Cellulose-based Nanomaterials Research Articles

Production of cellulose nano/microfibers through simultaneous milling and enzymatic hydrolysis with an optimized cocktail of cellulase/xylanase/LPMO

Cellulose nanofibers (CNF) and microfibrillated cellulose (MFC) are biodegradable micro and nanomaterials derived from plant cellulose. The properties of CNF, influenced by fibril length, impact the strength of cellulose-based nanomaterials. This study uses enzymatic milling to explore pretreatments, enzymatic optimization, and CNF/MFC production. The study found that hammer milling and lamination are effective pretreatments for preserving fibers. The optimal enzymatic mixture contained 75 % cellulase and 25 % xylanase, yielding 68.7 % and 2.86 %/h productivity, respectively. The addition of the LPMO enzyme increased the yield by 10–13 %, depending on its concentration. Enzymatic milling was introduced as an innovative approach to CNF production, reducing hydrolysis time and creating milder processing conditions. The combined process of ball milling and enzymatic hydrolysis on pre-ground pulp in the hammer mill achieved a maximum CNF yield of 45.83 % and productivity of 13.10 %/h. X-ray diffraction showed that the lamination-pre-treated pulp had a high crystallinity index of 84.34 %. Scanning electron microscopy revealed fibers with diameters ranging from 52 nm to 296 nm. These findings support the search for sustainable and eco-friendly alternatives to non-renewable resources, enabling sustainable CNF production at room temperature with reduced processing time.

Design Strategies for Creating Cellulose-Based Nanomaterials with Tailored Optical Functionality

Design Strategies for Creating Cellulose-Based Nanomaterials with Tailored Optical Functionality

Performance evaluation and efficiency of functionalized cellulose nanocomposites for the removal of pharmaceutical contaminants from the aqueous environment

Water pollution caused by pharmaceuticals has raised many concerns about the potential risks to human health and living organisms. Therefore, it is important to develop a high-efficiency adsorbent for the removal of organic pollutants from wastewater. Cellulose-based nanomaterials can be effectively used for wastewater treatment. In the present work, new nanocomposites are designed through the functionalization of cellulose with β-cyclodextrin (β-CD/Cell), cucurbit [6] (CUR/Cell), and calixarene (CAL/Cell) groups with Tetrafluoroterephthalonitrile (TFP) linker. Then, the adsorption of pharmaceutical agents such as propranolol (PRO), levofloxacin (LEV), and metformin (MET) is examined on nanocomposites as efficient adsorbents. The obtained results show that the systems containing the β-CD functional group have a higher adsorption for all three types of drugs compared to the other two nanocomposites. It should be noted that both types of interactions (Van der Waals and electrostatic) between β-CD/Cell and CAL/Cell nanocomposites with micropollutant molecules are significant, whereas, between CUR/Cell and drugs, the electrostatic interaction is dominant. Also, the most number of hydrogen bonds exist between the MET drug and nanocomposite membranes, which leads to stronger electrostatic interactions. In addition, our findings confirm that the system containing β-CD/Cell nanocomposite and LEV drug has the highest number of contacts (2300) at the beginning of the simulation and the most interaction energy (368.5 kJ/mol). It is worth mentioning that the negative values of the interaction energies show that all of the investigated drug molecules exothermically and spontaneously adsorbed on the surface of cellulose nanocomposites.

Wetting of native and acetylated cellulose by water and organic liquids from atomistic simulations

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.

Nanotechnology as an efficient and effective alternative for wastewater treatment: an overview.

The increase in the surface and groundwater contamination due to global population growth, industrialization, proliferation of pathogens, emerging pollutants, heavy metals, and scarcity of drinking water represents a critical problem. Because of this problem, particular emphasis will be placed on wastewater recycling. Conventional wastewater treatment methods may be limited due to high investment costs or, in some cases, poor treatment efficiency. To address these issues, it is necessary to continuously evaluate novel technologies that complement and improve these traditional wastewater treatment processes. In this regard, technologies based on nanomaterials are also being studied. These technologies improve wastewater management and constitute one of the main focuses of nanotechnology. The following review describes wastewater's primary biological, organic, and inorganic contaminants. Subsequently, it focuses on the potential of different nanomaterials (metal oxides, carbon-based nanomaterials, cellulose-based nanomaterials), membrane, and nanobioremediation processes for wastewater treatment. The above is evident from the review of various publications. However, nanomaterials' cost, toxicity, and biodegradability need to be addressed before their commercial distribution and scale-up. The development of nanomaterials and nanoproducts must be sustainable and safe throughout the nanoproduct life cycle to meet the requirements of the circular economy.

In vitro immune and redox response induced by cationic cellulose-based nanomaterials

Cellulose nanocrystals (CNCs) display remarkable strength and physicochemical properties with significant potential applications. To better understand the potential adjuvanticity of a nanomaterial, it is important to investigate the extent of the immunological response, the mechanisms by which they elicit this response, and how this response is associated with their physicochemical characteristics. In this study, we investigated the potential mechanisms of immunomodulation and redox activity of two chemically related cationic CNC derivatives (CNC-METAC-1B and CNC-METAC-2B), using human peripheral blood mononuclear cells and mouse macrophage cells (J774A.1). Our data demonstrated that the biological effects caused by these nanomaterials occurred mainly with short term exposure. We observed opposite immunomodulatory activity between the tested nanomaterials. CNC-METAC-2B, induced IL-1β secretion at 2 h while CNC-METAC-1B decreased it at 24 h of treatment. In addition, both nanomaterials caused more noticeable increases in mitochondrial reactive oxygen species (ROS) at early time. The differences in apparent sizes of the two cationic nanomaterials could explain, at least in part, the discrepancies in biological effects, despite their closely related surface charges. This work provides initial insights about the complexity of the in vitro mechanism of action of these nanomaterials as well as foundation knowledge for the development of cationic CNCs as potential immunomodulators.

Fabrication and performance of nitrocellulose nanoparticles reinforced environment-friendly waterborne ethyl cellulose (Surelease®) nanocomposites

In terms of eco-friendly materials, cellulose-based nanomaterials have received widespread attention as nano-functional fillers due to their lower production costs, better biodegradability, and excellent interfacial compatibility with polymers. In this paper, a nitrocellulose (NC) nano aqueous dispersion was successfully prepared using a simple, low-energy solvent displacement method. The effect of the organic: aqueous phase mixing order and kinetics, organic solvent, stirring speed, and organic: aqueous phase mixing ratio on the particle size and polydispersity index (PDI) of the nanoparticles were investigated. The obtained NC dispersion had a small particle size (Z-average particle diameter (Zave) < 100 nm), uniform size distribution (polydispersity index (PDI) < 0.2), and relatively good stability (Zeta potential is about −30 mV). And a series of Surelease® nanocomposites incorporated with various content of NC nanoparticles were fabricated via a facile solution casting/solvent evaporation method. The micromorphology, chemical structure, thermal properties, and water vapor sorption behavior of the nanocomposites were systematically investigated by Field scanning electron microscopy (SEM), Fourier-transform infrared (FTIR) spectrometer, Differential scanning calorimetry, Thermogravimetric analysis, and dynamic vapor sorption technology. The results show that the nanocomposites have good resistance to moisture absorption (<3 %) and effective thermal properties.

Unraveling the Supramolecular Structure and Nanoscale Dislocations of Bacterial Cellulose Ribbons Using Correlative Super-Resolution Light and Electron Microscopy.

Cellulose is a structural linear polysaccharide that is naturally produced by plants and bacteria, making it the most abundant biopolymer on Earth. The hierarchical structure of cellulose from the nano- to microscale is intimately linked to its biosynthesis and the ability to process this sustainable resource for materials applications. Despite this, the morphology of bacterial cellulose microfibrils and their assembly into higher order structures, as well as the structural origins of the alternating crystalline and disordered supramolecular structure of cellulose, have remained elusive. In this work, we employed high-resolution transmission electron and atomic force microscopies to study the morphology of bacterial cellulose ribbons at different levels of its structural hierarchy and provide direct visualization of nanometer-wide microfibrils. The non-persistent twisting of cellulose ribbons was characterized in detail, and we found that twists are associated with nanostructural defects at the bundle and microfibril levels. To investigate the structural origins of the persistent disordered regions that are present along cellulose ribbons, we employed a correlative super-resolution light and electron microscopy workflow and observed that the disordered regions that can be seen in super-resolution fluorescence microscopy largely correlated with the ribbon twisting observed in electron microscopy. Unraveling the hierarchical assembly of bacterial cellulose and the ultrastructural basis of its disordered regions provides insights into its biosynthesis and susceptibility to hydrolysis. These findings are important to understand the cell-directed assembly of cellulose, develop new cellulose-based nanomaterials, and develop more efficient biomass conversion strategies.

Systematic investigation of the adsorption potential of lignin- and cellulose-based nanomaterials towards pharmaceuticals

Understanding the interaction of wood-based nanomaterials with different pharmaceuticals is basic for future engineering of nanostructured wood-based adsorbents for pharmaceutical pollutants.

Biofabrication of a Hyaluronan/Bacterial Cellulose Composite Nanofibril by Secretion from Engineered Gluconacetobacter.

Naturally occurring polysaccharides, such as cellulose, hemicellulose, and chitin, have roles in plant skeletons and/or related properties in living organisms. Their hierarchically regulated production systems show potential for designing nanocomposite fabrication using engineered microorganisms. This study has demonstrated that genetically engineered Gluconacetobacter hansenii (G. hansenii) individual cells can fabricate naturally composited nanofibrils by simultaneous production of hyaluronan (HA) and bacterial cellulose (BC). The cells were manipulated to contain hyaluronan synthase and UDP-glucose dehydrogenase genes, which are essential for HA biosynthesis. Fluorescence microscopic observations indicated the production of composited nanofibrils and suggested that HA secretion was associated with the cellulose secretory pathway in G. hansenii. The gel-like nanocomposite materials produced by the engineered G. hansenii exhibited superior properties compared with conventional in situ nanocomposites. This genetic engineering approach facilitates the use of G. hansenii for designing integrated cellulose-based nanomaterials.

Mechanistic Insights on the Redox Activity and Immunogenicity of Cellulose-based Nanomaterials

Mechanistic Insights on the Redox Activity and Immunogenicity of Cellulose-based Nanomaterials

Applications of Cellulose Nanomaterials in Stimuli-Responsive Optics.

As one of the most abundant biopolymers, cellulose has been a basic but essential building block of human society, with its use dating back thousands of years. With recent developments in nanotechnology and increasing environmental concerns, cellulose-based nanomaterials are now gaining attention as promising green material candidates for many high-value applications as a result of their biocompatibility and advantageous physical and chemical properties. In particular, cellulose nanocrystals are notable for their optical properties that can respond to various environmental stimuli as a result of the unique chiral nematic structure of the material. Compositing cellulosic materials with functional polymers, small molecules, and other nanomaterials can further stabilize and amplify these responsive optical signals and introduce multiple new functionalities. On the basis of these capabilities, many advanced applications of cellulose nanomaterials have been proposed, including chemical sensors, photonic papers, decorative coatings, data security, and smart textiles. In this review, we discuss and summarize recent advances in this emerging field of stimuli-responsive optics based on cellulose nanomaterials.

The Influence of Electrolyte Solutions on the Mechanical Properties of Bacterial Cellulose

The mechanical characteristics of bacterial cellulose (one of the most promising cellulose-based nanomaterials) fundamentally depend on its moisture content. It has been found that the effect of aqueous solutions of alkali metal chlorides on its strength and deformation properties is determined by the mobility of water molecules in the near coordination spheres of cation hydration shells.

Theoretical and experimental study of dissolution mechanism of cellulose

Cellulose is one of the most abundant, sustainable and renewable materials on Earth. Accordingly, its utilization in different forms on different scales is in focus. Cellulose-based nanomaterials are considered to be one of the most exciting nanomaterials. Preparation of cellulose-based materials necessitates formation of cellulose-based solutions using environmentally hazardous solvents, which stems from the chemical nature of cellulose. In this work, an experimental and theoretical study of cellulose dissolution is described. As a model system, dissolution of cellulose in Schweizer's reagent is studied experimentally and theoretically as a model non-derivatizing method, elucidating and describing the physico-chemical aspects of the process. Dissolution of individual fibers pulled off banana woolery and cotton linters is studied experimentally. It is observed that a fiber can begin to swell before dissolution, even though it does not happen always. Then, the cross-sectional fiber size diminishes linearly in time, allowing direct measurement of the rate of cellulose dissolution. The theoretical model developed here links the rate of dissolution with the number of hydrogen bonds associated with hydroxyls on the surface of cellulose molecule required to be broken by chelating copper ions. This number is shown to be within the range of 1.28 × 1010–4.05 × 1010 cm−2, indicating that nanocellulose fibrils of length of 100–1000 nm are chipped off from cellulose during dissolution process. In concert with the dissolution rate, osmotically- driven flow of solvent towards the dissolving cellulose surface was also found.

Knoevenagel Condensation for Modifying the Reducing End Groups of Cellulose Nanocrystals.

Herein, we demonstrate an effective approach toward functionalization of cellulose nanocrystal (CNC) reducing ends by means of a Knoevenagel condensation reaction with a reactive β-diketone (acetylacetone). The end-wise modification was elucidated by advanced NMR analysis, which was facilitated by dissolving the CNCs in ionic liquid electrolyte and by the concomitant assignment of a model compound derived from d-cellobiose. The diffusion-edited 1H experiment afforded a simple method to identify the assigned model resonances in the reducing end-modified CNCs. The condensations can be carried out in aqueous bicarbonate solutions, avoiding the use of hazardous solvents. Under these preliminary aqueous conditions, end-group conversion of up to 12.5% could be confirmed. These results demonstrate the potential of β-diketone chemistry and the Knoevenagel condensation for functionalizing cellulose reducing ends. Application of this liquid-state NMR method for confirming and quantifying reducing end conversion is also shown to be invaluable. Extension of this chemistry to other 1,3-dicarbonyl compounds and solvation conditions should allow for the topochemical and (axially) chirotopic installation of functional moieties to CNCs, paving the way to asymmetric cellulose-based nanomaterials with unique properties.

Recent advances in nanoengineering cellulose for cargo delivery

The recent decade has witnessed a growing demand to substitute synthetic materials with naturally-derived platforms for minimizing their undesirable footprints in biomedicine, environment, and ecosystems. Among the natural materials, cellulose, the most abundant biopolymer in the world with key properties, such as biocompatibility, biorenewability, and sustainability has drawn significant attention. The hierarchical structure of cellulose fibers, one of the main constituents of plant cell walls, has been nanoengineered and broken down to nanoscale building blocks, providing an infrastructure for nanomedicine. Microorganisms, such as certain types of bacteria, are another source of nanocelluloses known as bacterial nanocellulose (BNC), which benefit from high purity and crystallinity. Chemical and mechanical treatments of cellulose fibrils made up of alternating crystalline and amorphous regions have yielded cellulose nanocrystals (CNC), hairy CNC (HCNC), and cellulose nanofibrils (CNF) with dimensions spanning from a few nanometers up to several microns. Cellulose nanocrystals and nanofibrils may readily bind drugs, proteins, and nanoparticles through physical interactions or be chemically modified to covalently accommodate cargos. Engineering surface properties, such as chemical functionality, charge, area, crystallinity, and hydrophilicity, plays a pivotal role in controlling the cargo loading/releasing capacity and rate, stability, toxicity, immunogenicity, and biodegradation of nanocellulose-based delivery platforms. This review provides insights into the recent advances in nanoengineering cellulose crystals and fibrils to develop vehicles, encompassing colloidal nanoparticles, hydrogels, aerogels, films, coatings, capsules, and membranes, for the delivery of a broad range of bioactive cargos, such as chemotherapeutic drugs, anti-inflammatory agents, antibacterial compounds, and probiotics. SynopsisEngineering certain types of microorganisms as well as the hierarchical structure of cellulose fibers, one of the main building blocks of plant cell walls, has yielded unique families of cellulose-based nanomaterials, which have leveraged the effective delivery of bioactive molecules.

A critical review of cellulose-based nanomaterials for water purification in industrial processes

At present, natural polymers have found applications in clothing, paper, medicine, fuel, etc. The advancement in science and technology has paved the way for nanotechnology, which combines the unique properties of these abundant polymers on a nanoscale to produce novel nanomaterials. Using mechanical or chemical treatment, cellulosic materials can be converted into cellulose nanofibers and nanocrystals which have excellent capabilities compared to microscale native cellulose fibers, especially in water purification applications. This review summarizes the most recent processing methods for nanocellulose and techniques employed for rational surface chemical modification. It also critically assesses the applications of cellulose-based nanomaterials with respect to their functionalization for removal of pollutants such as heavy metals, organic compounds and pharmaceutical residues from water.

Cellulose-Based Nanomaterials for Energy Applications.

Small 2017, 13, 1702240 The article was originally published online on September 13, 2017 with Figures 1–12 inverted, and in print on November 13, 2017 with Figures 4–12 inverted. The online version of the article was corrected on November 24, 2017. The editorial office apologizes for any inconvenience this error may have caused.

Cellulose-Based Nanomaterials for Energy Applications.

Cellulose is the most abundant natural polymer on earth, providing a sustainable green resource that is renewable, degradable, biocompatible, and cost effective. Recently, nanocellulose-based mesoporous structures, flexible thin films, fibers, and networks are increasingly developed and used in photovoltaic devices, energy storage systems, mechanical energy harvesters, and catalysts components, showing tremendous materials science value and application potential in many energy-related fields. In this Review, the most recent advancements of processing, integration, and application of cellulose nanomaterials in the areas of solar energy harvesting, energy storage, and mechanical energy harvesting are reviewed. For solar energy harvesting, promising applications of cellulose-based nanostructures for both solar cells and photoelectrochemical electrodes development are reviewed, and their morphology-related merits are discussed. For energy storage, the discussion is primarily focused on the applications of cellulose-based nanomaterials in lithium-ion batteries, including electrodes (e.g., active materials, binders, and structural support), electrolytes, and separators. Applications of cellulose nanomaterials in supercapacitors are also reviewed briefly. For mechanical energy harvesting, the most recent technology evolution in cellulose-based triboelectric nanogenerators is reviewed, from fundamental property tuning to practical implementations. At last, the future research potential and opportunities of cellulose nanomaterials as a new energy material are discussed.

97 - Curcumin Attenuates S-Glutathionylation of the NLRP3 Protein and Alters NLRP3 Inflammasome Protein-Protein Interactions in LPS/CNC-AEMA2 Stimulated-Macrophages

Recently we have demonstrated that needle-like, cellulose-based nanomaterials, such as cationic derivatives of cellulose nanocrystals (CNCs, CNC-AEMA2) evoke immunological responses through NLRP3 inflammasome/IL-1β inflammatory pathway. We also previously demonstrated that curcumin, a naturally occurring polyphenolic compound isolated from Curcuma longa (Zingiberaceae), was able to suppress, at least in part, this immunological response, as observed by diminished IL-1β secretion in LPS/CNC-AEMA2-stimulated macrophages. These results are not a totally surprise because curcumin is a well-known antioxidant and antinflammatory natural compound. In addition to acting as “scavenger” of reactive oxygen species (ROS), several studies indicate that curcumin also upregulates antioxidant enzymes by activating the Nfr2 signaling pathway. However, the mechanisms by which this natural compound exerts its protective activity is still under investigation. We hypothesize that curcumin may also affect the redox status, such as S-glutathionylation, of key proteins involved in the NLRP3 inflammasome/IL-1β pathway, and therefore impacts their protein-protein interactions. The goal of this study was to investigate the effects of curcumin on the S-glutathionylation of NLRP3 induced by CNC-AEMA2 in LPS-primed mouse macrophages (J774A.1), as well as interactions among proteins of the NLRP3 inflammasome complex using immunoprecipitation and Western blot techniques. Cells were primed for 4h with lipopolysaccharide (LPS) in presence or absence of curcumin, and CNC-AEMA2 was added for another 20h. Our main finding indicates that the addition of curcumin concomitantly with LPS caused the greatest decrease in NLRP3 and increase in caspase-1 S-glutathionylation, which appears to favor protein-protein interactions in the NLRP3 complex. Taking together our results suggest that, at least in part, the antinflammatory activity of curcumin is associated with changes in S-glutathionylation of key NLRP3 inflammasome components, and perhaps resulting in sustained complex assembly and suppression of IL-1β secretion.