aerogels, whereby the nanocellulose component was found to have the largest effect on the resulting aerogel properties. Although electrostatic interactions between these two classes of charged nanoparticles allow us to avoid the use of any cross-linking agents, the resulting aerogels demonstrate a simple additive performance as compared to their respective single-component aerogels. This lack of synergy indicates that although electrostatic complexation certainly leads to the formation of local aggregates, these interactions alone may not be strong enough to synergistically improve bulk aerogel properties. Nevertheless, the results reported herein represent a critical step toward a broader understanding of biohybrid materials based on cellulose and proteins.

Amyloid Fibril Templated MOF Aerogels for Water Purification

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.

Hierarchically Fabricated Amyloid Fibers via Evaporation-Induced Self-Assembly

Multiscale hierarchical nano- and microstructures of amyloid fibrils are fabricated by evaporation-induced self-assembly combined with topographic surface patterning techniques. The continuous stick-and-slip motion induces uniaxial alignment of amyloid fibrils characterized by high orientational order during the drying process. The optical textures of the resultant amyloid aggregates are directly observed by polarized optical microscopy (POM) and atomic force microscopy (AFM). The resulting fiber structure can be tuned by varying the width of the topographic pattern, e.g., the microchannel width, inducing different separation between the deposited amyloid fibers on the glass substrate. Additionally, amyloid fibrils are decorated with gold nanoparticles to produce conductive microwires showing good conductivity (∼10^-3 S/m). The finely controlled deposited amyloid fibers presented here can show a way to use naturally-abundant biomaterials for practical applications such as nanowires and sensors.

Protein nanofibrils and their use as building blocks of sustainable materials

The development towards a sustainable society requires a radical change of many of the materials we currently use. Besides the replacement of plastics, derived from petrochemical sources, with renewable alternatives, we will also need functional materials for applications in areas ranging from green energy and environmental remediation to smart foods. Proteins could, with their intriguing ability of self-assembly into various forms, play important roles in all these fields. To achieve that, the code for how to assemble hierarchically ordered structures similar to the protein materials found in nature must be cracked. During the last decade it has been demonstrated that amyloid-like protein nanofibrils (PNFs) could be a steppingstone for this task. PNFs are formed by self-assembly in water from a range of proteins, including plant resources and industrial side streams. The nanofibrils display distinct functional features and can be further assembled into larger structures. PNFs thus provide a framework for creating ordered, functional structures from the atomic level up to the macroscale. This review address how industrial scale protein resources could be transformed into PNFs and further assembled into materials with specific mechanical and functional properties. We describe what is required from a protein to form PNFs and how the structural properties at different length scales determine the material properties. We also discuss potential chemical routes to modify the properties of the fibrils and to assemble them into macroscopic structures.

Lead(II) ions adsorption onto amyloid particulates: An in depth study

The production of new cost-effective biocompatible sorbent sustainable materials, with natural origins, able to remove heavy metals from water resources is nowadays highly desirable in order to reduce pollution and increase clean water availability. In this context, self-assembled protein materials with amyloid structures seem to have a great potential as natural platform for a broader development of highly-tunable structures. In this work we show how protein particulates, a generic form of protein aggregates, with spherical micro sized shape can be used as adsorbents of Pb²⁺ ions from aqueous solution. The effect of pH, ionic medium, ionic strength and temperature of the metal ion solution on the adsorption ability and affinity has been evaluated revealing the complexity of adsorption mechanisms which are the result of the balance of specific interactions with functional groups in protein structure and not specific ones common to all polypeptide chains, and possibly related to amyloid state and to modification of particulates hydration layer.

Biopolymer-Based Membrane Adsorber for Removing Contaminants from Aqueous Solution: Progress and Prospects

The demand for energy-efficient water treatment as well as the limitation in adsorption of existing membranes has motivated the pursuit of membranes that can break the selectivity-permeability trade-off and provide high selective adsorption for chemicals of interest. The membrane adsorbers have received a lot of attention for removing contaminants from aqueous solution due to combine both advantages of adsorption and membrane separation. Membrane adsorbers constructed by biopolymer with many functional groups are widely used in water purification, because the biopolymers are easily available from biomass materials in nature, degradable, and low-cost. This paper summarizes the characteristics and important development direction of these types of biomass-based membrane adsorption materials to adsorb organic/inorganic contaminants of water and analyzes the preparation methods of natural biomacromolecule cellulose, chitosan, sodium alginate, and protein to construct the membrane adsorption materials, as well as the application of pollutant removal from aqueous solutions. According to the current problems and shortcomings in the research of biopolymer-based membrane adsorbers, it is proposed to improve the understanding of the adsorption mechanism of biopolymer-based membrane adsorbers and accelerate the development of practical applications as the focus of future research.