Nano Fibrils Research Articles

Efficient natural piezoelectric nanogenerator: Electricity generation from fish swim bladder

An efficient bio-piezoelectric nanogenerator (BPNG) is fabricated from the fish swim bladder (FSB), composed of well-aligned natural collagen nano–fibrils. The self-alignment of highly ordered structure in the FSB collagen has been confirmed by angular dependent near edge X-ray absorption fine structure (NEXAFS) spectroscopy. Compressive normal stress by human finger can able to drive the BPNG that generates an open-circuit voltage of 10V and short-circuit current of 51nA. The generated electricity from the FSB instantly turns on more than 50 commercial blue light emitting diodes (LEDs), indicates to use as a sustainable power source in portable electronic devices where the bulky battery counterpart can be avoided. The instantaneous piezoelectric power generation (~4.15μW/cm2) and substantial energy conversion efficiency (~0.3%) of BPNG promises an emerging application, particularly to built self-powered biomedical sensors because collagen itself one of the most abundant protein available in human body.

Mixing of cellulose nanofibrils and individual furnish components: Effects on paper properties and structure

Thermo-mechanical pulp (TMP) handsheets with different fractions of cellulose nano fibrils (CNF) and ground calcium carbonate (GCC) were made. CNF and retention chemicals were added in three differ ...

An environmentally friendly method for the isolation of cellulose nano fibrils from banana rachis fibers

Cellulose nano fibrils (CNFs) were isolated from banana rachis bran using enzyme hydrolysis with subsequent ultra-sonic treatment. The CNFs and bran were characterized by particle size distribution (only the CNFs), X-ray diffraction (XRD), Thermogravimetric analysis (TGA) and Fourier-transform infrared spectroscopy; the morphology of the banana rachis fiber and CNFs was observed using scanning electron microscopy and transmission electron microscopy, respectively. The furnished nano fibrils had an average diameter of 14.02 ± 2.10 nm and length of 619.6 ± 90.7 nm. The aspect ratio of the CNFs is in the range of long fibrils, that is 44.18. XRD studies revealed that CNFs (48.83%) were more crystalline than the banana bran (27.76%). TGA and derivative thermogravimetry thermograms showed that CNFs were more thermally stable than the bran.

A facile route to prepare cellulose-based films

Cellulose is the most abundant renewable and biodegradable material available in nature. Its insoluble character in water as well as common organic and inorganic liquids, however, curtails the wholesome utility. The continuous rise for biodegradable products based on cellulose coupled with its intrinsic ability to form a viable substitute for the petroleum-based materials necessitates the critical need for solubilizing the cellulose. Herein, we demonstrate the feasibility of ZnCl2 solutions, especially the 64–72% concentrations, to dissolve cellulose. FTIR results suggest that Zn2+ ions promote Zn⋯O3H interactions, which in-turn weaken the intrinsic O3H⋯O5 hydrogen bonds that are responsible for strengthening the cellulose chains. Interestingly, Ca2+ ions promote interactions among the Zn-cellulose chains leading to the formation of nano fibrils and yield gelling solutions. The tensile strength of the Ca2+ added Zn-cellulose films increases by around 250% compared to the Zn-cellulose films. Overall, utilization of inorganic salt solutions to solubilize and crosslink cellulose is cost-effective, recyclable and certainly stands out tall among the other available systems. More importantly, the proposed protocol is simple and is a “green” process, and thus its large-scale adaptability is quite feasible. We strongly believe that the outcome opens up a new window of opportunities for cellulose in the biomedical, pharmaceutical, food and non-food applications.

Protective Effect of Chitin Urocanate Nanofibers against Ultraviolet Radiation.

Urocanic acid is a major ultraviolet (UV)-absorbing chromophore. Chitins are highly crystalline structures that are found predominantly in crustacean shells. Alpha-chitin consists of microfibers that contain nanofibrils embedded in a protein matrix. Acid hydrolysis is a common method used to prepare chitin nanofibrils (NFs). We typically obtain NFs by hydrolyzing chitin with acetic acid. However, in the present study, we used urocanic acid to prepare urocanic acid chitin NFs (UNFs) and examined its protective effect against UVB radiation. Hos: HR-1 mice coated with UNFs were UVB irradiated (302 nm, 150 mJ/cm2), and these mice showed markedly lower UVB radiation-induced cutaneous erythema than the control. Additionally, sunburn cells were rarely detected in the epidermis of UNFs-coated mice after UVB irradiation. Although the difference was not as significant as UNFs, the number of sunburn cells in mice treated with acetic acid chitin nanofibrils (ANFs) tended to be lower than in control mice. These results demonstrate that ANFs have a protective effect against UVB and suggest that the anti-inflammatory and antioxidant effects of NFs influence the protective effect of ANFs against UVB radiation. The combination of NFs with other substances that possess UV-protective effects, such as urocanic acid, may provide an enhanced protective effect against UVB radiation.

Influence of retinoic acid on mesenchymal stem cell differentiation in amyloid hydrogels.

This paper presents data related to the research article “Self healing hydrogels composed of amyloid nano fibrils for cell culture and stem cell differentiation” [1]. Here we probed the collective influence of all-trans retinoic acid (RA) and substrate properties (amyloid hydrogel) on human mesenchymal stem cell (hMSC) differentiation. Stem cells were cultured on soft amyloid hydrogels [1], [2] in the presence and absence of matrix encapsulated RA. The cell morphology was imaged and assessed via quantification of circularity. Further immunostaining and quantitative real time PCR was used to quantify various markers of differentiation in the neuronal lineage.

Self healing hydrogels composed of amyloid nano fibrils for cell culture and stem cell differentiation

Amyloids are highly ordered protein/peptide aggregates associated with human diseases as well as various native biological functions. Given the diverse range of physiochemical properties of amyloids, we hypothesized that higher order amyloid self-assembly could be used for fabricating novel hydrogels for biomaterial applications. For proof of concept, we designed a series of peptides based on the high aggregation prone C-terminus of Aβ42, which is associated with Alzheimer's disease. These Fmoc protected peptides self assemble to β sheet rich nanofibrils, forming hydrogels that are thermoreversible, non-toxic and thixotropic. Mechanistic studies indicate that while hydrophobic, π–π interactions and hydrogen bonding drive amyloid network formation to form supramolecular gel structure, the exposed hydrophobic surface of amyloid fibrils may render thixotropicity to these gels. We have demonstrated the utility of these hydrogels in supporting cell attachment and spreading across a diverse range of cell types. Finally, by tuning the stiffness of these gels through modulation of peptide concentration and salt concentration these hydrogels could be used as scaffolds that can drive differentiation of mesenchymal stem cells. Taken together, our results indicate that small size, ease of custom synthesis, thixotropic nature makes these amyloid-based hydrogels ideally suited for biomaterial/nanotechnology applications.

Nanofibrillation of TEMPO-oxidized bleached hardwood kraft cellulose at high solids content

AbstractCellulose nanofibrils (NF) are usually produced by disintegration processes at low solids content (<5%). However, the high water content reduces the capacity of production, increases the transportation costs of NF suspensions and narrows the possible applications of NF. The goal of the present study was to test a grinding technique based on oscillatory ball milling. Bleached kraft pulp cellulose was nanofibrillated at high solids contents (≥50%), which was obtained from 2,2,6,6-tetramethylpiperidine-1-oxyl radical-oxidized pulp. The grinding method was only successful when the charge density was at least 0.5 mmol g-1. NFs and cellulose nanocrystals were identified at a charge density of 1.1 mmol g-1and a solids content of 50%. The size reduction of the formed particles was observed by means of flow fractionation and imaging and viscosity measurements after increasing the charge density from 0.3 to 1.1 mmol g-1. A solids content increment and a charge density decrement resulted in particles with low aspect ratio rather than in nanofibrils. Wide angle X-ray diffraction measurements showed the transformation of crystalline cellulose into amorphous material in the case of grounding at 93% solids content.

Supramolecular Assembly of Functional Hybrid Fibrils with Peptide-π-System-Peptide Monomers Near Silver-Nanoparticles

Abstract Oligopeptides containing internal π-system units are shown to self-assemble in water near nanoparticles into fibrillar nanostructures. We have investigated the biopolymer hybrid monomer of the overall structure `peptide-π-system-peptide' with the sequence VDFAG – perylene diimide (PDI) – GAFDV in the presence of Ag-nanoparticles. Unique to these self-assembling monomers is the fact that the π-conjugated unit has been directly embedded within the peptide backbone by way of a special synthetic coupling. The symmetric peptide-based molecular design enforces intimate π-π communication within the aggregates after self-assembly, making these nano structures attractive for optical or electronic applications. The assembly process can in principle be followed by the change in optical spectra of the monomer and ordered monomer π-systems. Here we show that the Ag-nanoparticles act as seeds for the fibrillation, which makes the fibrils grow in a defined fashion and the supramolecular assembly can be followed via the optical spectrum of the plasmon resonances of the silver nanoparticles, which depend sensitively upon the local environment, making the optical plasmon resonance spectra a nice probe for the assembly process, as well as the interaction of monomers and fibrillar structures in contact with the nanoparticles. While it has been known that these systems may aggregate under certain conditions towards nano fibrils the new aspect here is the controlled and accelerated fibrillation near silver nanoparticles, which results in fibrils of 15–150 nm in diameter and up to 10 μm long, partially incorporating the seed nanoparticles. This approach provides a novel avenue to synthesize bioorganic-hybrid systems (in high yields) in contact with Ag metal nanoparticles and possibly enables us to control the location of growth for the materials in future applications.

Morphological and Thermal Properties of Cellulose Nanofibrils Reinforced Epoxy Nanocomposites

Epoxy resins have gained attention as important adhesives because they are structurally stable, inert to most chemicals, and highly resistant to oxidation. Different particles can be added to adhesives to improve their properties. In this study, cellulose nanofi brils (CNFs), which have superior mechanical properties, were used as the reinforcing agent. Cellulose nanofi brils were added to epoxy in quantities of 1 %, 2 % and 3 % by weight to prepare nanocomposites. Morphological characterization of the composites was done with scanning electron microscopy (SEM). Thermal properties of the nanocomposites were investigated with Thermogravimetric Analyzer (TGA/DTG) and Differential Scanning Calorimeter (DSC). SEM images showed that the cellulose nanofi brils were dispersed partially homogenous throughout the epoxy matrix for 1 % CNF. However, it was observed that the cellulose nanofi brils were aggregated (especially for 2 and 3 % CNFs) in some parts of the SEM images, and the ratios of the aggregated parts increased as the loading rate of the cellulose nanofi brils increased. The TGA curve showed that DTG and decomposition temperature of pure epoxy was higher than that of the nanocomposites. The DSC curve showed that the glass transition temperature (T g ) value of pure epoxy was found to be similar with Tg of the nanocomposites.

Assessment of Nano Cellulose from Peach Palm Residue as Potential Food Additive: Part II: Preliminary Studies.

High consumption of dietary fibers in the diet is related to the reduction of the risk of non-transmitting of chronic diseases, prevention of the constipation etc. Rich diets in dietary fibers promote beneficial effects for the metabolism. Considering the above and recognizing the multifaceted advantages of nano materials, there have been many attempts in recent times to use the nano materials in the food sector including as food additive. However, whenever new product for human and animal consumption is developed, it has to be tested for their effectiveness regarding improvement in the health of consumers, safety aspects and side effects. However, before it is tried with human beings, normally such materials would be assessed through biological tests on a living organism to understand its effect on health condition of the consumer. Accordingly, based on the authors' finding reported in a previous paper, this paper presents body weight, biochemical (glucose, cholesterol and lipid profile in blood, analysis of feces) and histological tests carried out with biomass based cellulose nano fibrils prepared by the authors for its possible use as food additive. Preliminary results of the study with mice have clearly brought out potential of these fibers for the said purpose.

MWCNTs/carbon nano fibril composite papers for fuel cell and super capacitor applications

Electrospinning process was optimized by using response surface methodology (RSM) to fabricate MWCNTs/PAN nanofibril composite non-woven fabrics of 180 nm average fiber diameter. The as-electrospun fabrics were hot-pressed to produce strong and flexible carbon nanofibril composite papers of 130 nm average fibril composite diameter. Dielectric constant of 300 and conductivity of 310 S/m were measured for these papers by using H10K13532-50LCR meter at 25,000 Hz. Analytical approach was introduced based on Lichtenecker modification formula to evaluate the electrical properties of the embedded MWCNTs, single nanofibers and single nanofibril composites as function in fabrics measured properties. 4156 S/m for MWCNTs, 360 S/m for carbonized electrospun PAN single nanofibers and 517 S/m for carbonized electrospun 5 wt% MWCNTs/PAN single nanofibril composites were reported. The ability to control the electrical properties of these papers over a wide range should position them as a versatile advanced material for numerous electronic, sensors and inter-connect applications.

Preparation, characterization, and antimicrobial activity of chitin nanofibrils reinforced carrageenan nanocomposite films.

Present study illustrates the preparation of chitin nanofibrils (CNF) reinforced carrageenan nanocomposite films by the solution-casting technique. CNF was prepared by acid hydrolysis of chitin, followed by high speed homogenization and sonication. FTIR result demonstrated that the chemical structure of chitin had not changed after acid hydrolysis. However, the crystalinity of CNF was found to be higher than chitin. The crystallite size of chitin and CNF was 4.73 and 6.27 nm, respectively. The char content at 600 °C of chitin (19.2%) was lower than the CNF (25%). The carrageenan/CNF composite films were smooth and flexible and the CNF was dispersed uniformly in the carrageenan polymer matrix. The tensile strength and modulus of carrageenan film were increased significantly (p<0.05) after CNF reinforcement with up to 5 wt%, however, elongation at break, water vapor permeability, and transparency decreased slightly. Carrageenan/CNF nanocomposite films showed strong antibacterial activity against a Gram-positive food-borne pathogen, Listeria monocytogenes.

Morphological Analysis of Micro-fibrillated Cellulose from Different Raw Materials for Fiber Plastic Composites

Polymer nanocomposites have attracted great interest during current years. Cellulose micro-fibrils may be function as biodegradable Nano fibrils in high performance composites. The production of Nano-scale cellulose i¬bers and their application in composite materials has gained increasing attention due to their high strength and stiffness combined with low weight, biodegradability and renewability. Adding small amounts of cellulose-based fillers to thermoplastic matrix polymers usually enhances the mechanical properties. However, the development of fully biodegradable nanocomposites is still a challenging area. Many researchers investigated production of micro cellulose microfibers through various methods. The most important and widely used methods for cellulose Nano fibers isolation are Chemical method (CM), Mechanical methods, Physical methods, Using microwave, Biological and High-pressure homogenizer. CM process is easier than milling process (MM) by which material is reduced from a large size to a smaller size ‘top-down’. In this work, a motor driven mechanical rotary microtome sheering device was used to produce microi¬brillated cellulose (MFC) particles from different types of cotton fibers and cotton waste, as well as flax. The morphological properties of the cellulose particles were investigated by means of scanning electron microscopy. Final length distribution of cellulose particles was determined. It was found that the maximum number of fibers was observed in the range from 0.5 to 2 microns with average aspect ratio 1.6. Depending on the source of the fibers, the particles with a diameter of 20 – 500 nm were observed.

Preparation of Cellulose Nanofibrils by High-Pressure Homogenizer and Zein Composite Films

Cellulose nanofibrils ( NF ) have several advantages such as biodegradability and safety toward human health. Zein is a biodegradable polymer with potential use in food packaging applications. It appears that polymer nanocomposites are one of the most promising applications of zein films. Cellulose NF were prepared from starting material Microcrystalline cellulose (MCC) by an application of a high-pressure homogenizer at 20,000 psi and treatment consisting of 15 passes. Methods such as atomic force microscopy were used for confirmation of nanoscale size production of cellulose. The average diameter 45 nm were observed. Zeincellulose NF nanocomposite films were prepared by casting ethanol suspensions of Zein with different amounts of cellulose NF in the 0% to 5%wt. The nanocomposites were characterized by using Fourier transform infrared spectroscopy ( FTIR ), Atomic force microscopy ( AFM ) and X-ray diffraction ( XRD ) analysis. From the FTIR spectra the various groups present in the Zein blend were monitored. The homogeneity, morphology and crystallinity of the blends were ascertained from the AFM and XRD data, respectively. The thermal resistant of the zein nanocomposite films improved as the nanocellulose content increased. These obtained materials are transparent, flexible and present significantly better physical properties than the corresponding unfilled Zein films.

Evaluation of the effects of chitin nanofibrils on skin function using skin models

Chitins are highly crystalline structures that are predominantly found in crustacean shells. Alpha-chitin is composed of microfibers, which are made up of nanofibrils that are 2–5nm in diameter and 30nm in length and embedded in a protein matrix. Crystalline nanofibrils can also be prepared by acid treatment. We verified the effect of chitin nanofibrils (NF) and nanocrystals (NC) on skin using a three-dimensional skin culture model and Franz cells. The application of NF and NC to skin improved the epithelial granular layer and increased granular density. Furthermore, NF and NC application to the skin resulted in a lower production of TGF-β compared to that of the control group. NF and NC might have protective effects to skin. Therefore, their potential use as components of skin-protective formulations merits consideration.

Cellulose Nanofibrils

Cellulose nanofi brils (CNF), also known as nanofi brillar cellulose (NFC), are an advanced biomaterial made mainly from renewable forest and agricultural resources that have demonstrated exceptional performance in composites. In addition, they have been utilized in barrier coatings, food, transparent fl exible fi lms and other applications. Research on CNF has advanced rapidly over the last decade and several of the fundamental questions about production and characterization of CNF have been addressed. An interesting shift in focus in the recent reported literature indicates increased efforts aimed at taking advantage of the unique properties of CNF. This includes its nanoscale dimensions, high surface area, unique morphology, low density and mechanical strength. In addition, CNF can be easily (chemically) modified and is readily available, renewable, and biodegradable. These facts are expected to materialize in a more widespread use of CNF. However, there is no clear indication of the most promising avenues for CNF deployment in commercial products. This review attempts to illustrate some exciting opportunities for CNF, specifi cally, in the development of aerogels, composites, bioactive materials and inorganic/organic hybrid materials.

Environmental ageing studies of chemically modified micro and nanofibril phenol formaldehyde composites

Cellulose micro and nano fibrils were extracted from banana macro fibres and chemically modified using sodium hydroxide, formic acid, 3-methacryloxy propyltrimethoxy silane. These untreated and chemically treated fibrils were incorporated into PF resin and the specimens were prepared. The composites were subjected to long-term water ageing, thermal ageing soil burial and outdoor weathering. The mechanical properties are reduced under all ageing conditions. The present study investigates the effects of different types of ageing on macro fibre, microfibril and nanofibril reinforced PF composites. The effect of chemical modifications of fibres on the degradability of the composites at different environments also has been analysed.

Direct visualization of shear dependent silk fibrillogenesis

Silk's desirable properties originate from the development of a multiscale hierarchical structure produced during spinning, but little is known regarding the origin of the micro and nano fibrils that are consistent and prominent features of spun fibres. This raises the important question: can shearing alone generate these filaments, or is further input and control by the physiology/morphology of the silk duct required? Combining confocal microscopy with rheology provides unique insights into the direct connection between applied shear and the fibrillation of silk proteins in as close to in vivo conditions as currently possible. Our measurements demonstrate that unlike typical synthetic polymers, native silk proteins are able to spontaneously self-assemble, fibrillate and develop hierarchical structures upon controlled shearing, and that the shear induced fibrilogenesis is accompanied by dramatic changes in the rheological response. These observations suggest that natural spinning may be far less complex than previously assumed.

Extraction of nanocellulose fibrils from lignocellulosic fibres: A novel approach

The objective of this work was to develop a simple process to obtain an aqueous stable colloid suspension of cellulose nano fibrils from various lignocellulosic fibres. For the preliminary analysis we have studied three different fibres: banana (pseudo stem), jute (stem) and pineapple leaf fibre (PALF). To study the feasibility of extracting cellulose from these raw fibres we have adopted steam explosion technique along with mild chemical treatment. These processes included usual chemical procedures such as alkaline extraction, bleaching, and acid hydrolysis but with a very mild concentration of the chemicals. The chemical constituents of the fibre in each processing step were determined by ASTM standard procedures. Morphological, spectroscopic and thermal analyses of the fibres were carried out and found that the isolation of cellulose nanofibres occurs in the final step of the processing stage and they possess improved thermal stability for various advanced nanotechnological applications.