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Exoglucanases are key enzymes required for the efficient hydrolysis of crystalline cellulose. It has been proposed that exoglucanases hydrolyze cellulose chains in a processive manner to produce primarily cellobiose. Usually, two functional modules are involved in the processive mechanism: a catalytic module and a carbohydrate-binding module (CBM). In this report, single molecule tracking techniques were used to analyze the molecular motion of CBMs labeled with quantum dots (QDs) and bound to cellulose crystals. By tracking the single QD, we observed that the family 2 CBM from Acidothermus cellulolyticus ( AcCBM2) exhibited linear motion along the long axis of the cellulose fiber. This apparent movement was observed consistently when different concentrations (25 μM to 25 nM) of AcCBM2 were used. Although the mechanism of AcCBM2 motion remains unknown, single-molecule spectroscopy has been demonstrated to be a promising tool for acquiring new fundamental understanding of cellulase action. [ABSTRACT FROM AUTHOR]

The recalcitrance of plant cell wall lignocellulosic biomass to deconstruction is a major hurdle to sustainable biofuel/bioproduct economy. A multitude of interactions stabilize lignocellulosic biomass structure. Among these, tight packing of hemicellulose-cellulose is partly responsible for biomass recalcitrance. Here, unrestrained molecular dynamics simulations are employed to understand the influence of the nature and pattern of naturally-occuring acetyl decorations of the xylan backbone on interactions with the (100) hydrophobic cellulose surface. Periodically O2-acetylated xylan (2AcX) assume twofold helical screw conformations that are stabilized by a combination of multiple hydrophobic contacts and hydrogen bonds with the hydrophobic cellulose surface. In contrast, acetylation at the O3 position in xylan obstructs interactions, thereby adopting threefold helical screw conformations that potentially preferably interact with lignin rather than cellulose. Fully acetylated xylan desorbs from the surface implying a minimum number of unsubstituted residues on the xylan backbone is required for interaction with the surface. The substituted residues must form ~ 20% fewer contacts than the unsubstituted residues to sustain stable twofold helical screw xylan conformations on the cellulose surface. Thus, specific roles of macromolecular conformations of cellulose and hemicellulose in influencing the supramolecular interactions and function of plant cell walls have been determined. [ABSTRACT FROM AUTHOR]

This work deals with enhancing the rice straw as precursor of cellulose-based nanoparticles in further application in production of nanogels for prolonging the bioactive compound (Carvedilol drug) release time (sustained release), till the release of the drug is continuous and useful, with minimal side effects. The benefit of the investigated nanogels was proved from comparing their sustaining release with patent and literature data. The nanogels were synthesized from chelating of cellulose-nanoparticles (ONC) in hybrid with palm extract (PE) by chitosan. The effective role of pulping reagent to prepare the pulp precursor of ONC was also assessed. The ONCs were prepared from different RS-pulp precursors, using soda, soda-anthraquinone-borohydride and AcOH-organosolv pulping reagents. FT-IR, SEM, non-isothermal TGA and swelling behavior of nanogels, in addition to their in vitro release of drug and kinetics were studied. The data showed that incorporating the PE to ONCs, especially from alkaline pulp-produced nanogels with highestsustaining behavior, where at 5 h the release % was decreased from ~ 50 to 33% and provided 50% CAR release at 24 h. This time was greater than reported by literature on using other drug carriers (10–18 h), which will stimulate the reduction of the number of doses. Almost all PE-containing gels followed the zero-order kinetic release. [ABSTRACT FROM AUTHOR]

Cellulose materials do not possess any inherent antibacterial properties, which greatly limits their application in medical and food packaging fields. Antibacterial cellulose-based materials offer exciting properties and functionalities. However, they are normally prepared by using unstable physically absorbed or complicated chemically grafted antibacterial agents under harsh conditions. Herein, an eco-friendly and simple strategy is performed to fabricate long-term antibacterial cellulose-based materials. Initially, cellulose fibers (CFs) were modified by sodium periodate (NaIO4) generating dialdehyde cellulose fibers (DCFs). Afterward, the 4-aminocinnamic acid was chemically grafted onto the DCFs yielding antibacterial CFs through Schiff base reaction. The 4-aminocinnamic modified DCFs (C-DCFs) exhibited excellent antibacterial activity against S. aureus and E. coli, with inhibition ratios greater than 99.6% and 99.0%, respectively. Quite encouragingly, the C-DCFs presented long-term antibacterial effectiveness, maintaining 99% antibacterial ratio after two months of exposure to the air environment. Therefore, grafting 4-aminocinnamic acid onto the CFs endowed the CFs with robust and sustained antibacterial properties that would make the material advantageous for use in relevant applications. Our strategy is efficient, green, easy to operate both in the work-up stage and purification, in conformity to principles of green chemistry. [ABSTRACT FROM AUTHOR]

This study is focused on the characterization of bacterial cellulose (BC) produced by Komagataeibacter xylinus strains DSM 2325, DSM 2004, and DSM 46604 from styrene/glucose mixtures. Styrene, the aromatic monomer of petrochemical plastics such as polystyrene, served as a co-substrate for bacterial cultivation, being assimilated by all strains, although with differing efficiency for BC biosynthesis. The best performing strain was K. xylinus DSM 2325 with a BC production of 2.70 ± 0.4 g/L. Interestingly, K. xylinus DSM 2004 produced BC from styrene as the sole carbon source, yielding 0.32 ± 0.02 g/L BC. The presence of styrene in the cultivation media had a minor influence on the produced BC chemical structure, thermal degradation temperature (318–337 °C), and morphology, where compact fibers of diameters ranging from 31 to 47 nm were observed. The crystallinity index of the samples was obtained through X-ray diffraction and showed that values varied according to the medium used (41–33%). However, the membranes synthesized in the presence of styrene were thinner (3–22 μm) than those produced from glucose (12–44 μm) and had low gas permeability. K. xylinus DSM 2325 and DSM 2004 membranes had also low permeability for O2 (1.1–2.5 barrer) and CO2 (2.5–5.8 barrer), while those produced by K. xylinus DSM 46604 had a higher permeability to CO2 (42.3 barrer) together with low permeability to O2 (2.5 barrer). Moreover, BC produced by K. xylinus DSM 2325 with styrene as an additive showed the highest crystallinity among all strains and mediums (46%). These results show the feasibility of using styrene as an effective co-substrate in a sustainable approach for its valorisation into a value-added biopolymer, with the advantage of tuning BC properties according to the envisaged application, by selecting the appropriate producing strain and culture medium. [ABSTRACT FROM AUTHOR]

Lytic polysaccharide monooxygenases (LPMOs) catalyze the oxidation of β-(1,4)-linked polysaccharides, such as cellulose, in a reaction that requires an electron donor and H2O2 as co-substrate. Several LPMOs include a carbohydrate-binding module (CBM), which promotes action on insoluble substrates. Herein, a fluorescent labeling technique was used to track LPMO action on microcrystalline cellulose and evaluate the impact of CBMs on the distribution of LPMO activity across the fiber surface. Confocal microscopic images revealed that the distribution of oxidized positions on the cellulose surface was CBM-dependent: fluorescent spots were concentrated in reactions with a CBM-containing LPMO whereas they were more dispersed for a CBM-deficient LPMO variant. The more dispersed oxidation pattern for the CBM-free LPMO coincided with the release of fewer soluble reaction products. [ABSTRACT FROM AUTHOR]

Healthy and sustainable solutions achieve remarkable interest to guarantee the freshness and quality of food products through packaging. Currently, packaging materials used in the food industries depend highly on non-degradable materials and thus cause environmental damage. Ideal packaging materials require outstanding mechanical and barrier properties without causing any damage to the packed items. In this sense, biodegradable nanomaterials with good antibacterial performance have much significance in the packaging industry. This review focuses on the growing field of nanocellulose-based packaging materials including the various cellulosic particles reinforced composites. Though cellulose-based materials report high mechanical strength, barrier resistance, and biodegradability, sometimes the antibacterial performance and industrial scaling up of the products are compromised. Therefore, the review aims in exploring the major challenges existing in the field, through a systematic but comprehensive study of existing research studies in the field. [ABSTRACT FROM AUTHOR]

Poly(butylene adipate-co-terephthalate)/polylactide (PBAT/PLA) blend nanocomposites containing cellulose nanocrystals (CNCs) are very attractive because all components are biodegradable. In most cases, PLA is rich phase with ductile PBAT as toughening agent and rigid CNCs as reinforcement. If PBAT would be the continuous phase, the roles of CNCs need redefinition. In this work, pristine and modified CNCs were introduced into PBAT/PLA (80/20) blend to prepare ternary composites for the study. The elongation is highly improved in the presence of modified CNCs and strength is well maintained. The CNCs selectively dispersed in PBAT matrix enhance cavitation before PBAT yield. In the yield process, the presence of PLA domains favors delamination of PBAT ligaments, promoting fibrillation of PBAT matrix, and with the development of plastic deformation, the PBAT/PLA interfaces anchored by the interfacially localized CNCs further enhance distortion of the fibrils, contributing to the improved ductility. Therefore, the CNCs act as plasticizer in the PBAT/PLA blend with rich PBAT phase. This work proposes a new role of CNCs in the immiscible polymer blends as plasticizer, and provides interesting information on tailoring plasticity of biodegradable polymer blend composites with rich phase of ductile polymer by regulating the selective localization of CNCs through the hydrophobic modification. [ABSTRACT FROM AUTHOR]

The lack of an alternative universal method for obtaining cellulose nanocrystals (CNCs), that would replace traditional sulfuric acid hydrolysis, encourages researchers to look for new methods and approaches. At the same time, alcoholysis of cellulose has long been known as a method of obtaining various alkyl glycosides and products of their further alcoholysis. In this paper, the authors propose to use controlled alcoholysis of cellulose in a medium of simple alcohols for CNC synthesis. Specifically, in this study, CNCs are prepared by controlled sulfuric acid alcoholysis of sulfate cellulose in a medium of four aliphatic alcohols (methanol, ethanol, propanol, and butanol-1). The paper also discusses the possible mechanism of cellulose alcoholysis during CNC preparation and shows that, in contrast to hydrolysis, cellulose alcoholysis can produce CNCs with a higher yield and under milder conditions (at a lower acid concentration). The physicochemical properties of the CNCs synthesized are studied. On the whole, the properties of the CNCs obtained by alcoholysis and hydrolysis are found out to be similar. However, alcoholysis is shown to produce CNC particles with a higher surface charge, which increases the colloidal stability of aqueous CNC suspensions and can be used to study their liquid crystal properties. Under the given conditions of CNC synthesis in alcoholic media (concentration of sulfate cellulose suspension of 0.025 g/mL, temperature of 50 °C, duration of 2 h), butanol-1 makes it possible to achieve the maximum possible CNC yield of 60%. [ABSTRACT FROM AUTHOR]

Recent studies on the plant cell wall assume that hemicellulosic polysaccharides interact closely with cellulose microfibrils through hydrophobic forces. In contrast, hydrogen bonds, which are still emphasized, play a significant role in stabilizing the conformation of the hemicellulose bound on the cellulose surface. However, there is still no consensus on the nature of the interactions between these polysaccharides and on potential interactions of pectins also with cellulose microfibrils. Since the natural plant cell wall is a very complex system, studies of model systems (in vitro) provide information about the interaction between plant polysaccharides. Adsorption studies, which describe the interactions between non-cellulosic polysaccharides and cellulose, are one of these methods. They help to determine the type of these interactions and characterize the adsorption process. This review aims to summarize the knowledge of the interactions between cellulose and representatives of hemicelluloses and pectins, which was mainly provided by adsorption studies. [ABSTRACT FROM AUTHOR]

Cellulose nanocrystals (CNCs) are commercially produced via hydrolysis by sulfuric acid, resulting in the formation of sulfate half-ester groups on the surface of the nanoparticles. The sulfate half-esters promote good colloidal stability but could affect other properties of the CNCs. To study the impact of the sulfate half-ester groups on the mechanical properties of CNC-natural rubber composites, sodium hydroxide was used as a desulfation agent to partially remove this chemical functionality. Mechanical characterizations revealed that CNCs conferred outstanding mechanical properties to the composites. At the same time, differences in the amounts of sulfate half-ester groups had remarkable consequences for the tensile strength and the dynamic mechanical properties, while the vulcanization properties of the composites were less influenced. [ABSTRACT FROM AUTHOR]

Here we propose a macromolecular approach for developing a composite using collagen and functionalized bacterial cellulose (f-BC) for tissue engineering with improved cell adhesion and an acceptable degradation profile. In this study, the pure bacterial cellulose (BC) synthesized from Acetobacter xylinus using a standard Hestrin–Schramm medium has been functionalized through four different chemical routes. The successful functionalization of BC was primarily evaluated using conductometric titration, attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), X-ray photoelectron spectroscopy, X-ray diffraction, and zeta potential measurements. The nano fibrous surface morphologies of the scaffolds were confirmed using field emission scanning electron microscopy. The porosity and surface area analysis of the scaffolds were carried out using N2 adsorption–desorption using standard BET and BJH methods. Hydrophilicity, comprehensive degradation profile, and buffer uptake ability of the scaffolds were found to be satisfactory for tissue engineering applications. After a series of in vitro characterizations, f-BC treated with amine (positively charged) and f-BC treated with (2,2,6,6-tetramethylpiperidin-1-yl)oxyl (negatively charged) were further selected for composite preparation with collagen and genipin as crosslinker for potential skin and bone tissue engineering. The functionalization process was carried out merely not only to enhance the biological functions of pure BC yet also to introduce sites for grafting other biomolecules to fabricate stable composites. The enhanced cell viability efficacy and non-toxicity were further observed for the proposed f-BC/collagen composite. [ABSTRACT FROM AUTHOR]

Xylans are the most abundant plant heteropolysaccharides and can account for over one-third of the content of cell walls in biomass. Xylans crystallize from dilute aqueous solution into crystal hydrates. Since lignin is closely associated with xylans in cell walls, we investigated the effect of residual lignin on crystal formation. We used β-(1 → 4) xylans from esparto grass, with and without 15% co-precipitated lignin. The xylan sample with lignin formed quasi-hexagonal platelets 605 nm in diameter, which were similar in morphology to those from the delignified xylan preparation. Crystallization, in this case, could serve as a mechanism for acquiring highly homogeneous and purified xylans. We then used Arabidopsis xylans that either contained or were deficient in glucuronic and 4-O-methylglucuronic acid sidechains—from wild-type and gux1/gux2 mutant plant lines, respectively—to test the effect of sidechains on xylan crystallization. We found that sidechains significantly impacted crystal dimensions, as xylans from wild-type Arabidopsis with sidechains formed smaller but highly crystalline nanoscale platelets with an average diameter of 412 nm. Xylans from the Arabidopsis mutant lacking sidechains formed spherulitic superstructures up to 5 microns in diameter. These spherulitic structures could be fragmented into crystallites measuring 46 nm by 27 nm. This study builds upon earlier xylan crystallization research, reporting, for the first time, on the preparation of a nanoparticle other than nanocellulose from a mutant plant line. Xylan hydrate crystals described herein expand the bioproduct repertoire for xylans and show that crystals with varying morphologies can be formed from a variety of xylan structures and purities. [ABSTRACT FROM AUTHOR]

X-ray scattering methods allow efficient characterization of cellulosic materials, but interpreting their results is challenging. By creating molecular dynamics models of cellulose microfibrils and calculating the scattering from them, we investigated how different properties of the structures affect their scattering intensities. We studied the effects of hemicelluloses and crystal size on small-angle and wide-angle X-ray scattering (SAXS, WAXS). Microfibril models with and without surface-bound hemicelluloses were built based on the chemical composition of spruce secondary cell walls. The effect of fibril size was investigated by comparing the scattering from fibrils with 14 to 40 cellulose chains. The hemicelluloses appeared in the SAXS region as an increase in the fibril radius and as a clear contribution of a shell around the fibril. The hemicelluloses also increased the crystal size as determined from the broadening of the 200 diffraction peak of cellulose I β . The SAXS and WAXS analysis provided consistent estimates for the size of the microfibrils, and their special features and challenges were discussed. In particular, the results of 18-chain microfibrils were consistent with prior experimental results. Carrying out the simulations in wet and dry environments had the most pronounced effect on fibrils with a hemicellulose coating. Twisting of the fibril had very little impact on most properties, except for a minor effect on the WAXS peaks. The results allow for more correct interpretation of experimental scattering results, leading to more accurate descriptions of microfibril structures in natural and processed cellulosic materials. [ABSTRACT FROM AUTHOR]

Cellulose is hierarchically arranged to form a sophisticated supramolecular structure. The structural complexity leads to a dilemma where the intrinsic luminescence properties of cellulose itself have not been well understood. In this study, crystalline and amorphous cellulose from tunicate was prepared to investigate the nonconventional photoluminescence property. In cellulose, the crystalline regions are in the form of cellulose nanocrystals (CNCs). After extraction from the original fibers, the CNCs are used in foams, in films made only of CNCs, and also in CNC/PVA films. In those different systems, there are different hydrogen bonding interactions among the hydroxy groups on the CNC surfaces. CNC foam has the strongest fluorescence emission intensity with the highest photoluminescence quantum yield (PLQY 10.94%), but lowest phosphorescence intensity with the shortest phosphorescence lifetime of 178.77 ms. The CNC/PVA films, on the other hand, have the lowest PLQY (5.15%) and longest phosphorescence lifetime (569.38 ms). The results indicate that hydrogen bonding interaction effectively inhibits the motion of hydroxyl groups on the surface of CNCs, which is favor for stronger phosphorescence emission and longer phosphorescence lifetime. Compared with the crystalline cellulose (pulp film), the highly amorphous cellulose (ReAC-Pulp film) exhibits stronger phosphorescence emission intensity and longer lifetime (808.33 ms), with the maximum emission wavelength significantly blue-shifted from 494 nm to 461 nm. This is attributed to the different intra- and intermolecular hydrogen bonding networks of amorphous cellulose and the lack of surface group motion on the nanocrystals. This hydrogen-bond assisted luminescence property may contribute to reveal the complicated supramolecular structure of cellulose materials. [ABSTRACT FROM AUTHOR]

Noncovalent interactions are vitally important to understand the structural stability and molecular assembly of cellulose and its analog molecules. Using density functional theory in conjunction with three popular generations of dispersion correction (D2, D3, D4), we systematically estimate the strength of inter-chain interaction for several β-1,4-linked crystalline polysaccharides (cellulose Iα, Iβ, II, IIII, α-chitin, β-chitin, chitosan) and their building block monomers (glucose, cellobiose). Switching on and off dispersion correction and combining the calculation of condensed and isolated chains allow the extraction of the intra- and inter-chain London dispersion interactions and the inter-chain electrostatic interaction. Regardless of the generations of dispersion correction and allomorphs, the estimated inter-chain London dispersion interaction is 45 ~ 74 kJ/mol per pyranose ring comparable to the inter-chain electrostatic interaction (47 ~ 88 kJ/mol). The upper limit of the strength of inter- or intra-chain hydrogen bonds is estimated to be 27 ~ 50 or 21 ~ 53 kJ/mol, respectively, based on energy profiles of hydroxy rotation. Our work quantitatively highlights that it is the London dispersion interaction rather than the hydrogen bonding interaction dominating in the tight assembly of polymer chains for β-1,4-linked crystalline polysaccharides, regardless of the crystal allomorph and types as well as the generations of dispersion correction of DFT. Thus, London dispersion interaction should be preferentially considered during their deconstruction, defibrillation, or dissolution processes. [ABSTRACT FROM AUTHOR]

Wetting of cellulose by different liquids is interesting from the point of view of the processing of cellulose-based nanomaterials. Here, the contact angles formed by water and several organic liquids on both native and acetylated cellulose were calculated from molecular dynamics simulations. It was found that liquid surface tension was crucial for their wetting behavior. Acetylation decreases the work of adhesion to most liquids investigated, even non-polar ones, while others are not affected. Water has the highest affinity to cellulose, both native and acetylated. The results have implications for liquid infiltration of nanocellulose networks and the interaction of cellulose with different liquids in general. [ABSTRACT FROM AUTHOR]

Abstract: A novel process for the separation of crystalline cellulose in water into single polysaccharide strands is proposed that does not require high temperatures or other chemical reactants. We have modeled the behavior of a 36-strand cellulose Iβ crystalline bundle when subjected to picosecond mid-infrared laser pulses using all-atom non-equilibrium molecular dynamics simulations. We show that mid-infrared laser pulses that induce resonance deformations in the C-O-H angles of the hydroxyl groups that are involved in the hydrogen bonding network of cellulose, rapidly cause the cellulose bundles to dissociate into single strands solvated by the water. The laser pulses selectively disrupt intra- and inter-chain hydrogen bonds that maintain the polysaccharide strands in sheets and bundles, causing cellulose to dissolve into single strands whose end-to-end lengths remain similar to those in the original cellulose crystalline bundle. This proof-of-concept work provides guidance for experiments that may provide insight into the mechanism of cellulase enzymes whose improvement could lead to increased production of ethanol from cellulose, and possibly spur the development of new nanomaterial engineering techniques.Graphical Abstract: [ABSTRACT FROM AUTHOR]

The utilization of cellulosic fibers is becoming increasingly widespread worldwide as promising raw material in polymer composite reinforcement. However, and despite the multiple advantages of cellulosic fibers like the lower density, cheap cost and biodegradability, their use is limited due to hydrophilic character which reduces their affinity with hydrophobic matrices. A natural fiber treatment, whether chemical or physical, is advised to address this issue. The purpose of this study is to characterize the Ampelodesmos mauritanicus plant (AM) fibers extracted by the chemical method (2% NaOH for 48 h) and treated (chemically and physically). We carried out acetylation, mercerization and microwaves modification of the AM plant fibers to reduce their hydrophilic character. The influence of chemical and physical treatments on the structure and morphology of AM plant fibers was characterized by analytical techniques as per International Standard. X-ray diffraction confirmed that the AM fibers have a good crystallinity index (52.4%). Microwave physical treatment at 550 W increased their density from 1.00 to 1.55 g/cm3, their Young's modulus and tensile strength from 11.0 to 18.6 GPa and from 155 to 290 MPa, respectively, giving the highest values. It is followed by chemical treatments: first with acetic anhydride (C4H6O3) for 4 h and then with 3% NaOH also for 4 h. It should be observed that the data have a very considerable dispersion that calls for statistical analysis (method of Weibull with two and three parameters was utilized). [ABSTRACT FROM AUTHOR]

Soybean hulls (SBHs) are one of the main by-products of soybean crushing, usually destined for animal feeding or to become a putrescible waste. In this work, we upgraded the SBHs to materials with antimicrobial properties. After the extraction of soybean peroxidase from SBHs, an enzyme applicable in different technological sectors and naturally present in soybean hulls, the exhausted biomass was subjected to an acid–base treatment to isolate cellulose. The obtained material was, in turn, functionalized with 3-aminopropyl triethoxysilane (APTES) to achieve new hybrids with antimicrobial properties. The synthetic procedure was optimized by varying the solvent type (ethanol or toluene) and APTES amount. Overall, the amino-functionalization process was effective and the activity was outstanding against both gram-positive and gram-negative bacteria, reaching complete disinfection practically in all cases. The samples were studied by means of several characterization techniques, demonstrating that the solvent and cellulose types had a significant influence on the physical–chemical features, together with the eco-sustainability of the process. In particular, the use of greener ethanol and waste cellulose (with respect to a commercial one) resulted in a higher APTES immobilization efficiency and superior thermal stability of the final materials. Interestingly, the presence of various unremoved compounds from the lignocellulosic SBH matrix, although in small quantities, emerged as a crucial factor, also in terms of antibacterial activity, hypothesizing a role of residual phytochemicals. [ABSTRACT FROM AUTHOR]

Extraction of cellulose nanocrystals (CNCs) from diverse cellulose sources is a promising and sustainable approach to produce nanocomposites. However, the traditional batch experiments are time/labor-consuming. Hence, three machine learning (ML) algorithms, i.e., decision regression tree, random forest, and artificial neural networks were applied to develop ML models. The dataset collected from published literature was used to train the ML models applicable to a wide range of cellulose source and reaction conditions. Among the three ML models, the random forest algorithm was the best one (R2 = 0.89, RMSE = 5.52) for the yield prediction, and the decision regression tree provided the highest accuracy (R2 = 0.86, RSME = 6.03) for the crystallinity prediction. The concentration of reagent and cellulose source was identified as the most important feature in yield and crystallinity prediction, respectively. The partial dependence analysis showed the impact of each input feature and their combined effects on the yield and crystallinity. This study may provide new perspectives and opportunities to understand and improve the preparation of CNCs. [ABSTRACT FROM AUTHOR]

This study reports on the preparation of lignin-free wood sections maintaining the anatomical structure of Cryptomeria japonica by means of alcoholysis combined with sodium chlorite treatment. To determine the optimal alcoholysis conditions, Fourier transform infrared spectroscopy was combined with multivariate analysis, and the obtained results indicated that the alcoholysis reaction proceeded over three stages. In the first stage, lignin and hemicellulose are partially removed. In the second stage, hemicellulose and amorphous cellulose are degraded and humin is formed. In the third stage, crystalline cellulose is degraded, further promoting the formation of humin. Since it is difficult to completely remove lignin by alcoholysis alone, the wood sections were subsequently subjected to sodium chlorite treatment. As a result, lignin-free sections were produced without degradation of the woody anatomical structure. Furthermore, alcoholysis at 140 °C for 1 h coupled with sodium chlorite treatment for 1 h succeeded in producing sections composed of essentially hemicellulose-free cellulose. These achievements make this protocol potentially applicable as a substrate for artificial cell walls and for the development of novel functional filters. [ABSTRACT FROM AUTHOR]

The cellulose-water interface is a dynamic environment mostly dominated by interactions between water molecules and hydroxyl groups protruding from the top layer of the polysaccharide chains. This interface has attracted increasing interest within the context of hydrolysis with glycosyl hydrolases, and studies on the role of tightly bound and free water has emerged. At the molecular level, cellulose-bound water has been considered important to allow enzymatic hydrolysis at industrial relevant conditions, i.e. at high dry matter (HDM) contents. In the presence of lytic polysaccharide monooxygenase enzymes, the hydrolysis can with effective yields be run at well beyond the dry matter limit previously set by the 1st generation of enzyme preparations lacking LPMOs. The oxidative cleavage of the cellulose chain performed by LPMOs allow a higher level of synergism with GH in terms of accessibility of the cellulose surface. In this work, we studied how cellulose oxidation by LPMO increases the cellulose-water interaction and the impact of this on cellulose saccharification. Low-field NMR, water constraint and enzyme kinetics at high dry matter contents were used to characterize the cellulose-water interaction and its implications in enzymatic cellulose hydrolysis. [ABSTRACT FROM AUTHOR]

This research work demonstrated that the extraction components from natural fibers (NFs) during microwave-assisted hydrothermal treatment is a selective and controllable method, since the process and the extraction mechanism depend on the dielectric heating (DH) of the lignocellulosic components of NFs, mainly hemicellulose, and cellulose. DH causes hemicellulose degradation, which allows its extraction from the internal part of NFs to the reaction medium (water). Moreover, the cellulose fraction showed high thermal stability; in this regard, the treated fiber (MW-NF) increased its crystallinity percentage from 80.91 to 96.23%, and the thermal degradation temperature shifted from 182 to 240 °C, maintaining its fibrillar morphology even when the fibers present a hollow aspect. Furthermore, a direct relationship between time/energy and extraction percentage was established, which allowed controlling of the final properties of the treated NFs. [ABSTRACT FROM AUTHOR]

Nuclear magnetic resonance (NMR) relaxometry is applied to provide direct measurement of water adsorption in anatomical fractions of corn stover. NMR transverse T2 relaxation time distribution measurements indicate multiple water populations, which vary with anatomical fraction and water adsorption. Measured T2 data are used to calculate thermodynamic properties of Brunauer-Emmet-Teller adsorption theory using a model to estimate mono and bilayer relaxation. T2 data are used directly to determine rotational diffusion correlation times indicating adsorption interaction strength. T1-T2 longitudinal-transverse relaxation time correlation measurements quantify differences in the molecular level structural order of the adsorbate surface water as a function of water activity, i.e. relative humidity or water vapor partial pressure. The T1/T2 ratio provides a measure of the surface energy related to the adsorption strength and surface diffusive mobility of the water adsorbate and differentiates the anatomical fractions. The results indicate that direct measurement of NMR relaxation times can be used to characterize corn stover biomass water adsorption, data relevant to processing and handling considerations. (Length scales from Chundawat et al. (2011)) [ABSTRACT FROM AUTHOR]

Biopolymers that mimic the extracellular matrix are favourable in tissue engineering. However, the rapid degradation and the lack of mechanical and enzymatic stabilities of these biopolymers prompt researchers to composite different biopolymers. In this study, we aim to develop an acellular gelatin-chitosan-cellulose nanocrystal (GCCNC) scaffold as a potential wound dressing. The GCCNC mixture was homogenised via ultrasonication and the genipin crosslinking was performed by magnetic stirring. The mixture was then frozen at − 80 °C for 6 h and freeze-dried. The effects of different ratios of gelatin and chitosan with cellulose nanocrystals on the physiochemical properties, mechanical properties, and cellular biocompatibility were studied. Our results herein showed that G3C7CNC demonstrated a homogenous interconnected porous structure with a good porosity (67.37 ± 9.09%) and pore size (148.46 ± 48.68 µm), acceptable swelling ratio (1071.11 ± 140.26%), adequate water vapour transmission rate (315.59 ± 25.27 g/m2/day), low contact angle (70.21 ± 6.79°), and sufficient mechanical strength (modulus of 64.67 ± 12.42 MPa). The lower biodegradation rate in the G3C7CNC (0.06 ± 0.01 mg/hr) compared to G10CNC (0.48 ± 0.07 mg/hr) together with the absence of glass transition phenomenon indicated an increase in both enzymatic and thermal stabilities. Furthermore, G3C7CNC was non-cytotoxic and biocompatible with human epidermal keratinocytes (HEKs) and human dermal fibroblasts (HDFs). The presence of collagen type I and α-smooth muscle actin expression in HDFs, together with the expression of cytokeratin-14 in HEKs, demonstrated our scaffold's ability to maintain normal skin physiological functions. Therefore, this study proposes that the fabricated GCCNC scaffold could serve as a potential acellular skin substitute in managing chronic wounds. [ABSTRACT FROM AUTHOR]

The low concentration of prepared cellulose nanofibril (CNF) suspension limits its large-scale application. In this study, bleached hardwood kraft pulp without any pretreatment was prepared into a CNF suspension with a concentration of about 1.0 wt% by a Supermasscolloider. The CNF suspension was dewatered by centrifugation to obtain concentrated CNFs (labeled 1-CNF). The 1-CNF sample was then mixed with water and dispersed by a high-speed homogenizer and dewatered again to obtain re-concentrated CNFs (labeled 2-CNF). The results showed that the suspension stability, water retention value and specific surface area of redispersed CNFs decreased compared to the unconcentrated CNFs. The cavities or pores formed by nanofibrils in the dewatering process were evaluated by the content of freezing bound water (FBW) that was calculated by differential scanning calorimetry with an isothermal step melting procedure. Pores were not observed in the starting unconcentrated CNFs, while the pores with a size of 0–395.8 nm were found in the two concentrated CNF samples (1-CNF and 2-CNF). The FBW content of the CNF samples increased as the solid content of the two concentrated CNFs increased. After re-concentration, the FBW content of 2-CNF decreased compared to that of 1-CNF. In sum, the concentration process of CNF suspension promoted the formation of pores and pores with small size formed first. However, in the re-dispersion and re-concentration process, the formed pores partially collapsed and shrunk. [ABSTRACT FROM AUTHOR]

Cellulose from vegetable sources is the most abundant biopolymer on earth. In plants, cellulose is a reinforcement element that conforms to a hierarchical structure. Cellulose micro-/nanofibers can be isolated from the cell wall by top-down strategies involving mechanical processes to be used in applications as a reinforcing material. Nonetheless, its use has been limited as its extraction in an aqueous medium is unfavorable when employed in low-hydrophilic matrices. Therefore, this work proposes a novel homogenization route in which cellulose micro-/nanofibers are directly obtained and dispersed in propylene glycol (PG), which generates more possibilities for these (nano) structures in applications that require water-free environments. Moreover, the influence on the cycle numbers in the morphological, chemical, thermal, and rheological properties was researched. Thus, the obtained micro-/nanofibers presented TEM diameters even below 20 nm. XRD analysis evidenced crystalline planes located at 1 1 ¯ 0 , 110, and 200, and crystallinity degree values up to 80%. Also, FTIR spectra bands in 3340 cm−1, 2890 cm−1, 1314 cm−1, and in the fingerprint region corresponded to native cellulose Iβ. FTIR and TGA confirmed no influence of mechanical cycles on cellulose fibers' chemical and thermal properties. Furthermore, the increase in the cycle number evidenced a shear-thinning rheological behavior of the suspensions. Considering the above results, it was concluded that the proposed high-pressure homogenization within PG is an approach for vegetable nanocellulose homogenization while maintaining high crystallinity, thermal, and chemical features with huge importance for subsequent processes in the development of nanocomposites with hydrophilic matrices for industrial applications. [ABSTRACT FROM AUTHOR]

Nanocellulose has a wide range of applications in the field of functional materials, and it has piqued the interest of researchers for some time. This is because nanocellulose inherits the advantages of environmental friendliness and easy availability of plant cell walls in nature, as well as the unique morphology of nanostructures. This review presents four types of nanocellulose including cellulose nanocrystals (CNCs), cellulose nanofibrils (CNFs), regenerated nanocellulose (RNC) and bacterial cellulose (BC), introduces the different preparation routes and their mechanisms, analyzes the advantages and drawbacks between these approaches, and summarizes the potential applications in the field of functional materials such as reinforced composite materials, biomedical materials, soft templates, and optical materials. Finally, future development directions are proposed including further enrichment of nanocellulose raw materials, improvement of preparation methods to adapt to more diversified raw materials, and classification of products according to their morphology and properties to improve the use efficiency. [ABSTRACT FROM AUTHOR]

The advances in bioprocess design, genetic engineering, and media optimization have enabled enhanced bacterial cellulose (BC) production and its application for diverse purposes. Following the requirements of a bioeconomy, numerous approaches were conducted to investigate alternative carbon or nitrogen sources from industrial by-products for BC biosynthesis. They can, however, not only affect the BC production but also its properties. Beet molasses, vinasse, and waste beer fermentation broth (WBFB) have thus been investigated in single and combined approaches for their BC production potential and effects on structural properties using Komagataeibacter xylinus DSM 2325. Therefore, the composition of each complex component was initially analyzed for total organic carbon (TOC), total bound nitrogen (TNb), sugars, organic acids, and alcohols. The polymer properties were characterized via gel permeation chromatography and X-ray diffraction. In dynamic shake flask cultivations, the exchange of Hestrin-Schramm (HS) medium components for a combination of all three complex substrates on a TOC- or TNb-based quantity resulted in the highest BC concentration (8.2 g L−1). Comparable concentrations were achieved when combining molasses and WBFB (8.1 g L−1). Each investigated complex component led to differing degrees of polymerization (DPn: 2751−4601) and BC crystallinities (26−58%) in comparison to HS medium. Beet molasses and vinasse were found to decrease the polymer crystallinity but induce higher DPn whereas the opposite occurred for WBFB. This study thus highlights beneficial effects of food industry by-products for BC biosynthesis and elucidates concomitantly occurring structural polymer alterations to enable further studies dealing with alternative substrates for structurally tailored BC production. [ABSTRACT FROM AUTHOR]

Hydrogels are a class of materials that have found many applications across society. Petrochemicals are a dominant, but unsustainable feedstock of crosslinked polymer networks that underpin functional hydrogels. Therefore an urgent need exists for sustainable biopolymer replacements, where agricultural by products, such as cellulose prove an ideal source of green hydrogels. These polymers are cheap and environmentally friendly, have excellent water absorption capacity and the products are inherently biodegradable and, most importantly for technical applications, can be easily functionalised. For example, 3-D cross linked hydrogel structures can be optimised by modifying the hydroxy groups of the parent structure into ether and ester derivatives that include additional functional groups. In this regard, carboxymethylcellulose (CMC) has emerged as a promising cellulose derivative as it possesses readily available carboxylic groups along the polymer chain. This property both imparts good water solubility and high chemical reactivity making it an ideal candidate for hydrogel synthesis. This review highlights recent developments in both the preparation and application of CMC based hydrogels. We discuss how the various physical and chemical properties of a range of CMC based hydrogels impinge on key parameters such as water absorption, mechanical strength and biodegradability. Finally, we will discuss key applications and the future potential of CMC hydrogels in various fields. [ABSTRACT FROM AUTHOR]