Nanofibrillated Cellulose Concentration Research Articles

In Vitro Characterizations of Poly(Ethylene Glycol) Dimethacrylate)-Nanofibrillated Cellulose as an Injectable Biomaterial Substitute for Herniated Nucleus Pulposus

Highlights: Novel synthetic biopolymer hydrogels were successfully prepared using photopolymerization method based on pristine PEGDMA and pristine NFC. Biocomposite hydrogel based on pristine PEGDMA: pristine NFC can be developed as a substitute biomaterial for the nucleus pulposus in cases of herniated nucleus pulposus which can afford for clinical application standards Abstract As many as 30-80% of cases low back pain (LBP) is frequently attributed to herniated nucleus pulposus (HNP) with 18-29% of instances reported in Indonesia. HNP can cause in motor weakness, sensory disturbances and decreased physiological reflexes. HNP occurs due to protrusion of the intervertebral disc through the annulus fibrosus which can be caused by the rupture of the annulus fibrosus or decreased proteoglycans (PGs). Hydrogel implant material is injected into the disc space, which can restore disc thickness caused by disc degeneration with minimal invasive. This study utilizes poly(ethylene glycol) dimethacrylate (PEGDMA):nanofibrillated cellulose (NFC) used to treat first-degree HNP using photopolymerization method. PEGDMA is very hydrophilic and is able to produce hydrogel. The addition of NFC to the PEGDMA precursor that forms a hydrogel was able to show mechanical properties as a hydrogel biocomposite candidate. This research to characterize of PEGDMA:NFC for biomaterial substitute of HNP. Characterizations involves Fourier Transform Infrared (FTIR) test, viscosity assessment and in vitro injection model test. PEGDMA:NFC concentrations explored include 1:0 (control), 1:0.5 (K1 sample), 1:0.75 (K2 sample) and 1:1 (K3 sample). FTIR test can indicating each functional group for hydrogel biomaterial of PEGDMA:NFC. Based on characterization results, the K3 sample has the best results with a concentration of 1:1. The viscosity value was 74,67 dPa.s and in vitro injection model test showed the addition of NFC indicates the hydrogel state when released from the mold will be not ruptured. Hydrogels can be injected with syringe 18 gauge. Consequently, the study concludes that the PEGDMA:NFC biocomposite hydrogel can be effectively applied in cases of herniated nucleus pulposus.

Pickering Emulsion Properties Generated by Nanofibrillated Cellulose Isolated from Oil Palm Fruit Bunch (OPEFB) as a Stabilizer

This study aims to find the optimal nanofibrillated cellulose (NFC) concentration isolated from oil palm empty fruit bunch (OPEFB) particles to form stable pickering emulsions against creaming and coalescence. The emulsification process is based on a combination of homogenizer and ultrasonication. Pickering emulsion was prepared by mixing the dispersed phase (palm oil) and the dispersing phase (NFC concentration of 0.05 - 0.7 w/v%) at the ratio of 10:90. Fresh emulsion has a milky white appearance and is homogeneous. However, some samples' creaming process occurred on the 30th day of storage. Microscopic observations show that the droplets are round with various sizes. Differences in NFC concentrations significantly affect droplet size, zeta potential, rheology, and emulsion stability. Increasing the NCF concentration resulted in smaller droplet sizes, viscosity, zeta potential, and pickering emulsion stability. The emulsion has high stability against coalescence and creaming. NFC at 0.7 w/v% generates an emulsion with the best characteristics and high stability against creaming and coalescence. OPEFB-based NFC has the potential as a pickering emulsion stabilizer particle that can be applied to the food and non-food industries.

Performance of nanofibrillated cellulose with chitosan as a wet-end additive for paper applications

The aim of this work is to evaluate of the effect of incorporating nanofibrillated cellulose (NFC) and chitosan (CH) in a dual system as dry additives during papermaking for unbleached bamboo alkaline sulfite anthraquinone methanol (ASAM) under different beating revolutions. Pulp beating at 4000 and 6000 revolutions has comparable properties with varying dosages of NFC (5% and 10%) and different chitosan concentrations (0.5%, 1, 1.5%, and 2%). Hand sheets of a basis weight (60 g/cm2) were produced and measured for thickness, tear, tensile, burst index, and resistance to folding under TAPPI standard methods. Results revealed that with an increase in the number of beating revolutions, there was a decrease in the value of freeness. All analyzed pulp had freeness values within the permissible amount of 300–500 mL in papermaking, except 10% NFC, which was 244–190 mL at 6000 revolutions. Furthermore, the addition of chitosan to 1.5% with 5% NFC at 6000 beating revolutions enhanced the tensile index (85.16 Nm/g) and burst index (7.69 kPa. m2/g) in comparison to the sample control. The incorporation of nanofibrillated cellulose and chitosan significantly altered the physical and mechanical strength. Optimal alkaline sulfite anthraquinone methanol ASAM-enhanced paper properties are displayed with 5% NFC and 1.5% chitosan at 6000 beating revolutions.

Astaxanthin-Loaded Pickering Emulsions Stabilized by Nanofibrillated Cellulose: Impact on Emulsion Characteristics, Digestion Behavior, and Bioaccessibility.

Astaxanthin (AX) is one of the major bioactives that has been found to have strong antioxidant properties. However, AX tends to degrade due to its highly unsaturated structure. To overcome this problem, a Pickering O/W emulsion using nanofibrillated cellulose (NFC) as an emulsifier was investigated. NFC was used because it is renewable, biodegradable, and nontoxic. The 10 wt% O/W emulsions with 0.05 wt% AX were prepared with different concentrations of NFC (0.3-0.7 wt%). After 30 days of storage, droplet size, ζ-potential values, viscosity, encapsulation efficiency (EE), and color were determined. The results show that more stable emulsions are formed with increasing NFC concentrations, which can be attributed to the formulation of the NFC network in the aqueous phase. Notably, the stability of the 0.7 wt% NFC-stabilized emulsion was high, indicating that NFC can improve the emulsion's stability. Moreover, it was found that fat digestibility and AX bioaccessibility decreased with increasing NFC concentrations, which was due to the limitation of lipase accessibility. In contrast, the stability of AX increased with increasing NFC concentrations, which was due to the formation of an NFC layer that acted as a barrier and prevented the degradation of AX during in vitro digestion. Therefore, high concentrations of NFC are useful for functional foods delivering satiety instead of oil-soluble bioactives.

Near-infrared analysis of nanofibrillated cellulose aerogel manufacturing

Biomaterial aerogel fabrication by freeze-drying must be further improved to reduce the costs of lengthy freeze-drying cycles and to avoid the formation of spongy cryogels and collapse of the aerogel structures. Residual water content is a critical quality attribute of the freeze-dried product, which can be monitored in-line with near-infrared (NIR) spectroscopy. Predictive models of NIR have not been previously applied for biomaterials and the models were mostly focused on the prediction of only one formulation at a time. We recorded NIR spectra of different nanofibrillated cellulose (NFC) hydrogel formulations during the secondary drying and set up a partial least square regression model to predict their residual water contents. The model can be generalized to measure residual water of formulations with different NFC concentrations and the excipients, and the NFC fiber concentrations and excipients can be separated with the principal component analysis. Our results provide valuable information about the freeze-drying of biomaterials and aerogel fabrication, and how NIR spectroscopy can be utilized in the optimization of residual water content.

Clean manufacturing of nanocellulose-reinforced hydrophobic flexible substrates

In this study, for the first time, a flexible substrate made from nanofibrillated cellulose in slurry form was fabricated using a hydrophobic polymer base. Previous studies practiced energy-intensive dry cellulose nanofiber dispersion to produce olefin-based composites: ecological and economic viability and industrial practicability are often neglected due to lack of innovation in cleaner production processes. In this context, a low-energy process, which is economically attractive and free of harmful organic solvents, was developed to achieve homogeneous distribution of nanofibrillated cellulose (NFC) in high-density polyethylene (HDPE). The dual interfacial role of the ethylene vinyl alcohol copolymer (EVAL – 48 mol% ethylene content) enhanced interfacial adhesion through the formation of nanobridges between HDPE and NFC. This method led to well-dispersed NFC in the HDPE, at 5 wt% NFC concentration, without the need of any chemical modification, solvent exchange or freeze-drying of NFC. The low interfacial tension between HDPE and EVAL and the presence of NFC in the ternary system led to enhanced dispersion during melt-mixing. Improvement in mechanical properties was achieved, with a 22% and 98% increase in the tensile strength and Young’s modulus, respectively, without significantly compromising thermal stability and barrier properties. The results shown in this study indicate a significant potential to replace synthetic and costly reinforcement additives while making nanofiber-reinforced flexible composites more sustainable and mechanically robust. In this context, a paradigm shift from fossil-based production technology to a cleaner production strategy such as those exemplified in this study will help achieve a circular production economy concept without hindering functionalities.

Nanofibrillated cellulose as coating agent for food packaging paper

Nanofibrillated cellulose (NFC), a promising bio-based nanomaterial, has received much attention in the field of coating preparation due to its unique properties. Herein, NFC was prepared from microcrystalline cellulose (MCC) via high-pressure homogenization process and deliberately employed as coating agent to enhance the properties of paper coatings and coated paper. The results demonstrated that the obtained paper coatings exhibited strong NFC concentration dependence on rheological behavior and displayed decreased water retention value with the increased NFC addition. Meanwhile, NFC addition was found to lead to the reduced Cobb value, improved air resistance, and enhanced tensile strength of coated paper. Under an optimized NFC addition of 0.30–0.40%, the properties of coated paper generally reached the optimum state. Moreover, SEM observation further confirmed that NFC addition imparted a relatively uniform surface structure to coated paper. Hence, NFC could be defined as an effective coating agent for developing high-performance coated paper for food packaging applications.

Poly(ethylene glycol)dimethacrylate – nanofibrillated cellulose bionanocomposites as injectable hydrogel for therapy of herniated nucleus pulposus patients

The highest disease caused by low back pain is herniated nucleus pulposus (HNP) where nucleus pulposus (NP) protrudes out through the annulus fibrosis. Injectable hydrogel is a method to restore NP function with minimal invasive surgery. Variation concentration of NFC were studied in detail toward affects on PEGDMA (poly(ethylene glycol)dimethacrylate):NFC hydrogel mechanically and injectability. The characteristics of PEGDMA and nanofibrillated cellulose (NFC) based injectable hydrogels through the photoinitiator Irgacure 2959 in the formation of hydrogels with variations composition 1:0; 1:0.25; 1:0.5; 1:0.75. In the morphological test on NFC a fibre with a diameter of 100nm was formed from the results of electrospinning on ethyl cellulose (EC). The FTIR showed of photopolymerization of the conjugation bond between Irgacure 2959 and PEGDMA producing C-C at a frequency of 1349.20cm−1. Swelling test used phosphate buffer saline (PBS) fulfilled the standard at a variation of 1:0.25; 1:0.5; and 1:0.75, 87.07%, 84.84% and 80.42% respectively. Viscosity test in the injectability of hydrogels showed a result of 73.67dPa.s. The compressive strength test obtained good results in samples 1:0.75 showed a result of 3.42kPa. In vitro injection model showed increasing of NFC concentration indicates the gel state when released from agarose will be less rupture. PEGDMA/NFC hydrogel biocomposite has the potential to be applied as an injectable hydrogel for the treatment of HNP patients based on the results.

Porosity, density and mechanical properties of the paper of steam exploded bamboo microfibers controlled by nanofibrillated cellulose

This study focused on preparation of microfibers from bamboo culms using steam explosion with and without chemical treatments, and utilization of the isolated fibers in formation of bamboo paper fabricated with nanofibrillated cellulose (NFC). Compared with those obtained from the steam explosion alone (S), the bamboo microfibers isolated using the steam explosion followed by bleaching process (S/A) exhibited a significantly reduced fiber width of 7.5μm and a markedly increased cellulose content of 97.85%. The S/A fiber showed an increased decomposition temperature, corresponding with lower contents of hemicellulose and lignin than those of the S fiber. The S/A microfibers were subsequently proceeded to paper formation. Physical and mechanical properties of the paper with an introduction of different NFC concentrations (0–50wt%) were investigated. The linear relationship between the density, porosity and mechanical properties of the paper and NFC contents was observed. The more the NFC content, the greater the density and the lower the porosity the paper exhibited. At 50wt% NFC, the paper density increased to 0.64gcm−3, and the paper porosity decreased to 57.0% whereas the paper without NFC showed a density of 0.39gcm−3 and porosity of 73.6%. Tensile strength and strain of the paper composed with 50wt% NFC were 10-fold and 3-fold, respectively, greater than those of the paper without NFC. The addition of NFC could manifest paper mechanical properties and porosity within the paper structure, which would be useful for scaffold and membrane applications.

Tailoring the Antimicrobial Response of Cationic Nanocellulose-Based Foams through Cryo-Templating.

To shed light on novel sustainable materials with antimicrobial functionality, in this contribution, we describe the use of cationic nanocellulose to produce foams featuring antibacterial activity against the powerful human pathogen Escherichia coli. Dialdehyde cellulose was cationized with Girard's reagent T (GRT), mechanically disintegrated into nanofibrillated cellulose (NFC), and shaped into foams through different protocols. All steps were carried out in aqueous media and in the absence of hazardous chemicals. While evaporative drying led to compact films (density of 1.3 g cm-3), freeze-casting (i.e., freezing and freeze-drying) produced monolithic cryogels with low densities (<50 mg cm-3) and porosities of ca. 98%. Although highly porous, the cryogels obtained through rapid freezing remarkably presented smaller pores than those that were previously frozen in a slow fashion. The quaternary ammonium groups of GRT-cationized NFC removed E. coli to different extents depending upon sample morphology. We demonstrated in an innovative manner that porosity, which is directly associated with surface area, and pore size play an essential role on the antimicrobial performance. This outcome arises from the inaccessibility of bacterial cells to cationic surfaces inside monoliths composed of small pores. We herein present an uncomplicated, environmentally friendly protocol for fine-tuning the porosity and pore size of all-cellulose materials through cryo-templating. Controlling these morphometric parameters allowed us to achieve a ca. 85% higher anti-E. coli activity when comparing samples made up of the very same material (i.e., the same NFC concentration and degree of substitution) but presented as dense films. These findings bear clear implications for the pursuit of sustainable materials presenting multifunctionality.

Nanofibrillated Cellulose as Functional Ingredient in Emulsion-Type Meat Products

The objective of this work was to introduce nanofibrillated cellulose (NFC) in the formulation of cooked emulsion-type sausages with the aim of assessing its feasibility to assume the role or compensate the lack of some conventional functional ingredients, such as polyphosphates, maize starch, and sodium caseinate. For this aim, sausages based on standard commercial formula (control) including all three ingredients and sausages containing 0.5% NFC instead of phosphates and starch (NFC-1) or instead of phosphates, starch, and sodium caseinate (NFC-2) were produced and characterized. In NFC-1 samples, 0.5% nanofibrillated cellulose succeeds in replacing 0.5% polyphosphates and 1% starch without significantly altering the composition, nor negatively affecting the fat and water retention properties, neither of the raw batter or the cooked sausages. However, less stable meat batters and sausages with significantly reduced water-holding capacity were obtained when 1.5% sodium caseinate, in addition to phosphates and starch, was also removed (NFC-2). Nevertheless, results were hopeful enough to encourage further optimization studies, using several NFC concentrations and/or cellulose with different nanofibrillation degrees, in order to clarify whether it is possible to successfully replace also non-meat proteins in cooked emulsion-type sausages.

Encapsulation of vitamin D3 in pickering emulsions stabilized by nanofibrillated mangosteen cellulose: Impact on in vitro digestion and bioaccessibility

Oil-in-water Pickering emulsions stabilized by nanofibrillated cellulose (NFC) were used to encapsulate and deliver vitamin D3. NFC was extracted from a waste product of the food industry, mangosteen (Garcinia mangostana L.) rind, using dissolution in a hot sodium hydroxide solution, bleaching using hydrogen peroxide, and shearing using a high-pressure homogenizer. This yielded cellulose fibers with a diameter of around 60 nm and a length of several micrometers. Emulsions containing 10% w/w oil (0.01% w/w vitamin D3 and 9.99% w/w soybean oil), 0.10–0.70% w/w NFC as emulsifier, and phosphate buffer (pH 7) were prepared. The effect of NFC on lipid digestion and vitamin bioaccessibility was investigated using a simulated gastrointestinal tract (GIT) model, which included mouth, stomach and small intestine phases. The rate and extent of lipid digestion, as well as the vitamin bioaccessibility, decreased with increasing NFC concentration. Numerous physicochemical phenomena may account for this effect, including the ability of NFC to: act as a physical barrier at the lipid droplet surfaces; to promote droplet flocculation in the gastric phase; and, to increase the viscosity of the aqueous phase. The slight decrease in vitamin D3 bioaccessibility at higher NFC levels, was probably due to the lower level of lipid digestion. Our results indicate that mangosteen fiber can be used to stabilize oil-in-water emulsions, and only has a minor effect on lipid digestion and vitamin bioaccessibility when used at relatively low levels. This information may be useful for the rational design of functional foods from natural waste-products, such as mangosteen rind.

Poly(vinyl alcohol) films reinforced with nanofibrillated cellulose (NFC) isolated from corn husk by high intensity ultrasonication

This work was aimed at fabricating and characterizing poly(vinyl alcohol) films that were reinforced by nanofibrillated corn husk celluloses using a combination of chemical pretreatments and ultrasonication. The obtained nanofibrillated celluloses (NFCs) possessed a narrow width ranging from 50 to 250nm and a high aspect ratio (394). The crystalline type of NFC was cellulose I type. Compared with the original corn husks, the NCF crystallinity and thermal stability increased due to the removal of the hemicelluloses and lignin. PVA films containing different NFC concentrations (0.5%, 1%, 3%, 5%, 7% and 9%, w/w, dry basis) were examined. The 1% PVA/NFC reinforced films exhibited a highly visible light transmittance of 80%, and its tensile strength and the tensile strain at break were increased by 1.47 and 1.80 times compared to that of the pure PVA film, respectively. The NFC with high aspect ratio and high crystallinity is beneficial to the improvement of the mechanical strength and thermal stability.

Concentration effect of TEMPO-oxidized nanofibrillated cellulose aqueous suspensions on the flow instabilities and small-angle X-ray scattering structural characterization

The rheological behavior of 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-oxidized nanofibrillated cellulose (NFC) suspensions at different concentrations were examined using Couette with smooth and serrated surfaces and vane-in-cup geometries. A slippage against the walls of rheometer rotor or/and stator (wall-slip) as well as flow localization within a specific volume of the sample (shear banding) took place. These phenomena were visualized using a technique based on introduction of titanium dioxide pigment into the specific volume of NFC suspension and monitoring its deformation. The flow instabilities appeared more pronounced with an increase of the NFC concentration. It was shown that the use of serrated geometry is necessary to compete with the wall-slip but is not sufficient to prevent it completely. Serrated Couette was found to be the most appropriate geometry (among the tested) to measure the rheological properties of NFC suspensions. Small-angle X-ray scattering was used to provide a supplementary information about the structural organization of NFC suspensions. The statistical average diameter of 4.8 nm was determined from the scattering data for the NFC swollen in water.

Network formation of nanofibrillated cellulose in solution blended poly(methyl methacrylate) composites

Composites of poly(methyl methacrylate) (PMMA) and nanofibrillated cellulose (NFC) were prepared by solution blending and further processed by injection and compression molding. To improve adhesion at the PMMA/NFC interface, the nanofibrils were covalently grafted with PMMA. Formation of a percolating nanofibril network was observed between 1 and 5wt.% of NFC by dynamic rotational rheometry in molten state. This observation was further supported by the behavior of glass transition temperature which decreased at low NFC concentrations but recovered above the percolation threshold, indicating a decreased mobility of the matrix polymer. This effect was more pronounced with ungrafted NFC, possibly due to a stronger network. The unmodified NFC induced a minor degradation of the molar mass of PMMA. As thin plates, the composites were transparent at low NFC concentrations but became partially aggregated at the highest NFC concentrations. Despite the continuous NFC network, tensile testing showed no improvement of the mechanical properties.