Nanofibrillar Cellulose Research Articles

Density Modifications Toward High Mechanical Performance Nanocellulose Aerogels

ABSTRACTMechanical properties are crucial for the application of nanocellulose aerogels. In this work, a series of nanocellulose aerogels with solid content concentration gradient (0.5, 1.0, 1.5, 2.0 wt%) of precursor dispersion are prepared by freeze‐drying method, and the effect of nanocellulose solid content on the mechanical properties of nanocellulose aerogels was investigated. As the solid content concentration increased, the internal microstructure of the aerogel underwent a transition from a sparse reticular structure to a tightly arranged lamellar structure. This transition led to a substantial improvement in the mechanical properties of the aerogel. At 50% strain, the compressive strength of the aerogel increased from 8.4 to 37.56 kPa with the increase of nanofibrillar cellulose solid content. Furthermore, the specific strength, specific modulus, and compressive modulus also increased, while maintaining a low density (20.02 mg/cm3) and high porosity (98.63%). This work confirms the feasibility of structural strengthening and mechanical property enhancement of nanocellulose aerogels by density modification, which provides a guidance for the design of durability enhancement of nanocellulose aerogels for broadening their application fields.

Electron beam pretreatment of carboxymethyl nanofibrillar cellulose reinforced polyvinyl alcohol-based degradable composite membranes: Preparation, characterization and property optimization

This study investigated the development of biodegradable composite films blending carboxymethyl-modified peanut hull nanocelluloses (CMNCs) pretreated by electron beam irradiation with polyvinyl alcohol (PVA). The films were characterized by their structure, physicochemical properties, and degradation characteristics. The carboxyl group of CMNCs and the hydroxyl group of PVA enhance the network structure of the film through hydrogen bonding. This is most notably manifested in the fact that when CMNCs with a substitution degree of 0.38 and an addition amount of 4 % were added, the CMNCs were uniformly dispersed in the PVA matrix with a flat and smooth surface of the plastic and a dense structure. Meanwhile, the water contact angle (57.14°), the tensile strength (47.28 N/mm2) and elongation at break (156 %) of the composite films were significantly increased, and the water content (12.71 %) was decreased. The hydrophobic and mechanical properties of the composite plastics were improved considerably. In addition, the addition of 4 % CMNCs with a degree of substitution of 0.66 and a high dose of electron beam irradiation (120 KGy) to PVA made the degradation rate of the composite plastic in the first week (31 %) much higher than that of pure PVA (3 %). At the same time, the light transmittance of the composite plastic decreased significantly in both visible and UV ranges. EBI pretreatment significantly improved the degradation and light barrier properties of the composite plastics. Therefore, this study may provide new ideas for EBI pretreatment-assisted chemical modification of nanocellulose to prepare functional composite films.

3D culture of ovarian follicles in granular and nanofibrillar hydrogels

3D culture of ovarian follicles in hydrogel matrices is an important emerging tool for basic scientific studies as well as clinical applications such as fertility preservation. For optimizing and scaling 3D culture of preantral follicles, there is a need for identifying biomaterial matrices that simplifies and improves the current culture procedures. At present, microencapsulation of follicles in alginate beads is the most commonly used approach. However, this technique involves notable manual handling and is best suited for encapsulation of single or several follicles. As a potential alternative, we here explore the suitability of different particle-based hydrogel matrices, where follicles can easily be introduced in tunable 3D environments, in large numbers. Specifically, we study the growth of secondary murine follicles in microgranular alginate and nanofibrillar cellulose matrices, with and without cell-binding cues, and map follicle growth against the viscoelastic properties of the matrices. We cultured follicles within the particle-based hydrogels for 10 days and continuously monitored their size, survival, and tendency to extrude oocytes. Interestingly, we observed that the diameter of the growing follicles increased significantly in the particle-based matrices, as compared to state-of-the-art alginate micro-encapsulation. On the other hand, the follicles displayed an increased tendency for early oocyte extrusion in the granular matrices, leading to a notable reduction in the number of intact follicles. We propose that this may be caused by impaired diffusion of nutrients and oxygen through thicker matrices, attributable to our experimental setup. Still, our findings suggest that viscoelastic, granular hydrogels represent promising matrices for 3D culture of early-stage ovarian follicles. In particular, these materials may easily be implemented in advanced culturing devices such as micro-perfusion systems.

How to Improve the Efficiency of Kinetic Hydrate Inhibitors Based on Nanofibrillar Cellulose?

How to Improve the Efficiency of Kinetic Hydrate Inhibitors Based on Nanofibrillar Cellulose?

Nano cells from fruit bunch residue: Nestling nanotechnology within the circular oil palm milling residue management

Nano-structured materials gain a vast market acceptance mainly due to their overarching endurance. Nanofibrillar cellulose (NFC) is one example of an augmenting agent unviable for production by small and medium enterprises (SMEs) due to the underlying process complexity. This study aims to characterise the NFC-alternative cells denoted as TRX-cellsⓇ, which is a mix of cellulose and non-cellulose components, ruling out its status as ‘cellulose nanofibers, CNF’. The aim to test-fit the TRX-cells® production process into the circularity model was executed by deliberating on the usability of the byproduct. In doing so, fibrous oil palm empty fruit bunch (EFB) was treated with dioxydanyl radicals (DIOR) and homogenised. The rapid EFB-DIOR reaction at 70°C targeting dearomatisation reaction in a 10%-solid open system was performed before refining the DIOR-treated EFB to micro-scale fibres. Subjecting the micro-fibres to 17 kWh/mt PFI-milling yielded 85–95% of nano-scale fibrous mass. Relative to the stiff micro-fibres, the nano-scale cells web exhibit 34–41% softness enhancement judged from the web tear resistance profile associated with inter-fibre space reduction. Advanced chromatographic evidence for 27% xylan amongst TRX-cells®’ total aldo-sugars was one form of the non-cellulose nano-component. High-resolution Transmission Electron Microscopy hyphenated to Energy Dispersive Analysis of X-ray (HRTEM-EDX) elemental mapping showed a 0.4 atomic percentage of nano-biominerals, confirming the presence of the redistributed dearomatised cells adjacent to cellulose held in the web of the hemicellulose. Shearing at the dearomatised inter-cell wall layers by PFI mill peeled 5 nm–100 nm thickness laminae. The smorgasbord of cellulose and non-celluloses resulted in crystallinity comparable to softwood NFC of approximately 60%, with unique preservation and precision-printing enabling properties. Given the non-recyclability of the DIOR-treated EFB microfibres, nestling the rapid waste transformation process into the circularity model shed light on circular bio-nanotechnology to the spectrum of opportunity for zero-waste, reduced emission and net zero carbon practices on top of an added value from waste transformation to a product.

Far-red light-triggered cargo release from liposomes bound to a photosensitizer-cellulose nanofiber hydrogel

In our research we used the anionic nanofibrillar cellulose (ANFC) as a platform for far-red light-induced release of cargo from liposomes. In contrast to previous works, where photosensitizers are usually in the liposomal bilayers, we used a cellulose-binding dye. Our phthalocyanine derivative has been shown to bind very strongly to cellulose and cellulose nanofiber hydrogels, allowing us to place it outside of the liposomes. Both the sensitizer and cationic liposomes bind strongly to the ANFC after mixing, making the system easy to fabricate. Upon light activation, the photosensitizer generates reactive oxygen species (ROS) within the ANFC hydrogel, where the reactive oxygen species oxidize unsaturated lipids in the liposomal membrane, which makes the liposomes more permeable, resulting in on-demand cargo release. We were able to achieve ca. 70 % release of model hydrophilic cargo molecule calcein from the hydrogels with a relatively low dose of light (262 J/cm2) while employing the straightforward fabrication techniques. Our system was remarkably responsive to the far-red light (730 nm), enabling deep tissue penetration. Therefore, this very promising novel cellulose-immobilized photosensitizer liposomal platform could be used as a controlled drug delivery system, which can have applications in externally activated coatings or implants.

Влияние нанофибриллярной целлюлозы на кинетику схватывания цементного теста

Влияние нанофибриллярной целлюлозы на кинетику схватывания цементного теста

Composite Bioprinted Hydrogels Containing Porous Polymer Microparticles Provide Tailorable Mechanical Properties for 3D Cell Culture.

The mechanical and architectural properties of the three-dimensional (3D) tissue microenvironment can have large impacts on cellular behavior and phenotype, providing cells with specialized functions dependent on their location. This is especially apparent in macrophage biology where the function of tissue resident macrophages is highly specialized to their location. 3D bioprinting provides a convenient method of fabricating biomaterials that mimic specific tissue architectures. If these printable materials also possess tunable mechanical properties, they would be highly attractive for the study of macrophage behavior in different tissues. Currently, it is difficult to achieve mechanical tunability without sacrificing printability, scaffold porosity, and a loss in cell viability. Here, we have designed composite printable biomaterials composed of traditional hydrogels [nanofibrillar cellulose (cellulose) or methacrylated gelatin (gelMA)] mixed with porous polymeric high internal phase emulsion (polyHIPE) microparticles. By varying the ratio of polyHIPEs to hydrogel, we fabricate composite hydrogels that mimic the mechanical properties of the neural tissue (0.1-0.5 kPa), liver (1 kPa), lungs (5 kPa), and skin (10 kPa) while maintaining good levels of biocompatibility to a macrophage cell line.

Improved Ballistic Impact Resistance of Nanofibrillar Cellulose Films with Discontinuous Fibrous Bouligand Architecture.

Natural protective materials offer unparalleled solutions for impact-resistant material designs that are simultaneously lightweight, strong, and tough. Particularly, the Bouligand structure found in the dactyl club of mantis shrimp and the staggered structure in nacre achieve excellent mechanical strength, toughness, and impact resistance. Previous studies have shown that hybrid designs by combining different bioinspired microstructures can lead to enhanced mechanical strength and energy dissipation. Nevertheless, it remains unknown whether combining Bouligand and staggered structures in nanofibrillar cellulose (NFC) films, forming a discontinuous fibrous Bouligand (DFB) architecture, can achieve enhanced impact resistance against projectile penetration. Additionally, the failure mechanisms under such dynamic loading conditions have been minimally understood. In our study, we systematically investigate the dynamic failure mechanisms and quantify the impact resistance of NFC thin films with DFB architecture by leveraging previously developed coarse-grained models and ballistic impact molecular dynamics simulations. We find that when nanofibrils achieve a critical length and form DFB architecture, the impact resistance of NFC films outperforms the counterpart films with continuous fibrils by comparing their specific ballistic limit velocities and penetration energies. We also find that the underlying mechanisms contributing to this improvement include enhanced fibril sliding, intralayer and interlayer crack bridging, and crack twisting in the thickness direction enabled by the DFB architecture. Our results show that by combining Bouligand and staggered structures in NFC films, their potential for protective applications can be further improved. Our findings can provide practical guidelines for the design of protective films made of nanofibrils.

Preparation of silica nanoparticles modified nanofibrillar cellulose and its metronidazole drug delivery properties

Nanofibrillar cellulose (NFC) was extracted by alkaline treatment of Yucca leaves followed by bleaching using H2O2, and then modified by silica nanoparticles (NPs). Obtained silica NPs modified NFC (SiO2 NPs-mNFC) was characterized using FT-IR, XRD, TGA, SEM, TEM and EDX analysis, and its metronidazole drug delivery properties were studied. However bare NFC showed higher loading of metronidazole than SiO2 NPs-mNFC, but NFC showed faster release of metronidazole than SiO2 NPs-mNFC. Release of metronidazole from NFC is not pH dependent, as 92.2% and 85.4% cumulative release percentage of metronidazole was released until 7.5 h, at both pH values of 4.5 and 7.4, respectively. However, SiO2 NPs-mNFC released the metronidazole very slowly, and was also pH sensitive, as cumulative release percentage of metronidazole were measured to be 53.3% at pH = 4.5, and 19.6% at pH = 7.4 after 48 h. Kinetic of the metronidazole release from SiO2 NPs-mNFC was studied by fitting the experimental data with well-known kinetic models, such as First order, Higuchi, Korsmeyer-Peppas, Hixson-Corwell and Baker-Lonsdale models. Results revealed that the metronidazole release is well fitted with Hixson–Crowell models at both pH values, confirming that the change in surface area of SiO2 NPs-mNFC during the process of dissolution has a significant effect on metronidazole release. Fickian diffusion of metronidazole at both pH was concluded by calculating n values of 0.3438 at pH = 7.4 and 0.4224 at pH = 4.5 by nonlinear fitting the release experimental data using Korsmeyer-Peppas model.

Preparation and characterization of nanofibrillar cellulose obtained from okara via synergizing chemical and physical functions

A new approach for the extraction of nano-fibrillar cellulose (CNFs) from okara via synergizing chemical action and physical force is developed. An Haake internal twin-roller mixer was used to provide high shear strength in deep eutectic solvent (DES) of oxalic acid. The twin-roller mixer can enhance fiber separation and deal with materials containing high concentrations using low energy. The effect of the shear strength on the nano-fibrillar cellulose extracted from okara was systematically investigated, in particular the effect of shear rate and shear insensitivity. The fabricated CNFs were characterized by SEM, XRD, Rheometer, and transparency. Results showed that the shear strength significantly improved the extraction efficiency through increasing the processing concentration (solid/DES solvent ratio in weight) from 1:20–1:1, with higher ratio obtained. It was found that the multi-functions were synergized by combining chemical and physical functions, in which DES weakens the hydrogen bonds, while shear force separates the cellulous fibers. The achievement provided an eco-friendly methodology with high efficiency to fabricate CNFs from okara.

Nucleation of Methane Hydrate in the Presence of Nanofibrillar Cellulose

Nucleation of Methane Hydrate in the Presence of Nanofibrillar Cellulose

Spatial-Temporal Heterogeneity in Large Three-Dimensional Nanofibrillar Cellulose Hydrogel for Human Pluripotent Stem Cell Culture

One approach to cell expansion is to use large hydrogel for growing a large number of cells. Nanofibrillar cellulose (NFC) hydrogel has been used for human induced pluripotent stem cell (hiPSCs) expansion. However, little is known about the status of hiPSCs at the single cell level inside large NFC hydrogel during culture. To understand the effect of NFC hydrogel property on temporal-spatial heterogeneity, hiPSCs were cultured in 0.8 wt% NFC hydrogel with different thicknesses with the top surface exposed to the culture medium. The prepared hydrogel exhibits less restriction in mass transfer due to the presence of macropores and micropores interconnecting the macropores. More than 85% of cells at different depths survive after 5 days of culture inside 3.5 mm thick hydrogel. Biological compositions at different zones inside the NFC gel were examined over time at a single-cell level. A dramatic concentration gradient of growth factors estimated in the simulation along 3.5 mm NFC hydrogel could be a reason for the spatial-temporal heterogeneity in protein secondary structure and protein glycosylation and pluripotency loss at the bottom zone. pH change caused by the lactic acid accumulation over time leads to changes in cellulose charge and growth factor potential, probably another reason for the heterogeneity in biochemical compositions. This study may help to develop optimal conditions for producing high-quality hiPSCs in large nanofibrillar cellulose hydrogel at scale.

Nano cellulose-laden alginate/chitosan sponge with enhanced biological and hemostatic behavior

Present study describes about hybrid hemostat developed with alginate (Alg), chitosan (Chito) and TEMPO-oxidized nanofibrillar cellulose (TOCNF) via lyophilization. All samples were analyzed under scanning electron microscopy (SEM) to determine their microstructure, size, and distribution of pores. Cell viability and proliferation of the scaffolds tested using fibroblast type L929 cells, showed it to be an excellent medium for cell generation. Blood coagulation started in ∼7.5 min, and most of the fibrin network formation took place in the Alg-Chito-TOCNF sponge, making it a suitable hemostatic material.

Exploring Supramolecular Interactions between the Extracellular-Matrix-Derived Minimalist Bioactive Peptide and Nanofibrillar Cellulose for the Development of an Advanced Biomolecular Scaffold.

It has been increasingly evident over the last few years that bioactive peptide hydrogels in conjugation with polymer hydrogels are emerging as a new class of supramolecular materials suitable for various biomedical applications owing to their specificity, tunability, and nontoxicity toward the biological system. Despite their unique biocompatible features, both polymer- and peptide-based scaffolds suffer from certain limitations, which restrict their use toward developing efficient matrices for controlling cellular behavior. The peptide hydrogels usually form soft matrices with low mechanical strength, whereas most of the polymer hydrogels lack biofunctionality. In this direction, combining polymers with peptides to develop a conjugate hydrogel can be explored as an emergent approach to overcome the limitations of the individual components. The polymer will provide high mechanical strength, whereas the biofunctionality of the material can be induced by the bioactive peptide sequence. In this study, we utilized TEMPO-oxidized nanofibrillar cellulose as the polymer counterpart, which was co-assembled with a short N-cadherin mimetic bioactive peptide sequence, Nap-HAVDI, to fabricate an NFC-peptide conjugate hydrogel. Interestingly, the mechanical strength of the peptide hydrogel was found to be significantly improved by combining the peptide with the NFC in the conjugate hydrogel. The addition of the peptide into the NFC also reduced the pore size within NFC matrices, which further helped in improving cellular adhesion, survival, and proliferation. Furthermore, the cells grown on the NFC and NFC-peptide hybrid hydrogel demonstrated normal expression of cytoskeleton proteins, i.e., β-tubulin in C6 cells and actin in L929 cells, respectively. The selective response of neuronal cells toward the specific bioactive peptide was further observed through a protein expression study. Thus, our study demonstrated the collective role of the cellulose-peptide composite material that revealed superior physical properties and biological response of this composite scaffold, which may open up a new platform for biomedical applications.

Functional Materials Based on Carboxylated Nanofibrillar Cellulose

Functional Materials Based on Carboxylated Nanofibrillar Cellulose

A quick pipeline for the isolation of 3D cell culture-derived extracellular vesicles.

Recent advances in cell biology research regarding extracellular vesicles have highlighted an increasing demand to obtain 3D cell culture‐derived EVs, because they are considered to more accurately represent EVs obtained in vivo. However, there is still a grave need for efficient and tunable methodologies to isolate EVs from 3D cell cultures. Using nanofibrillar cellulose (NFC) scaffold as a 3D cell culture matrix, we developed a pipeline of two different approaches for EV isolation from cancer spheroids. A batch method was created for delivering high EV yield at the end of the culture period, and a harvesting method was created to enable time‐dependent collection of EVs to combine EV profiling with spheroid development. Both these methods were easy to set up, quick to perform, and they provided a high EV yield. When compared to scaffold‐free 3D spheroid cultures on ultra‐low affinity plates, the NFC method resulted in similar EV production/cell, but the NFC method was scalable and easier to perform resulting in high EV yields. In summary, we introduce here an NFC‐based, innovative pipeline for acquiring EVs from 3D cancer spheroids, which can be tailored to support the needs of variable EV research objectives.

Exploring the TEMPO-Oxidized Nanofibrillar Cellulose and Short Ionic-Complementary Peptide Composite Hydrogel as Biofunctional Cellular Scaffolds.

Multicomponent self-assembly is an emerging approach in peptide nanotechnology to develop nanomaterials with superior physical and biological properties. Inspired by the multicomponent nature of the native extracellular matrix (ECM) and the well-established advantages of co-assembly in the field of nanotechnology, we have attempted to explore the noncovalent interactions among the sugar and peptide-based biomolecular building blocks as an approach to design and develop advanced tissue scaffolds. We utilized TEMPO-oxidized nanofibrillar cellulose (TO-NFC) and a short ionic complementary peptide, Nap-FEFK, to fabricate highly tunable supramolecular hydrogels. The differential doping of the peptide into the TO-NFC hydrogel was observed to tune the surface hydrophobicity, microporosity, and mechanical stiffness of the scaffold. Interestingly, a differential cellular response was observed toward composite scaffolds with a variable ratio of TO-NFC versus Nap-FEFK. Composite scaffolds having a 10:1 (w/w) ratio of TO-NFC and the Nap-FEFK peptide showed enhanced cellular survival and proliferation under two-dimensional cell culture conditions. More interestingly, the cellular proliferation on the 10:1 matrix was found to be similar to that of Matrigel in three-dimensional culture conditions, which clearly indicated the potential of these hydrogels in advanced tissue engineering applications. Additionally, these composite hydrogels did not elicit any significant inflammatory response in Raw cells and supported their survival and proliferation, which further emphasized their ability to form versatile scaffolds for tissue regeneration. This multicomponent assembly approach to construct biomolecular composite hydrogels to access superior physical and biological properties within the scaffold is expected to improve the scope for designing novel ECM-mimicking biomaterials for regenerative medicine.

Chitosan Based Aerogels with Low Shrinkage by Chemical Cross-Linking and Supramolecular Interaction.

Chitosan (CTS) aerogel is a new type of functional material that could be possibly applied in the thermal insulation field, especially in energy-saving buildings. However, the inhibition method for the very big shrinkage of CTS aerogels from the final gel to the aerogel is challenging, causing great difficulty in achieving a near-net shape of CTS aerogels. Here, this study explored a facile strategy for restraining CTS-based aerogels’ inherent shrinkage depending on the chemical crosslinking and the interpenetrated supramolecular interaction by introducing nanofibrillar cellulose (NFC) and polyvinyl alcohol (PVA) chains. The effects of different aspect ratios of NFC on the CTS-based aerogels were systematically analyzed. The results showed that the optimal aspect ratio for NFC introduction was 37.5 from the comprehensive property perspective. CTS/PVA/NFC hybrid aerogels with the aspect ratio of 37.5 for NFC gained a superior thermal conductivity of 0.0224 W/m·K at ambient atmosphere (the cold surface temperature was only 33.46 °C, despite contacting the hot surface of 80.46 °C), a low density of 0.09 g/cm3, and a relatively high compressive stress of 0.51 MPa at 10% strain.

Composite chitosan and quaternary ammonium modified nanofibrillar cellulose anion exchange membranes for direct ethanol fuel cell applications

Fuel cells are a promising technology for energy production, but their commercialization is hindered mainly due to high costs. Direct alkaline ethanol fuel cells (DAFC) are receiving increasing attention as they can utilize cheaper, non-precious metal catalysts. A vital component of a DAFC is the anion exchange membrane (AEM). Currently, the commercially available AEMs don’t possess satisfactory properties. This indicates a need for the development of new highly efficient, environmentally friendly, and economically viable AEMs. Synthesis of synthetic polymer AEMs is usually complex and time-consuming, as well as environmentally unfriendly. Therefore, it is highly desired that the membrane material is bio-renewable, non-toxic and environmentally benign. In this work, a series of biopolymer membranes were designed by a simple, cost-effective, dispersion-casting procedure, fully complying with green-chemistry principles. Design of experiments was used as a methodology for identifying optimal combinations of influencing factors and their relations within selected responses. The obtained chitosan-Mg(OH)2 composite membranes containing modified nanofibrillar cellulose (CNF) fillers with quaternary ammonium groups were investigated for their mechanical properties, swelling ratio, ethanol permeability and ion exchange properties. Obtained data suggest the applicability of newly prepared, biopolymeric composites as eco-friendly AEMs in DAFC technologies.