Improved Cell Adhesion on Self-Assembled Chiral Nematic Cellulose Nanocrystal Films.

Chirality is ubiquitous in nature, and closely related to biological phenomena. Nature-originated nanomaterials such as cellulose nanocrystals (CNCs) are able to self-assemble into hierarchical chiral nematic CNC films and impart handedness to nano and micro scale. However, the effects of the chiral nematic surfaces on cell adhesion are still unknown. Herein, this work presents evidence that the left-handed self-assembled chiral nematic CNC films (L-CNC) significantly improve the adhesion of L929 fibroblasts compared to randomly arranged isotropic CNC films (I-CNC). The fluidic force microscopy-based single-cell force spectroscopy is introduced to assess the cell adhesion forces on the substrates of L-CNC and I-CNC, respectively. With this method, a maximum adhesion force of 133.2 nN is quantified for mature L929 fibroblasts after culturing for 24 h on L-CNC, whereas the L929 fibroblasts exert a maximum adhesion force of 78.4 nN on I-CNC under the same condition. Moreover, the instant SCFS reveals that the integrin pathways are involved in sensing the chirality of substrate surfaces. Overall, this work offers a starting point for the regulation of cell adhesion via the self-assembled nano and micro architecture of chiral nematic CNC films, with potential practical applications in tissue engineering and regenerative medicine.

Enhancement efficiency delivery of antiviral Molnupiravir-drug via the loading with self-assembly nanoparticles of pycnogenol and cellulose which are decorated by zinc oxide nanoparticles for COVID-19 therapy.

The target of the study is to modify the efficiency of Molnupiravir-drug (MOL) for COVID-19 therapy via the rearrangement of the building engineering of MOL-drug by loading it with self-assembly biomolecules nanoparticles (NPs) of pycnogenol (Pyc) and cellulose (CNC) which are decorated by zinc oxide nanoparticles. The synthesis and characterization of the modified drug are performing successfully, the loading and release process of the MOL drug on a nano surface is measured by UV-Vis spectroscopy under room temperature and different pH. The release efficiency of the MOL drug is calculated to be 65% (pH 6.8) and 69% (pH 7.4). The modified MOL drug displays 71% (pH 6.8) and 78% (pH 7.4) for CNC@Pyc.MOL nanocomposite, while CNC@Pyc.MOL.ZnO nanocomposite gave values at 76% (pH 6.8) and 78% (pH 7.4), the efficiency recorded after 19 h. The biological activity of the MOL-drug and modified MOL-drug is measured, and the cytotoxicity is performed by SRB technique, where the self-assembly (CNC@Pyc) appears to be a safe healthy, and high viability against the examined cell line. The antioxidant activity and anti-inflammatory are evaluated, where the nanocomposite that has ZnO NPs (CNC@Pyc.MOL.ZnO) gave high efficiency compared to the composite without ZnO NPs. The CPE-inhibition assay is used to identify potential antivirals against CVID-19 (229E virus), the viral inhibition (%) was reported at 37.6 % (for 800 µg/ml) and 18.02 % (for 400 µg/ml) of CNC@Pyc.MOL.ZnO. So, the modified MOL-drug was suggested as a replacement drug for the therapy of COVID-19 compared to MOL-drug, but the results need clinical trials.

Accelerated full-thickness skin wound tissue regeneration by self-crosslinked chitosan hydrogel films reinforced by oxidized CNC-AgNPs stabilized Pickering emulsion for quercetin delivery.

BACKGROUND: The non-toxic self-crosslinked hydrogel films designed from biocompatible materials allow for controlled drug release and have gathered remarkable attention from healthcare professionals as wound dressing materials. Thus, in the current study the chitosan (CS) film is infused with oil-in-water Pickering emulsion (PE) loaded with bioactive compound quercetin (Qu) and stabilized by dialdehyde cellulose nanocrystal-silver nanoparticles (DCNC-AgNPs). The DCNC-AgNPs play a dual role in stabilizing PE and are involved in the self-crosslinking with CS films. Also, this film could combine the advantage of the controlled release and synergistic wound-healing effect of Qu and AgNPs. RESULTS: The DCNC-AgNPs were synthesized using sodium periodate oxidation of CNC. The DCNC-AgNPs were used to stabilize oil-in-water PE loaded with Qu in its oil phase by high speed homogenization. Stable PEs were prepared by 20% v/v oil: water ratio with maximum encapsulation of Qu in the oil phase. The Qu-loaded PE was then added to CS solution (50% v/v) to prepare self-crosslinked films (CS-PE-Qu). After grafting CS films with PE, the surface and cross-sectional SEM images show an inter-penetrated network within the matrix between DCNC and CS due to the formation of a Schiff base bond between the reactive aldehyde groups of DCNC-AgNPs and amino groups of CS. Further, the addition of glycerol influenced the extensibility, swelling ratio, and drug release of the films. The fabricated CS-PE-Qu films were analyzed for their wound healing and tissue regeneration potential using cell scratch assay and full-thickness excisional skin wound model in mice. The as-fabricated CS-PE-Qu films showed great biocompatibility, increased HaCat cell migration, and promoted collagen synthesis in HDFa cells. In addition, the CS-PE-Qu films exhibited non-hemolysis and improved wound closure rate in mice compared to CS, CS-Qu, and CS-blank PE. The H&E staining of the wounded skin tissue indicated the wounded tissue regeneration in CS-PE-Qu films treated mice. CONCLUSION: Results obtained here confirm the wound healing benefits of CS-PE-Qu films and project them as promising biocompatible material and well suited for full-thickness wound healing in clinical applications.

Biomimetic Ultratough, Strong, and Ductile Artificial Polymer Fiber Based on Immovable and Slidable Cross-links.

It remains a challenge to artificially fabricate fibers with the macroscopic mechanical properties and characteristics of spider silk. Herein, a covalently cross-linked double-network strategy was proposed to disrupt the inverse relation of strength and toughness in the fabrication of ultratough and superstrong artificial polymer fibers. Our design utilized a strong fishnet-like structure based on immovable cellulose nanocrystal cross-links to mimic the function of the ß-sheet nanocrystallites and a slidable mechanically interlocked network based on polyrotaxane to imitate the dissipative stick-slip motion of the ß-strands in spider silk. The resultant fiber exhibited superior mechanical properties, including gigapascal tensile strength, a ductility of over 60%, and a toughness exceeding 420 MJ/m3. The fibers also showed robust biological functions similar to those of spider silks, demonstrating mechanical enhancement, energy absorption ability, and shape memory. A composite with our artificial fibers as reinforcing fibers exhibited remarkable tear and fatigue resistance.

Harmonized Life-Cycle Inventories of Nanocellulose and Its Application in Composites.

Cellulose nanocrystals (CNC) and nanofibers (CNF) have been broadly studied as renewable nanomaterials for various applications, including additives in cement and plastics composites. Herein, life cycle inventories for 18 previously examined processes are harmonized, and the impacts of CNC and CNF production are compared with a particular focus on GHG emissions. Findings show wide variations in GHG emissions between process designs, from 1.8-1100 kg CO2-eq/kg nanocellulose. Mechanical and enzymatic processes are identified as the lowest GHG emission methods to produce CNCs and CNFs. For most processes, energy consumption and chemical use are the primary sources of emissions. However, on a mass basis, for all examined production methods and impact categories (except CO emissions), CNC and CNF production emissions are higher than Portland cement and, in most cases, are higher than polylactic acid. This work highlights the need to carefully consider process design to prevent potential high emissions from CNCs and CNF production despite their renewable feedstock, and results show the magnitude of conventional material that must be offset through improved performance for these materials to be environmentally favorable.

Electrohydrodynamic convection instabilities observed in suspensions of cellulose nanocrystals.

Cellulose nanocrystals are slender, negatively charged nanoparticles that spontaneously form a cholesteric liquid crystal in aqueous suspension above a critical concentration. When they are suspended in apolar solvents such as toluene using surfactants, the application of an AC electric field leads to the reorientation and then distortion of the cholesteric order until the cholesteric structure completely unwinds into a nematic-like order, typically above 0.4-0.6 kV/cm at 1kHz. In this work, we show that at much higher electric fields (≥ 4.6 kV/cm at 1 kHz) the sample develops a periodic pattern that varies with the field amplitude. We ascribed this pattern to electrohydrodynamic convection instabilities. These instabilities usually present complex regimes varying with the field, the voltage, the frequency and the geometry. However, the typical geometry where these instabilities were most documented across the literature differs from the geometry used in this work. This work concludes with possible future experimental investigations to clarify the exact regime of instability responsible for these observations. Supplementary Information: The online version contains supplementary material available at 10.1007/s10570-023-05391-6.

Dynamically Tunable All-Weather Daytime Cellulose Aerogel Radiative Supercooler for Energy-Saving Building.

A passive cooling strategy without any electricity input has shown a significant impact on overall energy consumption globally. However, designing tunable daytime radiative cooler to meet requirement of different weather conditions is still a big challenge, especially in hot, humid regions. Here, a novel type of tunable, thermally insulating and compressible cellulose nanocrystal (CNC) aerogel coolers is prepared via chemical cross-linking and unidirectional freeze casting process. Such aerogel coolers can achieve a subambient temperature drop of 9.2 °C under direct sunlight and promisingly reached the reduction of ∼7.4 °C even in hot, moist, and fickle extreme surroundings. The tunable cooling performance can be realized via controlling the compression ratio of shape-malleable aerogel coolers. Furthermore, energy consumption modeling of using such aerogel coolers in buildings in China shows 35.4% reduction of cooling energy. This work can pave the way toward designing high-performance, thermal-regulating materials for energy consumption savings.

Fabrication of Silane-Grafted Cellulose Nanocrystals and Their Effects on the Structural, Thermal, Mechanical, and Hysteretic Behavior of Thermoplastic Polyurethane.

Reinforcement of polymer nanocomposites can be achieved by the selection of the appropriate fabrication method, surface modification, and orientation of the filler. Herein, we present a nonsolvent-induced phase separation method with ternary solvents to prepare thermoplastic polyurethane (TPU) composite films with excellent mechanical properties using 3-Glycidyloxypropyltrimethoxysilane-modified cellulose nanocrystals (GLCNCs). ATR-IR and SEM analyses of the GLCNCs confirmed that GL was successfully coated on the surface of the nanocrystals. The incorporation of GLCNCs in TPU resulted in the enhancement of the tensile strain and toughness of pure TPU owing to the enhanced interfacial interactions between them. The GLCNC-TPU composite film had tensile strain and toughness values of 1740.42% and 90.01 MJ/m3, respectively. Additionally, GLCNC-TPU exhibited a good elastic recovery rate. CNCs were readily aligned along the fiber axis after the spinning and drawing of the composites into fibers, which further improved the mechanical properties of the composites. The stress, strain, and toughness of the GLCNC-TPU composite fiber increased by 72.60%, 10.25%, and 103.61%, respectively, compared to those of the pure TPU film. This study demonstrates a facile and effective strategy for fabricating mechanically enhanced TPU composites.

Effect of nanocellulose polymorphism on electrochemical analytical performance in hybrid nanocomposites with non-oxidized single-walled carbon nanotubes.

Two cellulose nanocrystals/single-walled carbon nanotube (CNC/SW) hybrids, using two cellulose polymorphs, were evaluated as electrochemical transducers: CNC type I (CNC-I/SW) and CNC type II (CNC-II/SW). They were synthesized and fully characterized, and their analytical performance as electrochemical sensors was carefully studied. In comparison with SWCNT-based and screen-printed carbon electrodes, CNC/SW sensors showed superior electroanalytical performance in terms of sensitivity and selectivity, not only in the detection of small metabolites (uric acid, dopamine, and tyrosine) but also in the detection of complex glycoproteins (alpha-1-acid glycoprotein (AGP)). More importantly, CNC-II/SW exhibited 20 times higher sensitivity than CNC-I/SW for AGP determination, yielding a LOD of 7 mg L-1.These results demonstrate the critical role played by nanocellulose polymorphism in the electrochemical performance of CNC/SW hybrid materials, opening new directions in the electrochemical sensing of these complex molecules. In general, these high-active-surface hybrids smartly exploited the preserved non-oxidized SW conductivity with the high aqueous dispersibility of the CNC, avoiding the use of organic solvents or the incorporation of toxic surfactants during their processing, making the CNC/SW hybrids promising nanomaterials for electrochemical detection following greener approaches.

Cellulose Nanocrystals Facilitate Needle-like Ice Crystal Growth and Modulate Molecular Targeted Ice Crystal Nucleation.

Ice nucleators are of crucial and important implications in various fields including chemistry, climate, agriculture, and cryobiology. However, the complicated extract and biocompatibility of ice nucleators remain unresolved, and the mechanism of ice nucleation remains largely unknown. Herein, we show that natural nanocrystalline cellulose materials possess special properties to enhance ice nucleation and facilitate needle-like ice crystal growth. We reveal the molecular level mechanism that the efficient exposure of cellulose hydroxyl groups on (-110) surface leads to faster nucleation of water. We further design chitosan-decorated cellulose nanocrystals to accomplish molecular cryoablation in CD 44 high-expression cells; the cell viability shows more than ∼10 times decrease compared to cryoablation alone and does not show evident systematic toxicity. Collectively, our findings also offer improved knowledge in molecular level ice nucleation, which may benefit multiple research communities and disciplines.

Preparation and characterization of cellulose nanocrystals from spent edible fungus substrate.

BACKGROUND: Spent edible fungus substrates were identified as potential sources to produce cellulose derivatives, namely purified cellulose and dicarboxyl cellulose nanocrystal (DCNC). Purified celluloses were obtained via chemical treatments and then oxidized by sequential periodate-chlorite without mechanical process. The structural properties of the DCNCs were characterized by transmission electron microscopy (TEM), Fourier-transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) and thermal gravimetric analysis (TGA). RESULTS: XRD results showed that the cellulose I structure was maintained, however, the crystallinity index decreased after oxidation process. The initial pyrolysis temperature of DCNCs ranged from 242 to 344 °C. TEM results revealed that DCNC was rod-shaped with an average length and width of 130.88 nm and 7.3 nm, respectively. The average specific surface area (SSA) was 366.67 m2  g-1 . The carboxyl content was around 3.485 mmol g-1 . Finally, the adsorption capacity for contaminations was 76.98, 126.22, 64.44 and 9.63 mg g-1 for copper ion (Cu2+ ), lead ion (Pb2+ ), chromium (Cr3+ ) and amoxicillin (AMX), respectively. CONCLUSION: This work showed a sequentially chemical oxidation for preparing nanocellulose from secondary agricultural waste with many functional applications. © 2021 Society of Chemical Industry.

Sustainable Superhydrophobic Surface with Tunable Nanoscale Hydrophilicity for Water Harvesting Applications.

Superwettable surfaces show great potential in water harvesting applications, however, a scalable water harvesting surface remains elusive due to the trade-off between water deposition and transport. Herein, we report a unique superhydrophobic surface with tunable nanoscale hydrophilicity constructed by structured Pickering emulsions. Preferential exposure of the cellulose nanocrystal's outer surface and wax microspheres accelerates droplet deposition allowing for the manipulation of droplet mobility. Appropriate tuning of the wetting characteristics of the surfaces, optimizing the hydrophobicity and density of the water affinity nanodomains enhance the water deposition rate without the sacrifice of water transport rate, achieving an optimal water harvesting flux of 3.402 L m-2 h-1 for a plate and 5.02 L m-2 h-1 for a mesh. This hydrophilic/superhydrophobic surface allows the controllable manipulation of droplet nucleation and removal to enhance the water harvesting efficiency.

A Theranostic Cellulose Nanocrystal-Based Drug Delivery System with Enhanced Retention in Pulmonary Metastasis of Melanoma.

Metastatic melanoma can be difficult to detect until at the advanced state that decreases the survival rate of patients. Several FDA-approved BRAF inhibitors have been used for treatment of metastatic melanoma, but overall therapeutic efficacy has been limited. Lutetium-177 (177 Lu) enables simultaneous tracking of tracer accumulation with single-photon emission computed tomography and radiotherapy. Therefore, the codelivery of 177 Lu alongside chemotherapeutic agents using nanoparticles (NPs) might improve the therapeutic outcome in metastatic melanoma. Cellulose nanocrystals (CNC NPs) can particularly deliver payloads to lung capillaries in vivo. Herein, 177 Lu-labeled CNC NPs loaded with vemurafenib ([177 Lu]Lu-CNC-V NPs) is developed and the therapeutic effect in BRAF V600E mutation-harboring YUMM1.G1 murine model of lung metastatic melanoma is investigated. The [177 Lu]Lu-CNC-V NPs demonstrate favorable radiolabel stability, drug release profile, cellular uptake, and cell growth inhibition in vitro. In vivo biodistribution reveals significant retention of the [177 Lu]Lu-CNC-V NPs in the lung, liver, and spleen. Ultimately, the median survival time of animals is doubly increased after treatment with [177 Lu]Lu-CNC-V NPs compared to control groups. The enhanced therapeutic efficacy of [177 Lu]Lu-CNC-V NPs in the lung metastatic melanoma animal model provides convincing evidence for the potential of clinical translation for theranostic CNC NP-based drug delivery systems after intravenous administration.

Lung toxicity and gene expression changes in response to whole-body inhalation exposure to cellulose nanocrystal in rats.

OBJECTIVE: Human exposure to cellulose nanocrystal (CNC) is possible during the production and/or use of products containing CNC. The objectives of the current study were to determine the lung toxicity of CNC and the underlying molecular mechanisms of the toxicity. METHODS: Rats were exposed to air or CNC (20 mg/m3, six hours/day, 14 d) by whole-body inhalation and lung toxicity and global gene expression profile were determined. RESULTS: Significant increases in lactate dehydrogenase activity, pro-inflammatory cytokine levels, phagocyte oxidant production, and macrophage and neutrophil counts were detected in the bronchoalveolar lavage cells or fluid from the CNC exposed rats. Mild lung histological changes, such as the accumulation of macrophages and neutrophils, were detected in the CNC exposed rats. Gene expression profiling by next generation sequencing identified 531 genes whose expressions were significantly different in the lungs of the CNC exposed rats, compared with the controls. Bioinformatic analysis of the lung gene expression data identified significant enrichment in several biological functions and canonical pathways including those related to inflammation (cellular movement, immune cell trafficking, inflammatory diseases and response, respiratory disease, complement system, acute phase response, leukocyte extravasation signaling, granulocyte and agranulocyte adhesion and diapedesis, IL-10 signaling, and phagosome formation and maturation) and oxidative stress (NRF2-mediated oxidative stress response, production of nitric oxide and reactive oxygen species in macrophages, and free radical scavenging). CONCLUSION: Our data demonstrated that inhalation exposure of rats to CNC resulted in lung toxicity mediated mainly through the induction of inflammation and oxidative stress.

Enhancing Removal of Cr(VI), Pb2+, and Cu2+ from Aqueous Solutions Using Amino-Functionalized Cellulose Nanocrystal.

In this work, the amino-functionalized cellulose nanocrystal (ACNC) was prepared using a green route and applied as a biosorbent for adsorption of Cr(VI), Pb2+, and Cu2+ from aqueous solutions. CNC was firstly oxidized by sodium periodate to yield the dialdehyde nanocellulose (DACNC). Then, DACNC reacted with diethylenetriamine (DETA) to obtain amino-functionalized nanocellulose (ACNC) through a Schiff base reaction. The properties of DACNC and ACNC were characterized by using elemental analysis, Fourier transform infrared spectroscopy (FT-IR), Kaiser test, atomic force microscopy (AFM), X-ray diffraction (XRD), and zeta potential measurement. The presence of free amino groups was evidenced by the FT-IR results and Kaiser test. ACNCs exhibited an amphoteric nature with isoelectric points between pH 8 and 9. After the chemical modification, the cellulose I polymorph of nanocellulose remained, while the crystallinity decreased. The adsorption behavior of ACNC was investigated for the removal of Cr(VI), Pb2+, and Cu2+ in aqueous solutions. The maximum adsorption capacities were obtained at pH 2 for Cr(VI) and pH 6 for Cu2+ and Pb2+, respectively. The adsorption all followed pseudo second-order kinetics and Sips adsorption isotherms. The estimated adsorption capacities for Cr(VI), Pb2+, and Cu2+ were 70.503, 54.115, and 49.600 mg/g, respectively.

Performance Enhancement of a Quartz Tuning Fork Sensor Using a Cellulose Nanocrystal-Reinforced Nanoporous Polymer Fiber.

A cellulose nanocrystal (CNC)-reinforced polymethylmethacrylate (PMMA) fiber was obtained via electrospinning, and then attached between the two tines of a quartz tuning fork (QTF). The change in the resonance frequency of the CNC/PMMA composite fiber-coated QTF (CP-QTF) was measured upon being exposed to various concentrations of ethanol vapor. The frequency decreased as the ethanol vapor concentration increased, because the modulus of the composite fiber decreased due to the adsorption of the ethanol vapor. The composite fiber obtained at a high relative humidity (RH; 60% RH, CP60 fiber) produced a highly porous structure as a result of the moisture adsorption-induced phase separation of PMMA. The porosity of the CP60 fiber was higher than that of a CNC/PMMA composite fiber obtained at 30% RH (CP30 fiber) or that of a plain PMMA fiber obtained at 60% RH (P60 fiber), because hygroscopic CNCs promote moisture adsorption. The CP60 fiber-coated QTF (CP60-QTF) exhibited a greater frequency change and faster response time than P60-QTF and CP30-QTF upon exposure to ethanol vapor at the same concentration. The enhanced performance of CP60-QTF was attributed to its higher surface area and larger fiber modulus.

Stable and Highly Ion-Selective Membrane Made from Cellulose Nanocrystals for Aqueous Redox Flow Batteries.

The design of chemically stable ion-exchange membranes with high selectivity for applications in an aqueous redox flow battery (RFB) at high acid concentrations remains a significant challenge. Herein, this study designed a stable and highly ion-selective membrane by utilizing proton conductive cellulose nanocrystals (CNCs) incorporated in a semicrystalline hydrophobic poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) matrix. The high hydrophobicity of the PVDF-HFP matrix mitigates crossover of the electrolytes, whereas the abundant and low-cost CNCs derived from wood provide high proton conductivity. The fundamental contributors for CNCs' excellent proton conductivity are the hydroxyl (-OH) functional groups, highly acidic sulfonate (-SO3H) functional groups, and the extensive intramolecular hydrogen bonding network. In addition, CNCs exhibit a mechanically and chemically stable structure in the harsh acidic electrolyte attributed to the high crystallinity (crystalline index of ∼86%). Therefore, because of the high proton conductivity, excellent ion selectivity, high chemical stability, and structural robustness, the vanadium redox flow battery (VRFB) assembled with the homogeneous CNCs and PVDF-HFP (CNC/PVDF-HFP) membrane achieved a Coulombic efficiency (CE) of 98.2%, energy efficiency (EE) of 88.2%, and a stable cycling performance for more than 650 cycles at a current density of 100 mA cm-2. The obtained membrane possesses excellent flexibility, high mechanical tensile strength, and superior selectivity. Meanwhile, the applied casting method is scalable for large-scale manufacturing.

Hybrid Nanocellulose-Copper (II) Oxide as Engine Oil Additives for Tribological Behavior Improvement.

Friction and wear are the main factors in the failure of the piston in automobile engines. The objective of this work was to improve the tribological behaviour and lubricant properties using hybrid Cellulose Nanocrystal (CNC) and Copper (II) oxide nanoparticles blended with SAE 40 as a base fluid. The two-step method was used in the hybrid nanofluid preparation. Three different concentrations were prepared in a range of 0.1% to 0.5%. Kinematic viscosity and viscosity index were also identified. The friction and wear behavior were evaluated using a tribometer based on ASTM G181. The CNC-CuO nano lubricant shows a significant improvement in term of viscosity index by 44.3-47.12% while for friction, the coefficient of friction (COF) decreases by 1.5%, respectively, during high and low-speed loads (boundary regime), and 30.95% during a high-speed, and low load (mixed regime). The wear morphologies results also show that a smoother surface was obtained after using CNC-CuO nano lubricant compared to SAE 40.

Solid-state 23Na NMR spectroscopy studies of ordered and disordered cellulose nanocrystal films.

Cellulose nanocrystal films with either disordered or chiral nematic structures of varying helical pitch were investigated using 23Na solid-state nuclear magnetic resonance (NMR) spectroscopy. Spin lattice relaxation of 1H correlated with 23Na analyzed by indirect observation using polarization transfer from 1H nuclei to 23Na nuclei showed that the Na+ cations are well hydrated in the cellulose nanocrystal films. Linewidth analysis in solid-state 23Na NMR showed that the Na+ cations move in confined spaces, and that the Na+ cations in the film having disordered structure are more dynamic than in the films having ordered structure. From lineshape analysis of the 23Na 2D nutation NMR spectra, we can distinguish the Na+ environments within the ordered and disordered films, and find trends in anisotropic interaction parameters between ordered samples with different pitches. These are the first detailed 23Na NMR spectroscopic studies of CNC-Na+ films, and they show that this technique may be a powerful probe for characterizing the extent of order in nanocellulose samples.

A New Sensor for Methyl Paraben Using an Electrode Made of a Cellulose Nanocrystal-Reduced Graphene Oxide Nanocomposite.

A new cellulose nanocrystal-reduced graphene oxide (CNC-rGO) nanocomposite was successfully used for mediatorless electrochemical sensing of methyl paraben (MP). Fourier-transform infrared spectroscopy (FTIR) and field-emission scanning electron microscopy (FESEM) studies confirmed the formation of the CNC-rGO nanocomposite. Cyclic voltammetry (CV) studies of the nanocomposite showed quasi-reversible redox behavior. Differential pulse voltammetry (DPV) was employed for the sensor optimization. Under optimized conditions, the sensor demonstrated a linear calibration curve in the range of 2 × 10-4-9 × 10-4 M with a limit of detection (LOD) of 1 × 10-4 M. The MP sensor showed good reproducibility with a relative standard deviation (RSD) of about 8.20%. The sensor also exhibited good stability and repeatability toward MP determinations. Analysis of MP in cream samples showed recovery percentages between 83% and 106%. Advantages of this sensor are the possibility for the determination of higher concentrations of MP when compared with most other reported sensors for MP. The CNC-rGO nanocomposite-based sensor also depicted good reproducibility and reusability compared to the rGO-based sensor. Furthermore, the CNC-rGO nanocomposite sensor showed good selectivity toward MP with little interference from easily oxidizable species such as ascorbic acid.