Rheology of Suspensions of TEMPO-Oxidised and Cationic Cellulose Nanofibrils-The Effect of Chemical Pre-Treatment.

Cellulose nanofibrils (CNFs) are particles with a high aspect ratio. Typically, chemically pre-treated CNFs (containing anionic or cationic charged groups) consist of long fibrils (up to 2 μm) with very low thickness (less than 10 nm). Derived from their high aspect ratio, CNFs form strong hydrogels with high elasticity at low concentrations.

Assessing the Genotoxicity of Cellulose Nanomaterials in a Co-Culture of Human Lung Epithelial Cells and Monocyte-Derived Macrophages.

Cellulose micro/nanomaterials (CMNMs) are innovative materials with a wide spectrum of industrial and biomedical applications. Although cellulose has been recognized as a safe material, the unique properties of its nanosized forms have raised concerns about their safety for human health. Genotoxicity is an endpoint that must be assessed to ensure that no carcinogenic risks are associated with exposure to nanomaterials.

Eco-Friendly Methods for Extraction and Modification of Cellulose: An Overview.

Cellulose is the most abundant renewable polymer on Earth and can be obtained from several different sources, such as trees, grass, or biomass residues. However, one of the issues is that not all the fractionation processes are eco-friendly and are essentially based on cooking the lignocellulose feedstock in a harsh chemical mixture, such as NaOH + NaS, and water, to break loose fibers. In the last few years, new sustainable fractionation processes have been developed that enable the obtaining of cellulose fibers in a more eco-friendly way.

Influence of dispersion of fibrillated cellulose on the reinforcement of coated papers.

The use of cellulose micro/nanofibrils (CMNFs) as reinforcement paper additive at industrial scale is delayed due to inconsistent results, suggesting a lack of proper consideration of some key parameters. The high influence of fibrillated nanocellulose dispersion has been recently identified as a key parameter for paper bulk reinforcement but it has not been studied for surface coating applications yet. This paper studies the effect of CMNF dispersion degree prior to their addition and during mixing with starch on the reinforcement of paper by coating.

Impact of bacterial cellulose on the physical properties and printing quality of fine papers.

Bacterial nanocellulose (BNC), due to its inherent nanometric scale and strength properties, can be considered as a good candidate to be used in papermaking. This work explored the possibility of using it in the production of fine paper as a wet-end component and for the paper coating. Filler-containing handsheet production was performed with and without the presence of common additives typically used in the furnish of office papers.

Improving the Barrier Properties of Paper to Moisture, Air, and Grease with Nanocellulose-Based Coating Suspensions.

Food packaging manufacturers often resort to lamination, typically with materials which are neither non-biodegradable nor biobased polymers, to confer barrier properties to paper and cardboard. The present work considers a greener solution: enhancing paper’s resistance to moisture, grease, and air by aqueous coating suspensions. For hydrophobization, a combined approach between nanocellulose and common esterifying agents was considered, but the water vapor transmission rate (WVTR) remained excessively high for the goal of wrapping moisture-sensitive products (>600 g m−2 d−1).

Assessment of the Performance of Cationic Cellulose Derivatives as Calcium Carbonate Flocculant for Papermaking.

Cationic polyacrylamides (CPAMs) are usually used as filler retention agents in papermaking formulations. However, increasing environmental restrictions and their non-renewable origin have driven research into bio-based alternatives. In this context, cationic lignocellulosic derivatives have been attracting considerable research interest as a potential substitute.

Micro-/Nanofibrillated Cellulose-Based Coating Formulations: A Solution for Improving Paper Printing Quality.

The use of micro-/nanofibrillated celluloses (M/NFCs) is often considered for the enhancement of paper properties, while it is still challenging to use them in lower weight gain coatings. This work explores how they might be used on the paper surface to improve the printing quality. In this regard, M/NFCs were produced using different pre-treatment methods, including mechanical (m-MFC), enzymatic (e-MFC), TEMPO-mediated oxidation (t-NFC) and cationization (c-NFC), and uniform coating formulations were developed through the cooking of starch and M/NFCs simultaneously.

Genotoxicity of Three Micro/Nanocelluloses with Different Physicochemical Characteristics in MG-63 and V79 Cells.

(1) Background: Nanocellulose is an innovative engineered nanomaterial with an enormous potential for use in a wide array of industrial and biomedical applications and with fast growing economic value. The expanding production of nanocellulose is leading to an increased human exposure, raising concerns about their potential health effects. This study was aimed at assessing the potential toxic and genotoxic effects of different nanocelluloses in two mammalian cell lines; (2) Methods: Two micro/nanocelluloses, produced with a TEMPO oxidation pre-treatment (CNFs) and an enzymatic pre-treatment (CMFs), and cellulose nanocrystals (CNCs) were tested in osteoblastic-like human cells (MG-63) and Chinese hamster lung fibroblasts (V79) using the MTT and clonogenic assays to analyse cytotoxicity, and the micronucleus assay to test genotoxicity; (3) Results: cytotoxicity was observed by the clonogenic assay in V79 cells, particularly for CNCs, but not by the MTT assay; CNF induced micronuclei in both cell lines and nucleoplasmic bridges in MG-63 cells; CMF and CNC induced micronuclei and nucleoplasmic bridges in MG-63 cells, but not in V79 cells; (4) Conclusions: All nanocelluloses revealed cytotoxicity and genotoxicity, although at different concentrations, that may be related to their physicochemical differences and availability for cell uptake, and to differences in the DNA damage response of the cell model.

Nanocelluloses: Production, Characterization and Market.

Nanocelluloses are a very promising material that has been widely explored for the most diverse applications. The pursuit for sustainable and environmentally friendly materials is in line with the nature of nanocelluloses and therefore they have emerged as the perfect candidate for plastics substitution, food additive, rheology controller, 3D printing of diverse structures, among many other possibilities. This derives from their interesting characteristics, such as reduced size and high specific surface area, high tensile strength, crystallinity and transparency, and from the fact that, such as cellulose, they are obtained from renewable sources, with relative ease for functionalization in order to obtain desired specificities.

Analysis of the In Vitro Toxicity of Nanocelluloses in Human Lung Cells as Compared to Multi-Walled Carbon Nanotubes.

Cellulose micro/nanomaterials (CMNM), comprising cellulose microfibrils (CMF), nanofibrils (CNF), and nanocrystals (CNC), are being recognized as promising bio-nanomaterials due to their natural and renewable source, attractive properties, and potential for applications with industrial and economical value. Thus, it is crucial to investigate their potential toxicity before starting their production at a larger scale. The present study aimed at evaluating the cell internalization and in vitro cytotoxicity and genotoxicity of CMNM as compared to two multi-walled carbon nanotubes (MWCNT), NM-401 and NM-402, in A549 cells.

Effect of cationization pretreatment on the properties of cationic Eucalyptus micro/nanofibrillated cellulose.

Micro/nanofibrillated celluloses (M/NFCs) have attracted considerable research interest over the past few decades, with various pretreatments being used to reduce energy consumption and/or increase fibrillation. To date, few studies have considered cationization as a pretreatment for their preparation. In this work, quaternary ammonium groups were attached to cellulose fibers by a direct reaction with 2,3-epoxypropyltrimethylammonium chloride or by a two-step method (periodate oxidation + Girard's reagent T).

Novel approach on the synthesis of starch betainate by transesterification.

Transesterification of starch with methyl betainate was studied for the first time, both in aprotic media and in solid state, and both under alkaline and acidic conditions. Betaine hydrochloride was first esterified in methanol, attaining a conversion of 86%. Starch was then converted into starch betainate in either N,N-dimethylformamide or dimethyl sulfoxide, and using sulfuric acid as catalyst or pre-activating the polymer in NaOH/ethanol.

A review on cationic starch and nanocellulose as paper coating components.

Starch and derivatives thereof have proven their usefulness in paper coating processes. Among these derivatives, cationic starch has been widely used in the paper industry as a flocculation, dispersion and ink fixing agent. In another context, nanoscale cellulosic materials have been shown to improve the strength, retention of fillers, the barrier properties of packaging paper products, and printing qualities.

Enzymatic nanocellulose in papermaking - The key role as filler flocculant and strengthening agent.

Nanocelluloses have been increasingly used in composites since their reduced size, high aspect ratio and stiffness confer great strength to the materials. In papermaking, it has been proved that harsh and expensive chemical pre-treatments to generate nanofibrils, such as TEMPO-mediated oxidation, are not the most favourable and therefore the use of cellulose microfibrils (CMF) have gained extra attention, especially those produced with the aid of enzymatic hydrolysis. In the present work, strategies to improve filler flocculation and the papermaking properties, by using enzymatic CMF, are provided.

Evaluating the genotoxicity of cellulose nanofibrils in a co-culture of human lung epithelial cells and monocyte-derived macrophages.

Cellulose nanofibrils (CNF) are manufactured nanofibres that hold impressive expectations in forest, food, pharmaceutical, and biomedical industries. CNF production and applications are leading to an increased human exposure and thereby it is of utmost importance to assess its safety to health. In this study, we screened the cytotoxic, immunotoxic and genotoxic effects of a CNF produced by TEMPO-mediated oxidation of an industrial bleached Eucalyptus globulus kraft pulp on a co-culture of lung epithelial alveolar (A549) cells and monocyte-derived macrophages (THP-1 cells).

On the morphology of cellulose nanofibrils obtained by TEMPO-mediated oxidation and mechanical treatment.

The morphological properties of cellulose nanofibrils obtained from eucalyptus pulp fibres were assessed. Two samples were produced with the same chemical treatment (NaClO/NaBr/TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl radical) oxidation), but distinct mechanical treatment intensities during homogenization. It was shown that the nanofibrils production yield increases with the mechanical energy.