Nanocellulose: From Fundamentals to Advanced Applications

Steady and Robust CNTs-Based Electric Heating Membrane Fabricated by Addition of Nanocellulose and Hot-Press Encapsulation

Herein, a type of biomass-based electric heating membrane (EHM) with excellent stability was fabricated; this was achieved by incorporating carbon nanotubes (CNTs) into the nanofibrillated cellulose (NFC) as a natural dispersant and a biological substrate, as well as via the control of ultrasonic dispersion, grammage, and encapsulation using poly(dimethylsiloxane) (PDMS) with hot pressing. NFC entangles with CNTs in the form of an intertwined network and non-covalent interactions to fabricate a flexible EHM with steady electric heating performance; this formation is attributed to not only their similar morphology and surface-active groups but also the use of NFC that avoids additional disturbances in the overlapped interface among CNTs as far as possible. The obtained steady resistance varies as low as 5.1% under energized operation. In the encapsulated EHM (EM), PDMS was anchored on its surface by using hot pressing and an intertwined structure to enhance flexibility and robustness. The encapsulated membrane can be used in low-voltage applications, which require flexibility, waterproofing, and insulation.

Isolation and modification of nano-scale cellulose from organosolv-treated birch through the synergistic activity of LPMO and endoglucanases

Nanocellulose isolation from lignocellulose is a tedious and expensive process with high energy and harsh chemical requirements, primarily due to the recalcitrance of the substrate, which otherwise would have been cost-effective due to its abundance. Replacing the chemical steps with biocatalytic processes offers opportunities to solve this bottleneck to a certain extent due to the enzymes substrate specificity and mild reaction chemistry. In this work, we demonstrate the isolation of sulphate-free nanocellulose from organosolv pretreated birch biomass using different glycosyl-hydrolases, along with accessory oxidative enzymes including a lytic polysaccharide monooxygenase (LPMO). The suggested process produced colloidal nanocellulose suspensions (ζ-potential -19.4 mV) with particles of 7-20 nm diameter, high carboxylate content and improved thermostability (T_o = 301 °C, T_max = 337 °C). Nanocelluloses were subjected to post-modification using LPMOs of different regioselectivity. The sample from chemical route was the least favorable for LPMO to enhance the carboxylate content, while that from the C1-specific LPMO treatment showed the highest increase in carboxylate content.

Recent Advances in the Synthesis of Nanocellulose Functionalized–Hybrid Membranes and Application in Water Quality Improvement

The increasing discharge of voluminous non or partially treated wastewaters characterized by complex contaminants poses significant ecological and health risks. Particularly, this practice impacts negatively on socio-economic, technological, industrial, and agricultural development. Therefore, effective control of water pollution is imperative. Over the past decade, membrane filtration has been established as an effective and commercially attractive technology for the separation and purification of water. The performance of membrane-based technologies relies on the intrinsic properties of the membrane barrier itself. As a result, the development of innovative techniques for the preparation of highly efficient membranes has received remarkable attention. Moreover, growing concerns related to cost-effective and greener technologies have induced the need for eco-friendly, renewable, biodegradable, and sustainable source materials for membrane fabrication. Recently, advances in nanotechnology have led to the development of new high-tech nanomaterials from natural polymers (e.g., cellulose) for the preparation of environmentally benign nanocomposite membranes. The synthesis of nanocomposite membranes using nanocelluloses (NCs) has become a prominent research field. This is attributed to the exceptional characteristics of these nanomaterials (NMs) namely; excellent and tuneable surface chemistry, high mechanical strength, low-cost, biodegradability, biocompatibility, and renewability. For this purpose, the current paper opens with a comprehensive yet concise description of the various types of NCs and their most broadly utilized production techniques. This is closely followed by a critical review of how NC substrates and their surface-modified versions affect the performance of the fabricated NC-based membranes in various filtration processes. Finally, the most recent processing technologies for the preparation of functionalized NCs-based composite membranes are discussed in detail and their hybrid characteristics relevant to membrane filtration processes are highlighted.

Nanocellulose-Graphene Hybrids: Advanced Functional Materials as Multifunctional Sensing Platform

Naturally derived nanocellulose with unique physiochemical properties and giant potentials as renewable smart nanomaterials opens up endless novel advanced functional materials for multi-sensing applications. However, integrating inorganic functional two-dimensional carbon materials such as graphene has realized hybrid organic-inorganic nanocomposite materials with precisely tailored properties and multi-sensing abilities. Altogether, the affinity, stability, dispersibility, modification, and functionalization are some of the key merits permitting their synergistic interfacial interactions, which exhibited highly advanced multifunctional hybrid nanocomposites with desirable properties. Moreover, the high performance of such hybrids could be achievable through green and straightforward approaches. In this context, the review covered the most advanced nanocellulose-graphene hybrids, focusing on their synthetization, functionalization, fabrication, and multi-sensing applications. These hybrid films exhibited great potentials as a multifunctional sensing platform for numerous mechanical, environmental, and human bio-signals detections, mimicking, and in-situ monitoring.

Cellulose-based micro-fibrous materials imaged with a home-built smartphone microscope

Micro-fibrous materials are one of the highly explored materials and form a major component of composite materials. In resource-limited settings, an affordable and easy to implement method that can characterize such material would be important. In this study, we report on a smartphone microscopic system capable of imaging a sample in transmission mode. As a proof of concept, we implemented the method to image handmade paper samples-cellulosic micro-fibrous material of different thickness. With 1 mm diameter ball lens, individual cellulose fibers, fiber web, and micro-porous regions were resolved in the samples. Imaging performance of the microscopic system was also compared with a commercial bright field microscope. For thin samples, we found the image quality comparable to commercial system. Also, the diameter of cellulose fiber measured from both methods was found to be similar. We also used the system to image surfaces of a three ply surgical facemask. Finally, we explored the application of the system in the study of chemical induced fiber damage. This study suggested that the smartphone microscope system can be an affordable alternative in imaging thin micro-fibrous material in resource limited setting.

Recent Developments in Nanocellulose-Reinforced Rubber Matrix Composites: A Review

Research and development of nanocellulose and nanocellulose-reinforced composite materials have garnered substantial interest in recent years. This is greatly attributed to its unique functionalities and properties, such as being renewable, sustainable, possessing high mechanical strengths, having low weight and cost. This review aims to highlight recent developments in incorporating nanocellulose into rubber matrices as a reinforcing filler material. It encompasses an introduction to natural and synthetic rubbers as a commodity at large and conventional fillers used today in rubber processing, such as carbon black and silica. Subsequently, different types of nanocellulose would be addressed, including its common sources, dimensions, and mechanical properties, followed by recent isolation techniques of nanocellulose from its resource and application in rubber reinforcement. The review also gathers recent studies and qualitative findings on the incorporation of a myriad of nanocellulose variants into various types of rubber matrices with the main goal of enhancing its mechanical integrity and potentially phasing out conventional rubber fillers. The mechanism of reinforcement and mechanical behaviors of these nanocomposites are highlighted. This article concludes with potential industrial applications of nanocellulose-reinforced rubber composites and the way forward with this technology.

In-Vitro Antibacterial and Anti-Inflammatory Effects of Surfactin-Loaded Nanoparticles for Periodontitis Treatment

Periodontitis is an inflammatory disease associated with biofilm formation and gingival recession. The practice of nanotechnology in the clinical field is increased overtime due to its potential advantages in drug delivery applications. Nanoparticles can deliver drugs into the targeted area with high efficiency and cause less damages to the tissues. In this study, we investigated the antibacterial and anti-inflammatory properties of surfactin-loaded κ-carrageenan oligosaccharides linked cellulose nanofibers (CO-CNF) nanoparticles. Three types of surfactin-loaded nanoparticles were prepared based on the increasing concentration of surfactin such as 50SNPs (50 mg surfactin-loaded CO-CNF nanoparticles), 100SNPs (100 mg surfactin-loaded CO-CNF nanoparticles), and 200SNPs (200 mg surfactin-loaded CO-CNF nanoparticles). The results showed that the nanoparticles inhibited the growth of Fusobacterium nucleatum and Pseudomonas aeruginosa. The reduction in biofilm formation and metabolic activity of the bacteria were confirmed by crystal violet and MTT assay, respectively. Besides, an increase in oxidative stress was also observed in bacteria. Furthermore, anti-inflammatory effects of surfactin-loaded CO-CNF nanoparticles was observed in lipopolysaccharide (LPS)-stimulated human gingival fibroblast (HGF) cells. A decrease in the production of reactive oxygen species (ROS), transcription factor, and cytokines were observed in the presence of nanoparticles. Collectively, these observations supported the use of surfactin-loaded CO-CNF as a potential candidate for periodontitis management.

New insensitive high-energy dense biopolymers from giant reed cellulosic fibers: their synthesis, characterization, and non-isothermal decomposition kinetics

Renewable giant reed has been explored for the first time to develop new advanced high-energy dense biopolymers through carbamate surface functionalization and nitration of native cellulose and cellulose microcrystals.

The Impact of Filler Geometry on Polylactic Acid-Based Sustainable Polymer Composites

Recently, biocomposites have emerged as materials of great interest to the scientists and industry around the globe. Among various polymers, polylactic acid (PLA) is a popular matrix material with high potential for advanced applications. Various particulate materials and nanoparticles have been used as the filler in PLA based matrix. One of the extensively studied filler is cellulose. However, cellulose fibres, due to their hydrophilic nature, are difficult to blend with a hydrophobic polymer matrix. This leads to agglomeration and creates voids, reducing the mechanical strength of the resulting composite. Moreover, the role of the various forms of pure cellulose and its particle shape factors has not been analyzed in most of the current literature. Therefore, in this work, materials of various shapes and shape factors were selected as fillers for the production of polymer composites using Polylactic acid as a matrix to fill this knowledge gap. In particular, pure cellulose fibres (three types with different elongation coefficient) and two mineral nanocomponents: precipitated calcium carbonate and montmorillonite were used. The composites were prepared by a melt blending process using two different levels of fillers: 5% and 30%. Then, the analysis of their thermomechanical and physico-chemical properties was carried out. The obtained results were presented graphically and discussed in terms of their shape and degree of filling.

Nanoscale Curvature Promotes High Yield Spontaneous Formation of Cell-Mimetic Giant Vesicles on Nanocellulose Paper

To date, techniques for the assembly of phospholipid films into cell-like giant unilamellar vesicles (GUVs) use planar surfaces and require the application of electric fields or dissolved molecules to obtain adequate yields. Here, we present the use of nanocellulose paper, which are surfaces composed of entangled cylindrical nanofibers, to promote the facile and high yield assembly of GUVs. Use of nanocellulose paper results in up to a 100 000-fold reduction in costs while increasing yields compared to extant surface-assisted assembly techniques. Quantitative measurements of yields and the distributions of sizes using large data set confocal microscopy illuminates the mechanism of assembly. We present a thermodynamic "budding and merging", BNM, model that offers a unified explanation for the differences in the yields and sizes of GUVs obtained from surfaces of varying geometry and chemistry. The BNM model considers the change in free energy due to budding by balancing the elastic, adhesion, and edge energies of a section of a surface-attached membrane that transitions into a surface-attached spherical bud. The model reveals that the formation of GUVs is spontaneous on hydrophilic surfaces consisting of entangled cylindrical nanofibers with dimensions similar to nanocellulose fibers. This work advances understanding of the effects of surface properties on the assembly of GUVs. It also addresses practical barriers that currently impede the promising use of GUVs as vehicles for the delivery of drugs, for the manufacturing of synthetic cells, and for the assembly of artificial tissues at scale.

Cellulose Composites with Graphene for Tissue Engineering Applications

Tissue engineering is an interdisciplinary field that combines principles of engineering and life sciences to obtain biomaterials capable of maintaining, improving, or substituting the function of various tissues or even an entire organ. In virtue of its high availability, biocompatibility and versatility, cellulose was considered a promising platform for such applications. The combination of cellulose with graphene or graphene derivatives leads to the obtainment of superior composites in terms of cellular attachment, growth and proliferation, integration into host tissue, and stem cell differentiation toward specific lineages. The current review provides an up-to-date summary of the status of the field of cellulose composites with graphene for tissue engineering applications. The preparation methods and the biological performance of cellulose paper, bacterial cellulose, and cellulose derivatives-based composites with graphene, graphene oxide and reduced graphene oxide were mainly discussed. The importance of the cellulose-based matrix and the contribution of graphene and graphene derivatives fillers as well as several key applications of these hybrid materials, particularly for the development of multifunctional scaffolds for cell culture, bone and neural tissue regeneration were also highlighted.

Carboxylated cellulose nanofiber/montmorillonite nanocomposite for the removal of levofloxacin hydrochloride antibiotic from aqueous solutions

Herein, we report the facile two-step synthesis of an effective carboxylated cellulose nanofiber/montmorillonite nanocomposite (CMNFs-MMT) adsorbent for levofloxacin hydrochloride (Levo-HCl). CMNFs-MMT was characterized using scanning electron microscopy, energy dispersive X-ray spectrometry, Brunauer-Emmett-Teller measurements, X-ray photoelectron spectroscopy, X-ray diffraction, and Fourier transform infrared spectroscopy. Based on the central composite design, the effects of various factors on the removal of Levo-HCl by the CMNFs-MMT were explored, wherein the effect of pH was the most significant. To gain a clearer perspective on the adsorption process of Levo-HCl onto CMNFs-MMT, the adsorption kinetics and isotherms were also measured, revealing that the reaction is pseudo-second-order and the Sips models provide the best fit with experimental data. Comparing the adsorption in pure water with the removal in river water, the rate of river water removal (90.37%) was slightly lower than that of pure water (93.97%) when adsorption equilibrium was reached, confirming that CMNFs-MMT is not easily influenced by environmental conditions. Reusability experiments indicate that CMNFs-MMT can maintain a certain adsorption capacity for Levo-HCl after six uses. Overall, this work indicates that CMNFs-MMT is an effective adsorbent for eliminating Levo-HCl from aqueous media in future engineering applications.

Towards the scalable isolation of cellulose nanocrystals from tunicates

In order for sustainable nanomaterials such as cellulose nanocrystals (CNCs) to be utilized in industrial applications, a large-scale production capacity for CNCs must exist. Currently the only CNCs available commercially in kilogram scale are obtained from wood pulp (W-CNCs). Scaling the production capacity of W-CNCs isolation has led to their use in broader applications and captured the interest of researchers, industries and governments alike. Another source of CNCs with potential for commercial scale production are tunicates, a species of marine animal. Tunicate derived CNCs (T-CNCs) are a high aspect ratio CNC, which can complement commercially available W-CNCs in the growing global CNC market. Herein we report the isolation and characterization of T-CNCs from the tunicate Styela clava, an invasive species currently causing significant harm to local aquaculture communities. The reported procedure utilizes scalable CNC processing techniques and is based on our experiences from laboratory scale T-CNC isolation and pilot scale W-CNC isolation. To our best knowledge, this study represents the largest scale where T-CNCs have been isolated from any tunicate species, under any reaction conditions. Demonstrating a significant step towards commercial scale isolation of T-CNCs, and offering a potential solution to the numerous challenges which invasive tunicates pose to global aquaculture communities.

Application of Nanotechnology in Wood-Based Products Industry: A Review

Wood-based industry is one of the main drivers of economic growth in Malaysia. Forest being the source of various lignocellulosic materials has many untapped potentials that could be exploited to produce sustainable and biodegradable nanosized material that possesses very interesting features for use in wood-based industry itself or across many different application fields. Wood-based products sector could also utilise various readily available nanomaterials to enhance the performance of existing products or to create new value added products from the forest. This review highlights recent developments in nanotechnology application in the wood-based products industry.

Recent Achievements in Polymer Bio-Based Flocculants for Water Treatment

Polymer flocculants are used to promote solid-liquid separation processes in potable water and wastewater treatment. Recently, bio-based flocculants have received a lot of attention due to their superior advantages over conventional synthetic polymers or inorganic agents. Among natural polymers, polysaccharides show many benefits such as biodegradability, non-toxicity, ability to undergo different chemical modifications, and wide accessibility from renewable sources. The following article provides an overview of bio-based flocculants and their potential application in water treatment, which may be an indication to look for safer alternatives compared to synthetic polymers. Based on the recent literature, a new approach in searching for biopolymer flocculants sources, flocculation mechanisms, test methods, and factors affecting this process are presented. Particular attention is paid to flocculants based on starch, cellulose, chitosan, and their derivatives because they are low-cost and ecological materials, accepted in industrial practice. New trends in water treatment technology, including biosynthetic polymers, nanobioflocculants, and stimulant-responsive flocculants are also considered.

Production of Levulinic Acid from Cellulose and Cellulosic Biomass in Different Catalytic Systems

The reasonable and effective use of lignocellulosic biomass is an important way to solve the current energy crisis. Cellulose is abundant in nature and can be hydrolyzed to a variety of important energy substances and platform compounds—for instance, glucose, 5-hydroxymethylfurfural (HMF), levulinic acid (LA), etc. As a chemical linker between biomass and petroleum processing, LA has become an ideal feedstock for the formation of liquid fuels. At present, some problems such as low yield, high equipment requirements, difficult separation, and serious environmental pollution in the production of LA from cellulose have still not been solved. Thus, a more efficient and green catalytic system of this process for industrial production is highly desired. Herein, we focus on the reaction mechanism, pretreatment, and catalytic systems of LA from cellulose and cellulosic biomass, and a series of existing technologies for producing LA are reviewed. On the other hand, the industrial production of LA is discussed in depth to improve the yield of LA and make the process economical and energy efficient. Additionally, practical suggestions for the enhancement of the stability and efficiency of the catalysts are also proposed. The use of cellulose to produce LA is consistent with the concept of sustainable development, and the dependence on fossil resources will be greatly reduced through the realization of this process route.

Cellulose Nanocrystals/Graphene Hybrids-A Promising New Class of Materials for Advanced Applications

With the growth of global fossil-based resource consumption and the environmental concern, there is an urgent need to develop sustainable and environmentally friendly materials, which exhibit promising properties and could maintain an acceptable level of performance to substitute the petroleum-based ones. As elite nanomaterials, cellulose nanocrystals (CNC) derived from natural renewable resources, exhibit excellent physicochemical properties, biodegradability and biocompatibility and have attracted tremendous interest nowadays. Their combination with other nanomaterials such as graphene-based materials (GNM) has been revealed to be useful and generated new hybrid materials with fascinating physicochemical characteristics and performances. In this context, the review presented herein describes the quickly growing field of a new emerging generation of CNC/GNM hybrids, with a focus on strategies for their preparation and most relevant achievements. These hybrids showed great promise in a wide range of applications such as separation, energy storage, electronic, optic, biomedical, catalysis and food packaging. Some basic concepts and general background on the preparation of CNC and GNM as well as their key features are provided ahead.

A promising energetic biopolymer based on azide-functionalized microcrystalline cellulose: Synthesis and characterization

In the current investigation, azidodeoxy-microcrystalline cellulose nitrate (AMCCN) as a novel promising nitrogen-rich energetic biopolymer was synthesized, and its features were compared to those of azidodeoxy-pristine cellulose nitrate (APCN), conventional cellulose nitrate (PCN) and microcrystalline cellulose nitrate (MCCN). The produced nitrated samples and their precursors were fully characterized using various analytical techniques. In addition, the heats of combustion and mechanical sensitivities of all nitrated biopolymers were evaluated, and their energetic performances were predicted by EXPLO5 V6.04 software. The obtained results provide evidence for the effectiveness of the applied chemical functionalization approach to synthesize the relatively insensitive AMCCN and APCN with nitrogen content of 22.75 % and 22.50 %, density of 1.718 g/cm³ and 1.706 g/cm³, and detonation velocity of 7707 m/s and 7533 m/s, respectively, which are higher than those of PCN. This work opens avenues to design promising energetic biopolymers based on renewable microcrystalline cellulose for potential application in advanced high performance solid propellants and explosives.

DNA Electrochemical Biosensor Based on Iron Oxide/Nanocellulose Crystalline Composite Modified Screen-Printed Carbon Electrode for Detection of Mycobacterium tuberculosis

Death from tuberculosis has resulted in an increased need for early detection to prevent a tuberculosis (TB) epidemic, especially in closed and crowded populations. Herein, a sensitive electrochemical DNA biosensor based on functionalized iron oxide with mercaptopropionic acid (MPA-Fe3O4) nanoparticle and nanocellulose crystalline functionalized cetyl trimethyl ammonium bromide (NCC/CTAB) has been fabricated for the detection of Mycobacterium tuberculosis (MTB). In this study, a simple drop cast method was applied to deposit solution of MPA-Fe3O4/NCC/CTAB onto the surface of the screen-printed carbon electrode (SPCE). Then, a specific sequence of MTB DNA probe was immobilized onto a modified SPCE surface by using the 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide/N-hydroxysuccinimide (EDC/NHS) coupling mechanism. For better signal amplification and electrochemical response, ruthenium bipyridyl Ru(bpy)32+ was assigned as labels of hybridization followed by the characteristic test using differential pulse voltammetry (DPV). The results of this biosensor enable the detection of target DNA until a concentration as low as 7.96 × 10-13 M with a wide detection range from 1.0 × 10-6 to 1.0 × 10-12 M. In addition, the developed biosensor has shown a differentiation between positive and negative MTB samples in real sampel analysis.