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Petrochemical-based plastics have not only contaminated all parts of the globe, but are also causing potentially irreversible damage to our ecosystem because of their non-biodegradability. As bioplastics are limited in number, there is an urgent need to design and develop more biodegradable alternatives to mitigate the plastic menace. In this regard, we report aquaplastic, a new class of microbial biofilm-based biodegradable bioplastic that is water-processable, robust, templatable and coatable. Here, Escherichia coli was genetically engineered to produce protein-based hydrogels, which are cast and dried under ambient conditions to produce aquaplastic, which can withstand strong acid/base and organic solvents. In addition, aquaplastic can be healed and welded to form three-dimensional architectures using water. The combination of straightforward microbial fabrication, water processability and biodegradability makes aquaplastic a unique material worthy of further exploration for packaging and coating applications.

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.

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.

Combination of proteins with other nanomaterials offers a promising strategy to fabricate novel hybrids with original functions in biology, medicine, nanotechnology, and materials science. Under carefully selected experimental conditions, we show that graphene nanosheets are able to direct one-dimensional self-assembly of silk fibroin, forming an unprecedented type of nanohybrids. These silk/graphene hybrids combine physical properties of both constituents and form functional composites with well-ordered hierarchical structures. Due to the facile fabrication process and their tunable nanostructures, the resultant hybrids show promise in applications as diverse as tissue engineering, drug delivery, nanoelectronics, nanomedicine, biosensors, and functional composites., ACS Macro Letters, 3 (2), ISSN:2161-1653

Para-nematic phases, induced by unwinding chiral helices, spontaneously relax to a chiral ground state through phase ordering dynamics that are of great interest and crucial for applications such as stimuli-responsive and biomimetic engineering. In this work, we characterize the cholesteric phase relaxation behaviors of β-lactoglobulin amyloid fibrils and cellulose nanocrystals confined into cylindrical capillaries, uncovering two different equilibration pathways. The integration of experimental measurements and theoretical predictions reveals the starkly distinct underlying mechanism behind the relaxation dynamics of β-lactoglobulin amyloid fibrils, characterized by slow equilibration achieved through consecutive sigmoidal-like steps, and of cellulose nanocrystals, characterized by fast equilibration obtained through smooth relaxation dynamics. Particularly, the specific relaxation behaviors are shown to emerge from the order parameter of the unwound cholesteric medium, which depends on chirality and elasticity. The experimental findings are supported by direct numerical simulations, allowing to establish hard-to-measure viscoelastic properties without applying magnetic or electric fields., Nature Communications, 11 (1), ISSN:2041-1723

Non-lamellar lyotropic liquid crystalline nanocarriers such as hexosomes and cubosomes are relatively unexplored lipid-based nanoparticles in nanomedicine that can be specifically formulated to match specific medical applications, thus exploiting the majority of the possible routes of administrations. A growing number of papers demonstrate intriguing features that make them good candidates as nanocarriers for therapeutically active molecules or imaging probes. Yet, important aspects, including pharmacokinetics, hemocompatibility, toxicity, and delivery properties, are not completely clarified, so that their full potential as nanomedicines remains to be assessed. This article reviews recent advances in the field and suggests possible new routes forward.

The impact of stereochemical purity of lipids on their self-assembly behavior is critical for establishing their true phase behavior from their commercial counterparts, which often contains stereoisomeric mixtures and other impurities. Here, stereochemically pure phytantriol (PT), (3,7,11,15-tetramethylhexadecane-1,2,3-triol) was synthesized from the natural trans-phytol and its thermotropic and lyotropic phase behavior in water investigated by small-angle X-ray scattering (SAXS), polarized optical microscopy (POM), and differential scanning calorimetry (DSC). These chemically pure lipids contain two chiral centers at the hydrophilic head group region and two chiral centers at the lipophilic tail region, allowing us to address the question of whether the molecular stereochemistry is related to the macroscopic phase behavior of phytantriol. In contrast to its commercial stereoisomeric mixtures, which form an isotropic micellar phase, neat (2S,3S,7R,11R)-3,7,11,15-tetramethylhexadecane-1,2,3-triol (S,S-PT) shows a smectic lamellar phase at room temperature, whereas (2R,3R,7R,11R)-3,7,11,15-tetramethylhexadecane-1,2,3-triol (R,R-PT) forms solid crystals. The lyotropic phase behavior of R,R-PT appears to be identical to that of the previously reported commercial stereoisomeric PT mixtures. In contrast, S,S-PT exhibits a different phase behavior. A lamellar crystalline phase (Lc) is formed instead of an isotropic micellar phase at a low water content, which also coexisted with other phases at low temperature. Subtle change in the shape of the diastereomers leads to variable steric interactions and subsequently affects the packing of the lipids at the molecular level, thereby influencing its self-assembling behavior. Finally, lipidic cubic phase crystallization of the membrane protein bacteriorhodopsin yielded a larger number of microcrystals with a higher average crystal length from S,S-PT than from commercial PT, suggesting faster nucleation.

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.

G-quadruplex, assembled from a square array of guanine (G) molecules, is an important structure with crucial biological roles in vivo but also a versatile template for ordered functional materials. Although the understanding of G-quadruplex structures is the focus of numerous studies, little is known regarding the control of G-quartet stacking modes and the spontaneous orientation of G-quadruplex fibrils. Here, the effects of different metal ions and their concentrations on stacking modes of G-quartets are elucidated. Monovalent cations (typically K + ) facilitate the formation of G-quadruplex hydrogels with both heteropolar and homopolar stacking modes, showing weak mechanical strength. In contrast, divalent metal ions (Ca 2+ , Sr 2+ , and Ba 2+ ) at given concentrations can control G-quartet stacking modes and increase the mechanical rigidity of the resulting hydrogels through ionic bridge effects between divalent ions and borate. We show that for Ca 2+ and Ba 2+ at suitable concentrations, the assembly of G-quadruplexes results in the establishment of a mesoscopic chirality of the fibrils with a regular left-handed twist. Finally, we report the discovery of nematic tactoids self-assembled from G-quadruplex fibrils characterized by homeotropic fibril alignment with respect to the interface. We use the Frank–Oseen elastic energy and the Rapini–Papoular anisotropic surface energy to rationalize two different configurations of the tactoids. These results deepen our understanding of G-quadruplex structures and G-quadruplex fibrils, paving the way for their use in self-assembly and biomaterials.

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.

Particle size measurements of cellulose nanocrystals (CNCs) are challenging due to their broad size distribution, irregular shape and propensity to agglomerate. Particle size is one of the key parameters that must be measured for quality control purposes and to differentiate materials with different properties. We report the results of an interlaboratory comparison (ILC) which examined atomic force microscopy (AFM) data acquisition and data analysis protocols. Samples of CNCs deposited on poly-L-lysine coated mica were prepared in the pilot laboratory and sent to 10 participating laboratories including academic, government and industrial organizations with varying levels of experience with imaging CNCs. The participant data sets indicated that the central location, width and asymmetry varied considerably for both length and height distributions. To deal with this variability we used a skew normal distribution to model the data from each laboratory and to obtain the consensus distribution that describes the CNC particle size. The skew normal distribution has 3 parameters: a central location (mean), distribution width (standard deviation) and asymmetry (shape) factor. This approach gave consensus distributions with mean, standard deviation and asymmetry factor of 94.9 nm, 37.3 nm and 6.0 for length and 3.4 nm, 1.2 nm and 2.8 for height, respectively. The use of multiple probes and/or deterioration of the probe with increased use are significant contributing factors to the variability in mean length between laboratories. There is less variability in height across participating laboratories and tests of applied imaging force indicate that it is possible to image without significant compression of the CNCs. The number of CNCs necessary to obtain a reliable data set depends on the probes and operating conditions, but with careful control of various parameters analysis of 250 and 300 CNCs should provide consistent data sets for height and length, respectively for one sample. Comparison of AFM with transmission electron microscopy (TEM) data obtained in the same ILC demonstrated excellent agreement between measured lengths for the 2 methods. By contrast AFM height was approximately one half the TEM width, a result that indicates the presence of a significant number of laterally agglomerated particles, consistent with literature data.

Despite their link to neurodegenerative diseases, amyloids of natural and synthetic sources can also serve as building blocks for functional materials, while possessing intrinsic photonic properties. Here, it is demonstrated that orientationally ordered amyloid fibrils exhibit polarization-dependent fluorescence, and can mechanically align rod-shaped plasmonic nanoparticles codispersed with them. The coupling between the photonic fibrils in liquid crystalline phases and the plasmonic effect of the nanoparticles leads to selective activation of plasmonic extinctions as well as enhanced fluorescence from the hybrid material. These findings are consistent with numerical simulations of the near-field plasmonic enhancement around the nanoparticles. The study provides an approach to synthesize the intrinsic photonic and mechanical properties of amyloid into functional hybrid materials, and may help improve the detection of amyloid deposits based on their enhanced intrinsic luminescence., Advanced Materials, 33 (51), ISSN:0935-9648, ISSN:1521-4095

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

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.

Chiral liquid crystals, or cholesteric phases, have been widely studied in the last decades, leading to fundamental advances and a multitude of applications and technologies. In general, the rich phenomenology of these systems depends directly on the molecular traits and conditions of the system, imposing precise symmetry to the resulting nematic field. By selecting amyloid fibrils as model filamentous chiral colloids, we report an unprecedented breadth of liquid crystalline morphologies, where up to six distinct configurations of the nematic field are observed under identical conditions. Amyloid-rich droplets show homogeneous, bipolar, radial, uniaxial chiral and radial chiral nematic fields, with additional parabolic focal conics in bulk. Variational and scaling theories allow rationalizing the experimental evidence as a subtle interplay between surface and bulk energies. Our experimental and theoretical findings deepen the understanding of chiral liquid crystals under confinement, opening to a more comprehensive exploitation of these systems in related functional materials., Scientific Reports, 9 (1), ISSN:2045-2322

In this work Nanoparticle Enhanced Laser Induced Breakdown Spectroscopy (NELIBS) has been employed for quantitative metal detection using amyloid fibrils coated with gold nanoparticles as enhancers. Amyloid fibrils represent, from one hand, an extremely interesting system for novel technologies, ranging from water purification to medical applications, and on the other hand, an ideal system for investigating the performance of laser-matter interaction in biological systems. The results obtained in this work show the potentiality of NELIBS for the quantification at sub-ppm (mg/kg) level of metallic elements (Cr, Pb, Tl and Cd) even in the protein and/or biological environment, employing amyloid fibrils with gold nanoparticles. Moreover, the single-shot measurements reveal the promising use of this technique in applications where high sensitivity and/or limitation in the sample amount are demanded.

Water is a ubiquitous liquid with unique physicochemical properties, whose nature has shaped our planet and life as we know it. Water in restricted geometries has different properties than in bulk. Confinement can prevent low-temperature crystallization of the molecules into a hexagonal structure and thus create a state of amorphous water. To understand the survival of life at subzero temperatures, it is essential to elucidate this behaviour in the presence of nanoconfining lipidic membranes. Here we introduce a family of synthetic lipids with designed cyclopropyl modifications in the hydrophobic chains that exhibit unique liquid-crystalline behaviour at low temperature, which enables the maintenance of amorphous water down to ~10 K due to nanoconfinement. The combination of experiments and molecular dynamics simulations unveils a complex lipid–water phase diagram in which bicontinuous cubic and lamellar liquid crystalline phases that contain subzero liquid, glassy or ice water emerge as a competition between the two components, each pushing towards its thermodynamically favoured state. A specifically designed family of synthetic lipids exhibits unique liquid-crystalline behaviour at low temperature, enabling maintenance of amorphous water down to about 10 K due to nanoconfinement.

Amyloid fibrils have evolved from purely pathological materials implicated in neurodegenerative diseases to efficient templates for last-generation functional materials and nanotechnologies. Due to their high intrinsic stiffness and extreme aspect ratio, amyloid fibril hydrogels can serve as ideal building blocks for material design and synthesis. Yet, in these gels, stiffness is generally not paired by toughness, and their fragile nature hinders significantly their widespread application. Here we introduce an amyloid-assisted biosilicification process, which leads to the formation of silicified nanofibrils (fibril–silica core–shell nanofilaments) with stiffness up to and beyond [Formula: see text] 20 GPa, approaching the Young’s moduli of many metal alloys and inorganic materials. The silica shell endows the silicified fibrils with large bending rigidity, reflected in hydrogels with elasticity three orders of magnitude beyond conventional amyloid fibril hydrogels. A constitutive theoretical model is proposed that, despite its simplicity, quantitatively interprets the nonmonotonic dependence of the gel elasticity upon the filaments bundling promoted by shear stresses. The application of these hybrid silica–amyloid hydrogels is demonstrated on the fabrication of mechanically stable aerogels generated via sequential solvent exchange, supercritical [Formula: see text] removal, and calcination of the amyloid core, leading to aerogels of specific surface area as high as 993 [Formula: see text] /g, among the highest values ever reported for aerogels. We finally show that the scope of amyloid hydrogels can be expanded considerably by generating double networks of amyloid and hydrophilic polymers, which combine excellent stiffness and toughness beyond those of each of the constitutive individual networks.

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

We investigate the static and dynamic states of water network during the phase transitions from double gyroid ((Formula presented.)) to double diamond ((Formula presented.)) bicontinuous cubic phases and from the latter to the reverse hexagonal (HII) phase in monolinolein based lipidic mesophases by combining FTIR and broadband dielectric spectroscopy (BDS). In both cubic(s) and HII phase, two dynamically different fractions of water are detected and attributed to bound and interstitial free water. The dynamics of the two water fractions are all slower than bulk water due to the hydrogen-bonds between water molecules and the lipid's polar headgroups and to nanoconfinement. Both FTIR and BDS results suggest that a larger fraction of water is hydrogen-bonded to the headgroup of lipids in the HII phase at higher temperature than in the cubic phase at lower temperature via H-bonds, which is different from the common expectation that the number of H-bonds should decrease with increase of temperature. These findings are rationalized by considering the topological ratio of interface/volume of the two mesophases., Angewandte Chemie. International Edition, 60 (48), ISSN:1433-7851, ISSN:1521-3773, ISSN:0570-0833

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

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.

The structure and functionality of foods are described from the perspective of recent advances in soft condensed matter physics. An overview is given of the structure and properties of food materials in terms of the physically relevant length scales. Recent developments in the understanding of the physics of gels, micelles, liquid crystals, biopolymer complexes and amorphous carbohydrates are presented.

Amyloid fibrils have garnered increasing attention as viable building blocks for functional material design and synthesis, especially those derived from food and agricultural wastes. Here, amyloid fibrils generated from β-lactoglobulin, a by-product from cheese industries, have been successfully used as a template for the design of a new class of high-performance conductive aerogels with sensing properties. These mechanically stable aerogels with three-dimensional porous architecture have a large surface area (≈159 m2 g-1), low density (≈0.044 g cm-3), and high electrical conductivity (≈0.042 S cm-1). A pressure sensing device is developed from these aerogels based on their combined electrical conductivity and compressible properties. More interestingly, these aerogels can be employed to design novel enzyme sensors by exploiting the proteinaceous nature of amyloid fibrils. This study expands the scope of structured amyloid fibrils as scaffolds for in situ polymerization of conducting polymers, offering new opportunities to design materials with multiple functionalities.

International audience; In the context of the emerging field of quantum plasmonics, we demonstrate in this manuscript the wavelength-dependent propagation and sorting of single plasmons launched in a two-dimensional crystalline gold flake by a broadband quantum nanoemitter. The stream of single plasmons in the visible is produced by a nanodiamond hosting a single nitrogen-vacancy color center positioned in the near field of the mesoscopic metallic microplatelet. Spatially and spectrally resolved images of the single plasmon propagation in the pristine hexagonal flake, and then in the same structure after insertion of a Bragg mirror, are obtained by filtered image-plane acquisitions on a leakage-radiation microscope. Our work on two-dimensional crystalline structures paves the way to future fundamental studies and applications in quantum plasmonics.

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.

Amyloid fibrils offer the possibility of controlling their contour length, aspect ratio, and length distribution, without affecting other structural parameters. Here we show that a fine control in the contour length distribution of β-lactoglobulin amyloid fibrils, achieved by mechanical shear stresses of different levels, translates into the organization of tactoids of different shapes and morphologies. While longer fibrils lead to highly elongated nematic tactoids in an isotropic continuous matrix, only sufficiently shortened amyloid fibrils lead to cholesteric droplets. The progressive decrease in amyloid fibrils length leads to a linear decrease of the anchoring strength and homogeneous tactoid → bipolar tactoid → cholesteric droplet transitions. Upon fibrils length increase, we first find experimentally and predict theoretically a decrease of the cholesteric pitch, before full disappearance of the cholesteric phase. The latter is understood to arise from the decrease of the energy barrier separating cholesteric and nematic phases over thermal energy for progressively longer, semiflexible fibrils.

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.

Intermediate filaments (IFs) are known for their extensibility, flexibility, toughness, and their ability to hydrate. Using keratin-like IFs obtained from slime fibers from the invertebrate Atlantic hagfish ( Myxine glutinosa), films were produced by drop-casting and coagulation on the surface of a MgCl2 buffer. Drop-casting produced self-supporting, smooth, and dense films rich in β-sheets (61%), whereas coagulation formed thin, porous films with a nanorough surface and a lower β-sheet content (51%). The films hydrated and swelled immediately when immersed in water and did not dissolve. X-ray diffraction showed that the β-crystallites remained stable upon hydration, that swelling presumably happens in the amorphous C-terminal tail-domains of the IFs, and that high salt conditions caused a denser network mesh size, suggesting polyelectrolyte behavior. Hydration resulted in a roughly 1000-fold decrease in apparent Young's modulus from 109 to 106 Pa as revealed by atomic force microscopy nanoindentation. Nanoindentation-based power-law rheology and stress-relaxation measurements indicated viscoelasticity and a soft-solid hydrogel character for hydrated films, where roughly 80% of energy is elastically stored and 20% is dissipated. By pulling coagulation films from the buffer interface, macroscopic fibers with highly aligned IF β-crystals similar to natural hagfish fibers were produced. We propose that viscoelasticity and strong hydrogen bonding interactions with the buffer interface are crucial for the production of such long biomimetic fibers with aligned β-sheets. This study demonstrates that hagfish fiber IFs can be reconstituted into functional biomimetic materials that are stiff when dry and retain the ability to hydrate to become soft and viscoelastic when in water.

The largest possible planar surfaces are highly sought for two-dimensional (2D) Au single-crystals applicable in catalysis, biomedicine, electronics, sensing, and optics. However, conventional chemical methods of synthesis are currently limited to planar area of 104 μm2. Here, the trans-scale and 2D growth of Au single-crystals is successfully achieved in a “kinetically controlled” pathway, taking advantage from natural fibrous proteins with different amino sequences and supramolecular architectures. It was found that silk fibroin (SF) has a uniquely suited amino sequence and supramolecular assembly ability to fulfill this task, enabling mild reducing ability and strong capping effects. By the synergetic aid of Cl– ions, 2D Au single-crystals were synthesized with an unprecedented lateral dimension exceeding 2 mm, yet with atomically smooth surfaces. When growing nanotips on their large planar surfaces, these 2D Au crystals stand as ideal platforms for single-molecule sensing (e.g., surface enhanced Raman...

Chirality is ubiquitous in nature and plays crucial roles in biology, medicine, physics and materials science. Understanding and controlling chirality is therefore an important research challenge with broad implications in fundamental and applied sciences. Unlike other classes of chiral colloids, such as nanocellulose or filamentous viruses, amyloid fibrils form nematic phases but appear to miss their twisted form in the phase diagram, the so-called cholesteric or chiral nematic phases, and this despite a well-defined chirality at the single fibril level. Here we report the discovery of cholesteric phases in amyloid fibrils, by using \b{eta}-lactoglobulin fibrils suitably shortened by shear stresses. The physical behavior of this new class of cholesteric materials exhibits unprecedented structural complexity, with confinement-drivenordering transitions between at least three types of nematic and cholesteric tactoids. We use energy functional theory to rationalize these results and demonstrate a chirality inversion upon increasing hierarchical levels, from the left-handed amyloids to the right-handed cholesteric droplets. These findings significantly deepen our understanding of chiral nematic phases and may pave the way to their optimal use in soft nanotechnology, nanomaterials templating and self-assembly.

The unique molecular architecture of lipidic cubic phases (LCPs) and their cubosome dispersions comprise a well-defined, curved bilayer that spans the entire three-dimensional (3-D) material space, encompassing a network of two periodic, curved, and nonintersecting 3-D aqueous channels. The ensuing large lipid/water interfacial area makes these biomaterials an interesting matrix for the lateral immobilization of organocatalysts to catalyze organic reactions in confined water. Herein, we report for the first time the design, synthesis, assembly, and characterization of catalytically active LCPs and cubosomes and demonstrate their applicability as self-assembled, biomimetic, and recyclable nanoreactor scaffolds. Small-angle X-ray scattering, cryo-transmission electron microscopy, and dynamic light scattering were applied for the characterization of the mesophases. These mesophases can be recycled and enable efficient catalytic activity as well as modulation of the diastereo- and enantioselectivity for the aldol reaction of several benzaldehyde derivatives and cyclohexanone in water.

Water contamination by organic pollutants is ubiquitous and hence a global concern due to detrimental effects on the environment and human health. Here, it is demonstrated that amyloid fibrils aerogels are ideal adsorbers for removing organic pollutants from water. To this end, amyloid fibrils prepared from β-lactoglobulin, the major constituent of milk whey protein, are used as building blocks for the fabrication of the aerogels. The adsorption of Bentazone, Bisphenol A, and Ibuprofen, as model pollutants, is evaluated under quasi-static conditions, without use of energy or pressure. Through adsorption by amyloid fibrils aerogel, excellent removal efficiencies of 92%, 78%, and 98% are demonstrated for Bentazone, Bisphenol A, and Ibuprofen, respectively. Furthermore, the maximum adsorption capacity of amyloid fibrils aerogel for Bentazone, Bisphenol A, and Ibuprofen is 54.2, 50.6, and 69.6 mg g-1 , respectively. To shed light on the adsorption equilibrium process, adsorption isotherms, binding constants, saturation limits, and the effect of pH are evaluated. Finally, the regeneration of the aerogel over three consecutive cycles is studied, exhibiting high reusability with no significant changes in its removal performance. These results point at amyloid fibrils aerogels as a sustainable, efficient, and inexpensive technology for alleviating the ubiquitous water contamination by organic pollutants.

We report a method to deposit amyloid fibrils on a substrate creating gradients in orientation and coverage on demand. For this purpose, we adapt a colloidal self-assembly method at liquid–liquid interfaces to deposit amyloid fibrils on a substrate from the water–hexane interface, while simultaneously compressing it. The amyloid fibril layers orient perpendicularly to the compression, ranging from isotropic to nematic distributions. We furthermore observe reproducible transitions from a monolayer to a bilayer and from a bilayer to multilayers with increasing surface pressures. The creation of each new layer is accompanied by a systematic drop in the structural order of the system, which is however regained upon further compression. This method shows great potential for overcoming the thin-film engineering challenges associated with the manipulation of sticky amyloid fibrils, and allows their ex situ visualisation under compression at the fluid–fluid interface, a situation relevant to understand the propagation of amyloid-related diseases, their functional role in biological systems, and their potential for technological applications., Soft Matter, 15 (42), ISSN:1744-683X, ISSN:1744-6848

By combining atomistic and higher-level modelling with solution X-ray diffraction we analyse self-assembly pathways for the IFQINS hexapeptide, a bio-relevant amyloid former derived from human lysozyme. We verify that (at least) two metastable polymorphic structures exist for this system which are substantially different at the atomistic scale, and compare the conditions under which they are kinetically accessible. We further examine the higher-level polymorphism for these systems at the nanometre to micrometre scales, which is manifested in kinetic differences and in shape differences between structures instead of or as well as differences in the small-scale contact topology. Any future design of structure based inhibitors of the IFQINS steric zipper, or of close homologues such as TFQINS which are likely to have similar structures, should take account of this polymorphic assembly., Scientific Reports, 9 (1), ISSN:2045-2322

Dendronized polymers (DPs) are large and compact main-chain linear polymers with a cylindrical shape and cross-sectional diameters of up to ∼15 nm. They are therefore considered molecular objects, and it was of interest whether given their experimentally accessible, well-defined dimensions, the density of individual DPs could be determined. We present measurements on individual, deposited DP chains, providing molecular dimensions from scanning and transmission electron microscopy and mass-per-length values from quantitative scanning transmission electron microscopy. These results are compared with density values obtained from small-angle X-ray scattering on annealed bulk specimen and with classical envelope density measurements, obtained using hydrostatic weighing or a density gradient column. The samples investigated comprise a series of DPs with side groups of dendritic generations g = 1-8. The key findings are a very large spread of the density values over all samples and methods, and a consistent increase of densities with g over all methods. While this work highlights the advantages and limitations of the applied methods, it does not provide a conclusive answer to the question of which method(s) to use for the determination of densities of individual molecular objects. We are nevertheless confident that these first attempts to answer this challenging question will stimulate more research into this important aspect of polymer and soft matter science.

The fine interplay between the simultaneous stretching and confinement of amyloid fibrils is probed by combining a microcapillary setup with atomic force microscopy. Single-molecule statistics reveal how the stretching of fibrils changed from force to confinement dominated at different length scales. System order, however, is solely ruled by confinement. Coarse-grained simulations support the results and display the potential to tailor system properties by tuning the two effects. These findings may further help shed light on in vivo amyloid fibril growth and transport in highly confined environments such as blood vessels.

For evolving biological and biomedical applications of hybrid protein?lipid materials, understanding the behavior of the protein within the lipid mesophase is crucial. After more than two decades since the invention of the in meso crystallization method, a protein-eye view of its mechanism is still lacking. Numerous structural studies have suggested that integral membrane proteins preferentially partition at localized flat points on the bilayer surface of the cubic phase with crystal growth occurring from a local fluid lamellar L? phase conduit. However, studies to date have, by necessity, focused on structural transitions occurring in the lipid mesophase. Here, we demonstrate using small-angle neutron scattering that the lipid bilayer of monoolein (the most commonly used lipid for in meso crystallization) can be contrast-matched using deuteration, allowing us to isolate scattering from encapsulated peptides during the crystal growth process for the first time. During in meso crystallization, a clear decrease in form factor scattering intensity of the peptides was observed and directly correlated with crystal growth. A transient fluid lamellar L? phase was observed, providing direct evidence for the proposed mechanism for this technique. This suggests that the peptide passes through a transition from the cubic QII phase, via an L? phase to the lamellar crystalline Lc phase with similar layered spacing. When high protein loading was possible, the lamellar crystalline Lc phase of the peptide in the single crystals was observed. These findings show the mechanism of in meso crystallization for the first time from the perspective of integral membrane proteins.

Controlling the assembly of colloids in dispersion is a fundamental approach toward the production of functional materials. Nanocrystalline cellulose (NCC) is a charged nanoparticle whose colloidal interactions can be modulated from repulsive to attractive by increasing ionic strength. Here, we combine polarized optical microscopy, rheology, and small-angle scattering techniques to investigate (i) the concentration-driven transition from isotropic dispersion to cholesteric liquid crystals and (ii) salt-induced NCC phase transitions. In particular, we report on the formation of NCC attractive glasses containing nematic domains. At increasing NCC concentration, a structure peak was observed in small-angle X-ray scattering (SAXS) patterns. The evolution of the structure peak demonstrates the decrease in NCC interparticle distance, favoring orientational order during the isotropic-cholesteric phase transition. Small amounts of salt reduce the cholesteric volume fraction and pitch by a decrease in excluded volume. Beyond a critical salt concentration, NCC forms attractive glasses due to particle caging and reduced motility. This results in a sharp increase in viscosity and formation of viscoelastic glasses. The presence of nematic domains is suggested by the appearance of interference colors and the Cox-Merz rule failure and was confirmed by an anisotropic SAXS scattering pattern at q ranges associated with the presence of nematic domains. Thus, salt addition allows the formation of NCC attractive glasses with mechanical properties similar to those of gels while remaining optically active owed to entrapped nematic domains.

Cellulose is a pervasive polymer, displaying hierarchical lengthscales and exceptional strength and stiffness. Cellulose's complex organization, however, also hinders the detailed understanding of the assembly, mesoscopic properties, and structure of individual cellulose building blocks. This study combines nanolithography with atomic force microscopy to unveil the properties and structure of single cellulose nanofibrils under weak geometrical confinement. By statistical analysis of the fibril morphology, it emerges that confinement induces both orientational ordering and self‐folding of the fibrils. Excluded volume simulations reveal that this effect does not arise from a fibril population bias applied by the confining slit, but rather that the fibril conformation itself changes under confinement, with self‐folding favoring fibril's free volume entropy. Moreover, a nonstochastics angular bending probability of the fibril kinks is measured, ruling out alternating amorphous–crystalline regions. These findings push forward the understanding of cellulose nanofibrils and may inspire the design of functional materials based on fibrous templates., Advanced Science, 6 (4), ISSN:2198-3844

Cellulose nanofibrils (CNFs) are a renewable and facile to produce nanomaterial that recently gained a lot of attention in soft material research. The nanostructural properties of the fibrils largely determine their self-organizing functionalities, and the ability to tune the CNF nanostructure through control of the processing parameters is therefore crucial for developing new applications. In this study, we systematically altered the CNF production parameters (i.e., variation in cellulose source, chemical, and mechanical treatment) to observe their impact on the nanostructural properties of the resulting fibrils. Atomic force microscopy (AFM) allowed detailed topological examination of individual CNFs to elucidate fibril properties such as contour length, kink distribution and the right-handed twist periodicity of individual fibrils. Statistical analysis revealed a large dependency of the fibril properties on the industrial treatment of the cellulose source material. Our results furthermore confirm that the average charge density of the fibrils regulates both contour length and twist periodicity and, thus, has a very strong impact on the final morphology of CNFs. These results provide a route to tune the detailed nanostructure of CNFs with potential impact on the self-organization of these biological colloids and their optimal use in new nanomaterials.

The transport behavior of inverse bicontinuous cubic phases is experimentally investigated as the combined outcome of solute molecular structure and geometrical details of the confining symmetry. Molecular diffusion is discussed in relation to curvature, bottlenecks, and interfacial properties of each cubic phase. Point-like molecules show faster diffusion across the double diamond (Pn3m) symmetry, while unfolded macromolecules display better performance inside the double primitive (Im3m) cubic phase. The former observation is in agreement with previous simulation work, whereas the latter indicates that dedicated theory needs to be developed for diffusing polymers. Furthermore, the effect of electrostatic interactions is assessed by a study of diffusion of nanoparticles and is rationalized via a combination of simulations and theoretical considerations as the result of a competition between water mobility and geometrical features of the channel., The Journal of Chemical Physics, 150 (9), ISSN:0021-9606, ISSN:1089-7690

Synthesis, processing, and characterization are reported for a series of tetracyanoplatinate Magnus' salt (TCN-MS) derivatives-soluble derivatives of the generally intractable Magnus' green salt-that feature the general structure [Pt(NH2R)(4)] [Pt(CN)(4)] where R is a branched alkyl group or a w-phenylalkyl group. In solutions, these coordination compounds generally dissolve on the level of individual ion pairs as shown by X-ray diffraction analysis. To enable the formation of quasi-one-dimensional linear stacks of Pt(II) atoms in thin films, the matrix-assisted assembly is employed, whereby the compounds are codissolved with poly(ethylene oxide) (PEO), followed by film casting, thermally activated assembly, and eventual removal of PEO. Remarkably, assembled TCN-MS inorganic polymers exhibit bright blue-green photoluminescence. A detailed investigation of the assembly process and simultaneously modified solid-state optical properties is performed using a range of microscopy, optical and vibrational spectroscopy, and thermal analysis techniques. Given their unusual combination of optical properties, namely, transparency in the visible region, high photoluminescence quantum efficiencies (up to 13% in first-demonstration samples), and large Stokes shifts (up to 1 eV), TCN-MS derivatives are proposed as a promising class of light-emitting materials for emerging applications in molecular optoelectronics, the potential and challenges of which are discussed., The work in Barcelona was financially supported by the Ministerio de Economía y Competitividad of Spain through the Severo Ochoa Programme for Centres of Excellence in R&D (SEV-2015-0496) and project MAT2015-70850-P and the European Research Council (ERC) under grant agreement no. 648901. The work in Madrid and Valencia was supported by the Spanish Ministerio de Economía y Competitividad (MINECO-FEDER project CTQ2017-87054); the work in Madrid was further supported by the Severo Ochoa Programme for Centers of Excellence in R&D program of the MINECO (SEV-2016-0686) and by the Campus of International Excellence (CEI) UAM + CSIC.

Angewandte Chemie. International Edition, 58 (22), ISSN:1433-7851, ISSN:1521-3773, ISSN:0570-0833

While stimuli-responsive polymers have received a huge amount of attention in the literature, responsive lipid-based mesophase systems offer unique opportunities in biomedical applications such as drug delivery and biosensing. The different mesophase equilibrium structures enables dynamic switching between nanostructures to facilitate drug release or as a transducer for recognition events. In drug delivery, this behavior offers researchers the means to deliver a therapeutic payload at a specific rate and time i.e. 'on-demand'. This review summarizes the distinctive features of these multifaceted materials and aggregates the current state of the art research from our groups and others into the use of these materials as bulk gels and nanostructured dispersions for drug delivery, biosensing and diagnostics.

Gelatin-graphene conductive biopolymer nanocomposites (CPCs) with ultralow percolation threshold are designed by reducing in situ graphene oxide nanosheets with ascorbic acid and suppressing the aggregation of the graphene nanosheets. The resulting conductive nanocomposites show a record-low electrical percolation threshold of 3.3 × 10(-2) vol%, which arises from the homogeneous dispersion of the graphene nanosheets within the gelatin matrix.

Proteinaceous materials based on the amyloid core structure have recently been discovered at the origin of biological functionality in a remarkably diverse set of roles, and attention is increasingly turning towards such structures as the basis of artificial self-assembling materials. These roles contrast markedly with the original picture of amyloid fibrils as inherently pathological structures. Here we outline the salient features of this class of functional materials, both in the context of the functional roles that have been revealed for amyloid fibrils in nature, as well as in relation to their potential as artificial materials. We discuss how amyloid materials exemplify the emergence of function from protein self-assembly at multiple length scales. We focus on the connections between mesoscale structure and material function, and demonstrate how the natural examples of functional amyloids illuminate the potential applications for future artificial protein based materials.