Multiple covalent modification enables nylon fiber biosensor with robust scrub-resistant and signal-capture ability for multiscenario health monitoring and security warning.

Nylon fibers have great potentials in smart textiles due to their excellent wear resistance, resilience, and chemical stability, whereas poor combination between nylon fibers and conductive materials causes discontinuous signal capture. In this work, nylon fibers/di-aldehyde cellulose nanocrystals/polypyrrole (NFACP) biosensors with robust scrub-resistant and signal-capture ability were fabricated by interfacial multiple covalent reactions. The best NFACP0.2 biosensor exhibited high conductivity (354 S/m), robust mechanical strength and stretching-releasing dynamic durability. Especially, its textile sensors still possessed high sensitivity and excellent sensing performance after repeated washing and friction. Moreover, NFACP0.2 biosensor can be designed into various multifunctional health monitoring and security warning systems for "stress reducing exercise" enthusiasts, high-altitude activities, and deep-sea exploration, demonstating great potentials of conductive nylon fiber biosensor in flexible electronics.

Tragacanth gum hydrogels with cellulose nanocrystals: A study on optimizing properties and printability.

This study investigates a novel all-polysaccharide hydrogel composed of tragacanth gum (TG) and cellulose nanocrystals (CNCs), eliminating the need for toxic crosslinkers. Designed for potential tissue engineering applications, these hydrogels were fabricated using 3D printing and freeze-drying techniques to create scaffolds with interconnected macropores, facilitating nutrient transport. SEM images revealed that the hydrogels contained macropores with a diameter of 100-115 µm. Notably, increasing the CNC content within the TG matrix (30-50 %) resulted in a decrease in porosity from 83 % to 76 %, attributed to enhanced polymer-nanocrystal interactions that produced denser networks. Despite the reduced porosity, the hydrogels demonstrated high swelling ratios (890-1090 %) due to the high water binding capacity of the hydrogel. Mechanical testing showed that higher CNC concentrations significantly improved compressive strength (27.7-49.5 kPa) and toughness (362-707 kJ/m3), highlighting the enhanced mechanical properties of the hydrogels. Thermal analysis confirmed stability up to 400 °C and verified ionic crosslinking with CaCl2. Additionally, hemolysis tests indicated minimal hemolytic activity, affirming the biocompatibility of the TG/CNC hydrogels. These findings highlight the potential of these hydrogels as advanced materials for 3D-printed scaffolds and injectable hydrogels, offering customizable porosity, superior mechanical strength, thermal stability, and biocompatibility.

Structure regulation of oxidized soybean cellulose nanocrystals/poly-acrylamide hydrogel and its application potential in wound dressing.

The development of functional dressings based on natural polysaccharide-based hydrogels remains a great challenge, and the specific roles of gel composition and drug-controlled release mechanisms were unclear. In this study, oxidized soybean cellulose nanocrystals (CNCs)/poly-acrylamide (PAM) hydrogel was prepared. The proportion of CNCs, crosslinkers, and water in the system was regulated to fine-tune the rheological performances, texture properties, transparency, and micro-network structures of CNCs/PAM hydrogel, and further explored its application potential in the field of wound dressings. It was found that CNCs improved the rigidity and adhesion of hydrogels, crosslinkers improved the network density, and water promoted the softening and fluidity of hydrogels. The effective filling of CNCs in the composite hydrogel was verified by FTIR, XRD, and NMR. Furthermore, the pH responsiveness and drug-loading potential of the smart hydrogel were tested by swelling and drug-controlled release experiments, elucidating drug-release dynamic mechanisms during the wound healing process. The inhibition zones (>7 mm) of gram-positive/negative bacteria and cell viability (>100 %) assay showed satisfactory biocompatibility, as the hydrogel effectively accelerated wound healing in a wound model. These results elucidated the regulation mechanism of the structures of CNCs/PAM hydrogel and revealed the application potential of CNCs/PAM hydrogel in wound dressings.

Biorenewable Exfoliation of Electronic-Grade Printable Graphene Using Carboxylated Cellulose Nanocrystals.

The absence of scalable and environmentally sustainable methods for producing electronic-grade graphene nanoplatelets remains a barrier to the industrial-scale application of graphene in printed electronics and conductive composites. To address this unmet need, here we report the utilization of carboxylated cellulose nanocrystals (CNCs) extracted from the perennial tall grass Miscanthus × giganteus as a biorenewable dispersant for the aqueous liquid-phase exfoliation of few-layer graphene nanoplatelets. This CNC-based exfoliation procedure was optimized using a Bayesian machine learning model, resulting in a significant graphite-to-graphene conversion yield of 13.4% and a percolating graphene thin-film electrical conductivity of 3.4 × 104 S m-1. The as-exfoliated graphene dispersions were directly formulated into an aerosol jet printing ink using cellulose-based additives to achieve high-resolution printing (∼20 µm line width). Life cycle assessment of this CNC-based exfoliation method showed substantial improvements for fossil fuel consumption, greenhouse gas emissions, and water consumption compared to incumbent liquid-phase exfoliation methods for electronic-grade graphene nanoplatelets. Mechanistically, potential mean force calculations from molecular dynamics simulations reveal that the high exfoliation yield can be traced back to the favorable surface interactions between CNCs and graphene. Ultimately, the use of biorenewable CNCs for liquid-phase exfoliation will accelerate the scalable and eco-friendly manufacturing of graphene for electronically conductive applications.

Eco-friendly and flexible polysaccharide-based packaging films for fruit preservation.

Food safety and wastage caused by fruit deterioration is a serious global problem. Effective packaging systems for extending the freshness period of fruit play a key role in food safety. In this work, we constructed an eco-friendly and flexible polysaccharide-based packaging film based on hydroxypropyl guar (HPG), cellulose nanocrystals (CNCs), deep eutectic solvents (DES) and anthocyanin (Anth). DES could endow polysaccharide films with multiple hydrogen bond numbers and good stability. Hydroxypropyl guar/cellulose nanocrystals/anthocyanin with 0.2 g deep eutectic solvents (HCA-DES0.2) had good tensile properties, oxygen barrier properties (3.01 cm3/m2·day·Pa), water resistance (WCA 111.97°), antibacterial (CFU ˂ 103), and transparency (55.4 %). The preservation tests of grape and blueberry showed that the shelf life of these two fruits was 12-20 days, and the polysaccharide film had great application potential in fruit preservation.

The Correlations between Microstructures and Color Properties of Nanocrystalline Cellulose: A Concise Review.

Cellulose nanocrystals (CNCs) are a green resource which can produce photonic crystal films with structural colors in evaporation-induced self-assembly; CNC photonic crystal films present unique structural colors that cannot be matched by other colored materials. Recently, the mechanisms of CNC photonic crystal films with a unique liquid crystal structure were investigated to obtain homogenous, stable, and even flexible films at a large scale. To clarify the mechanism of colorful CNC photonic crystal films, we briefly summarize the recent advances from the correlations among the preparation methods, microstructures, and color properties. We first discuss the preparation process of CNCs, aiming to realize the green application of resources. Then, the behavior of CNCs in the formation of liquid crystal phases is studied, considering the influence of the CNCs' size and shape, surface properties, and the types and concentrations of solvents. Finally, the film formation process of CNCs and the control of structural colors during the film formation are summarized, as well as the mechanisms of CNC photonic crystal films with full color. In summary, considering the above factors, obtaining reliable commercial CNC photonic crystal films requires a comprehensive consideration of the subsequent preparation processes starting from the preparation of CNCs.

Rational design of pH-responsive nano-delivery system with improved biocompatibility and targeting ability from cellulose nanocrystals via surface polymerization for intracellular drug delivery.

Cellulose nanocrystals (CNCs), derived from diverse sources and distinguished by their inherent biodegradability, excellent biocompatibility, and facile cellular engulfment due to their rod-like structure, hold great promise as carriers for the development of nano-delivery systems. In this work, highly efficient rod-like CNCs were employed as substrates for grafting glycidyl onto their surfaces through ring-opening polymerization, forming hyperbranched polymers with superior cell uptake properties. Subsequently, 4-vinylbenzeneboronic acid (VB) and poly (ethylene glycol) methyl ether methacrylate (PEGMA) were employed as monomers in the polymerization process to fabricate a pH-responsive targeted nano-delivery system, denoted as CNCs-VB-PEGMA, via single electron transfer reactive radical polymerization (SET-LRP) reaction. The CNCs-VB-PEGMA was successfully prepared and used for the loading of curcumin (Cur) to form a pH-responsive nano-delivery system (CNCs-VB-PEGMA-Cur), and the loading rate of Cur was as high as 70.0 %. Studies showed that this drug delivery system could actively targeting liver cancer cells with the 2D cells model and 3D tumor microsphere model, showing efficient liver cancer cell-killing ability. Collectively, the CNCs-VB-PEGMA drug delivery system has potential applications in liver cancer therapy as an actively targeting and pH-responsive drug delivery system.

Cellulose nanocrystals from agriculture and forestry biomass: synthesis methods, characterization and industrial applications.

Agricultural and forestry biomass wastes, often discarded or burned without adequate management, lead to significant environmental harm. However, cellulose nanocrystals (CNCs), derived from such biomass, have emerged as highly promising materials due to their unique properties, including high tensile strength, large surface area, biocompatibility, and renewability. This review provides a detailed analysis of the lignocellulosic composition, as well as the elemental and proximate analysis of different biomass sources. These assessments help determine the yield and characteristics of CNCs. Detailed discussion of CNC synthesis methods -ranging from biomass pretreatment to hydrolysis techniques such as acid, mineral, solid acid, ionic liquid, and enzymatic methods-are provided. The key physical, chemical, and thermal properties of CNCs are also highlighted, particularly in relation to their industrial applications. Recommendations for future research emphasize the need to optimize CNC synthesis processes, identify suitable biomass feedstocks, and explore new industrial applications.

Lignin-containing cellulose nanocrystals from maple leaves: A natural Pickering emulsion stabilizer for food preservation.

Cellulose nanocrystals have been obtained from maple leaves for stabilizing Pickering emulsions, but a chemical modification is required to improve hydrophobicity and the yield is relatively low due to the removal of non-cellulose components. Herein, lignin was retained while isolating cellulose from maple leaves, and the prepared lignin-containing cellulose nanocrystals (LCNCs) were applied as natural Pickering emulsion stabilizers. Rod-like shaped LCNCs with tunable lignin contents had suitable hydrophobicity and high aspect ratios, resulting in long-term stability of LCNC-stabilized Pickering emulsions. The obtained emulsions provided good encapsulation and protection of cinnamaldehyde, and the controlled release of cinnamaldehyde promoted sustained antibacterial efficacy. Both direct-contact and non-contact preservation modes were investigated for shrimp preservation, where headspace release of cinnamaldehyde from emulsions at non-contact mode was more effective in inhibiting bacterial proliferation compared to direct-contact (spray-coating) mode. This work demonstrates the feasibility of developing value-added LCNCs from maple leaves as sustainable Pickering emulsion stabilizers.

High-tear resistant gels crosslinked by DA@CNC for 3D printing flexible wearable devices.

Photocurable gels have broad application prospects in biomedicine, bionics, flexible wearable devices and other fields. However, there are still some problems in the current photocurable gels, such as notch sensitivity, that is, poor tear resistance. In this study, we provided a photocurable gel with excellent tear resistance. The gel prepolymer is mainly composed of hydroxymethylacrylamide (NAM) and cellulose nanocrystals (CNC) modified with dopamine hydrochloride (DA), referred to as DA@CNC. After photocuring, the prepared gels show excellent mechanical properties such as tear resistance, elasticity and toughness. The introduction of DA@CNC not only endows gels with a large amount of energy dissipation through hydrogen bond crosslinking, but also effectively resists crack expansion as a nano-sized reinforcing phase, which greatly improves the tear resistance of the gels. Even at a 40 % gap, the elongation at break of the gel can still reach 1445 %. In addition, the DA can endow the gel with good electrical conductivity and excellent sensitivity (GF = 23.8). Some flexible wearable devices like finger sleeve and wristband can be customized by photocurable 3D printing using the gel with high toughness. This high-performance gel has great application potential in flexible wearable devices.

Surface modification of cellulose nanomaterials with amine functionalized fluorinated ionic liquids for hydrophobicity and high thermal stability.

A highly hydrophobic fluorinated ionic liquid (IL), 3-aminopropyl-tributylphosphonium bis(trifluoromethylsolfonyl)imide ([aP4443][NTf2]), was synthesized, and applied for the surface modification of cellulose nanomaterials (CNMs) by reductive amination. The modified CNMs were fully characterized for their chemical structure, morphology, thermal stability, and surface hydrophobicity. Results obtained from Nuclear Magnetic Resonance spectroscopy (1H, 13C, 19F and 31P), Fourier Transform Infrared spectroscopy, X-ray Photoelectron Spectroscopy, and X-ray diffraction confirmed the successful grafting of [aP4443][NTf2] onto the surface of CNMs up to a degree of surface functionalization of 2.5 %. Transmission Electron Microscopy analysis confirmed the dimensions of the CNMs were retained after modification but with significant aggregation for modified cellulose nanocrystals (CNCs). Thermal Gravimetric Analysis demonstrated significant increases in the degradation temperatures of modified CNCs from ∼252 °C to ∼310 °C. Modified cellulose nanofibers (CNFs) did not show any increase in thermal stability. The modified CNM suspensions showed reduced affinity for water and the formation of aggregates in aqueous media. Furthermore, a water contact angle test demonstrated enhanced hydrophobicity for modified CNMs. This modification approach holds potential for the use of the [aP4443][NTf2] IL for functional materials to achieve novel hydrophobic CNMs suitable for aqueous processing with thermoplastics, for fabrication of thermally stable composite materials, and for polymer gel electrolytes for batteries.

Fabrication of thermo-responsive microcapsule pesticide delivery system from maleic anhydride-functionalized cellulose nanocrystals-stabilized pickering emulsion template.

The overuse of pesticides has shown their malpractices. Novel and sustainable formulations have consequently attracted abundant attention but still appear to have drawbacks. Here, we use a maleic anhydride-functionalized cellulose nanocrystals-stabilized Pickering emulsions template to prepare thermo-responsive microcapsules for a pesticide delivery system via radical polymerization with N-isopropyl acrylamide. The microcapsules (MACNCs-g-NIPAM) are characterized by the microscope, SEM, FTIR, XRD, TG-DTG, and DSC techniques. Imidacloprid (IMI) is loaded on MACNCs-g-NIPAM to form smart release systems (IMI@MACNCs-g-NIPAM) with high encapsulation efficiency (~88.49%) and loading capability (~55.02%). The IMI@MACNCs-g-NIPAM present a significant thermo-responsiveness by comparing the release ratios at 35°C and 25°C (76.22% vs 50.78%). It also exhibits advantages in spreadability, retention and flush resistance on the leaf surface compared with the commercial IMI water-dispersible granules (CG). IMI@MACNCs-g-NIPAM also manifest a significant advantage over CG (11.12 mg/L vs 38.90 mg/L for LC50) regarding activity tests of targeted organisms. In addition, IMI@MACNCs-g-NIPAM has shown excellent biocompatibility and low toxicity. All the benefits mentioned above prove the excellent potential of IMI@MACNCs-g-NIPAM as a smart pesticide formulation.

Emulsifying properties of cellulose nanocrystals with different structures and morphologies from various solanaceous vegetable residues.

The stems of solanaceous vegetables with attractive source of cellulose, have caused severe environmental problems as agricultural residues. For the reutilization of the residues, this study isolated cellulose nanocrystals (CNs) from the stems of tomato, eggplant, and pepper to explore their applications in Pickering emulsions. Detailed analyses of the crystalline structure and morphology revealed differences in their emulsifying properties. Tomato stem CNs had higher crystallinity of 82.1 % and a short, straight rod-like shape with a low aspect ratio of 8.0, while eggplant and pepper CNs were long, curved whisker-like fibers with lower crystallinities of 75.3 % and 75.4 %, respectively. Tomato stem CNs exhibited the best emulsifying properties, attributed to their relatively higher crystallinity and larger crystal brick size enhancing amphiphilicity, along with their lower aspect ratio improving interface coverage, which resulted in stable emulsions across different temperatures, pH levels, and ionic strengths. This study enhances our understanding of how the structure and morphology of CNs influence their emulsifying properties, thereby contributing to the promotion of agricultural waste reutilization.

Influence of buffer on colloidal stability, microstructure, and rheology of cellulose nanocrystals in hyaluronic acid suspensions.

Hyaluronic acid (HA) is a natural biopolymer found in various human tissues, while cellulose nanocrystals (CNCs) extracted from pulp fibers have unique rheological properties and biocompatibility. Due to the superior biomechanical properties of CNC and HA, a CNC-based HA suspension may be useful in biomedical applications. While buffers are an essential constituent of any suspension used for biomedical applications to maintain the desired pH level, they can significantly affect the properties of the suspension, including colloidal stability, microstructure, and rheological characteristics. To our knowledge, this is the first study analyzing the influence of buffer solutions on the suspension characteristics of HA/CNC systems, integrating both theoretical and experimental approaches. The results revealed an alignment between predictions of the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory and results from experiments characterizing a buffer-specific trend in colloidal stability. Suspensions with a higher energy barrier showed higher colloidal stability, with a lower tendency for phase separation and agglomerate formations. The microstructural analysis of CNC tactoids in the suspension revealed the existence of the hedgehog defect when dispersed in different buffer solutions. The defect is predicted to be caused by the pH-dependent protonation and deprotonation of HA. Furthermore, steady shear viscometry showed a microstructural-dependent shear viscosity trend, which, in turn, depends on the buffer solution. The study provides novel insights into the microstructural and bulk properties of HA and CNC suspensions in various buffer solutions. The results highlight the importance of solvent choice in tailoring the properties of the suspension for specific biomedical applications. These findings may be helpful in formulating HA and CNC suspensions for different biomedical applications, including drug delivery systems and viscosupplement injections.

Lignin-containing cellulose nanocrystals enhanced electrospun polylactic acid-based nanofibrous mats: Strengthen and toughen.

Biodegradable polylactic acid (PLA) nanofibrous mats prepared by electrospinning serve as suitable packaging materials. However, their practical applications are limited by their weak mechanical properties, poor thermal stability, and high cost. In this study, green and low-cost lignin-containing cellulose nanocrystals (LCNCs) with different lignin contents were developed and employed as reinforced materials to synergistically enhance the thermal, mechanical, and hydrophobic properties of PLA electrospun nanofibrous mats. The presence of moderate lignin improved the interfacial compatibility between the LCNCs and PLA, resulting in excellent mechanical properties of the nanofibrous mats. Compared to pure PLA mats, the tensile strength of the composites reached up to 21.0 MPa, representing a 6.6-fold increase. Its toughness was synchronously enhanced by 16 times, reaching a maximum of 3.6 MJ/m3. The maximum decomposition temperature of PLA/LCNCs electrospun nanofibrous mats increased from 339 °C to 365 °C. Furthermore, the increase in lignin in the LCNCs positively contributed to improving the hydrophobicity of the PLA/LCNCs electrospun nanofibrous mats. This bio-based strategy of LCNCs employed in the enhancement of fully bio-based PLA nanofibrous mats offers a viable approach for the advancement of packaging films.

Magnetic modulation on chiroptical activities of nematically assembled carbon dots.

Effectively harnessing the assembly of achiral carbon dots into a chiral manner is a prominent step for applying carbon dots into the area of stereoselective optoelectronics and theranostics. Herein, magnetic-modulated and circularly polarized luminescence (CPL)-active photonic thin films were presented in this article via co-assembly and magnetic-mediation strategy of cellulose nanocrystals, carbon dots and magnetic nanoparticles. The photonic bandgap of the composite films is modulated via interfacial interactions between the building blocks, and more efficiently via external magnetic field which can further enhance the selective reflection of the films with a maximum CPL anisotropic factor as high as -0.92, indicating the optimized condition for achieving CPL signals is basically when the photonic bandgap (PBG) are close to the emission peaks of nanocomposite films, which may essentially facilitate the selective reflection effect and leads to the output of opposite CPL signals. Such strategy would inevitably boost the development of carbon dots based chiral devices and reagents into the realm of chirality-related biological issues and next generation chiral optoelectronics.

Encapsulation, characterization and in vitro releasing of xylanase and glucose oxidase (GOD) into cellulose nanocrystals stabilized three-layer microcapsules.

The xylanase and glucose oxidase (GOD) are easily inactivated, restricting their applicaiton in food and agriculture fields. In this work, xylanase and glucose oxidase (GOD) were encapsulated into cellulose nanocrystals (CNC) stabilized three-layer microcapsules via ionic gelation technique to improve their bioavailability and targeted delivery. Encapsulation efficiency (EE), physicochemical properties, and in vitro releasing of xylanase and GOD encapsulated in microcapsules were investigated. EE of xylanase and GOD reached the highest values (73.34 % and 67.16 %, respectively) at an enzyme concentration of 35 mg/mL. In vitro experiments revealed that cumulative release of both enzymes encapsulated in microcapsules was greater than that of controls in simulated gastric tract (SGT) and simulated intestinal tract (SIT). The release of xylanase increased from 41.62 % (gastric tract) to 77.13 % (intestine tract), and release of GOD increased from 42.63 % to 72.11 %, respectively. Novel hydrogel carriers as enzymes encapsulation system could effectively improve the survival rate of enzymes in harsh environments and could be widely employed in food, feed and other industries.

Magneto-Responsive Chiral Optical Materials: Flow-Induced Twisting of Cellulose Nanocrystals in Patterned Magnetic Fields.

Magnetic fields have been used to uniformly align the lyotropic chiral nematic (cholesteric) liquid crystalline (LC) phase of biopolymers to a global orientation and optical appearance. Here, we demonstrate that, in contrast, weak and patterned magnetic field gradients can create a complex optical appearance with the variable spatial local organization of needle-like magnetically decorated cellulose nanocrystals. The formation of optically patterned thin films with left- and right-handed chiral and achiral regions is observed and related to local magnetic gradient-driven vortices during LC suspension flow. We trace the localized flow directions of the magnetically decorated nanocrystals during evaporation-induced assembly, demonstrating how competing evaporation and field-induced localized flow affect the twisted organization within magnetically induced vortices. The simulations suggested that localized twisting inversion originates from the interplay between the direction and strength of the local-depth-related magnetic gradients and the receding front through peripheral magnetic gaps. We propose that this finding will lead to magnetically patterned photonic films.

Sulfuric acid solvolysis of cellulose in a butanol-1/benzene mixture for isolating cellulose nanocrystals.

The absence of a universal method for isolating cellulose nanocrystals (CNCs) has prompted researchers to explore alternative approaches to traditional sulfuric acid hydrolysis. In this study, the authors continue their previous research by investigating CNC synthesis through cellulose solvolysis in an alcoholic environment. The CNCs were successfully obtained utilizing controlled sulfuric acid solvolysis of sulfate cellulose in a butanol-1/benzene mixture. The highest CNC yield (over 60 %) was achieved at strictly controlled acid-to-benzene ratios in a butanol-1/benzene/sulfuric acid reaction mixture, with a significant reduction in the optimal acid concentration. The study also analyzes the physicochemical properties of the isolated CNCs. No surface alkylation of the synthesized CNCs was observed during the cellulose solvolysis in the butanol-1/benzene mixture. Besides, the properties of these CNCs closely resembled those obtained through traditional sulfuric acid hydrolysis. The paper also discusses the potential mechanism of cellulose solvolysis in the process of CNC production.

Butterfly wing-inspired superhydrophobic photonic cellulose nanocrystal films for vapor sensors and asymmetric actuators.

Cellulose nanocrystals (CNCs)-based stimuli responsive photonic materials demonstrate great application potential in mechanical and chemical sensors. However, due to the hydrophilic property of cellulose molecular, a significant challenge is to build a water-resistant photonic CNCs material. Here, inspired by butterfly wings with vivid structural color and superhydrophobic property, we have designed a CNCs based superhydrophobic iridescent film with hierarchical structures. The iridescent colored layer is ascribed to the chiral nematic alignment of CNCs, the superhydrophobic layer is ascribed to the micro-nano structures of polymer microspheres. Specially, superhydrophobic iridescent CNCs film could be used as an efficient colorimetric humidity sensor due to the existence of 'stomates' on superhydrophobic layer, which allowed the humid gas to enter into and out from the humidity responsive chiral nematic layers. Meanwhile, superhydrophobic iridescent films show out-standing self-cleaning and anti-fouling performance. Moreover, when the one side of the CNCs film was covered with superhydrophobic layer, the Janus film displays asymmetric expansion and bending behaviors as well as responsive structural colors in hydrous ethanol. This CNCs based hierarchical photonic materials have promising applications including photonic sensors suitable for extreme environment and smart photonic actuators.