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Emerging cellulose nanomaterials (CNMs) may have commercial impacts in multiple sectors, being their application particularly explored in the food sector. Thus, their potential adverse effects in the gastrointestinal tract should be evaluated before marketing. This work aimed to assess the safety of two CNMs (CNF–TEMPO and CMF–ENZ) through the investigation of their cytotoxicity, genotoxicity (comet and micronucleus assays), and capacity to induce reactive oxygen species in human intestinal cells, and their mutagenic effect using the Hprt gene mutation assay. Each toxicity endpoint was analysed after cells exposure to a concentration-range of each CNM or to its digested product, obtained by the application of a standardized static in vitro digestion method. The results showed an absence of cytotoxic effects in intestinal cells, up to the highest concentration tested (200 µg/mL or 25 µg/mL, for non-digested and digested CNMs, respectively). Of note, the cytotoxicity of the digestion control limited the top concentration of digested samples (25 µg/mL) for subsequent assays. Application of a battery of in vitro assays showed that CNF–TEMPO and CMF–ENZ do not induce gene mutations or aneugenic/clastogenic effects. However, due to the observed DNA damage induction, a genotoxic potential cannot be excluded, even though in vitro digestion seems to attenuate the effect. The lowest digested CNF–TEMPO concentration induced chromosomal damage in Caco-2 cells, leading to an equivocal outcome. Ongoing research on epigenotoxic effects of these CNMs samples may strengthen the lines of evidence on their safety when ingested, paving the way for their innovative application in the food industry. [ABSTRACT FROM AUTHOR]

In the present work, solvent casting and Pickering emulsion methods are studied to enhance the mechanical properties of polylactic acid (PLA) composites containing surface-modified cellulose nanomaterials. To enhance the compatibility and the adhesion at the interface, cellulose nanocrystal (CNC) was functionalized by 2,4-methylene diphenyl diisocyanate (MDI) and castor oil. Their results demonstrated that the Pickering emulsion method led to better dispersion of CNC in composites, resulting in improved tensile strength, flexibility, and thermal stability (compared with solvent-casted ones). In particular, the tensile strength increased by 20% and the crystallinity increased by 15% using the Pickering emulsion technique, indicating their potential as a new generation of sustainable packaging. The findings of this research could help in creating eco-friendly packaging options by improving the mechanical features of biodegradable composites and exploring potential alternatives to overcome their limitations. [ABSTRACT FROM AUTHOR]

Cellulose nanomaterials provide a promising avenue for combining composite materials with natural polymers or bio-based plastics, however, current studies on rheological characterization at high shear rates is limited. In this study, a capillary rheometer was employed to investigate the rheological characteristics of aqueous cellulose nanofibril (CNF) suspensions at room temperature and shear rates above 1000 s - 1 . The shear rate-dependent viscosity of aqueous CNFs was characterized and monitored for viscosity-related indicators of fibril decomposition or entanglement due to the stresses induced by the high shear-rate flow. Traditional capillary rheology corrections for entrance pressure loss and irregular flow profiles were attempted to compare apparent and true rheological behaviors. Large entanglements of fibrils made the characterization of the suspensions difficult due to their ability to clog the capillary. However, appropriate preprocessing steps enabled better measurement resolution and enhanced dispersion of cellulose nanofibers, as verified by atomic force microscopy. The suspensions display shear thinning behavior and demonstrate higher entrance pressures for lower shear rates. Similar preprocessing techniques could be implemented on a large scale to enhance fibril distribution in CNF suspensions. [ABSTRACT FROM AUTHOR]

Cellulose nanomaterial (CNM) aspect ratio strongly influences sheet formation and resulting mechanical, optical, and barrier properties. However, there is a lack of fast and reliable methods for CNM aspect ratio determination, limiting the reliable production of nanocellulose at industrial-scale. Current laboratory approaches comprise microscopic (e.g. atomic force microscopy (AFM) and transmission electron microscopy (TEM)), and sedimentation methods, which are time-consuming and limited to specific CNM fibre sizes. Here, we describe a new rheological method to determine the aspect ratios for the whole size range of cellulose fibres using rheology. Cellulose nanocrystals (CNCs), cellulose nanofibres (CNFs), and wood fibres in the form of Bleached Eucalyptus Kraft (BEK) were investigated. The aspect ratios of these three scales of cellulose fibres were determined by measuring the specific viscosity profiles of their suspensions at different concentrations from high to low shear rates (2000–0.001 s−1), and evaluating whether the fibre suspensions exhibited entangled or disentangled behaviour. The rheological results agreed well with those produced by AFM and sedimentation methods. Furthermore, cellulose fibre aspect ratios determined with specific viscosity measurements were generated in 5 hours for each feedstock, while sedimentation and AFM required at least 2 days to produce the same results. Ultimately, we demonstrate that rheology is a rapid and accurate method to determine the aspect ratio for the whole range of cellulose fibre sizes, a critical step towards facilitating their full-scale application. [ABSTRACT FROM AUTHOR]

The rapid development of the petroleum industry has led to increasing demands for high-performance oilfield working fluids, such as drilling fluids, fracturing fluids, and fluids for enhanced oil recovery. Liquid foam is widely utilized as the oilfield working fluids due to its advantages, including low density, high mobility, superior cutting suspending ability, excellent fluid diversion capacity, and outstanding sweep efficiency. However, the short lifespan of foam limits its broad application in the oilfield. Considering the advantages of environmental protection, renewability, high specific surface area, tailorable surface chemistry, and excellent rheological properties of cellulose nanomaterials (CNMs), Pickering foams stabilized by CNMs offer improved eco-friendliness and foam stability. In this review, the classification and preparation methods of CNMs are briefly introduced. Subsequently, the preparation methods, properties, and application prospects of CNM-stabilized Pickering foams as oilfield working fluids are summarized. Finally, the challenges and prospects of CNM-stabilized Pickering foam are outlined, aiming to pave the way for the development of petroleum industry in an eco-friendlier manner. [ABSTRACT FROM AUTHOR]

Abstract Cellulose nanopaper has shown great potential in diverse fields including optoelectronic devices, food packaging, biomedical application, and so forth, owing to their various advantages such as good flexibility, tunable light transmittance, high thermal stability, low thermal expansion coefficient, and superior mechanical properties. Herein, recent progress on the fabrication and applications of cellulose nanopaper is summarized and discussed based on the analyses of the latest studies. We begin with a brief introduction of the three types of nanocellulose: cellulose nanocrystals, cellulose nanofibrils and bacterial cellulose, recapitulating their differences in preparation and properties. Then, the main preparation methods of cellulose nanopaper including filtration method and casting method as well as the newly developed technology are systematically elaborated and compared. Furthermore, the advanced applications of cellulose nanopaper including energy storage, electronic devices, water treatment, and high-performance packaging materials were highlighted. Finally, the prospects and ongoing challenges of cellulose nanopaper were summarized.

Highlights: Preparation strategies of cellulose nanopaper were elaborated. Functionalization of cellulose nanopaper and its advanced applications were summarized. Prospects and challenges of cellulose nanopaper were discussed.Cellulose nanopaper has shown great potential in diverse fields including optoelectronic devices, food packaging, biomedical application, and so forth, owing to their various advantages such as good flexibility, tunable light transmittance, high thermal stability, low thermal expansion coefficient, and superior mechanical properties. Herein, recent progress on the fabrication and applications of cellulose nanopaper is summarized and discussed based on the analyses of the latest studies. We begin with a brief introduction of the three types of nanocellulose: cellulose nanocrystals, cellulose nanofibrils and bacterial cellulose, recapitulating their differences in preparation and properties. Then, the main preparation methods of cellulose nanopaper including filtration method and casting method as well as the newly developed technology are systematically elaborated and compared. Furthermore, the advanced applications of cellulose nanopaper including energy storage, electronic devices, water treatment, and high-performance packaging materials were highlighted. Finally, the prospects and ongoing challenges of cellulose nanopaper were summarized. [ABSTRACT FROM AUTHOR]

A semi-automatic image analysis program, SMART, was used to analyze transmission electron microscopy (TEM) images from four laboratories that participated in an interlaboratory comparison study by Meija et al. on CNC particle size measurement by TEM using conventional manual image analysis approaches. Detailed image-to-image comparisons found that the percentage of "correctly" identified CNCs by SMART was 58% to 78%, while manual was 70% to 87%, depending on TEM image quality from a given laboratory. SMART was able to parameterize image quality, and it was found that SMART had difficulties in CNC identification for images with a combination of higher noise, lower contrast, and higher CNC density. Overall, the SMART image analysis was consistent with the manual approach. SMART showed lower laboratory-laboratory variation as compared to manual, suggesting that the variability of analyst bias of manual approach was removed and demonstrates an opportunity with SMART to improve the standardization of CNC size characterization. An approach to estimate the likelihood of reaching a representative measurement for CNC particle size was developed. SMART area analysis found that less than 10% of CNCs were used in morphology characterization; to assess more CNC material, SMART was used to analyze CNC agglomerates as a proof-of-concept demonstration. The total SMART image analysis time for each laboratory, having between 115 and 244 images, was less than 15 min, after selection of appropriate parameters. The SMART code is now available for the public to use for free at Github™. [ABSTRACT FROM AUTHOR]

Cellulose nanomaterials (CNMs) have emerged recently as an important group of sustainable bio-based nanomaterials (NMs) with potential applications in multiple sectors, including the food, food packaging, and biomedical fields. The widening of these applications leads to increased human oral exposure to these NMs and, potentially, to adverse health outcomes. Presently, the potential hazards regarding oral exposure to CNMs are insufficiently characterised. There is a need to understand and manage the potential adverse effects that might result from the ingestion of CNMs before products using CNMs reach commercialisation. This work reviews the potential applications of CNMs in the food and biomedical sectors along with the existing toxicological in vitro and in vivo studies, while also identifying current knowledge gaps. Relevant considerations when performing toxicological studies following oral exposure to CNMs are highlighted. An increasing number of studies have been published in the last years, overall showing that ingested CNMs are not toxic to the gastrointestinal tract (GIT), suggestive of the biocompatibility of the majority of the tested CNMs. However, in vitro and in vivo genotoxicity studies, as well as long-term carcinogenic or reproductive toxicity studies, are not yet available. These studies are needed to support a wider use of CNMs in applications that can lead to human oral ingestion, thereby promoting a safe and sustainable-by-design approach. [ABSTRACT FROM AUTHOR]

Carboxylated cellulose nanocrystals (cCNCs) can be prepared directly from biomass in a one-step ammonium persulfate (APS) oxidation. However, the cellulose in the biomass is not fully utilized because APS oxidation degrades the cellulose amorphous regions. In this paper, to improve cellulose utilization rate, a two-step method (enzymatic pre-hydrolysis and APS oxidation) was developed to co-produce fermentable sugar and cCNCs from xylooligosaccharides manufacturing waste residue (XOR) of corncob. Enzymatic pre-hydrolysis produced 26.1 g of glucose per 100 g of XOR with a cellulase loading of 5 FPU/g cellulose in 24 h. Subsequent oxidation produced 22.9 g cCNCs with 0.5 M APS in 8 h. In contrast, the one-step APS method only produced 28.3 g cCNCs per 100 g of XOR. The total cellulose utilization rate by the two-step method increased by 73 % compared to the one-step APS method. Structural characteristics of cCNCs prepared by the two-step method were slightly different from those of the one-step method, but good properties were maintained. Therefore, the co-production method could prepare glucose and cCNCs with stable properties from XOR with a greatly improved cellulose utilization rate. [Display omitted] • Maximizing the utilization of cellulose in the biomass waste residues. • Coproducing glucose and cCNCs via enzyme pre-hydrolysis and persulfate oxidation. • The two-step method reduced the loss of cellulose by one-step persulfate oxidation. • The total cellulose utilization rate increased by 73 % after enzyme pre-hydrolysis. [ABSTRACT FROM AUTHOR]

Recyclable cellulose nanofibril (CNF) and lignin-containing cellulose nanofibril (LCNF) coated wood flour composites were fabricated using a vacuum-filtration process for food serving applications. The coated cellulose nanofibril composites had excellent mechanical, and oil, and grease barrier properties compared to a commercial container. However, the composites with both LCNF and CNF coating layers had poor performance in wet conditions compared to the commercial container. The addition of 1 wt.% aluminum sulfate (alum) to the CNF and LCNF coating layer significantly improved the water-resistance of the composites. CNF + 1% alum coated composites had inferior water resistance and lower mechanical strength in wet conditions compared to the commercial container. However, the LCNF + 1% alum coated composites had comparable water resistance and higher wet mechanical properties than the commercial container. The recyclability of the composites was assessed through the disintegration of the samples in water and subsequent reformation, and it was found that the composites were fully recyclable. The composites could fully retain their mechanical and excellent oil and grease barrier properties after each recycling level. These recyclable fully bio-based nanocomposites can be an eco-friendly alternative for currently used food container systems that use harmful chemicals. [ABSTRACT FROM AUTHOR]

Hemicellulose plays a key role in both the production of cellulose nanofibrils (CNF) and their properties as suspensions and films. While the use of enzymatic and chemical pre-treatments for tailoring hemicellulose levels is well-established, post-treatment methods using enzymes remain relatively underexplored and hold significant promise for modifying CNF film properties. This study aimed to investigate the effects of enzymatic xylan removal on the properties of CNF film for packaging applications. The enzymatic post-treatment was carried out using an enzymatic cocktail enriched with endoxylanase (EX). The EX post-treated-CNFs were characterized by LALLS, XRD, and FEG-SEM, while their films were characterized in terms of physical, morphological, optical, thermal, mechanical, and barrier properties. Employing varying levels of EX facilitated the hydrolysis of 8 to 35 % of xylan, yielding CNFs with different xylan contents. Xylan was found to be vital for the stability of CNF suspensions, as its removal led to the agglomeration of nanofibrils. Nanostructures with preserved crystalline structures and different morphologies, including nanofibers, nanorods, and their hybrids were observed. The EX post-treatment contributed to a smoother film surface, improved thermostability, and better moisture barrier properties. However, as the xylan content decreased, the films became lighter (lower grammage), less strong, and more brittle. Thus, the enzymatic removal of xylan enabled the customization of CNF films' performance without affecting the inherent crystalline structure, resulting in materials with diverse functionalities that could be explored for use in packaging films. [Display omitted] • Xylan content in CNF was tailored through endoxylanase (EX) post-treatment. • EX post-treatments at varied loadings resulted in up to 35 % of xylan hydrolysis. • EX post-treated CNFs showed varied morphology and preserved crystalline structure. • Xylan removal affected CNF suspensions, film formation and its properties. • EX post-treated CNF films showed suitable performance for packaging film applications. [ABSTRACT FROM AUTHOR]

Barrier materials are crucial in preserving product quality, safety and longevity across numerous applications, thereby contributing to sustainability, reducing waste and advancing technology. Among these materials, cellulose nanomaterials (CNs) have emerged as promising alternatives for traditional petroleum-based polymers. However, the wide range of sources and the different methods used to isolate and process CN-based materials can result in significant variations in moisture and oxygen barrier performance. In this review, we provide an in-depth discussion on the latest advancements in CN-based green barrier materials. We begin by offering a critical assessment of the barrier performance of CNs, both in their isolated form and when combined as hybrid materials. This includes their applications as standalone films, fillers and coatings in nanocomposites. This review also covers the influence of the isolation process and the stages of film formation on barrier efficacy. We further discuss the implications of the recycling process on barrier properties of CN-based materials, drawing a connection between barrier characteristics and the product's end-of-life. We conclude by highlighting the significant developments over the past five years, the present challenges, and the prospective future of CN-based materials in barrier applications. [Display omitted] [ABSTRACT FROM AUTHOR]

The current materials predominately come from fossil feedstocks and minerals. The pressures from climate change and plastic pollution challenge us to develop a bioeconomy, replacing petroleum-based products with bio-based and biodegradable products. Cellulose emerges as a versatile biopolymer to make hydrogels for absorbents, aerogels for insulation, membranes for filters, films for packaging, and fibers for textiles and reinforcements. Wood-based cellulose is increasingly perceived by relevant stakeholders to be renewable, biodegradable, and sustainable. Can the properties of cellulose-based materials compete with conventional synthetic materials? Knowledge and discoveries concerning cellulose properties and applications are scattered throughout the scientific literature base. This paper surveys the mechanical properties of cellulose-based materials in the literature using tensile properties as indicators and visualizes the data compared with other competitive materials. The goal is to provide insights into the potential and challenges of using cellulose-based products to replace synthetic materials for a sustainable society. [ABSTRACT FROM AUTHOR]

Disease outbreaks are a major impediment to aquaculture production, and vaccines are integral for disease management. Vaccines can be expensive, vary in effectiveness, and come with adjuvant-induced adverse effects, causing fish welfare issues and negative economic impacts. Three-dimensional biopolymer hydrogels are an appealing new technology for vaccine delivery in aquaculture, with the potential for controlled release of multiple immunomodulators and antigens simultaneously, action as local depots, and tunable surface properties. This research examined the intraperitoneal implantation of a cross-linked TEMPO cellulose nanofiber (TOCNF) hydrogel formulated with a Vibrio anguillarum bacterin in Atlantic salmon with macroscopic and microscopic monitoring to 600-degree days post-implantation. Results demonstrated a modified passive integrated transponder tagging (PITT) device allowed for implantation of the hydrogel. However, the Atlantic salmon implanted with TOCNF hydrogels exhibited a significant foreign body response (FBR) compared to sham-injected negative controls. The FBR was characterized by gross and microscopic external and visceral proliferative lesions, granulomas, adhesions, and fibrosis surrounding the hydrogel using Speilberg scoring of the peritoneum and histopathology of the body wall and coelom. Acutely, gross monitoring displayed rapid coagulation of blood in response to the implantation wound with development of fibrinous adhesions surrounding the hydrogel by 72 h post-implantation consistent with early stage FBR. While these results were undesirable for aquaculture vaccines, this work informs on the innate immune response to an implanted biopolymer hydrogel in Atlantic salmon and directs future research using cellulose nanomaterial formulations in Atlantic salmon for a new generation of aquaculture vaccine technology. • Cellulose nanomaterials are an attractive biopolymer for aquaculture vaccines systems. • Cellulose nanomaterials crosslinked into hydrogels for vaccines triggered a foreign body response (FBR) in Atlantic salmon. • FBR was characterized macroscopically and histologically in Atlantic salmon by 600-degree days compared to the sham controls. • Acute gross monitoring displayed results consistent with early stage FBR. • Further tunability of CNM as a biopolymer hydrogel for aquaculture vaccine technology is needed. [ABSTRACT FROM AUTHOR]

This review describes the recent advances in the production and application of cellulose nanomaterials. Cellulose nanomaterials (CNMs), especially cellulose nanocrystals and cellulose nanofibers, can be produced using different preparation processes resulting in materials with unique structures and physicochemical properties that are exploited in different fields such as, biomedical, sensors, in wastewater treatment, paper and board/packaging industry. These materials possess attractive properties such as large surface area, high tensile strength and stiffness, surface tailor-ability via hydroxyl groups and are renewable. This has been a driving force to produce these materials in industrial scale with several companies producing CNMs at tons-per-day scale. The recent developments in their production rate and their applications in various fields such as medical sector, environmental protection, energy harvesting/storage are comprehensively discussed in this review. We emphasize on the current trends and future remarks based on the production and applications of cellulose nanomaterials. [ABSTRACT FROM AUTHOR]

Determination of nanofibril orientation is crucial for predicting the properties of films and membranes made from cellulose nanofibrils (CNF) because of their inherent anisotropic nature. A novel method is proposed based on image analysis of the polarized light micrographs to quantify and map nanofibril orientation in the film structure. Thin films (average 30 µm in thickness) of CNF were produced using a filtration method and were wet-stretched to two extension levels. Randomly-oriented films were also produced as the control without applying stretch. Samples were imaged at − 45°, 0° and + 45° between crossed polarizers using a polarized light microscope. A BOI was developed based on the interference color changes between the two angles (+ 45° and − 45°). The proposed BOI values range between − 1 and + 1 differentiating orientation in perpendicular directions. The index was shown to work successfully for mapping of the fibril orientation in CNF films. Statistical analysis of the tensile test results confirmed significant difference between tensile modulus of CNF films produced using different stretch ratios. This difference was also supported by the good agreement between the tensile properties of the films, the BOI and directionality results obtained from the surface analysis of scanning electron micrographs. The method was validated by applying to single pulp fibers with known orientation as well as un-stretched and stretched polyvinyl chloride films and oriented cellulose nanocrystals. The advantages of the proposed method over other conventional methods used for orientation analysis are discussed. [ABSTRACT FROM AUTHOR]

Recently, enhancing the performance of polyurethane (PU) coatings with cellulose nanomaterials (CNM) has been actively researched. Cellulose nanomaterials exhibit considerable potential to increase the mechanical strength of PU coatings due to their high aspect ratios and elastic moduli. In this study, PU reinforced with CNM was coated onto paper to enhance the paper’s mechanical strength and soiling resistance. To investigate the reinforcing effect, two different CNM, cellulose nanocrystals (CNC) and 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO)-oxidized cellulose nanofibers (TOCN), were selected, and suspensions with different ratios of PU and CNM were prepared. After coating the paper with each of them, the mechanical properties of the paper, including tensile strength, folding endurance, and soiling resistance, were evaluated. The mechanical strength and anti-soiling performance of the PU-CNM coated papers were greatly enhanced. Especially, PU-TOCN had superior properties as a durable paper coating despite a low TOCN concentration, less than 2%, because the TOCN crosslinked with PU via polyaziridine. Furthermore, the PU-CNM coating protected the paper from being contaminated, which was confirmed by scanning electron microscopy and energy dispersive X-ray mapping. Consequently, durable paper exhibiting soiling resistance was fabricated by coating the paper with PU-TOCN suspensions. [ABSTRACT FROM AUTHOR]

The focus of this study is to (i) understand the effect of the fiber type and content on the mechanical properties of sheet-molding compounds composites and (ii) investigate possible lightweight alternatives to glass fibers-sheet molding compound composites. Glass fiber and basalt fibers are used to make sheet-molding compound composites and the mechanical performance are determined as a function of the fiber type and content. In addition, cellulose nanocrystals are used to enhance the properties of the sheet-molding compound resin system. The possibility of lightweighting the basalt fiber/epoxy and glass fiber/epoxy sheet-molding compound composites is explored by replacing a portion of the fibers, i.e. 12–16 wt%, with a small amount cellulose nanocrystals, i.e. 1–2 wt%. No significant difference was found between the basalt fiber/epoxy and glass fiber/epoxy sheet-molding compound composites in terms of mechanical and impact properties. When cellulose nanocrystals were added to the composites, the properties of glass fiber/epoxy sheet-molding compound composites were enhanced while those of basalt fiber/epoxy sheet-molding compound composites deteriorated. [ABSTRACT FROM AUTHOR]

Highlights • Preparation of CNCs and CNFs was briefly introduced. • Fabrication of CNCs and CNFs based hydrogels was elaborated. • Emerging methods such as 3D printing were highlighted. • Biomedical applications of CNCs and CNFs based hydrogels were summarized. • Prospects and challenges of CNCs and CNFs based hydrogels were discussed. Abstract The production of cellulose nanomaterials from lignocellulosic biomass opens an opportunity for the development and application of new materials in nanotechnology. Over the last decade, cellulose nanomaterials based hydrogels have emerged as promising materials in the field of biomedical applications due to their low toxicity, biocompatibility, biodegradability, as well as excellent mechanical stability. In this review, recent progress on the preparation of cellulose nanocrystals (CNCs) and cellulose nanofibrils (CNFs) based hydrogels and their biomedical applications is summarized and discussed based on the analyses of the latest studies (especially for the reports in the past five years). We begin with a brief introduction of the differences in preparation methods and properties of two main types of cellulose nanomaterials: CNCs and CNFs isolated from lignocellulosic biomass. Then, various processes for the fabrication of CNCs based hydrogels and CNFs based hydrogels were elaborated, respectively, with the focus on some new methods (e.g. 3D printing). Furthermore, a number of biomedical applications of CNCs and CNFs based hydrogels, including drug delivery, wound dressings and tissue engineering scaffolds were highlighted. Finally, the prospects and ongoing challenges of CNCs and CNFs based hydrogels for biomedical applications were summarized. This work demonstrated that the CNCs and CNFs based hydrogels have great promise in a wide range of biomedical applications in the future. [ABSTRACT FROM AUTHOR]

Researches of cellulose nanomaterials have seen nearly exponential growth over the past several decades for versatile applications. The characterization of nanostructural arrangement and local chemical distribution is critical to understand their role when developing cellulose materials. However, with the development of current characterization methods, the simultaneous morphological and chemical characterization of cellulose materials at nanoscale resolution is still challenging. Two fundamentally different nanoscale infrared spectroscopic techniques, namely atomic force microscope based infrared spectroscopy (AFM-IR) and infrared scattering scanning near field optical microscopy (IR s-SNOM), have been established by the integration of AFM with IR spectroscopy to realize nanoscale spatially resolved imaging for both morphological and chemical information. This review aims to summarize and highlight the recent developments in the applications of current state-of-the-art nanoscale IR spectroscopy and imaging to cellulose materials. It briefly outlines the basic principles of AFM-IR and IR s-SNOM, as well as their advantages and limitations to characterize cellulose materials. The uses of AFM-IR and IR s-SNOM for the understanding and development of cellulose materials, including cellulose nanomaterials, cellulose nanocomposites, and plant cell walls, are extensively summarized and discussed. The prospects of future developments in cellulose materials characterization are provided in the final part.

An optimal methodology for locating and tracking cellulose nanofibers (CNFs) in vitro and in vivo is crucial to evaluate the environmental health and safety properties of these nanomaterials. Here, we report the use of a new boron-dipyrromethene (BODIPY) reactive fluorescent probe, meso-DichlorotriazineEthyl BODIPY (mDTEB), tailor-made for labeling CNFs used in simulated or in vivo ingestion exposure studies. Time-correlated single photon counting (TCSPC) fluorescence lifetime imaging microscopy (FLIM) was used to confirm covalent attachment and purity of mDTEB-labeled CNFs. The photoluminescence properties of mDTEB-labeled CNFs, characterized using fluorescence spectroscopy, include excellent stability over a wide pH range (pH2 to pH10) and high quantum yield, which provides detection at low (μM) concentrations. FLIM analysis also showed that lignin-like impurities present on the CNF reduce the fluorescence of the mDTEB-labeled CNF, via quenching. Therefore, the chemical composition and the methods of CNF production affect subsequent studies. An in vitro triculture, small intestinal, epithelial model was used to assess the toxicity of ingested mDTEB-labeled CNFs. Zebrafish (Danio rerio) were used to assess in vivo environmental toxicity studies. No cytotoxicity was observed for CNFs, or mDTEB-labeled CNFs, either in the triculture cells or in the zebrafish embryos.

This review article was prompted by a remarkable growth in the number of scientific publications dealing with the use of nanocellulose (especially nanofibrillated cellulose (NFC), cellulose nanocrystals (CNC), and bacterial cellulose (BC)) to enhance the barrier properties and other performance attributes of new generations of packaging products. Recent research has confirmed and extended what is known about oxygen barrier and water vapor transmission performance, strength properties, and the susceptibility of nanocellulose-based films and coatings to the presence of humidity or moisture. Recent research also points to various promising strategies to prepare ecologically-friendly packaging materials, taking advantage of nanocellulose-based layers, to compete in an arena that has long been dominated by synthetic plastics. Some promising approaches entail usage of multiple layers of different materials or additives such as waxes, high-aspect ratio nano-clays, and surface-active compounds in addition to the nanocellulose material. While various high-end applications may be achieved by chemical derivatization or grafting of the nanocellulose, the current trends in research suggest that high-volume implementation will likely incorporate water-based formulations, which may include water-based dispersions or emulsions, depending on the end-uses.

Abstract: 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.Graphical abstract: [ABSTRACT FROM AUTHOR]

Nanotechnology with bionanomaterials have tremendous potential to enhance and utilize for nutrient and bioactive absorption, drug delivery systems, pharmaceutical, and nutraceutical field through various applications. Cellulose nanomaterials are green materials that are obtained from renewable sources and possess exceptional mechanical strength and biocompatibility. The associated unique physical and chemical properties have made various nanocomposite materials an intriguing prospect for different application in the biomedical, food, and nutraceutical industries. In this review, we have discussed and provided a summary of the recent researches in the utilization of cellulosic nanomaterials in applications related to food packaging, bone tissue engineering, wound dressing, drug delivery, and nutraceutical research area and industries. [ABSTRACT FROM AUTHOR]

Cellulose is the most abundant natural polymer, is readily available, biodegradable, and inexpensive. Recently, interest is growing around nano-scale cellulose due to the sustainability of these materials, the novel properties, and the overall low environmental impact. The rapid expansion of nanocellulose uses in various applications makes the study of the toxicological properties of these materials of great importance to public health regulators. However, most of the current toxicological studies are highly conflicting, inconclusive, and contradictory. The major reason for these discrepancies is the lack of standardized methods to produce industryrelevant reference nanocellulose and relevant characterization that will expand beyond the traditional cellulose characterization for applications. In order to address these issues, industry-relevant synthesis platforms were developed to produce nanocellulose of controlled properties that can be used as reference materials in toxicological studies. Herein, two types of nanocellulose were synthesized, cellulose nanofibrils and cellulose nanocrystals using the friction grinding platform and an acid hydrolysis approach respectively. The nanocellulose structures were characterized extensively regarding their physicochemical properties, including testing for endotoxins and bacteria contamination. [ABSTRACT FROM AUTHOR]

• Cellulose nanomaterials (CNMs) hold promising applications in oil and gas industry. • Characteristics of CNMs related to their uses in oil and gas sectors are summarized. • Research progress on the upstream, midstream and downstream are overviewed. • Critical challenges, corresponding solutions and future opportunities are outlined. With the increase in global fossil fuel consumption and growing demand for sustainability, the advancement of novel technologies and green materials in the oil and gas industry are becoming critically essential. Given the merits of abundance, cost-effectiveness, and renewability, together with high specific surface area, tunable surface chemistry, and exceptional mechanical, barrier, thermal and rheological properties, cellulose nanomaterials (CNMs) have received enormous interest in oil and gas industry, in an effort to make the oil and gas development more sustainable and environmentally-friendly. In particular, three families of CNMs, i.e., cellulose nanofibers (CNFs), cellulose nanocrystals (CNCs), and bacterial cellulose (BC), can be produced via a series of top-down and bottom-up strategies. Lignocellulosic nanomaterials, i.e., lignocellulosic nanofibers (LCNFs) and lignocellulosic nanocrystals (LCNCs), exhibit similar morphology with CNMs, but some tiny globular-shaped lignin nanoparticles can be retained in similarly production to CNMs. Due to the variation in production approaches and parameters, CNMs exhibit distinctive morphology, crystallinity, and surface chemistry, leading to different final product performance. Herein, the classification, production, and properties of CNMs are summarized, aiming to provide a better understanding of the production-structure–property relationships and thus make it possible to more efficiently use CNMs in the oil and gas industry. Then, we overview the recent advances of CNMs in three major sectors of oil and gas industry, i.e., i) upstream - exploration and production, ii) midstream - transportation and storage, and iii) downstream - refining and purifying. Finally, the opportunities, challenges, as well as future perspectives of CNMs and their application in oil and gas industry are outlined. [ABSTRACT FROM AUTHOR]

Wastewater (WW) remediation technologies were the most crucial issues all over the world at present time. Thus, the remediation of Cr (VI) ions from real WW was conducted using green biocompatible and biodegradable pristine (CNM) and succinic anhydride functionalized cellulose nanomaterial (S-CNM) adsorbents. Both CNM and S-CNM adsorbents were prepared by using sulfuric acid hydrolysis method and characterized for particle sizes, functional groups, and surface morphologies by using XRD, FT-IR, and SEM instruments, respectively. The physicochemical properties of the collected WW were investigated. Next, both the prepared adsorbents were applied for the remediation of Cr (VI) ions from WW. The remediation processes is spontaneous and have higher remediation efficiencies of Cr (VI) ions from WW. The Cr (VI) ions remediation mechanism was evaluated from both the Cr (VI) ions adsorption isotherms and kinetic concepts. Both Langmuir and Freundlich Cr (VI) ions adsorption isotherm models were certainly fixed to a maximum Cr (VI) ions uptake capability (q _max ) of 60.24 and 156.25 mg g ^−1 by CNM and S-CNM sorbents, respectively, and it follows pseudo-second-order (PSO) kinetics model through chemisorption processes. The Cr (VI) ions uptake capabilities were hindered by the presence of organic matter and any other competing pollutants in the WW. The S-CNM sorbent was selected for the regeneration study due to its higher efficiencies of remediation relative to CNM sorbent and the study was conducted through desorption of Cr (VI) ions by using HCl. Findings have shown that the sorbent was easily recyclable and applicable for the remediation of pollutants from real WW after consecutive 13th cycles.

Lab-processed cellulose nanofibrils (CNF-L), commercial cellulose nanofibrils (CNF-C), and cellulose nanocrystals (CNC) were used in this study as reinforcing materials in phenol formaldehyde (PF) resin. The mechanical modification of adhesives and cell wall layers (S2 and compound corner-middle lamellae [CCML]) by the three types of cellulose particles was investigated by nanoindentation. Results showed that cellulose nano-materials can improve the mechanical properties of both adhesives and the cell wall structure. CNF-C had the most obvious reinforcing effect on the elastic modulus (Er) and hardness within the glue line. With modification, the Er and hardness reached 13.0 and 0.436 GPa, respectively, in the S2 layer far from the glue line. In comparison, the control sample had an Er and hardness of 7.31 and 0.256 GPa, respectively.

Cellulose nanofibril foams are cellulose-based porous materials with outstanding mechanical properties, resulting from the high strength-to-weight ratio of nanofibrils. Here we report the development of an optimized fabrication process for highly porous cellulose foams, based on a well-controlled freeze-thawing-drying (FTD) process at ambient pressure. This process enables the fabrication of foams with ultra-high porosity, up to 99.4%, density of 10 mg/cm3, and liquid (such as oil) absorption capacity of 100 L/kg. The proposed approach is based on the ice-templating of nanocellulose suspension in water, followed by thawing in ethanol and drying at environmental pressures. As such, the proposed fabrication route overcomes one of the major bottle-necks of the classical freeze-drying approach, by eliminating the energy-demanding vacuum drying step required to avoid wet foam collapse upon drying. As a result, the process is simple, environmentally friendly, and easily scalable. Details of the foam development fabrication process and functionalization are thoroughly discussed, highlighting the main parameters affecting the process, e.g., the concentration of nanocellulose and additives used to control the ice nucleation. The foams are also characterized by mechanical tests and oil absorption measurements, which are used to assess the foam absorption capability as well as the foam porosity. Compound water-in-oil drop impact experiments are used to demonstrate the potential of immiscible liquid separation using cellulose foams.

Cellulose nanofibrils (CNF) and cellulose nanocrystals (CNC) were used to improve the mechanical properties of tapes and yarns produced from natural fibers as a new application of cellulose nanomaterials in textile-based composite products. Hemp and flax slivers were used as natural fibers for the production of yarns and tapes. CNC, unground CNF and two different ground CNF suspensions were used as the reinforcement agents. Fiber strands from each natural fiber were soaked in the cellulose nanomaterial suspension and then were processed into tapes or yarns. Individual hemp and flax fibers where also soaked in the same suspensions and dried. SEM microscopy of the surfaces and cross-sections of the yarns and tapes showed that cellulose nanomaterial suspensions affected the morphology of the natural fiber yarns and tapes by filling gaps and adhering the fibers together. Results of studies on tensile properties of single fibers showed improvement in initial modulus and strength of flax fibers after soaking in nanocellulose suspensions especially when CNF was used. Such consistent results were not however seen for hemp single fibers. Yarns and tapes produced by soaking fiber strands in different nanocellulose suspensions had considerably higher tensile properties in terms of strength and initial modulus than controls. Furthermore, it was shown that mixing cellulose nanomaterial suspensions with natural fibers improved the dewatering/drying process, a necessary step should cellulose nanomaterials be used in composite applications. [ABSTRACT FROM AUTHOR]

Cellulose nanomaterials (CNs)-incorporated emulsion coatings with improved moisture barrier, wettability and surface adhesion onto fruit surfaces were developed for controlling postharvest physiological activity and enhancing storability of bananas during ambient storage. Cellulose nanofiber (CNF)-based emulsion coating (CNFC: 0.3% CNF/1% oleic acid/1% sucrose ester fatty acid (w/w wet base)) had low contact angle, high spread coefficient onto banana surfaces, and lower surface tension (ST, 25.4 mN/m) than the critical ST (35.2 mN/m) of banana peels, and exhibited good wettability onto banana surfaces. CNFC coating delayed the ethylene biosynthesis pathway and reduced ethylene and CO 2 production, thus delaying fruit ripening. As the result, CNFC coating minimized chlorophyll degradation, weight loss, and firmness of bananas while ensuring the properly fruit ripening during 10 d of ambient storage. This study demonstrated the effectiveness of CNF based emulsion coatings for improving the storability of postharvest bananas. [ABSTRACT FROM AUTHOR]

Abstract: This study demonstrates the feasibility of tailored and integrated production of carboxylated cellulose nanocrystals (CNC) with nanofibrils (CNF) from bleached pulp fibers through hydrolysis using a recyclable dicarboxylic acid. Hydrolysis experiments were conducted using ranges of 15–75 wt % maleic acid concentrations, 60–120 °C temperatures, and 5–300 min reaction times. Maleic acid esterified cellulose resulted in carboxylated CNC and CNF. Furthermore, the acid‐hydrolysis solubilized xylan and depolymerized cellulose, which substantially reduced the energy input for the production of CNF through subsequent mechanical fibrillation. A combined hydrolysis factor (CHF), a measure of hydrolysis severity, was developed to map xylan dissolution and cellulose depolymerization over the entire reaction space. It was found that CHF can be used to predict the morphological and chemical properties of the resultant CNC and CNF, independent of the individual reaction process variables. This is important for process scale‐up design in order to tailor the properties of CNC and CNF for specific applications. With the low temperature hydrolysis and low energy input in mechanical fibrillation, along with the recyclability of maleic acid, the presented process has promise of achieving commercial success in the low‐cost and sustainable production of CNC and CNF. [ABSTRACT FROM AUTHOR]

A scalable technique was introduced to produce high volume lightweight composites using sheet molding compound (SMC) manufacturing method by replacing 10 wt% glass fibers (GF) with a small amount of cellulose nanocrystals (CNC). The incorporation of 1 and 1.5 wt% CNC by dispersing in the epoxy matrix of short GF/epoxy SMC composites with 25 wt% GF content (25GF/CNC-epoxy) produced 7.5% lighter composites with the same tensile and flexural properties of 35GF/epoxy composites with no CNC. The addition of 1 wt% CNC in 25GF/CNC-epoxy SMC composites resulted in increases of 15% in elastic modulus, 11% in flexural modulus and 14% in flexural strength, reaching the corresponding properties of 35GF/epoxy SMC composites. Moreover, it was found that although addition of CNC did not alter the impact energy, removing 10 wt% GF resulted in reduction of impact energy. [ABSTRACT FROM AUTHOR]

This review article was prompted by a remarkable growth in the number of scientific publications dealing with the use of nanocellulose (especially nanofibrillated cellulose (NFC), cellulose nanocrystals (CNC), and bacterial cellulose (BC)) to enhance the barrier properties and other performance attributes of new generations of packaging products. Recent research has confirmed and extended what is known about oxygen barrier and water vapor transmission performance, strength properties, and the susceptibility of nanocellulose-based films and coatings to the presence of humidity or moisture. Recent research also points to various promising strategies to prepare ecologically-friendly packaging materials, taking advantage of nanocellulose-based layers, to compete in an arena that has long been dominated by synthetic plastics. Some promising approaches entail usage of multiple layers of different materials or additives such as waxes, high-aspect ratio nano-clays, and surface-active compounds in addition to the nanocellulose material. While various high-end applications may be achieved by chemical derivatization or grafting of the nanocellulose, the current trends in research suggest that high-volume implementation will likely incorporate water-based formulations, which may include water-based dispersions or emulsions, depending on the enduses. [ABSTRACT FROM AUTHOR]

A recent publication in "Particle and Fibre Toxicology" reported on the gender differences in pulmonary toxicity from oro-pharyngeal aspiration of a high dose of cellulose nanocrystals. The study is timely given the growing interest in diverse commercial applications of cellulose nanomaterials, and the need for studies addressing pulmonary toxicity. The results from this study are interesting and can be strengthened with a discussion of how differences in the weights of female and male C57BL/6 mice was accounted for. Without such a discussion, the observed differences could be partially explained by the lower body weights of females, resulting in higher doses than males when standardized to body weight or lung volume. Further, few conclusions can be drawn about the pulmonary toxicity of cellulose nanocrystals given the study design: examination of a single high dose of cellulose nanocrystals, administered as a bolus, without positive or negative controls or low dose comparisons, and at an unphysiological and high dose rate. Simulating the bolus type delivery by inhalation would require a highly unrealistic exposure concentration in the g/m3 range of extremely short duration. A discussion of these limitations is missing in the paper; further speculative comparisons of cellulose nanocrystals toxicity to asbestos and carbon nanotubes in the abstract are both unwarranted and can be misleading, these materials were neither mentioned in the manuscript, nor evaluated in the study. [ABSTRACT FROM AUTHOR]

Quantification of the mechanical properties of cellulose nanomaterials is key to the development of new cellulose nanomaterial based products. Using contact resonance atomic force microscopy we measured and mapped the transverse elastic modulus of three types of cellulosic nanoparticles: tunicate cellulose nanocrystals, wood cellulose nanocrystals, and wood cellulose nanofibrils. These modulus values were calculated with different contact mechanics models exploring the effects of cellulose geometry and thickness on the interpretation of the data. While intra-particle variations in modulus are detected, we did not observe a measureable difference in modulus between the three types of cellulose particles. Improved practices and experimental complications for the characterization of cellulosic nanomaterials with atomic force microscopy are discussed. [ABSTRACT FROM AUTHOR]