Types Of Nanocellulose Research Articles

Effects of nanocellulose formulation on physicomechanical properties of Aquazol–nanocellulose composites

Aquazol [poly(2-ethyl-2-oxazoline)] is a widely used polymeric material for conservation because of its high reversibility and excellent compatibility with various types of material. However, it is hydrophilic and not recommended for use in weight-bearing applications. The objective of this study is to introduce cellulose nanocrystals (CNCs) and cellulose nanofibers (CNFs) into Aquazol to evaluate the physicomechanical properties of the resultant composites. Several nanocellulose addition formulations involving two types of nanocellulose were designed at various addition levels. Water sorption investigations revealed that the addition of CNCs or CNFs reduced the maximum moisture content of the resultant composites when compared to the unfilled Aquazol. The tensile test results showed that the critical addition level of CNF (2 wt%) is lower than that of CNC (10 wt%) for the nanocellulose to start acting effectively as a mechanically reinforcing agent. Notably, compared with using a single type of nanocellulose for reinforcement, greater reinforcement was observed when both CNCs and CNFs were combinedly added. Field emission scanning electron microscopy indicated that these strong reinforcement outcomes were probably a result of branch-like structures forming among the mixed fillers. The addition of nanocellulose in general resulted in composites having marginally lower thermal stability and optical transparency. In this study, we demonstrated the increased retention of mechanical properties in variously filled composites exposed to anticipated service conditions (55% RH; 23 °C). Crucially, the discoveries in this study indicate that mixed CNC and CNF fillers could be a reasonable option for future applications where lower levels of nanocellulose are desired for optical transparency considerations.

Nanocellulose-Based Inks for 3D Bioprinting: Key Aspects in Research Development and Challenging Perspectives in Applications-A Mini Review.

Nanocelluloses have emerged as a catalogue of renewable nanomaterials for bioink formulation in service of 3D bioprinting, thanks to their structural similarity to extracellular matrices and excellent biocompatibility of supporting crucial cellular activities. From a material scientist’s viewpoint, this mini-review presents the key research aspects of the development of the nanocellulose-based bioinks in 3D (bio)printing. The nanomaterial properties of various types of nanocelluloses, including bacterial nanocellulose, cellulose nanofibers, and cellulose nanocrystals, are reviewed with respect to their origins and preparation methods. Different cross-linking strategies to integrate into multicomponent nanocellulose-based bioinks are discussed in terms of regulating ink fidelity in direct ink writing as well as tuning the mechanical stiffness as a bioactive cue in the printed hydrogel construct. Furthermore, the impact of surface charge and functional groups on nanocellulose surface on the crucial cellular activities (e.g., cell survival, attachment, and proliferation) is discussed with the cell–matrix interactions in focus. Aiming at a sustainable and cost-effective alternative for end-users in biomedical and pharmaceutical fields, challenging aspects such as biodegradability and potential nanotoxicity of nanocelluloses call for more fundamental comprehension of the cell–matrix interactions and further validation in in vivo models.

NANOCELLULOSE AND ITS POTENTIAL USE FOR SUSTAINABLE INDUSTRIAL APPLICATIONS

Nanocellulose (NC) and its wide applications have attracted high attention due to its desirable properties such as high surface area, extraordinary mechanical properties, high reactivity and easy modification of NC surface due to the presence of primary hydroxyl groups. NC also presents several environmental benefits, including high potential availability because its production is coming from natural sources, renewability and nontoxicity. This paper briefly summarizes some of the activities of the research group “Cellulose, Paper and Water Advanced Treatments” from Complutense University of Madrid that were presented in CAIQ 2019, including the main types of NC, the production processes and their characterization. Additionally, the most promising NC applications are described such as for paper and board, for wastewater treatment, food and cement-based materials. Moreover, a market perspective of NC is also presented.

Electrospun Nanocomposites Containing Cellulose and Its Derivatives Modified with Specialized Biomolecules for an Enhanced Wound Healing.

Wound healing requires careful, directed, and effective therapies to prevent infections and accelerate tissue regeneration. In light of these demands, active biomolecules with antibacterial properties and/or healing capacities have been functionalized onto nanostructured polymeric dressings and their synergistic effect examined. In this work, various antibiotics, nanoparticles, and natural extract-derived products that were used in association with electrospun nanocomposites containing cellulose, cellulose acetate and different types of nanocellulose (cellulose nanocrystals, cellulose nanofibrils, and bacterial cellulose) have been reviewed. Renewable, natural-origin compounds are gaining more relevance each day as potential alternatives to synthetic materials, since the former undesirable footprints in biomedicine, the environment, and the ecosystems are reaching concerning levels. Therefore, cellulose and its derivatives have been the object of numerous biomedical studies, in which their biocompatibility, biodegradability, and, most importantly, sustainability and abundance, have been determinant. A complete overview of the recently produced cellulose-containing nanofibrous meshes for wound healing applications was provided. Moreover, the current challenges that are faced by cellulose acetate- and nanocellulose-containing wound dressing formulations, processed by electrospinning, were also enumerated.

Comparison Of Mechanical And Chemical Nanocellulose As Additives To Reinforce Recycled Cardboard

Recycling cycles cause a decrease in mechanical paper properties due to cellulose fiber degradation. The use of cellulose micro/nanofibers (CMF/CNF) to reinforce paper strength has been well studied, although it has been found to have negative effects on drainage. However, the application of CMF/CNF as paper reinforcement is affected by the nanocellulose type. Thus in this study mechanical and chemical treatments in CNF production were compared. Old corrugated container (OCC) pulp used to produce recycled cartonboard was reinforced with 1) CMF from never-dried northern bleached softwood kraft pulp (NBSK) highly refined in a 16-inch low consistency refiner at 1200 rpm and 25 kW of net power; and 2) CNF from NBSK pulp treated by TEMPO-mediated oxidation and homogenization at 600 bars. CMF/CNF and OCC were pulped at the same time and handsheets formed with cationic starch (CS) as retention system. Mechanical, drainage and flocculation properties were evaluated and compared. Data were also compared with other sources of TEMPO CNF. Results show an improvement in mechanical properties, drainage and flocculation when OCC is reinforced with CMF obtained with LCR. Therefore, high fibrillation was not necessary to improve mechanical paper or cardboard properties.

Nanofibrils vs nanocrystals bio-nanocomposites based on sodium alginate matrix: An improved-performance study

To develop bio-nanocomposites using natural biopolymers, nanocomposite films were prepared based on sodium alginate and kapok nanofibrils (CNFs). CNFs when subjected to TEMPO-mediated oxidation gave rise to cellulose nanocrystals (TOCNCs), with carboxyl groups at the surface (Ka/Kb = 3.64). The differences between the two types of nanocelluloses (nanofibrils and nanocrystals) and their impact in the preparation of bio-nanocomposites, were studied. When incorporated in the matrix, the CNFs particles have the tendency to form surface aggregation (Ka/Kb = 2.37), distorting the alginate network, creating heterogeneous films, with high surface roughness (Sa = 29.37 nm), porosity (Dp = 0.087 cm2/min) and vulnerability to heat. The TOCNCs present good dispersion creating a 3D network, which forms uniform (Dp = 0.122 cm2/min) and homogeneous films, with smooth surface (Sa = 16.83 nm). The ultrasonication treatment facilitated the dispersion improving the interfacial interaction between the reinforcing phase and the matrix. The results show the reinforcement potential of kapok nanocellulose in an industrially and medically important biopolymer, sodium alginate, especially when TOCNCs and ultrasonication were used.

Evaluation of nanocellulose interaction with water pollutants using nanocellulose colloidal probes and molecular dynamic simulations

Atomic Force Microscope (AFM) probes were successfully functionalized with two types of nanocellulose, namely 2,2,6,6-tetramethylpiperidine-1-oxylradical (TEMPO)-mediated oxidized cellulose nanofibers (TOCNF) and cellulose nanocrystals (CNC) and used to study interfacial interactions of nanocellulose with Cu(II) ions and the Victoria blue B dye in liquid medium. TOCNF modified tip showed higher adhesion force due to adsorption of Cu(II) ions and dye molecules compared to CNC ones. Exploring the adsorption properties through classical reactive molecular dynamics simulations (ReaxFF) at the atomic scale confirmed that the Cu(II) ions promptly migrated and adsorbed onto the nanocelluloses through the co-operative chelating action of carboxyl and hydroxyl species. The adsorbed Cu(II) ions showed the tendency to self-organize by forming nano-clusters of variable size, whereas the dye adopted a flat orientation to maximize its adsorption. The satisfactory agreement between the two techniques suggests that functionalized AFM probes can be successfully used to study nanocellulose surface interactions in dry or aqueous environment.

Ice-templated freeze-dried cryogels from tunicate cellulose nanocrystals with high specific surface area and anisotropic morphological and mechanical properties

High aspect ratio cellulose nanocrystals (CNCs) extracted from tunicate were used to create so-called cryogels from an ice-templating directional freeze-drying process. The structure of the resulting solid foam was investigated at the micro- and nanoscales by scanning electron microscopy and nitrogen adsorption measurements were used to extract the specific surface area. The mechanical properties were probed by compression tests. To highlight the specificities of tunicate CNC-based cryogels, results were compared with the one obtained from two other types of nanocellulose, namely cellulose nanofibrils (CNFs) from wood and CNCs from cotton, which exhibit different dimensions, aspect ratio, flexibility and crystallinity. While CNF- and cotton CNC-based cryogels exhibited a classical morphology characterized by a sheet-like structure, a particular honeycomb organization with individual particles was obtained in the case of tunicate CNC cryogels. The latter cryogels presented a very high specific surface area of about 122 m2 g−1, which is unexpected for foams prepared from a water-based process and much higher than what was obtained for CNF and cotton CNC cryogels (25 and 4 m2 g−1, respectively). High mechanical resistance and stiffness were also obtained with such tunicate CNC cryogels. These results are explained by the high crystallinity, aspect ratio and rigidity of the tunicate CNCs combined with the particular honeycomb architecture of the cryogel.

Preparation and thermostability of cellulose nanocrystals and nanofibrils from two sources of biomass: rice straw and poplar wood

Two types of nanocellulose (cellulose nanocrystals—CNCs and cellulose nanofibrils—CNFs) were isolated from two biomass resources. The morphology, crystallinity and thermal stability of the nanocelluloses were systematically compared in this paper. CNCs derived from rice straw (CNC-Rs) and poplar wood (CNC-Ps) by sulfuric acid hydrolysis had short rod-shaped structures and average diameters of 9.1 nm for CNC-Rs and 11.4 nm for CNC-Ps. CNFs derived from rice straw (CNF-Rs) and poplar wood (CNF-Ps) by grinding had web-network structures and average diameters of 13.3 nm for CNF-Rs and 18.5 nm for CNF-Ps. After freeze-drying, the CNCs and CNFs retained their nano structures. CNFs and CNC-Ps consisted of the typically pure cellulose I, while CNC-Rs consisted of cellulose I and II. The CrI of the nanocellulose followed the order of CNC-Ps (72.9%) > CNC-Rs (68.0%) > CNF-Ps (56.4%) > CNF-Rs (54.4%). The thermal stability of the nanocellulose was correlated with their source biomass materials and preparation method, which led to the differences in their dimensions, crystallinity, and sulfate groups. Nanocellulose isolated from poplar wood showed the slightly higher thermal stability than that of nanocellulose from rice straw. CNFs exhibited the higher thermal stability than that of CNCs. The apparent activation energy (E) was calculated to evaluate the degradation process. The nanocellulose had E of 85.17–101.98 kJ/mol for CNCs and 94.92–108.76 kJ/mol for CNFs.

Processing nanocellulose to bulk materials: a review

Various types of nanocellulose have been isolated from the cellulosic feedstock. It was expected that nanocellulose could be used to replace fossil-based plastic in certain areas because it is biodegradable, biocompatible, environment-friendly, and has outstanding performance. Unlike conventional plastic processing, nanocellulose is generally isolated and processed in aqueous environments. Therefore, dewatering and drying are essential unit operations for nanocellulose processing. Different drying methods for colloidal nanocellulose suspension mediated different self-assembly behaviors and thus resulted in different nanocellulose morphology and physical properties. The most utilized techniques for nanocellulose processing, such as spinning, vacuum/pressurized filtration, solvent casting and roll to roll casting, coating and roll to roll coating, and additive manufacturing are investigated. Process parameters such as temperature, pH, ion species, concentration, and external electrical field, affect the orientation and assembly behavior of nanocellulose, which in turn influence the properties of the prepared materials. Therefore, the method for assembling nanocellulose into bulk materials in a controlled way is vital for the properties of the fabricated nanocellulose composites. Here, some of the recent advances in the processing of nanocellulose for bulk materials are reviewed.

In vitro investigation of the influence of nano-cellulose on starch and milk digestion and mineral adsorption

Three types of nanocellulose, namely nano-fibrilated cellulose (NFC, also called cellulose nano-fibrils (CNF)), TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl radical) oxidized cellulose nano-fibrils (TEMPO-CNF), and nano-crystalline cellulose (NCC, also called cellulose nano-crystals (CNC)), were studied in terms of their effects on in vitro milk digestion and mineral adsorption. The effects of anionic NC (TEMPO-CNF and CNC) on in vitro starch digestion and glucose diffusion were also investigated. Results show that TEMPO-CNF and CNC at high concentrations caused significant reductions in glucose diffusion, especially at 0.36% (w/w) TEMPO-CNF and 2–4% (w/w) CNC. In addition, CNF and TEMPO-CNF at 0.30% (w/w) significantly reduced the amount of free fatty acid produced during intestinal digestion of milk fat. CNC at a concentration of 0.3% (w/w) delayed diffusion of free amino nitrogen during intestinal digestion of milk protein. All three types of NC adsorbed significant amount of Fe, and CNC adsorbed significant amount of Zn, while no significant adsorption was observed on other minerals (Ca, Mg, Zn, Cu and Ag). Results from this study suggest that all three types of NC, when incorporated in food or supplements as zero-calorie fiber, may affect food digestion and nutrient absorption.

Influence of Different Nanocellulose Additives on Processing and Performance of PAN-Based Carbon Fibers.

Nanocellulose, as a biobased versatile nanomaterial that can be derived with tailorable surface functionalities, dimensions, and morphologies, has considerable implications for modifying the rheology, mechanical reinforcement, and influencing the carbonization efficiency in the production of polyacrylonitrile (PAN)-based carbon fibers. Herein, we report the influence of three different nanocellulose types, varying in the derivatization method, source, and aspect ratio, on the mechanical properties and thermal transformations of solution-spun PAN/nanocellulose nanocomposite fibers into carbon fibers. The incorporation of 0.1 wt % nanocellulose into solution-spun PAN fibers led to a 7–19% increase in tensile modulus and 0–27% increase in tensile strength in the solution-spun fibers, compared to a control PAN fiber. These improvements varied depending on the nanocellulose type. After low-temperature carbonization at 1200 °C, improvements in the mechanical properties of the nanocellulose-reinforced carbon fibers, compared with a PAN fiber, were also observed. In contrast to the precursor fibers, the improvement % in the carbonized fibers was found to be dependent on the nanocellulose morphology and was linearly correlated with increasing aspect ratio of nanocellulose. For example, in carbon fibers with a cotton-derived low-aspect-ratio cellulose nanocrystal and spinifex-derived high-aspect-ratio CNC and nanofiber, up to 4, 87, and 172% improvements in tensile moduli were observed, respectively. Due to the processing methods used, the nanocellulose aspect ratio and crystallinity are inversely related, and as such, the increase in the carbon fiber mechanical properties was also related to a decrease in crystallinity of the nanocellulose reinforcers. Raman spectra and electron microscopy analysis suggest that mechanical improvement after carbonization is due to internal reinforcement by highly ordered regions surrounding the carbonized nanocellulose, within the turbostratic carbon fibers.

Thermal and mechanical behavior of biodegradable polyester films containing cellulose nanofibers

Agricultural waste is a valuable source of advanced materials. Cheap nanocellulose may be obtained from plum shells agricultural residues and further used instead of expensive nanocellulose as reinforcement in biopolymers. In this work, two types of nanocellulose, cellulose nanocrystals (CN) and cellulose nanofibers (CF), were isolated from plum seed shells using two different approaches. CN and CF from plum seed shells were used for the first time as reinforcing agents in a polylactic acid/poly(3-hydroxybutyrate) (PLA/PHB) matrix using a solvent casting method. The surface morphology, thermal (TG and DSC), static and dynamic mechanical (DMA) properties of the resulted biocomposite films were characterized and compared to the neat matrix. Atomic force microscopy—peak force quantitative nanomechanical mapping emphasized the influence of nanocellulose type upon the crystalline structure of PLA/PHB biocomposites and the dispersion of nanofibers/nanocrystals in the polymer matrix. Thermal and XRD analyses showed that the incorporation of CN increased the thermal stability and crystallinity of PLA/PHB biocomposite film. Young’s modulus and storage modulus of PLA/PHB/CN biocomposite were higher compared to that of PLA/PHB/CF showing the better reinforcing capability of CN compared to CF. This is consistent with the better dispersion of CN observed by PF QNM. The good effect of cellulose nanocrystals obtained from plum seed shells on the properties of PLA/PHB matrix highlights the potential of this cheap nanocellulose to obtain biocomposites in very advantageous conditions. This approach is proposed as an affordable and efficient tool to employ agricultural wastes as raw materials for high added-value products.

Characterization of polystyrene nanocomposites and expanded nanocomposites reinforced with cellulose nanofibers and nanocrystals

Expanded nanocomposite production is an evolutionary and emerging technology in the field of porous materials, because it’s characterized by combining the structural characteristics of the nanocomposites with the lightness of the polymeric foams. Three different processes were used in the present study: (1) extraction of two types of nanocellulose: cellulose nanofibers (CNFs) and cellulose nanocrystals (CNCs), both from curaua fibers. CNFs were obtained by mechanical defibrillation method and CNCs by 2,2,6,6-tetramethylpiperidine-1-oxyl (T.E.M.P.O.)-mediated oxidation method. (2) incorporation of reinforcement in a polystyrene matrix, producing nanocomposites in the following concentrations: 0.25%, 0.50% and 1.00% (w/w). (3) nanocomposite expansion with supercritical carbon dioxide fluid (scCO2), a new expander agent trend. The nanocomposites all had increased storage and loss moduli in relation to neat PS. In the expanded nanocomposites, the incorporation of CNFs promoted an increase in the compressive strength and a decrease in the cell size in comparison to the samples reinforced with CNCs and polystyrene foam. In the nanocomposites produced with CNCs, no significant variations were observed when compared to pure polystyrene foam.

Nano-lignocellulose from recycled fibres in coatings from aqueous and ethanolic media: effect of residual lignin on wetting and offset printing quality

Abstract Nano-lignocellulose (NLC) and lignin-free nanocellulose (nano-holocellulose, NHC) were used in paper coating to investigate their effect on coating layer quality and offset printing. The NLC was produced by microfluidisation of unbleached secondary fibres while the reference NHC was obtained from the same fibre source after lignin removal (OHEPH bleaching), following the same mechanical process. TEMPO-mediated oxidation of the fibres prior to microfluidisation was applied to increase the electrostatic charge and hydrophilicity of the nanofibrils. The coatings, displaying given surface morphology and energy, were applied on Kraft, printing-grade papers at three grammage levels. The structure of the coated and uncoated (reference) papers were accessed (SEM and AFM) and IGT printing was carried out to determine the print density, print gloss, rub-off resistance, surface energy, roughness, ink transfer, dry pick resistance, water interference and set-off. The results highlight the important effect of residual lignin or type of nanocellulose on the coating layer and the development of offset printing properties. It was observed that roughness was a key factor leading to a deterioration of the print properties, predominantly affecting the NLC coating. Considering the lower hydrophilicity of NLC, an alternative dispersion with water-alcohol mixtures is proposed. By using this dispersing medium, tailorable surface coverage, surface smoothness, ink acceptance and improved printability was achieved. We show that under these conditions and compared to NHC, NLC is equally effective as a coating layer.

Characterization of lipid emulsions during in vitro digestion in the presence of three types of nanocellulose

HypothesisNanocellulose (NC) has been a topic of significant interest due to its multiple applications, including that as a potential food ingredient. Due to the viscous property of NC and its potential use as emulsion stabilizers, presence of NC in food may affect properties and digestion of lipid emulsions systems. In this study, the behavior of three types of nanocellulose and its influence on lipid emulsions during digestion were investigated. ExperimentsThe changes in physicochemical characteristics (including particle size, microstructure, viscosity, and zeta potential) of the emulsions as well as the amount of free fatty acid released were studied and compared among the addition of different types/concentrations of fiber as well as digestion phases. FindingsThe colloidal stability of three types of NC differed during each digestion phase. Specifically, cellulose nanocrystals (CNC) formed hydrogel networks during the gastric phase, resulting in increased digesta viscosity. Cellulose nano-fibrils (CNF) were stable and had no morphological changes during digestion. TEMPO-oxidized cellulose nano-fibrils (TEMPO-CNF) de-swelled and showed aggregation at the gastric phase. Results showed that all three types of nanocellulose at high concentrations (1% CNF, 0.25–0.36% TEMPO-CNF or 2–3% CNC) delayed initial in vitro digestion of emulsions, though the final lipolysis extent was nearly the same amongst all (47–55%).

Influence of nanocellulose on in vitro digestion of whey protein isolate

Three types of nanocellulose (NC), namely cellulose nano-fibrils (CNF), TEMPO-oxidized CNF and cellulose nanocrystals (CNC), were studied in terms of their effects on in vitro digestion of whey protein isolate (WPI). The behavior of NC itself during digestion was monitored by particle size, confocal microscopy imaging, viscosity, and zeta potential. 1% CNF and 4% CNC significantly retarded free amino nitrogen (FAN) diffusion (23% and 50% respectively) mainly due to high viscosity. 4% CNC also significantly reduced %FAN release during intestinal digestion. Anionic NC (TEMPO-CNF and CNC) bound with WPI causing less protein aggregation at the gastric phase as well as reductions in mean particle size and/or viscosity of digesta. However, cellulose and CNF did not bind with WPI. The findings from this study lay a foundation for future applications of nanocellulose in the food industry as rheology modifiers and development of functional foods for delaying gastric emptying and promoting satiety.

Tailored nanocellulose structure depending on the origin. Example of apple parenchyma and carrot root celluloses

Cellulose is the major polysaccharide of cell walls in every plant, making it one of the most abundant natural polymers on Earth. However, despite many decades of investigations, the supramolecular structure of cellulose and especially its variation in the cell walls of different plants have still not been fully revealed. In the present study, cellulose from the parenchymatic tissue of apple fruits and carrot roots was isolated, and nanocellulose was further prepared by high-intensity ultrasonication. AFM revealed that the obtained nanocellulose differed in dimension between the two plant species. Compared with carrot cellulose, whose nanocellulose was obtained in the form of whiskers, apple cellulose had longer and thinner nanofibrils. Both nanocellulose types also differed in terms of their crystalline structure. XRD data indicated that, compared with the apple cellulose, the carrot cellulose had a higher degree of crystallinity and larger crystallites. Moreover, FTIR and Raman spectroscopy revealed differences between the cellulose types in terms of their methine environment, hydroxymethyl conformations and skeletal vibrations. Additionally, with respect to their mechanical properties, the less crystalline apple cellulose and nanocellulose films were more elastic than the stiffer carrot cellulose and nanocellulose films. The possible reason for such differences between the two cellulose types is related to differences in plant tissue morphology and function. During development, apple fruit cell walls must withstand increasing turgor, probably higher that in the case of carrot tissue; therefore, the cellulose scaffolding must be elastic and strong. On the other hand, carrot, a root vegetable, also has to be strong enough to penetrate the soil as well as for its own growth; thus, the cell wall and cellulose scaffold have to be stiff and tough. Thus the structure of nanocellulose depends not only on the treatment but also on the cellulose source.

Stability and rheological behavior of nanocellulose-modified UF resin compositions

The aim of this work was to investigate the influence of nanocellulose on the storage stability and rheological properties of urea formaldehyde (UF)-based adhesive compositions for wood-based panels. Three types of UF resins characterized by different F/U molar ratios were used for this research. Resin modifications with nanocrystalline cellulose and a nanofibrillated cellulose content of 1.0% to 5.0% by dry weight of resin were prepared. The flow curve characteristics and storage stability were studied. The viscosity values mainly depended upon the type of nanocellulose used, as well as its loading in the composition. The UF resins modified with nanocrystalline cellulose kept their rheological behavior and proper viscosity after 4 weeks in storage, which lowered the percentage of viscosity retention by approximately 1.5 times compared with that of industrial resins. Nanocrystalline cellulose might be used as a stabilizer in resin compositions during long-term storage, while nanofibrillated cellulose might act as a thickening agent through the limited extent of loading in a composition.

Evaluating mucoadhesion properties of three types of nanocellulose in the gastrointestinal tract in vitro and ex vivo

The mucoadhesive properties of three types of nanocellulose (CNF, CNC, and Tempo-CNF) was investigated in the digestive condition with ex vivo and in vitro assays. In the ex vivo flow-through method, three nanocellulose materials showed different levels of retention on porcine gastric and intestinal mucosal surfaces. Fluorescence microscopy confirmed that retention of CNF could be due to entanglement with the mucosal layer, while retention of Tempo-CNF could be due to instantaneous gelling on the mucosal surface. In an in vitro viscometric method, 2% CNC showed the highest viscosity synergism (relative enhancement=11.80 ± 1.14) in the gastric condition, while Tempo-CNF only displayed synergism under gelling concentrations (0.1%). Evaluation of zeta potential revealed that 0.025–0.1% CNC interacted with mucin particles by changing the surface charge of the mucin-nanocellulose system. These results indicate that nanocellulose shows mucoadhesive properties in digestive tract, where the level of adhesion depends on type of nanocellulose, its concentration and the gastrointestinal section.