Bioproducts Institute

Insights into the effect of dilute acid, hot water and alkaline pretreatment on the cellulose accessible surface area and the overall porosity of <italic>Populus</italic>.

The demand for biodegradable materials across various industries has recently surged due to environmental concerns and the need for the adoption of renewable materials. In this context, lignin has emerged as a promising alternative, garnering significant attention as a biogenic resource that endows functional properties. This is primarily ascribed to its remarkable origin and structure that explains lignin's capacity to bind other molecules, reinforce composites, act as an antioxidant, and endow antimicrobial effects. This review summarizes recent advances in lignin-based composites, with particular emphasis on innovative methods for modifying lignin into micro and nanostructures and evaluating their functional contribution. Indeed, lignin-based composites can be tailored to have superior physicomechanical characteristics, biodegradability, and surface properties, thereby making them suitable for applications beyond the typical, for instance, in ecofriendly adhesives and advanced barrier technologies. Herein, we provide a comprehensive overview of the latest progress in the field of lignin utilization in emerging composite materials.

The recalcitrance of natural<italic>Populus</italic>variants was elucidated.

Poplar organosolv lignins were investigated for structural changes after rheology treatment as a carbon fiber precursor.

Fluorescent and thermo-responsive cellulose nanocrystals (CNCs) with tuned polymer brushes were prepared <italic>via</italic> surface initiated activators generated by electron transfer for atom transfer radical polymerization.

Interactions of sub-micron lignin particles dependent on precursor kraft lignin chemistry and molecular weight.

It has been known that the yield of lignin monomers during lignin depolymerization is limited by the irreversible condensations of lignin in the fractionation and/or depolymerization process. In this study, we report a new oxidative catalytic fractionation (OCF) process with a simple and effective one-pot but two-step approach to depolymerize lignin to lignin-derived chemicals (LDCs) using polyoxometalate (POM) as the only catalyst. First, the POM effectively catalyzed the methoxylation of the active α-OH groups of lignin in a methanol and water mixture at low temperature (100 °C), and 96% of the stabilized lignin in the lignocellulose sawdust was extracted to the solution simultaneously. Then the lignin solution was heated to an elevated temperature (140 °C) in the same solvent. As a result, 74.0 wt % of the lignin (based on the weight of the Klason lignin in the wood) was converted to LDCs, including 45.9 wt % aromatic monomers.

Oleophobic paper with tunable hydrophilicity is fabricated by varying the concentration of polar groups using non-fluorinated coating materials.

The surfaces of covalent adaptable network polymers can be welded together through bond exchange reactions occurring at the interface, resulting in new bonds crossing the interface and connecting the two materials.

), while being stable in the wet state (50% of dry strength), which warrants consideration as biobased absorbent systems. In addition, according to cell proliferation and viability of rat cardiac myoblast H9c2 and mouse bone osteoblast K7M2, the wet-spun ChNF microfibers showed excellent results and can be considered as fully safe for biomedical uses, such as in sutures, wound healing patches and cell culturing.

A series of composite films based on tetragonal barium titanate (BTO) and cellulose nanofibrils (CNF) with high dielectric constant are prepared using a casting method in aqueous solution. No organic solvent is involved during the preparation, which demonstrates the environmental friendliness of the novel material. With less than 30 wt% of filler loading, the excellent distribution of BTO nanoparticles within the CNF matrix is revealed by the FE-SEM images. The dielectric constant of the CNF/BTO (30 wt%) composite film reaches up to 188.03, which is about seven times higher than that of pure CNF (25.24), while the loss tangent only rises slightly from 0.70 to 1.21 (at 1 kHz). The thin films kept their dielectric properties on an acceptable level after repeatedly twisting or rolling 10 times. The improvement of thermal stability is observed with the presence of BTO. The outstanding dielectric properties of the CNF/BTO composite film indicates its great potential to be utilized in energy storage applications.

calculations suggesting that newly created M-OH terminations on the cellulose nanofibrils increase hydrogen bond strength between fibers and impede CNF hydration and dispersion. ALD treated nanopapers are also found to preferentially transport hexane over water, suggesting their potential use in oil/water demulsification devices.

Populus natural variants have been shown to realize a broad range of sugar yields during saccharification, however, the structural features responsible for higher sugar release from natural variants are not clear. In addition, the sugar release patterns resulting from digestion with two distinct biological systems, fungal enzymes and Clostridium thermocellum, have yet to be evaluated and compared. This study evaluates the effect of structural features of three natural variant Populus lines, which includes the line BESC standard, with respect to the overall process of sugar release for two different biological systems. Populus natural variants, SKWE 24-2 and BESC 876, showed higher sugar release from hydrothermal pretreatment combined with either enzymatic hydrolysis or Clostridium thermocellum fermentation compared to the Populus natural variant, BESC standard. However, C. thermocellum outperformed the fungal cellulases yielding 96.0, 95.5, and 85.9% glucan plus xylan release from SKWE 24-2, BESC 876, and BESC standard, respectively. Among the feedstock properties evaluated, cellulose accessibility and glycome profiling provided insights into factors that govern differences in sugar release between the low recalcitrant lines and the BESC standard line. However, because this distinction was more apparent in the solids after pretreatment than in the untreated biomass, pretreatment was necessary to differentiate recalcitrance among Populus lines. Glycome profiling analysis showed that SKWE 24-2 contained the most loosely bound cell wall glycans, followed by BESC 876, and BESC standard. Additionally, lower molecular weight lignin may be favorable for effective hydrolysis, since C. thermocellum reduced lignin molecular weight more than fungal enzymes across all Populus lines. Low recalcitrant Populus natural variants, SKWE 24-2 and BESC 876, showed higher sugar yields than BESC standard when hydrothermal pretreatment was combined with biological digestion. However, C. thermocellum was determined to be a more robust and effective biological catalyst than a commercial fungal cellulase cocktail. As anticipated, recalcitrance was not readily predicted through analytical methods that determined structural properties alone. However, combining structural analysis with pretreatment enabled the identification of attributes that govern recalcitrance, namely cellulose accessibility, xylan content in the pretreated solids, and non-cellulosic glycan extractability.

BACKGROUND: There are many different types of pretreatment carried out to prepare cellulosic substrates for fermentation. In this study, one- and two-stage hydrothermal pretreatment were carried out to determine their effects on subsequent fermentations. The two substrates were found to behave differently during fermentation. The two substrates were then characterized using physical and chemical parameters. RESULTS: The one-stage substrate was found to have higher carbohydrate content and lower lignin content. It exhibited a higher level of viscosity, a larger settled volume, and a slower settling time than the two-stage substrate. It also showed higher polarity and reduced crystallinity. Glycome profiling showed physical differences between the two substrates, specifically pointing toward higher levels of pectin and hemicellulose in the one-stage substrate (MS1112) as compared to the two-stage substrate (MS1107). CONCLUSIONS: We hypothesize that these physical and chemical differences between the substrates contribute to the differences seen during fermentation including: ethanol yield, ethanol titer, fermentation rate, fermentation completion time, mixing, and substrate solubilization. These findings can be used in optimizing pretreatment parameters to maximize ethanol conversion and overall process yield for hardwood substrates.

By using a designed mixture of zeolites (Y and mordenite), the upgraded pyrolysis oil exhibited the advantages caused from both zeolites, which represents a biofuel precursor has a very low molecular weight (70–170 g mol⁻¹) and a low acidity.

We present the preparation, morphological analysis, and rheological characterization of ultra-low solid content gels prepared by physically cross-linking TEMPO-oxidized cellulose nanofibrils (TEMPO-CNF) with the soluble plant-cell-wall polysaccharide, mixed-linkage β-glucan (MLG). Of particular note, gel formation was rapidly induced by very small amounts of MLG (e.g. 0.125% w/v) at extremely low TEMPO-CNF concentration (0.05% w/v), which independently were otherwise fluid and thus easily handled. Rheology of these bionanocomposite gel systems as a function of MLG and TEMPO-CNF concentrations revealed that the critical gel concentration of MLG and TEMPO-CNF followed a power-law relation of the concentration of the other component. Surprisingly, these systems also exhibited an additional transition to thick gels at high TEMPO-CNF and MLG concentrations that was visible only at low frequencies. Cryogenic scanning electron microscopy (cryo-SEM) imaging of admixture solutions and gels revealed increased network crowding with increasing MLG amounts. The data are consistent with the hypothesis that non-covalent cellulose-MLG interactions, analogous to those occurring within plant cell walls, drive gel formation. The ability to tune gel physical properties simply by controlling CNF (a promising forest bioproduct) and MLG (a readily available agricultural polysaccharide) fractions at very low solid and polymer content opens new possibilities for material applications in diverse industries.

Moisture-driven actuators featuring programmable stimuli-responsiveness and a rapid response have garnered substantial research attention. Cellulose-based actuators face challenges, including prolonged and unstable responsiveness, along with inadequate interfacial bonding. Herein, we developed a bilayer structured moisture actuator by integrating multiscale cellulose fibers with chitosan. The protonated chitosan forms strong electrostatic attractions with negatively charged cellulose nanofibrils (CNF), achieving a robust interfacial interaction. Leveraging the hierarchically porous structure and varying hygroscopicity of microfibrillated cellulose (MFC) and CNF, the film establishes an effective wettability gradient, enabling a stable and rapid moisture actuation performance. The bilayer film exhibits large deformation toward moisture with a bending angle of 60°, a short response time of 12 s, good stability over 50 wetting and drying cycles, and promising recyclability. Harnessing these advantageous properties, the bilayer film was demonstrated for its applications in automatic cooling textiles, contactless electrical switches, and artificial moisture-activated muscles, showing great potential for practical use.

The immuno-oncology-microbiome (IOM) axis, referring to the gut microbiota-regulated immune interactions on the tumor microenvironment and systemic immunity, is essential for cancer therapies. However, the cytotoxicity of chemotherapeutic agents (Chemos) disrupts the gut microbiota- and gut microbiota-manipulated IOM axis, further diminishing the therapeutic efficacy. Here, we developed oral nanoarmored live bacterial biotherapeutics (supraLBT), to reshape the tumor microenvironment and enhance chemotherapy via reestablishing the IOM axis. The cyto-adhesive polyphenol-based supraparticles, made from green tea polyphenol and food-grade milk protein, attached on microbes (Escherichia coli Nissle1917, EcN) resisted a range of clinically relevant Chemos via phenolic-mediated noncovalent interactions, enhancing supraLBT survival by 27-fold compared with bare EcN. SupraLBT restored the intestinal microbiota and the disrupted IOM axis, thereby reducing the infiltration of regulatory T cells, increasing the recruitment of cytotoxic CD8+ T cells to the tumor bed, and further inhibiting tumor proliferation and demonstrating enhanced systemic immune responses. Notably, oral supraLBT combined with chemotherapy (doxorubicin) exhibited 2.35-fold greater tumor regression than that of doxorubicin alone, indicating that oral supraLBT can enhance the chemotherapeutic effect. Further investigations revealed that supraLBT reprogrammed the immune tumor microenvironment by upregulating antitumor cytokines and altering the gut microbial composition. Given the intricate interplay between gut microbiota, host immune system, and tumor microenvironment, this work presents a facile and biomaterial-engineered microorganism-based strategy to enhance the synergistic immuno-chemotherapy effects.

Jet fuel is relatively small in terms of energy consumption and carbon dioxide emissions (10% of U.S. transportation sector in 2021, expected to increase to 14% by 2050). Still airlines have ambitious goals to reduce their greenhouse footprints from carbon-neutral growth beginning this year to reducing greenhouse gas emission for international flights by 50% by 2050 compared to 2005 levels. The challenge is heightened by the longevity of the current fleet (30–50 years) and by the difficulty in electrifying the future fleet because only 5% of the commercial aviation greenhouse gas footprint is from regional flights that might, conceivably be electrified using foreseeable technology. Therefore, large amounts of sustainable aviation fuel will be needed to reach the aggressive targets set by airlines. Only 3 million gallons (11.4 ML) of sustainable aviation fuel (SAF) (with a heat of combustion totaling about 400 TJ = 0.0004 EJ) was produced in the U.S. in 2019 for a 26 billion gallon per year market (3.6 EJ/year). Fischer-Tropsch and ethanol oligomerization (alcohol-to-jet) are considered for producing SAF, including the use of renewable electricity and carbon dioxide. In sequencing the energy transition, cleaning the U.S. grid is an important first step to have the largest greenhouse gas emissions reduction. While carbon dioxide and clean electricity can potentially provide the SAF in the future, an ethanol oligomerization option will require less energy.

We have observed intriguing stick-slip behavior during capillary pressure driven filling of borosilicate microtubes coated with hydrogel on their inner wall. Swelling of hydrogel upon exposure to a translating waterfront is accompanied by "stick-and-slip" motion. This results in the macroscopic filling velocity for water penetration into glass capillaries coated with poly(N-isopropylacrylamide) (PNIPAM) being constant throughout the filling process, and reduced by three orders of magnitude when compared to filling of uncoated capillaries. A simple scaling analysis is used to introduce a possible explanation by considering the mechanisms responsible for pinning and unpinning of the contact line. The explanation assumes that the time scale for water diffusion into a hydrogel film and the resulting swelling/change of the local meniscus contact angle define the duration of each "stick" event. The "slip" length scale is in turn established by the elastocapillary deformation of dry hydrogel at the pinning point of the contact line. The sequential dynamics of these processes then determine the rate of water filling into a swelling capillary. Collectively, these experimental and theoretical results provide a new conceptual framework for liquid motion confined by soft, dynamically evolving polymer interfaces, in which the system creates an energy barrier to further motion through elasto-capillary deformation, and then lowers the barrier through diffusive softening. This insight has implications for optimal design of microfluidic and lab-on-a-chip devices based on stimuli-responsive smart polymers.