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There is interest in developing sustainable materials displaying circularly polarized room-temperature phosphorescence, which have been scarcely reported. Here, we introduce biobased thin films exhibiting circularly polarized luminescence with simultaneous room-temperature phosphorescence. For this purpose, phosphorescence-active lignosulfonate biomolecules are co-assembled with cellulose nanocrystals in a chiral construct. The lignosulfonate is shown to capture the chirality generated by cellulose nanocrystals within the films, emitting circularly polarized phosphorescence with a 0.21 dissymmetry factor and 103 ms phosphorescence lifetime. By contrast with most organic phosphorescence materials, this chiral-phosphorescent system possesses phosphorescence stability, with no significant recession under extreme chemical environments. Meanwhile, the luminescent films resist water and humid environments but are fully biodegradable (16 days) in soil conditions. The introduced bio-based, environmentally-friendly circularly polarized phosphorescence system is expected to open many opportunities, as demonstrated here for information processing and anti-counterfeiting. [ABSTRACT FROM AUTHOR]

Cellulose has shown great potential in the development of green triboelectric nanogenerators. Particularly, regenerated cellulose (R-cellulose) has shown remarkably high output power density but the structural features and key parameters that explain such superior performance remain unexplored. In this work, wood cellulose fibers were dissolved in a LiOH(aq)-based solvent to produce a series of R-cellulose films. Regeneration in different alcohols (from methanol to n-pentanol) was performed and the films' structural features and triboelectric performance were assessed. Nonsolvents of increased hydrophobicity led to R-cellulose films with a more pronounced (1–10) diffraction peak. An open-circuit voltage (VOC) of up to ca. 260 V and a short-circuit current (ISC) of up to ca. 150 µA were measured for R-cellulose against polytetrafluoroethylene (as negative counter-layer). However, R-cellulose showed an increased VOC of 175% (from 88.1 V) against polydimethylsiloxane when increasing the alcohol hydrocarbon chain length from methanol to n-pentanol. The corresponding ISC and output power also increased by 76% (from 89.9 µA) and by 382% (from 8.8 W m–2), respectively. The higher R-cellulose hydrophilicity, combined with soft counter-tribolayer that follow the surface structures increasing the effective contact area, are the leading reasons for a superior triboelectric performance. [ABSTRACT FROM AUTHOR]

Nanocellulose is very hydrophilic, preventing interactions with the oil phase in Pickering emulsions. This limitation is herein addressed by incorporating lignin nanoparticles (LNPs) as co-stabilizers of nanocellulose-based Pickering emulsions. LNP addition decreases the oil droplet size and slows creaming at pH 5 and 8 and with increasing LNP content. Emulsification at pH 3 and LNP cationization lead to droplet flocculation and rapid creaming. LNP application for emulsification, prior or simultaneously with nanocellulose, favors stability given the improved interactions with the oil phase. The Pickering emulsions can be freeze–dried, enabling the recovery of a solid macroporous foam that can act as adsorbent for pharmaceutical pollutants. Overall, the properties of nanocellulose-based Pickering emulsions and foams can be tailored by LNP addition. This strategy offers a unique, green approach to stabilize biphasic systems using bio-based nanomaterials without tedious and costly modification procedures. [ABSTRACT FROM AUTHOR]

A vast range of extraction processes, chemistries, and wet processing methods have been explored to improve the opto-mechanical properties of nanocellulosic materials. However, the stresses that arise during drying have been scarcely examined, in particular for their impact on performance. As with papermaking, drying is a critical step that significantly impacts the properties of nanocellulosic materials. The nano- and micro-scaled dimensions of nanocelluloses provide opportunities beyond those achievable in paper science, as the associated drying stresses are several orders of magnitude higher than those at the macroscale. Drying may be utilized towards the generation of assemblies with functional structures and enhanced properties. Herein, we highlight recent examples where such drying stresses are tethered to the structure of nanocellulosic materials. Using cellulose nanocrystals (CNCs), we investigate how the stresses that develop upon consolidation, and that remain thereafter (i.e., residual stresses), correlate with the mechanical performance of the obtained materials. We extend this analysis through results that highlight the impact of the "history" of drying of CNCs on the dynamics of the residual stresses. We also briefly discuss how inhomogeneous concentration gradients in drying suspensions may play an important role in the formation of superstructures across a range of nanocellulosic materials. Overall, by highlighting the importance of drying, we expect a more closely scrutinized science of drying to improve the properties of structures based on nanocellulose. [ABSTRACT FROM AUTHOR]

Phase separation is a universal physical transition process whereby a homogeneous mixture splits into two distinct compartments that are driven by the component activity, elasticity, or compositions. In the current work, we develop a series of heterogeneous colloidal suspensions that exhibit both liquid-liquid phase separation of semiflexible binary polymers and liquid crystal phase separation of rigid, rod-like nanocellulose particles. The phase behavior of the multicomponent mixture is controlled by the trade-off between thermodynamics and kinetics during the two transition processes, displaying cholesteric self-assembly of nanocellulose within or across the compartmented aqueous phases. Upon thermodynamic control, two-, three-, and four-phase coexistence behaviors with rich liquid crystal stackings are realized. Among which, each relevant multiphase separation kinetics shows fundamentally different paths governed by nucleation and growth of polymer droplets and nanocellulose tactoids. Furthermore, a coupled multiphase transition can be realized by tuning the composition and the equilibrium temperature, which results in thermotropic behavior of polymers within a lyotropic liquid crystal matrix. Finally, upon drying, the multicomponent mixture undergoes a hierarchical self-assembly of nanocellulose and polymers into stratified cholesteric films, exhibiting compartmentalized polymer distribution and anisotropic microporous structure. Phase separation is driven by the component activity, elasticity, or composition of a homogeneous mixture. Here the authors, develop heterogeneous colloidal suspensions exhibiting both liquid-liquid phase separation of polymers and liquid crystal phase separation of nanoparticles controlled by the trade-off between thermodynamics and kinetics. [ABSTRACT FROM AUTHOR]

Alginate and chitosan are commonly used materials for applications such as tissue engineering due to their biocompatibility and bioactivity that promotes growth and differentiation to interest cell types. A common modifying component to improve mechanical and electric properties are gold nanoparticles. However, the capping agent is rarely described and the interaction of them with the polysaccharides are understudied. This work used thin model films in sensors for QCM-D and MP-SPR to follow these interactions and better describe them. AFM images were obtained to correlate the adsorption measured with their arrangement on the surface. Herein, it was found that citrate-capped nanoparticles had the best adsorption behavior with chitosan, most likely driven by electrostatic interactions. Meanwhile, the addition of proteins such as BSA served to improve the nanoparticles dispersibility, both in solution and on surface, as well as their adsorption to the alginate/chitosan mix, which had lowered their capacity to form electrostatic interactions through their functional groups, which were utilized while forming the films. Hence, the BSA helped promote hydrophobic and entropic phenomena, driving the deposition onto the surface. This work proves that the capping agent had a great impact on the behavior of the materials, thus understanding them should serve for the betterment of scaffolding design. [ABSTRACT FROM AUTHOR]

Light is a powerful and sustainable resource, but it can be detrimental to the performance and longevity of optical devices. Materials with near-zero light reflectance, i.e. superblack materials, are sought to improve the performance of several light-centered technologies. Here we report a simple top-down strategy, guided by computational methods, to develop robust superblack materials following metal-free wood delignification and carbonization (1500 °C). Subwavelength severed cells evolve under shrinkage stresses, yielding vertically aligned carbon microfiber arrays with a thickness of ~100 µm and light reflectance as low as 0.36% and independent of the incidence angle. The formation of such structures is rationalized based on delignification method, lignin content, carbonization temperature and wood density. Moreover, our measurements indicate a laser beam reflectivity lower than commercial light stoppers in current use. Overall, the wood-based superblack material is introduced as a mechanically robust surrogate for microfabricated carbon nanotube arrays.Superblack materials could innovate light-centered technologies, however, advances in superblack materials have been constrained by their complex and costly fabrication routes. Here, the authors report a simple top-down strategy, guided by computational methods, to develop robust superblack materials following metal-free wood delignification and carbonization. [ABSTRACT FROM AUTHOR]

Rapid diagnostic systems are essential in controlling the spread of viral pathogens and efficient patient management. The available technologies for low-cost viral antigen testing have several limitations, including a lack of accuracy and sensitivity. Here, we introduce a platform based on cellulose II nanoparticles (oppositely charged NPan and NPcat) for effective control of surface protein interactions, leading to rapid and sensitive antigen tests. Passivation against non-specific adsorption and augmented immobilization of sensing antibodies is achieved by adjusting the electrostatic charge of the nanoparticles. The interactions affecting the performance of the system are investigated by microgravimetry and confocal imaging. As a proof-of-concept test, SARS-CoV-2 nucleocapsid sensing was carried out by using saliva-wicking by channels that were stencil-printed on paper. We conclude that inkjet-printed NPcat elicits strong optical signals, visible after a few minutes, opening the opportunity for cost-effective and rapid diagnostic. [ABSTRACT FROM AUTHOR]

The self-assembly of cellulose nanocrystals can tether their interfacial interactions and the associated properties of their constructs. For instance, assemblies of highly aligned cellulose nanocrystals (CNCs) bear improved mechanical strength, barrier properties, and piezoelectric response. In this study, the self-assembly of CNC superstructure was assessed under various confinement geometries, enabling optimization of the long-range order within the microstructures formed. The confinement involved the planar capillary (with a rectangular cross-section)formed between two glass substrates with silicone boundaries. The impact of temperature, width and thickness of the capillary plane on self-assembly of the micro-scaled lamellar structures was evaluated. Thinner capillaries and lower temperatures were found to considerably improve long-range order and increase the frequency of the periodic microstructures formed. The drying process was monitored by rheological analysis, which showed an initial fast drying followed by slow drying due to the hindered diffusion through lamellae. The adhesive properties of the formed superstructures were evaluated. The shear strength was shown to depend on the orientation of the superstructures and therefore of the CNCs. About 4 MPa adhesion strength was obtained when the lamellar superstructures were perpendicularly aligned with respect to the in-plane force applied, while ca. 3 MPa adhesion was obtained for parallel alignment. The experimental framework described herein enabled the evaluation of the impact of the dimensions of a drying meniscus on self-assembly of anisometric colloids while also linking cellulosic assemblies with their interfacial supramolecular interactions. This simple framework brings forward the possibility to correlate the behavior of nanometric objects with micro- and macro-scaled observations, e.g., macro-scaled mechanics of adhesion. [ABSTRACT FROM AUTHOR]

We introduce a simple spray drying method for the scaleup production of spherical organic (lignin) particles with sizes between 0.85 and 1.57 µm. We assess the surface energy of the lignin particles by inverse gas chromatography to reveal their role in composites synthesized with unsaturated polyester. Such nanocomposites are shown to be transparent to electromagnetic irradiation (millimeter wave bands). The permittivity and tanδ of the composite material reached values 3.01 and 0.01 at 28 GHz with 10% lignin content. Vinyl groups were introduced on the surface of the particles to achieve enhanced interfacial adhesion, and resulted in a reduced relative permittivity (2.75). Together with wave interactions, the mechanical and thermal properties of the composites are put in perspective, opening new opportunities in the development of bio-based devices for 5G high-speed communication. [ABSTRACT FROM AUTHOR]

A system for the rapid and ultra-sensitive detection of Staphylococcus aureus (S. aureus), a prevalent foodborne pathogen is introduced. Limitations of typical electrochemical sensing, often subjected to interference from non-specific protein adsorption are addressed. A dual-aptamer-based sandwich immunobiosensor is shown for its benefits regarding specificity and anti-fouling capacity, endowed by a sulfonated polyaniline layer combined with signal amplification via highly conductive gold nanoparticles. EIS spectra (Nyquist plots) were recorded at pH 7.4 PBS containing 5 mM Fe(CN)63−/Fe(CN)64−, in order to verify the possibility of the electrochemical sensing for detection of S. aureus. Results demonstrated that the constructed immunobiosensor presents an extended detection range (1 × 101 to 1 × 105 CFU/mL) and detection limit as low as 2 CFU/mL. The resistance values of the immunobiosensor developed maintain at a stable value during 2 weeks. Besides, the specificity of the system is highlighted by testing raw milk, and the results of which demonstrate the excellent prospects of the system for monitoring foodborne pathogens. [ABSTRACT FROM AUTHOR]

The remarkable efficiency of chemical reactions is the result of biological evolution, often involving confined water. Meanwhile, developments of bio-inspired systems, which exploit the potential of such water, have been so far rather complex and cumbersome. Here we show that surface-confined water, inherently present in widely abundant and renewable cellulosic fibres can be utilised as nanomedium to endow a singular chemical reactivity. Compared to surface acetylation in the dry state, confined water increases the reaction rate and efficiency by 8 times and 30%, respectively. Moreover, confined water enables control over chemical accessibility of selected hydroxyl groups through the extent of hydration, allowing regioselective reactions, a major challenge in cellulose modification. The reactions mediated by surface-confined water are sustainable and largely outperform those occurring in organic solvents in terms of efficiency and environmental compatibility. Our results demonstrate the unexploited potential of water bound to cellulosic nanostructures in surface esterifications, which can be extended to a wide range of other nanoporous polymeric structures and reactions. The efficiency of chemical reactions in biological systems is often connected to the properties of confined water, but the developments and applications of artificial mimicking systems are impeded by the complexity of the biological systems. Here, the authors show how surface bound water in nanoporous cellulosic fibers can increase the reaction rate of surface acetylation reactions and enable regioselectivity of the reaction [ABSTRACT FROM AUTHOR]

Cellulose is the most abundant biopolymer on Earth, found in trees, waste from agricultural crops and other biomass. The fibres that comprise cellulose can be broken down into building blocks, known as fibrillated cellulose, of varying, controllable dimensions that extend to the nanoscale. Fibrillated cellulose is harvested from renewable resources, so its sustainability potential combined with its other functional properties (mechanical, optical, thermal and fluidic, for example) gives this nanomaterial unique technological appeal. Here we explore the use of fibrillated cellulose in the fabrication of materials ranging from composites and macrofibres, to thin films, porous membranes and gels. We discuss research directions for the practical exploitation of these structures and the remaining challenges to overcome before fibrillated cellulose materials can reach their full potential. Finally, we highlight some key issues towards successful manufacturing scale-up of this family of materials.Opportunities for the application of fibrillated cellulose materials—which can be extracted from renewable resources—and broader manufacturing issues of scale-up, sustainability and synergy with the paper-making industry are discussed. [ABSTRACT FROM AUTHOR]

Cellulose utilization at its full potential often requires its dissolution which is challenging. Aqueous NaOH is the solvent of choice due to the rapid, non-toxic, low cost and environmentally friendly dissolution process. However, there are several limitations, such as the required low temperature and cellulose´s moderately low degree of polymerization and concentration. Moreover, there is a tendency for gelation of semidilute solutions with time and temperature. The addition of ZnO aids cellulose dissolution and hinders self-aggregation in the NaOH solution; however, the exact role of ZnO has remained as an open question. In this work, we studied cellulose dissolution in the aqueous NaOH–ZnO system as well as the reactivity of the dissolved cellulose by oxidation with 4-AcNH-TEMPO+ (TEMPO+). Based on Raman spectroscopic studies and the TEMPO+-reactivities, we propose a new structure for cellulose dissolved in aqueous NaOH–ZnO. [ABSTRACT FROM AUTHOR]

We investigate the adsorption of hexavalent uranium, U(VI), on phosphorylated cellulose nanofibers (PHO-CNF) and compare the results with those for native and TEMPO-oxidized nanocelluloses. Batch adsorption experiments in aqueous media show that PHO-CNF is highly efficient in removing U(VI) in the pH range between 3 and 6. Gelling of nanofiber hydrogels is observed at U(VI) concentration of 500 mg/L. Structural changes in the nanofiber network (scanning and transmission electron microscopies) and the surface chemical composition (X-ray photoelectron spectroscopy) gave insights on the mechanism of adsorption. The results from batch adsorption experiments are fitted to Langmuir, Freundlich, and Sips isotherm models, which indicate a maximum adsorption capacity of 1550 mg/g, the highest value reported so far for any bioadsorbent. Compared to other metals (Zn, Mn, and Cu) and typical ions present in natural aqueous matrices the phosphorylated nanofibers are shown to be remarkably selective to U(VI). The results suggest a solution for the capture of uranium, which is of interest given its health and toxic impacts when present in aqueous matrices. [ABSTRACT FROM AUTHOR]

Cotton gin trash (CGT), a residual lignocellulosic biomass generated during the ginning process of cotton fibres, is proposed for valorization and application in environmental remediation. Taking advantage of its availability and composition, rich in hydroxyl, carboxyl, and carbonyl groups, CGT is studied for its suitability for dye removal. Cotton gin trash films are synthesized using a single-step process with formic acid and tested for methylene blue (MB) adsorption. The morphology, chemical structure, surface area, zeta potential and crystallinity of the films are also reported. The hydroxyl groups in CGT increased by the film preparation and further enhanced the zeta potential of CGT towards the negative direction. Overall, the adsorption process is governed by the physisorption characteristic, where a greater potential difference between CGT and cationic MB improved the dye uptake. The adsorption system is described as favourable, fitting better with Langmuir isotherm model. The maximum adsorption capacity of the CGT films is 209 mg/g, which compares favourably against other reported lignocellulosic materials. Overall, the results indicate the CGT has an enormous potential as an adsorbent material for dye separation from wastewaters. [ABSTRACT FROM AUTHOR]

The specific interaction between carbohydrate binding modules (CBMs) and substrates is of utmost importance due to it affects the biological activity of the parent enzymes and determines the chemo-mechanical properties of protein-cellulose composites. In this investigation, a quartz crystal microbalance with dissipation monitoring was employed to study, in situ and in real-time, the adsorption behaviors, conformational changes and associated thermodynamics that define the specific interactions between type A CBMs (CBM1 and CBM3) and cellulose (crystalline, CNC and nanofibrillated, CNF). CBM1 and CBM3 specifically bind to CNC and CNF substrates, with the CBM3 forming more rigid adsorbed layers at 25 °C. Despite the wide variation in adsorption enthalpy (ΔH) and entropy (ΔS), depending on the experimental conditions, a negative Gibbs free energy (ΔG) was determined from the adsorption isotherms for both CBMs. Particularly, the ΔH and ΔS associated with CBM3 adsorbing on CNF exhibited significant greater values than others due to cellulose chain disorder when swelling. The results further our understandings on the interactions between type A CBMs and cellulose substrates. [ABSTRACT FROM AUTHOR]

The availability of microbially-safe drinking water is a challenge in many developing regions. Due to the well-known antibacterial effect of silver ions, materials used for their controlled release have been widely studied for point-of-use water disinfection. However, even if it is in principle known that chloride anions can suppress the antibacterial efficiency of silver, the majority of previous studies, surprisingly, have not focused on chloride concentrations relevant for freshwaters and thus for practical applications. Here, we prepared low-cost nanocellulose-aluminium oxyhydroxide nanocomposites functionalized with silver nanoparticles. Field samples obtained from Chennai, India were used as a guideline for choosing relevant chloride concentrations for the antibacterial studies, i.e., 10, 90, and 290 ppm. The antibacterial performance of the material against Escherichia coli and Bacillus subtilis was demonstrated and the influence of chloride concentration on the antibacterial effect was studied with E. coli. A 1 h contact time led to bacterial reductions of 5.6 log10, 2.9 log10, and 2.2 log10, respectively. This indicates that an increase of chloride concentration leads to a substantial reduction of antibacterial efficiency, even within chloride concentrations found in freshwaters. This work enables further insights for designing freshwater purification systems that utilize silver-releasing materials. [ABSTRACT FROM AUTHOR]

Correction to: I Nature Communications i https://doi.org/10.1038/s41467-023-41054-7, published online 29 August 2023 The original version of this Article contained an error in Fig. 3, in which a black rectangle overlays the multiphase region of the Figure 3c. This has been corrected in both the PDF and HTML versions of the Article. [Extracted from the article]

Electrospun nanofibers obtained from cellulose acetate before (CA) and after (DCA) deacetylation were used as electrolyte membranes in dye-sensitized solar cells. As holders of the active components of the device and compared to the reference system, the CA and DCA membranes increased the average device efficiency by as much as 14%. The membranes enhanced the charge transfer at the counter electrode (assessed by the Ohmic and charge transfer resistance and corresponding Helmholtz capacitance). Simultaneously, the photoelectrode did not interfere with the performance as measured by the short-circuit current density, open circuit voltage, fill factor and conversion efficiency. Long-term stability tests (light soaking) showed that the CA- and DCA-based solar cells sustain operation for at least 500 h. For long term use and/or to serve as a scaffold for other purposes, DCA performs better than CA. The proposed active electrolyte membranes are expected to open the way toward rapid and continuous assembly of dye sensitize solar cells using cellulose esters. [ABSTRACT FROM AUTHOR]

Abstract: The iridescence displayed by films made from cellulose nanocrystals (CNCs) has long been the subject of fundamental research. This has expanded our understanding of colloidal self-assembly towards the development of advanced materials. However, the application of such findings is less reported for visual designs that exploit structural color. Aesthetic outputs are already in reach, but requires input from trend setters in the design and art industries. In this realm, the CNC-based iridescence uniquely offers broadband, multi-colored reflections through the "coffee ring" effect, which arises upon evaporation-induced self-assembly (EISA). Although this effect has been thoroughly studied in the context of axisymmetric patterns, complex geometries remain to be evaluated for large-scale implementation. This is central to the present efforts, where EISA of CNC suspensions occurred onto non-circular surfaces. We used orientation-dependent contact angle measurements, profilometry and fixed-light source photography to unveil the effect of asymmetric drying fluxes at sharp angles, between 30° and 90°, on CNC particle deposition and resulting color patterns. We also demonstrate the causality between increased capillary fluxes and deposition with the help of modelling via energy minimization of the suspension volume onto a given surface and using the diffusion equation to obtain the local concentration of water vapor during EISA. Lastly, we study the effect of background reflections as well as light and temperature resistance of CNC-based reflectors, both important for any deployment. The results from this multidisciplinary effort, involving applied design, art and colloid chemistry, point to the excellent prospects of CNC films for the development of structured and chromatic patterns.Graphical abstract: [ABSTRACT FROM AUTHOR]

A new chemo-enzymatic treatment is proposed to produce cellulosic fibers suitable for heterogeneous- or homogeneous-phase acetylation. The procedure included enzymatic (laccase-violuric acid) lignin removal from the precursor fibers (unbleached sulfite pulp) followed by hydrogen peroxide treatment. An optional intermediate stage included partial hydrolysis (endoglucanase) to increase fiber reactivity. The obtained “biobleached” fibers were acetylated in the heterogeneous phase with acetic anhydride in nonpolar solvents, yielding various acetyl group contents, depending on the severity of the reaction. The degree of acetylation was highly sensitive to the treatment conditions, mainly the acetic anhydride activity in the system. The results were compared to those obtained after acetylation of commercial, dissolving-grade fibers, used as reference. The effect of the inherent nature of the fibers tested were elucidated as far as hemicellulose content, fiber length, fine content and crystallinity. Acetyl group content of up to 24% were determined after heterogeneous reaction with the chemoenzymatic fibers. The substitution of hydroxyl groups by acetyl moieties resulted in a lower hydrophilicity, as assessed by measurement of the water contact angle. Homogeneous acetylation of the chemo-enzymatic and reference fibers resulted in relatively similar acetyl group content (up to 36 and 33%, respectively). These samples were soluble in acetone and produced transparent films (via solvent casting), with enhanced dry strength and lower hydrophilicity. Overall, it is concluded that the proposed chemo-enzymatic treatment is a feasible alternative for the production of fibers that are suitable for efficient acetylation. [ABSTRACT FROM AUTHOR]

Biobased aerogels were used as environmentally friendly replacement for synthetic polymers as electrolyte carrier membranes in quantum dot-sensitized solar cell (QDSC). Integration of polymeric components in solar cells has received increased attention for sustainable energy generation. In this context, biobased aerogels were fabricated to apply as freestanding, porous and eco-friendly electrolyte holding membranes in QDSC. Bacterial cellulose (BC), cellulose nanofibers (CNF), chitin nanofibers (ChNF) and TEMPO-oxidized CNF (TOCNF) were selected because of their fibrilar structures and water-holding capability to investigate their inherent differences in terms of surface groups and electrostatic charge on the electrolyte redox reaction and the photocell function. BC, CNF, ChNF and TOCNF were selected due to different surface functional groups (hydroxyl, N-acetylglucosamine and carboxyl units) and fibrilar structures that can form highly interconnected and robust network. These aerogels enabled easy handling, effective electrolyte filling and efficient redox reactions, while keeping the solar cell performance on par to that of traditional reference cells without membranes. The aerogel membranes maintained the photocell performance since they took only a very small space of the electrolyte volume, which allowed efficient charge transfer. The results indicated that aerogels did not interfere with the cell operation, as confirmed by quartz crystal microgravimetry with bio-interphases in contact with the polysulfide-based electrolyte. The electrochemical measurements also suggested that the respective functional groups (hydroxyl, N-acetylglucosamine and carboxyl units) did not interfere with the redox reaction of the polysulfide electrolyte. [ABSTRACT FROM AUTHOR]

Seven selected Eucalyptus varieties grown under the same conditions were collected to investigate the relationships between specie type and cellulose composition as well as structural and thermo-chemical properties. This systematic investigation used E. badjensis, E. benthamii, E. dunnii, E. globulus, E. nitens, E. smithii and two hybrids, E. nitens × E. globulus, from which holocellulose and alpha-cellulose were isolated. The results indicated no significant correlation between the molecular fingerprints and higher order structural features (crystallinity via X-ray diffraction, CrI XRD). Compared to the cellulosic source, the same techniques revealed higher CrI for the isolated holocellulose. The opposite applied to the CrI of alpha-cellulose. CrI spanned the range between 39 and 55%, and crystallite sizes spanned 1.8–4.4 nm range. The cellulose from the Eucalyptus samples displayed distinctive chemical fingerprints and thermal degradation (thermogravimetric analysis, TGA), the latter of which occurred in a wide range of temperature, between 338 and 369 °C. Most remarkably, a significant correlation was observed between CrI XRD and TGA from the wood samples. Moreover, the thermal degradation of alpha-cellulose correlated strongly with the crystallite size. In wood and holocellulose samples, E. badjensis and E. smithii showed the lowest CrI and thermal degradation of cellulose, while En × Eg hybrids showed the highest values. Alpha-cellulose from E. dunni underwent the highest thermal degradation and E. smithii displayed the highest CrI. Such differences are expected to be relevant to the processing and quality of cellulose derivatives, a subject that is yet to be evaluated. [ABSTRACT FROM AUTHOR]

We report a facile approach to tailor the wettability of ligno-cellulosic substrates via photo-induced thiol-yne click coupling. First, cellulosic surfaces were functionalized with 4-pentynoic acid to introduce terminal alkyne moieties for the subsequent photo-induced coupling in heterogeneous phase. Next, the (primed) surfaces were reacted with various thiol-containing molecules to systematically tailor the surface energy. Finally, the method was applied to nanocellulose films and paper to develop micro-patterned surfaces via UV lithography, endowing the substrates with thin hydrophilic channels (~ 250 μm thickness) and hydrophobic boundaries between neighboring water droplets, as small as 100 μm in width. Overall, we propose thiol-click as a facile method toward spatially-resolved wetting that enables paper-based electronics in smart labels and point-of-care bioplatforms. [ABSTRACT FROM AUTHOR]

Among the most abundant biopolymers in the biosphere, lignin represents an untapped opportunity to create novel bioproducts. In this article, we discuss possibilities to synthesize nano- and microparticles by harnessing lignin’s inherent tendency to associate and to develop new material compositions and functions by controlling its capacity to assemble into supramolecular structures. Because lignin is biodegradable, antimicrobial, antioxidative, and carbon neutral, inexpensive industrial lignin streams could generate value-added particulate materials that preserve the structure, composition, and colloidal features inherent to this macromolecule. We present available routes for synthesis or isolation of lignin particles, including antisolvent and aerosol processing. Metallic and polymeric lignin particle hybrids for magnetic, antibacterial, catalytic, photonic, and other applications are also discussed. Overall, the facile formation of nano- and microparticles from lignins is expected to open new pathways toward future material development. [ABSTRACT FROM AUTHOR]

Nanocellulose has been used with promising results as reinforcement material in composites, many of which include hydrophobic polymers. However, the hydrophilic nature of nanocellulose can be better exploited in composites that incorporate high surface energy systems as well as in applications that can benefit from such properties. In fact, proteins can be ideal components in these cases. This paper reviews such aspects, which are based on the remarkable mechanical properties of nanocellulose. This material also exhibits low density, high aspect ratio, high surface area, and can be modified by substitution of its abundant hydroxyl groups. It also shows biocompatibility, low toxicity, and biodegradability. Convenient biotechnological methods for its production are of interest not only because of the possible reduction in processing energy but also because of positive environmental aspects. Thus, enzymatic treatments are favorable for effecting fiber deconstruction into nanocellulose. In addition to reviewing nanocellulose production by enzymatic routes, we discuss incorporation of enzyme activity to produce biodegradable systems for biomedical applications and food packaging. Related applications have distinctive features that take advantage of protein–cellulose interactions and the possibility of changing nanocellulose properties via enzymatic or protein treatments. [ABSTRACT FROM AUTHOR]

Microfibrillated celluloses (MFCs) with diameters predominantly in the range of 10-100 nm liberated from larger plant-based fibers have garnered much attention for the use in composites, coatings, and films due to large specific surface areas, renewability, and unique mechanical properties. Energy consumption during production is an important aspect in the determination of the 'green' nature of these MFC-based materials. Bleached and unbleached hardwood pulp samples were processed by homogenization, microfluidization, and micro-grinding, to determine the effect of processing on microfibril and film properties, relative to energy consumption. Processing with these different methods affected the specific surface area of the MFCs, and the film characteristics such as opacity, roughness, density, water interaction properties, and tensile properties. Apparent film densities were approximately 900 kg/m for all samples and the specific surface area of the processed materials ranged from approximately 30 to 70 m/g for bleached hardwood and 50 to 110 m/g for unbleached hardwood. The microfluidizer resulted in films with higher tensile indices than both micro-grinding and homogenization (148 Nm/g vs. 105 Nm/g and 109 Nm/g, respectively for unbleached hardwood). Microfluidization and micro-grinding resulted in films with higher toughness values than homogenization and required less energy to obtain these properties, offering promise for producing MFC materials with lower energy input. It was also determined that a refining pretreatment required for microfluidization or homogenization can be reduced or eliminated when producing MFCs with the micro-grinder. A summary of the fiber and mechanical energy costs for different fibers and processing conditions with economic potential is presented. [ABSTRACT FROM AUTHOR]

Self-bonding boards were manufactured with treated fibers at different concentrations of a laccase enzyme. This enzyme induced the generation of phenoxy radicals in the fiber lignin which can generate covalent bonds and cross-linked by radical-radical coupling. The effect of laccase concentration on the properties of obtained fiberboards was evaluated. The formation of free radicals and changes in the lignin macromolecule was measured using scavenging activity test, infrared spectroscopy, electron paramagnetic resonance and scanning electron microscopy. Thermal and mechanical properties of the resulting fiberboards were determined by differential scanning calorimetry, thermo gravimetric analysis and flexion tests. Increased thermal stability, modulus of elasticity and modulus of rupture and also, a reduction in thickness swelling and water absorption, were observed at higher concentrations of laccase. These results are ascribed to the effect of the free radicals that were generated during the enzymatic treatment. [ABSTRACT FROM AUTHOR]

The interactions with water and the physical properties of microfibrillated celluloses (MFCs) and associated films generated from wood pulps of different yields (containing extractives, lignin, and hemicelluloses) have been investigated. MFCs were produced by combining mechanical refining and a high pressure treatment using a homogenizer. The produced MFCs were characterized by morphology analysis, water retention, hard-to-remove water content, and specific surface area. Regardless of chemical composition, processing to convert macrofibrils to microfibrils resulted in a decrease in water adsorption and water vapor transmission rate, both important properties for food packaging applications. After homogenization, MFCs with high lignin content had a higher water vapor transmission rate, even with a higher initial contact angle, hypothesized to be due to large hydrophobic pores in the film. A small amount of paraffin wax, less than 10%, reduced the WVTR to a similar value as low density polyethylene. Hard-to-remove water content correlated with specific surface area up to approximately 50 m2/g, but not with water retention value. The drying rate of the MFCs increased with the specific surface area. Hornified fibers from recycled paper also have the potential to be used as starting materials for MFC production as the physical and optical properties of the films were similar to the films from virgin fibers. In summary, the utilization of lignin containing MFCs resulted in unique properties and should reduce MFC production costs by reducing wood, chemical, and energy requirements. [ABSTRACT FROM AUTHOR]

Coagulation is a critical process in the assembly of cellulose nanofibrils into filaments by wet spinning; however, so far, the role of the coagulation solvent has not been systematically elucidated in this context. This work considers organic non-solvents (ethanol, acetone) and aqueous electrolyte solutions (NaCl(aq), HCl(aq), CaCl2(aq)) for the coagulation of negatively charged cellulose nanofibrils via wet spinning. The associated mechanisms of coagulation with such non-solvents resulted in different spinnability, coagulation and drying time. The properties of the achieved filaments varied depending strongly on the coagulant used: filaments obtained from electrolytes (using Ca2+ and H+ as counterions) demonstrated better water/moisture stability and thermomechanical properties. In contrast, the filaments formed from organic non-solvents (with Na+ as counterions) showed high moisture sorption and low hornification when subjected to cycles of high and low humidity (dynamic vapor sorption experiments) and swelled extensively upon immersion in water. Our observations highlight the critical role of counter-ions and non-solvents in filament formation and performance. Some of the fundamental aspects are further revealed by using quartz crystal microgravimetry with model films of nanocelluloses subjected to the respective solvent exchange. [ABSTRACT FROM AUTHOR]