No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
Nanocellulose, a tiny fiber with huge applications
Abstract
Nanocellulose is of increasing interest for a range of applications relevant to the fields of material science and biomedical engineering due to its renewable nature, anisotropic shape, excellent mechanical properties, good biocompatibility, tailorable surface chemistry, and interesting optical properties. We discuss the main areas of nanocellulose research: photonics, films and foams, surface modifications, nanocomposites, and medical devices. These tiny nanocellulose fibers have huge potential in many applications, from flexible optoelectronics to scaffolds for tissue regeneration. We hope to impart the readers with some of the excitement that currently surrounds nanocellulose research, which arises from the green nature of the particles, their fascinating physical and chemical properties, and the diversity of applications that can be impacted by this material.
... These properties contribute to their suitability for various biomedical applications, such as wound dressings, tissue engineering scaffolds, and drug delivery systems. Applications: used in wound dressings, drug delivery systems, and tissue engineering scaffolds due to their high strength and ability to support cell growth [155,156]. • Regenerated cellulose nanofibers (RCNFs): RCNFs are produced using advanced methods to extract and refine cellulose fibers to the nanometer scale. They offer enhanced mechanical properties, high surface area, and improved interactions with biological tissues. ...
... Properties of some new regenerated cellulose fibers[155][156][157][158][159][160][161][162][163][164][165]. ...
Regenerated cellulose fibers are a highly adaptable biomaterial with numerous medical applications owing to their inherent biocompatibility, biodegradability, and robust mechanical properties. In the domain of wound care, regenerated cellulose fibers facilitate a moist environment conducive to healing, minimize infection risk, and adapt to wound topographies, making it ideal for different types of dressings. In tissue engineering, cellulose scaffolds provide a matrix for cell attachment and proliferation, supporting the development of artificial skin, cartilage, and other tissues. Furthermore, regenerated cellulose fibers, used as absorbable sutures, degrade within the body, eliminating the need for removal and proving advantageous for internal suturing. The medical textile industry relies heavily on regenerated cellulose fibers because of their unique properties that make them suitable for various applications, including wound care, surgical garments, and diagnostic materials. Regenerated cellulose fibers are produced by dissolving cellulose from natural sources and reconstituting it into fiber form, which can be customized for specific medical uses. This paper will explore the various types, properties, and applications of regenerated cellulose fibers in medical contexts, alongside an examination of its manufacturing processes and technologies, as well as associated challenges.
... 20,33 Materials based on cellulose nanocrystals (CNCs) have gained attention in TE research because of their alignment with the key concepts of Tissue Engineering, including biocompatibility, good mechanical properties, sustainability, and ability to promote cell differentiation and growth. 21,34 Manufacturing tissue engineering (TE) scaffolds have been extensively researched in the past two decades, including numerous techniques such as electrospinning, 3D printing, solvent casting, and freeze-drying. 17,29 Cellulose nanocrystals have consistently demonstrated their potential in various TE formulations, particularly for tissue repair, especially after modifying their physical and chemical properties. ...
Nanocellulose (NC) is one of the most prominent green materials for various applications. They have received increasing attention owing to their unique properties. In this review, a brief background on cellulose, its abundance in nature, chemical structure, and properties is described. Subsequently, the structure of nanocellulose, the procedures of its production, and its characteristics are discussed. This was followed by elaborating on the recent use of nanocellulose in medical and dental fields.
... During the strong acid hydrolysis process, the amorphous regions of the cellulose are hydrolyzed and broken down, while the crystalline regions are preserved [48]. Consequently, CNCs possess exceptionally high crystallinity, typically reaching up to 80% [49]. Unlike the elongated form of CNFs, CNCs exhibit a high aspect ratio with diameters typically ranging above 5-50 nm (Figure 3(c)). ...
Environmental pollution is a serious global challenge, and nanocellulose, as an emerging bio-based functional material, offers novel perspectives for addressing this issue. As an abundant and sustainable material, nanocellulose exhibits properties such as high strength, high modulus, light weight, surface rich in functional groups, and biodegradability. These properties allow it to be chemically or physically modified to confer conductivity, magnetism, or other functionalities, thus showing great promise in the development of self-adaptive materials. This paper reviews the latest advancements in the diverse production of nanocellulose-based self-adaptive materials across various dimensions and their applications in intelligent scenarios from the perspective of diversified functional materials production. It begins with a concise overview of the preparation methods and structural features of different types of nanocellulose. Subsequently, it introduces the preparation of one-dimensional (1D), two-dimensional (2D), and three-dimensional (3D) nanocellulose-based functional materials through assembly, integration, and specific structural design. Following this, the applications of nanocellulose-based materials of different dimensions in self-adaptive product fields such as sensors, actuators, supercapacitors, flexible electrodes, drug delivery, and electromagnetic shielding. Finally, the paper provides insights into the prospects and challenges of these products in smart applications and proposes feasible solutions.
... However, it's crucial to note that the dimensions and degree of crystallinity of these particles vary depending on the source of the cellulose and the specific extraction conditions. This variability has been documented in studies by researchers such as Habibi et al. [122][123][124]. ...
Made from a variety of natural sources, Nano Crystalline Cellulose (NCC) is a unique renewable nanomaterial with a wide range of applications due to its high stiffness and strength, low weight, biodegradability, and environmental benefits. Because of its special inherent qualities, NCC is one of the most renewable materials to be addressed by nanomaterials. The origins, manufacture, characteristics, and applications of nanomaterials, including NCC and nanofibers, have been extensively studied by a large number of researchers throughout the years. Strong chemical reactivity, crystallinity, strength and stiffness, biocompatibility, biodegradability, shape, and nanoscale dimensions are just a few of the remarkable properties that these nanomaterials have been shown to possess in countless investigations. These characteristics enable the application of these nanoparticles in a number of fields, including medicine. Among the most traditional and popular techniques. Electrospinning is one of the earliest and most popular techniques for producing nanofibers. This method works well and can be modified to produce continuous nanofibers. NCC-based nanofibers are novel materials in the biomaterials industry. Recent studies demonstrated that electrospun nanofibers could be efficiently loaded with a wide range of drugs, such as proteins, chemotherapeutic agents, antibiotics, and analgesics with anti-inflammatory qualities. One application of NCC and nanofibers in the medical field is drug delivery. This review highlights a number of issues related to NCC nanofibers and their use in drug delivery applications, beginning with discussing the various natural polymer types used in drug delivery applications, the physicochemical and biological properties of NCC, its various applications, its significance, and its preparation techniques.
... CNFs are well-suited for various advanced material applications due to their availability and exceptional properties (Rostamabadi et al., 2024) (Islam et al., 2023). CNFs have low density, high crystallinity, a large specific surface area, rheological properties, surface chemical reactivity, biocompatibility, biodegradability, non-toxicity, and good mechanical properties (Sultana et al., 2020) (Dai et al., 2019) (Abitbol et al., 2016) (Ichwan et al., 2023) (Balea et al., 2019) (Thomas et al., 2018). Polyvinyl alcohol (PVA) is a biodegradable, non-toxic, water-soluble, and biocompatible polymer. ...
... 3,4 In recent years, nanomaterials derived from cellulose have garnered significant attention due to their inherent biobased nature and advantageous properties such as high strength, stiffness, durability and chemical functionality, which allow for versatile design possibilities and applications such as thin barriers, flexible electronics substrates and optoelectronic materials. [5][6][7][8][9][10] Cellulose nanofibrils (CNFs) are fibrous nanomaterials with diameters around 3 nm and micrometerscale lengths, dispersed in aqueous media with charged surfaces ensuring colloidal stability. 11 These charges facilitate assembly strategies such as layer-by-layer adsorption, 12 or by mediating interactions during drying by the addition of smallmolecule or polymeric additives. ...
Biobased cellulose nanofibrils (CNFs) constitute important building blocks for biomimetic, nanostructured materials, and considerable potential exists in their hybridization with tailorable polymeric nanoparticles. CNFs naturally assemble into oriented, fibrillar structures...
... Nanoselulosa sering dianggap sebagai kandidat bahan penguat yang ideal untuk komposit polimer karena kekakuannya yang tinggi, kristalinitas yang tinggi, luas permukaan spesifik yang besar, sumber daya alam terbarukan dan sifat biodegradabilitas yang baik [3,4]. Nanoselulosa yang disintesis dari serat alami sangat berpotensi sebagai alternatif untuk pengisi berukuran mikro dalam campuran bahan komposit [5]. Nanoselulosa adalah serat dengan luas spesifik yang sangat tinggi dan porositas tinggi dengan interkonektivitas pori yang sangat baik yang memiliki dimensi 100 nm atau kurang [6]. ...
... Nanocellulose refers to natural cellulose with a nanometer size in a certain dimension [71] and mainly includes cellulose nanocrystals (CNCs), cellulose nanofibers (CNFs), and bacterial cellulose (BC). In addition to the properties of natural cellulose, nanocellulose has excellent mechanical properties, large specific surface area, low density, good biocompatibility, natural degradation, and other excellent properties [72][73][74], and it can be used as friction materials in the TENG. Nanocellulose's high specific surface area, high crystallinity, and excellent mechanical properties enable it to capture more frictional charge, significantly improve the charge density and output performance of the TENG, and improve the mechanical stability and durability of the TENG. ...
The progression of wearable technology has revealed that cellulose-based triboelectric nanogenerators (TENG) possess considerable promise in self-powered micro-sensing technology; this is attributed to their superior biocompatibility, sustainability, and mechanical characteristics. This paper aims to explore the application of the cellulose-based TENG self-powered micro-sensing technology in wearable systems for human health monitoring. First, the working principles and modes of TENG are summarized, along with the characteristics of the cellulose, nanocellulose, cellulose derivatives and the advantages of the cellulose-based TENG. Next, we discuss in detail the applications of the cellulose-based TENG in monitoring physiological parameters, such as heart rate, motion, respiration, and pulse, and we analyze their advantages and challenges in practical applications. Additionally, we explore the integration of the cellulose-based TENG human–machine interaction sensors in health monitoring devices. Finally, we outline the current challenges and future research directions in this field, including the enhancement of triboelectric performance, adaptability to diverse environments, controllable degradability, and multi-scenario real-world applications. This review provides a comprehensive perspective on the application of the cellulose-based TENG self-powered micro-sensing technology in wearable health monitoring systems and offers guidance for future research and development.
... Highly durable, lightweight, and degradable celluloses, which are the most abundant organic compounds in nature, have recently attracted considerable attention as eco-friendly and renewable biomaterials owing to their thermal stability, robustness, and low weight. [1][2][3][4] Chitosan, primarily derived from marine products, is the second most abundant biomass after cellulose and has a structure similar to that of cellulose. 5,6 Biodegradable chitosan has gained significant interest owing to its remarkable properties, 7 including filtration capabilities. ...
In this study, the electrical conducting properties of six types of biomaterials, comprising cellulose and chitosan derived from terrestrial plants and marine products, respectively, were investigated using electron spin resonance (ESR) and Schottky junction characteristics. Kenaf, chitosan, conifer, and RCH2OH (R = C11H17O9) exhibited ESR spectra showing unpaired electrons at 295 K, demonstrating rectifying effects at room temperature. In contrast, RCOONa (C12H17O11Na) and α-chitin, which did not exhibit observable ESR spectra, showed ohmic conduction behavior. The ESR g value was used to determine the organic radical species, suggesting that electrons originate from the glycosidic C1–O1•–C4 radical in cellulose and the aminyl N•–H radical in chitosan. RCOONa and α-chitin, which possess C=O bonds, suppress electron-induced effects and consequently inhibit the transport of free radicals, resulting in ohmic conduction.
... Nanocellulose is a natural compound taken out via several extraction methods from the lignocellulosic biomass and because of its environment-friendly characteristics and maintaining environmental sustainability; it can be utilized in various industrial sectors which may include biomedical and pharmaceutical, where they serve an important role in wound dressing and grafting purposes, also it has been used in drug delivery systems as it helps stabilizing the drugs; cosmeceutical, food industries, and packaging sectors, where they function in maintaining the stability of food and also used in its packaging. Moreover, it has been found to be involved in the synthesis of supercapacitors and polymer matrices (Abitbol, T. et al. 2016;. At present, lignocellulosic biomass, specially obtained from agrobased sectors has been gaining more recognition, even for obtaining nanocelluloses, because of their great availability, low price, and ecofriendly nature. ...
Lignocellulolytic Enzymes: Potential Biocatalysts to Pre-Treat Lignocellulosic Biomass for Its Biotechnological and Industrial Applications
Manisha Malhotra, Karishma Mittal, Vikas Kumar Yadav et al.
† Corresponding Author’s Email: akhilesh.kumar@bhu.ac.in.
Lignocellulosic biomass, otherwise considered waste from agricultural
and forest areas, has found its potential application in various sectors
such as biomedical, cosmeceutical, pharmaceutical sectors, etc.
Moreover, they can be utilized to produce bioplastic and can be used as
a sustainable alternative for energy production. However, the lignin
content present in the lignocellulosic biomass poses a hindrance in its
complete utilization. Therefore, to delignify the lignocellulosic biomass,
traditionally, various physical and chemical pre-treatment methods have
been introduced, which again are not only expensive but also prove to be
hazardous for the environment as the chemical treatment of the
lignocellulosic biomass may result in harmful end products. Hence, to
eliminate these problems, research has now been focused on utilizing
biological methods to delignify and detoxify the lignocellulosic biomass
which includes various lignocellulosic enzymes such as laccase, lignin
peroxidase, manganese peroxidase, and versatile peroxidase for its pretreatment. This chapter, therefore, aims to summarize the introduction of various lignocellulosic enzymes and their potential role in the pretreatment of the lignocellulosic biomass, in order to make the biomass applicable for various biotechnological and industrial applications as well as for the production of bioethanol.
... Nanocellulose is a natural compound taken out via several extraction methods from the lignocellulosic biomass and because of its environment-friendly characteristics and maintaining environmental sustainability; it can be utilized in various industrial sectors which may include biomedical and pharmaceutical, where they serve an important role in wound dressing and grafting purposes, also it has been used in drug delivery systems as it helps stabilizing the drugs; cosmeceutical, food industries, and packaging sectors, where they function in maintaining the stability of food and also used in its packaging. Moreover, it has been found to be involved in the synthesis of supercapacitors and polymer matrices (Abitbol, T. et al. 2016;. At present, lignocellulosic biomass, specially obtained from agrobased sectors has been gaining more recognition, even for obtaining nanocelluloses, because of their great availability, low price, and ecofriendly nature. ...
... Consequently, the preparation process is relatively straightforward and can be accomplished with minimal effort through the use of mild treatment [6]. Additionally, BC possesses exceptional physicochemical properties, such as high crystallinity, high specific surface area, high elasticity, relatively high mechanical strength in the wet state, hydrophilicity, and excellent biocompatibility [7,8]. These distinctive characteristics render BC an appealing proposition from a technological, ecological, and financial standpoint. ...
Bacterial cellulose (BC) is a subject of interest for researchers due to its advantageous characteristics, including a straightforward manufacturing process, biocompatibility, and extensive modification potential. The hydrophilic nature of the material is beneficial in some applications, yet a limiting factor in others. This study aimed to develop BC-based materials with goFogureod moisture resistance. The modification of bacterial cellulose (BC) using apple powder, stearic acid, or a combination of these modifiers resulted in the formation of a range of materials, some of which had their surfaces additionally functionalised by coating with a mixture of apple powder and stearic acid (HSt). The nature and type of changes were confirmed by FTIR and theoretical analysis, which was conducted by modelling the interaction between cellulose and homogalacturonan or rhamnogalacturonan using SCIGRESS v.FJ 2.7 software. Changes in hydrogen bonding resulting in a weakening of the interactions between cellulose and water in the presence of pectin were demonstrated by both empirical data and modelling. The effectiveness of BC functionalisation was confirmed by material wettability. The water contact angle changed from 38° for the unmodified material to 125° for the material obtained by modification of the bacterial cellulose with glycerol followed by modification with a mixture of HSt at a concentration of 10% and AP at a concentration of 60%. The modifications produced a material with a robust hydrophobic surface. The results suggest that the surface roughness may not be the primary factor influencing the hydrophilicity or hydrophobicity of these materials but that it is more likely to be related to the interactions of components. None of the tested materials demonstrated antimicrobial activity against Escherichia coli, Bacillus subtilis, Staphylococcus aureus, Aspergillus niger, or Candida albicans.
... C. A. Maestri (a) , M. Abrami (b) , S. Hazan (c) , E. Chistè (a) , Y. Golan (c,d) , J. Rohrer (e) , A. Bernkop-Schnürch (e) , M. Grassi (b) , M. Scarpa (a) INTRODUCTION Nanocellulose (NC) is a renewable and biocompatible material with interesting and versatile properties which allow its integration in a huge number of applications, as has been extensively reviewed [1,2]. The procedures to break natural cellulose and obtain nano-sized structures are usually based on the combination of chemical modification or enzymatic hydrolysis with mechanical refinement [3,4]. ...
Sol-gel transition of carboxylated cellulose nanocrystals is investigated using rheology, SAXS, NMR and optical spectroscopies to unveil the distinctive roles of ultrasounds treatment and ions addition. Besides cellulose fibers fragmentation, sonication treatment induces fast gelling of the solution. Gelation is induced independently on the addition of cations, while the final rheological properties are highly influenced by the type, the concentration as well as on the sequence of the operations since salts must be added before sonication to produce stiff gels. Cations with various charge and dimension have been associated to ultrasounds to induce gelation and the gel elastic modulus increase proportionally with the charge over the ion size ratio. SAXS analysis of the Na+ hydrogel and Ca2+ hydrogel to which the ion was added after sonication shows the presence of structurally ordered domains where water is confined as indicated by 1H-NMR investigation of the dynamic of water exchange in the hydrogels. Conversely, separated phases containing essentially free water, characterize the hydrogels obtained by sonication after Ca2+ addition, confirming that this ion induces irreversible fiber aggregation. The rheological properties of the hydrogels depend on the duration of the ultrasound treatment and it enables the design of materials programmed with tailored energy dissipation response.
... Bacterial cellulose (BC) is a highly researched biopolymer due to its desirable properties, including high mechanical strength, chemical stability, and biocompatibility. It also exhibits high surface area, hydrophilicity, transparency, crystallinity, magnetic and electric susceptibility, proton conductivity, and rich surface chemistry (Abitbol et al. 2016). These properties make BC interesting for various applications in multiple domains. ...
Living organisms are constantly exposed to cosmic, terrestrial, and internal sources of radiation. As a result, they have developed natural radioprotective mechanisms. However, in some cases, these mechanisms may not be sufficient. Elevated doses and prolonged exposure to radiation, such as during radiotherapy or in extreme environments like spaceflight, can cause damage to DNA and increase the abundance of reactive oxygen species, which can affect biological processes. In contrast to synthetic ingredients, naturally produced radioprotective materials have good biocompatibility and are easy to recycle. This work investigates the radioprotective properties of the hydrogel biofilm produced by the kombucha microbial consortium. The shielding properties of kombucha’s bacterial cellulose (KBC) were examined using gamma quanta with energies ranging from 122 to 1408 keV and an AmBe neutron source. The native form of KBC contains more than 80% water content. To enhance the radioprotection of kombucha’s biofilm, metallic components (K, Fe, Mxenes) and biological additives were tested. Rhodobacter sphaeroides and Synechocystis sp. PCC6803, which are resistant to oxidative stress, were added to the cultivation media. Physical properties were characterized using microscopy, ion leaching, and contact angle measurements. Post-processed dried KBC wristbands were analyzed for absorption parameters to enhance protective shielding. Possible levels of radioprotection for various types of bacterial cellulose thickness and forms were computed based on the obtained results. The findings encourage the use of bacterial cellulose in a circular economy for future bioregenerative systems.
... Nanocellulose films possess remarkable mechanical properties, including high tensile strength, stiffness, and flexibility. The intrinsic strength of cellulose, combined with the alignment of nanocellulose entities, contributes to their outstanding mechanical performance (Abitbol et al., 2016). These properties make nanocellulose films suitable for applications where mechanical stability is crucial, such as in flexible electronics and wearable sensors (Horta-Velázquez & Morales-Narváez, 2022). ...
Nanocellulose derived from biomass is a sustainable, lightweight, and mechanically strong material. Extensive research has been directed towards applying nanocellulose for advanced applications. Nanocellulose-based films are novel and unique for designing functional materials considering their combination of sustainability with new properties. Nanocellulose films can be fabricated through simple strategies and make it easy to access various applications, such as barriers, sensors, energy storage, and so on. In this chapter, we summarized the preparation methods of nanocellulose-based films while focusing on nanocellulose as the film matrix and highlighting some representative applications. Given the sustainability of the nanocellulose and ease of introducing functional groups, we believe that nanocellulose-based films promise great potential for future advanced applications.
... [27] Common approaches to enhance the packaging properties of CNF include single or multi-layer coating, blending, grafting functional compounds onto the surface of CNF films, and chemical functionalization of the surface. [27][28][29][30][31][32][33][34][35][36] Herein, we propose a green pathway toward synthesizing a novel renewable photo-responsive functional coating based on diglycerol, used as a tetra-functional linker, and lignin-derivable aldehyde vanillin, two non-toxic bio-based compounds. The UVcrosslinkable functional molecule was coated over cellulose nanofiber (CNF) films [ Figure 1]. ...
Paper‐based packaging can offer a sustainable replacement for plastics. However, paper provides a poor barrier to water, oxygen and moisture. This study presents a novel renewable lignocellulosic composite made from a hydrophobic photo‐reversible coating deposited onto a cellulose nanofiber film that has improved barrier properties and can be reprocessed. Diglycerol and lignin‐derivable aldehyde were reacted to form a tetra‐functional monomer with photo‐responsive unsaturated double bonds that can be converted to covalent cyclobutane rings to create reversibly crosslinkable network upon UV‐irradiation. The photo‐responsive compound was applied as a thin coating of thickness 2.7±0.4 μm over cellulose nanofiber (CNF) films of thickness 80±19 μm. The surface of the coated films became hydrophobic with a contact angle (CA) of 93.1±1.7° and displayed a low water vapour transmission rate (WVTR) of 16±2 g/m²/day vs. 30.7±1.5° CA and 81±11 g/m²/day WVTR for uncoated CNF films. The coated film is also oleophobic, an attractive feature for food packaging applications. The reversible photo‐reaction enables the crosslinked covalent network to be broken down to unsaturated double bonds once exposed to a higher‐energy UV irradiation, allowing reprocessing and recycling. The novel coating was developed using a sustainable green synthesis method (process simple E factor 0.9).
... Nanocellulose is referred to as cellulose in its nanostructured nature. Nanocellulose is of expanding enthusiasm for a scope of uses that are significant to the fields of material science and biomedical designing because of its renewable nature, anisotropic shape, tailorable surface science, fabulous mechanical properties, great biocompatibility, and fascinating optical properties (Abitbol, 2016;Evyan et al., 2017). Nanocellulose is extended from cellulose chains that are bundled together in a highly ordered region which can be later isolated as nano-particles with high specific surface area (Foster et al., 2018). ...
The most common scenario in agriculture and food manufacturing is they utilize the fruit or stem of the plants but discard the leaves by open burning or disposing them into the river which causes water and air pollution. Nanocellulose fabricated from abundant agricultural waste could be one of the alternative solutions to overcome environmental pollution. In this study, nanocellulose was extracted from the dried leaves of Cocos nucifera (Coconut). The process was carried out using formic acid, peroxy formic acid and sodium hypochlorite bleaching. The interaction of three independent variables was studied during the formic acid pulping stage. The optimum condition for the formic acid pulping was set by 85% concentration of formic acid and incubation in the water bath at 70℃ for 1 hr. This study showed a simple and inexpensive method to extract nanocellulose. The products provided insight into the kinetic model of nanocellulose and the potential usages of nanocellulose as substitutes for renewable sources of energy and applications in various fields.
The growing demand for sustainable and eco-friendly energy storage technologies has spurred extensive research into novel materials for batteries. This review investigates alternatives to traditional batteries that use synthetic polymers, such as polyethylene oxide (PEO), polyvinylidene fluoride (PVDF), and polypropylene (PP), which often involve hazardous materials and significant environmental impact. It focuses on cellulose, a biopolymer derived from renewable sources, and its derivative, nanocellulose, as promising, eco-friendly alternatives for various battery components. Cellulose, a biopolymer derived from renewable sources, has emerged as a promising candidate due to its abundant availability, low cost, and inherent eco-friendliness. Cellulose is greatly used in development of polymer electrolyte, anode, and cathode materials, acts as binder or additives and as a separator. These uses are discussed, showcasing their electrochemical performance, capacity retention, and rate capability. Nanocellulose, with its nanoscale porosity and mechanical stability, is shown to be a promising separator material, enhancing ion transport, and improving battery cyclability. Moreover, potential modifications and optimization strategies to improve battery performance have been discussed. Despite their potential advantages, cellulose-based batteries are still in the research and development stage. Several challenges must be addressed, including manufacturing scalability, optimizing energy density, and achieving high power outputs. However, ongoing research and advancements in polymer electrolyte materials bring us closer to commercialising these promising battery technologies. Cellulose-based batteries offer reduced environmental impact throughout their life cycle, from sourcing to disposal, contributing to a greener and more circular economy. In conclusion, cellulose-based batteries demonstrate great promise as an environmentally friendly and sustainable energy storage solution. This review aims to provide concise and insightful information on cellulose’s application in different components of batteries, showcasing its potential to transform the energy storage landscape and contribute to a cleaner and more sustainable future.
Plant fibers (PFs) have been increasingly employed in cement-based gel composites (CCs) on account of their excellent mechanical properties, toughness and sustainability. Researchers have engaged in a lot of studies on plant fiber-reinforced cement-based gel composites (PFRCCs). Based on these studies, the chemical components and mechanical characteristics of PFs are summed up in this review. In addition, the modification methods for matrices and PFs are also discussed. The mechanical properties of PFRCCs, including static and dynamic properties, are reviewed. Predictive equations for the mechanical properties of PFRCCs are summarized in this paper. In the end, the characteristics of the interface transition zones between PFs and CCs are analyzed. According to the results of previous studies, the addition of PFs can enhance the flexural strength and tensile strength of CCs, but it can have an uncertain effect on compressive strength. The elastic modulus and fracture behavior of PFRCCs increases with the addition of PFs. At the same time, modification methods have been proved to be useful in reducing the degradation of PFs in CCs. Generally speaking, PFRCCs are new building materials which have extensive application prospects. The aim of this review is to help researchers understand the mechanical properties of PFRCCs and to promote the application of PFRCCs in future projects.
Nanocellulose (NC) extraction from agricultural waste and lignocellulosic biomass residues has drawn considerable interest due to its low cost and wide availability. The environmental issues linked to nonrenewable materials have underscored the need for renewable alternatives that are biocompatible, biodegradable, and eco‐friendly. This study aimed to investigate the potential of Ethiopian highland bamboo Arundinaria alpina for NC extraction by using acid hydrolysis. An experimental design incorporating response surface methodology (RSM) was applied to identify the optimal hydrolysis process parameters for NC extraction. The optimum conditions for NC extraction were a reaction time of 60 min, temperature of 40°C, and acid concentration of 61.40 wt%, with a yield of 43.15%. Bamboo and extracted NC were characterized for their chemical composition, particle size distribution, and crystallinity, using Fourier‐transform infrared spectroscopy (FTIR), dynamic light scattering (DLS), and X‐ray diffraction (XRD), respectively. The resulting NC had a particle size of 79.64 nm. XRD analysis revealed the crystallinity indices of the bamboo and its corresponding NC was 44.60% and 74.07%, respectively. These results indicate that highland bamboo A. alpina is a promising lignocellulosic source for sustainable NC extraction, optimization, and industrial applications.
This chapter offers an extensive review of polymer-based microneedles (MNs) as an important technique for transdermal drug delivery systems (TDDS). Polymer MNs, produced from biocompatible, biodegradable, and/or synthetic polymers, have numerous benefits in TDDS, such as facile manufacture, customizable drug release profiles, and reduced invasiveness. MNs could efficiently penetrate tissues, preserving continuous contact without injury while generating a strong adhesive force. The design concepts and materials choice for polymer-based MNs emphasize the characteristics of frequently utilized polymers, including poly(lactic-co-glycolic acid) (PLGA), polyvinyl alcohol (PVA), cellulose, carboxymethyl cellulose and hydrogel-based materials. Cellulose has garnered considerable attention in the production of MNs due to its distinctive qualities, such as high mechanical strength, low cost, and ease of fabrication. These polymers can be customized for several therapeutic uses, facilitating the efficient delivery of various drugs, from small organic molecules to large biomacromolecules. The study also addresses MNs production techniques like micro-molding, drawing lithography, 3D printing, and solvent casting, as well as the mechanical and drug-delivery efficiency properties of polymer MNs, such as insertion ability and skin penetration. Finally, it evaluates the use of cellulose/organic polymer-based MNs in a variety of therapies, such as vaccinations, drug/protein delivery, and pain management. This chapter highlights the promise of polymer-based MNs for TDDS by breaking down existing barriers and providing a less intrusive alternative to injection-based therapy.
With a tremendous progress observed over the last decade, nanoscience already has become a frontier of technology by enabling almost endless possibilities in many fields. It creates the opportunity to work on a matter representing near-atomic scale in order to invent the novel, so far unknown solutions. Due to the fact that some of these discoveries are implemented into a development of innovative, high-performance materials, this field can be considered as an indicator of the progress in modern times. Nanotechnology offers the strong potential also for a wood industry sector which might lead to numerous advances in, for example, wood-based materials manufacturing. As indicated by the indexes of consumption of wood-containing composites around the world, it is a dynamically developing branch of industry. Therefore, it attracts a lot of attention of scientists who are still looking for innovative ways to improve these materials. Nanoparticles owe their reinforcing nature to a number of excellent properties such as, for example, tremendous surface area and high thermal conductivity which are rather rare in the case of their bulk counterparts. This is why they were found to effectively improve characteristics of wood-based composites bonded with synthetic or natural adhesives. It is particularly important because the implementation of such modifications may contribute to the extension of their use. Therefore, the purpose of this chapter is to sum up the current knowledge on the potential of nanomaterials such as mineral nanoparticles, nano-oxides, nano-silver, carbon-based nanoparticles, nanocellulose, and nanolignin in the enhancement of both strength and water-related properties of wood-based materials bonded with synthetic and bio-based adhesives (based on starch, tannins, and lignin).
Agriculture, as a cornerstone of global food security, faces the intricate challenge of feeding a growing population while mitigating its environmental footprint. The expanding global population and food demands have led to an enormous increase in agro-industrial operations and products with a concomitant increase in non-consumable biomass—agro-industrial wastes. These wastes are largely left untreated resulting in environmental degradation and economic losses. Owing to their biochemical heterogeneity and presence of vital bioactive compounds like carbohydrates, proteins, and minerals, these can be used as feedstock for biorefinery for generation of a diversified variety of products including composts, organic fertilizers, and biochar, to name a few. With the advent of new techniques, the valorization of agro-industrial wastes as environment-friendly and sustainable tools for addressing the problems about conventional agricultural practices has grown tremendously. In recent decades, green nanotechnology has emerged as an acceptable approach for utilizing agro-industrial wastes to synthesize nanomaterials with excellent surface properties and biocompatibility which include, but are not limited to, nanoparticles and nanocomposites. This chapter focuses on examining and characterizing agro-industrial wastes as potential resources for generating cost-effective value-added nanomaterials, along with nano-management of agro-waste to improve the agricultural output. Furthermore, an assemblage of the approaches adopted for synthesis of various nanoparticles, along with the possible applications is put forth.
Mesenchymal stem cells (MSCs) have emerged as a promising therapeutic tool in stem cell-based therapy due to their immunomodulatory or regenerative characteristics. Nowadays, controlled application of nonpathogenic bacterial cells and their derivatives has shown promise in preconditioning and manipulating MSC behavior. This approach is being explored in various fields, including immunotherapy, tissue engineering, and cell therapy. However, recent discoveries have elucidated the complex interactions between MSCs and microorganisms, especially bacteria and viruses, raising concerns regarding the utility of MSCs in clinical applications. In this review, we discussed the interactions between MSCs and microorganisms and highlighted both positive and negative aspects. We also examined the use of bacterial-derived compounds in MSCs-mediated interventions. The balanced colonization of the microbiome in organs, such as the oral cavity, not only does not hinder therapeutic interventions but also could be crucial for achieving desirable outcomes. On the contrary, disturbances in the microbiome have been found to disturb the biological potential of MSCs, such as migration, osteogenic differentiation, and cell proliferation. Evidence also suggests that commensal bacteria, following certain interventions, can transition to a pathogenic state when interacting with MSCs, leading to acute inflammation. Indeed, the maintenance of homeostasis through various approaches, such as probiotic application, results in an optimal equilibrium during MSCs-based therapies. However, further investigation into this matter is imperative to identify efficacious interventions.
Hydroponics is an advanced agricultural technique that involves growing plants without soil. Instead, plants are cultivated in a nutrient-rich water solution that provides all the essential minerals they need to thrive, allowing plants to grow either with their roots directly in the solution or supported by inert substrates like pine bark, coconut husk fiber, and rice husk. The solid waste generated from hydroponic cultivation is valuable due to its low cost, abundance, biodegradability, and renewability. These residues are rich in lignocellulosic materials, which can be extracted and refined to produce cellulose and nanocellulose (NC). In this work, cellulose and nanocellulose were extracted from residues of coconut husk fiber and a mixture of pine bark and coconut husk fiber, used in tomato and strawberry hydroponics, respectively. The residues were ground, washed, and chemically treated to obtain cellulose and NC. The chemical process involved several stages: (i) acid treatment, alkaline treatment, and bleaching to isolate cellulose, and (ii) acid hydrolysis followed by ultrasonication to obtain NC. Both materials underwent characterization using various techniques such as TGA, DSC, XRD and FTIR-ATR, which confirmed very low levels of lignin and hemicellulose. Morphological characterization through SEM revealed the presence of micro- and nano-crystals in the cellulose and NC samples, respectively, highlighting the effectiveness of the extraction method. The high purity and quality of the extracted materials make them competitive with commercially available products, suitable for applications in healthcare, food packaging, and automotive industries, while supporting recycling and reuse principles.
Abstract
Biodegradability, biocompatibility, non-toxicity, eco-friendly, and renewability make biopolymers as excellent and safe fillers for biopolymer matrices to fabricate nano-composites. However, most of biopolymers are hydrophilic and possess inadequate mechanical properties, thus uses of biopolymers in food coating and packaging are limited. There is a particular solution as follows: some particular biopolymers (cellulose, chitin, and starch) are good candidates as fillers to improve oxygen, moisture, and gas barrier and mechanical properties of hydrophilic natural polymers as continuous phases. Literature reports have shown that the above-mentioned biopolymers and their derivatives as nano-fillers improved mechanical and barrier properties of hydrophilic biopolymer matrices. The following conclusions were derived from some literature reports; (i) the advantages of bio-nanocomposites made from bio-fillers and biopolymers matrices over other bio-nanocomposites are: these nanomaterials are 100% biodegradable and recyclable, i.e., both continuous and discontinuous phases (matrix and filler) are safe for human and environment. The resulting nanocomposites are green nanomaterials; (ii) nano-bio-fillers have potential to improve gas and WVB properties of biomacromolecule continuous phases; (iii) use of nano-bio-fillers reduces cost for fabrication of desirable nanocomposites and reduce dependency to other types of fillers such as metal oxides; and (iv) use of nano-bio-fillers and biopolymer matrices in food packaging systems will certainly protect food from deterioration attacks, prolong shelf-life of food, and maintain the quality and safety of foodstuffs.
This chapter explores the transformative potential of cellulosic nanomaterials in addressing global challenges and advancing sustainable development. As our planet faces interconnected crises of climate change, resource depletion, pollution, and public health, traditional materials and technologies are proving inadequate. Cellulosic nanomaterials, derived from the most abundant biopolymer on Earth, offer a promising solution. The chapter delves into the unique properties of cellulosic nanomaterials, including cellulose nanocrystals (CNCs) and cellulose nanofibrils (CNFs), highlighting their exceptional strength, biocompatibility, and renewability. It examines how manipulation at the nanoscale unlocks extraordinary functionalities, enabling innovations across various sectors such as advanced materials, energy storage, sustainable chemical processes, healthcare, and environmental monitoring. The text emphasizes the role of cellulosic nanomaterials in creating a more sustainable future, offering alternatives to petroleum-based products, and addressing critical global issues. While acknowledging the challenges in production, integration, and environmental impact assessment, the chapter underscores the rapid advancements in research and development aimed at overcoming these hurdles. By providing an in-depth exploration of cellulosic nanomaterials’ properties, production methods, and applications, this chapter aims to accelerate their development and deployment. It presents a vision of a greener, more sustainable future enabled by these innovative materials, positioning them as key players in the transition towards a more resilient and environmentally conscious society. At the outset, this compilation demonstrates how cellulosic nanomaterials contribute to achieving UN’s SDGs 3, 6, 7, 9, 12, 13, and 15, offering innovative solutions for health, clean water, renewable energy, sustainable industry, responsible consumption, climate action, and environmental protection.
Cellulose nanocrystal (CNC) is one of the most important biomass-derived materials for reinforcing hydrogels. Nevertheless, there is a lack of comparative studies examining the impact of CNC synthesized via disparate methodologies on the toughening of hydrogels. This study synthesized two different CNCs through the sulfate hydrolysis and deep eutectic solvent (DES) synthesis methods from Gleditsia sinensis peel, a forest residue, and compared their effects on the enhancement of the mechanical properties of SA/PAAM hydrogels. The comprehensive characterizations demonstrated that the mechanical properties of hydrogels derived from DES-CNC are superior to those derived from S-CNC. The DES-CNC/SA/PAAM hydrogels revealed a homogeneous structure with excellent strain (2534%), high transparency (90%), and self-adhesiveness (15 kPa). The flexible sensor assembled using hydrogels exhibited accurate real-time monitoring capabilities for minor and larger strains during movement. To investigate the enhancement mechanism of CNCs on hydrogels, this work evaluated weak interaction forces between DES-CNC/SA/PAAM components through the quantum chemical theoretical calculations, with the combination of wave function analysis method and Molecular dynamics (MD) simulation. This work provides comparative tests of forestry biomass sources in hydrogel synthesis and sensing applications and suggests a new idea for high-value utilization of biomass feedstocks.
Cellulose from macroalgae is potential for the extraction of nanomaterials due to its availability and its great fraction in the biomass. Cladophora rupestris is a macroalgae and is a good material to which a cellulose may be extracted. The said macroalgae has no value-added products or uses yet. It has a lignocellulosic profile of: alpha-cellulose, 33.43 %; hemicellulose, 15.48%; holocellulose, 48.93; acid soluble lignin, 2.22%; acid insoluble lignin, 22.33%, extractives, 5.67% and total ash, 39.65%. Identifying the best method and conditions for the extraction of cellulose from the said material is a challenge that needs to be addressed. The process for the cellulose extraction considered variations on drying (oven, air, and sun drying), defatting (using solvents: methanol and hexane; and extraction time: 8 hrs and 4 days), solvent drying (oven and air drying), alkaline pre-treatment (0.1, 0.5, and 1M NaOH), fixed conditions on bleaching, bleached biomass oven drying. The biomass weight losses were monitored for some steps, attributing this on the removal of the lignin and extractives. The lignocellulosic profile of the crude cellulose extracted from the macroalgae using the best conditions was determined indicating an increased fraction of the cellulose components in the biomass and a transformation of the rigid biomass into a soft and paper-like texture. The functional groups present on the cellulose was determined. The extracted cellulose was used to produced cellulose nanofibril (CNF) with fiber diameter of the CNF ranges on 14.29 – 37.50 nm and crystallinity index of 92.48%. Attempts were done on extraction of cellulose nanocrystal (CNC) utilizing microwave-assisted acid hydrolysis (MAAH) and semi-batch acid hydrolysis (SBAH); and variation on the acid used (sulfuric acid, and oxalic acid), concentration of the acid, and the temperature conditions.
Cellulose nanocrystals (CNCs) are renewable, sustainable nanomaterials, typically produced by strong sulfuric acid hydrolysis of lignocellu-losic biomass. CNCs can self-assemble in aqueous, and other, suspensions at a critical concentration, or under evaporation, into chiral nematic organization to exhibit anisotropic structural color. The degree of sulfation is critical for producing both stable colloidal suspensions and iridescent films by evaporation-induced self-assembly. CNCs also possess electromagnetic and piezoelectric properties, as well as active surface groups that render them suitable for tailored functionalization. This chapter presents a framework of how CNCs can be used to (i) template in/organic mesoporous photonic and electronic materials and structures, and (ii) develop sustainable, flexible electronics. Using a novel supramolecular co-templating approach, the first example of functional, mesoporous, photonic cellulose films, or nanopaper, has been produced. The CNC-templating approach is a scalable, effective tool for imparting long-range chirality in a number of distinct materials (polymer, silica, metal oxides, carbon) with promising applications in, for example, optoelectronics, biosensors, actuators, functional membranes, 3D printing, and tissue engineering.
Cellulose nanocrystals (CNCs) are rod-shaped colloids that have inherent liquid crystalline properties and form chiral nematic phases under certain conditions. Here, we discuss the factors that influence chiral nematic phase formation and the parameters that modulate pitch, such as aspect ratio, ionic strength, sonication energy, and temperature. We describe how the orientation of CNCs in suspension can be preserved in solid films. Emphasis is placed on the techniques used to characterize chiral nematic CNC suspensions and films, and on the applications of these liquid crystals, including as iridescent pigments, alignment media for protein NMR, and templates for mesoporous carbon, silica, and hydrogel materials.
All-cellulose nanocomposite films containing crystalline TEMPO-oxidized cellulose nanofibrils (TOCNs) of 0-1 wt% were fabricated by mixing aqueous TOCN dispersions with alkali/urea/cellulose (AUC) solutions at room temperature. The mixtures were cast on glass plates, soaked in an acid solution, and the regenerated gel-like films were washed with water and then dried. The TOCN did not form agglomerates in the composites, and had the structure of TOCN-COOH, forming hydrogen bonds with the hydroxyl groups of the regenerated cellulose molecules. X-ray diffraction analysis revealed that the matrix cellulose molecules increased the cellulose II crystal size upon incorporation of TOCN. As a result, the TOCN/AUC composite films had high Young's modulus, tensile strength, thermal stability and oxygen-barrier properties. The TOCN/AUC composite films are promising all-cellulose nanocomposites for versatile applications as new bio-based materials.
Proliferation, integration, and neurite extension of PC12 cells, a widely used culture model for cholinergic neurons, were studied in nanocellulose scaffolds biosynthesized by Gluconacetobacter xylinus to allow a three-dimensional (3D) extension of neurites better mimicking neuronal networks in tissue. The interaction with control scaffolds was compared with cationized nanocellulose (trimethyl ammonium betahydroxy propyl [TMAHP] cellulose) to investigate the impact of surface charges on the cell interaction mechanisms. Furthermore, coatings with extracellular matrix proteins (collagen, fibronectin, and laminin) were investigated to determine the importance of integrin-mediated cell attachment. Cell proliferation was evaluated by a cellular proliferation assay, while cell integration and neurite propagation were studied by simultaneous label-free Coherent anti-Stokes Raman Scattering and second harmonic generation microscopy, providing 3D images of PC12 cells and arrangement of nanocellulose fibrils, respectively. Cell attachment and proliferation were enhanced by TMAHP modification, but not by protein coating. Protein coating instead promoted active interaction between the cells and the scaffold, hence lateral cell migration and integration. Irrespective of surface modification, deepest cell integration measured was one to two cell layers, whereas neurites have a capacity to integrate deeper than the cell bodies in the scaffold due to their fine dimensions and amoeba-like migration pattern. Neurites with lengths of >50 μm were observed, successfully connecting individual cells and cell clusters. In conclusion, TMAHP-modified nanocellulose scaffolds promote initial cellular scaffold adhesion, which combined with additional cell-scaffold treatments enables further formation of 3D neuronal networks.
Molecular biomimetic models suggest that proteins in the soft matrix of nanocomposites have a multimodular architecture. Engineered proteins were used together with nanofibrillated cellulose (NFC) to show how this type of architecture leads to function. The proteins consist of two cellulose-binding modules (CBM) separated by 12-, 24-, or 48-mer linkers. Engineering the linkers has a considerable effects on the interaction between protein and NFC in both wet colloidal state and a dry film. The protein optionally incorporates a multimerizing hydrophobin (HFB) domain connected by another linker. The modular structure explains effects in the hydrated gel state, as well as the deformation of composite materials through stress distribution and crosslinking. Based on this work, strategies can be suggested for tuning the mechanical properties of materials through the coupling of protein modules and their interlinking architectures.
© 2015 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA. This is an open access article under the terms of the Creative Commons Attribution Non-Commercial NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.
Cellulose nanocrystals were grafted with imidazole functionalities up to DS 0.06 using a one-pot functionalization strategy. The resulting nanocrystals were shown to have a pH responsive surface charge which was found to be positive below pH 6 and negative above pH 7. These imidazolyl cellulose nanocrystals were tested for flocculation of Chlorella vulgaris using CO2 to induce flocculation. Up to 90 % flocculation efficiency was achieved with 200 mg L−1 dose. Furthermore, the modified cellulose nanocrystals showed good compatibility with the microalgae during cultivation, giving potential for the production of reversible flocculation systems.
Bacterial cellulose (BC) and silk fibroin (SF) are natural biopolymers successfully applied in tissue engineering and biomedical fields. In this work nanocomposites based on BC and SF were prepared and characterized by scanning electron microscopy (SEM), infrared spectroscopy (FT-IR), X-ray diffraction (XRD) and thermogravimetric analysis (TGA). In addition, the investigation of cytocompatibility was done by MTT, XTT and Trypan Blue dye technique. Cellular adhesion and proliferation were detected additionally. The evaluation of genotoxicity was realized by micronucleus assay. In vitro tests showed that the material is non-cytotoxic or genotoxic. SEM images revealed a greater number of cells attached at the BC/SF:50% scaffold surface than the pure BC one, suggesting that the presence of fibroin improved cell attachment. This could be related to the SF amino acid sequence that acts as cell receptors facilitating cell adhesion and growth. Consequently, BC/SF:50% scaffolds configured an excellent option in bioengineering depicting its potential for tissue regeneration and cultivation of cells on nanocomposites.
Copyright © 2015 Elsevier Ltd. All rights reserved.
In this work, adsorption of a neutral flexible polysaccharide, xyloglucan (XG), onto thin cellulose nanocrystals (CNC) surfaces has been investigated to get more insight into the CNC-XG association. Gold-coated quartz crystals were spin-coated with one layer of CNC, and XG adsorption was monitored in situ by quartz crystal microbalance with dissipation (QCM-D). The adsorption of XG under flow at different concentrations did not result in the same surface concentration, which evidenced a kinetically-controlled process. In an attempt to describe the binding of XG to CNC, adsorption data were fitted to a kinetic model comprising a contribution from XG adsorption onto uncovered CNC surfaces and a contribution from XG adsorption after rearrangement. Kinetic studies evidenced the presence of two adsorption regimes as a function of XG concentration. For low XG concentrations, the kinetic constant for chain rearrangement is comparable to the kinetic constant for adsorption. This fact implies a rearrangement and alignment of XG molecules on CNC. Differently, for higher XG concentrations, the kinetic constant related to the conformational rearrangement decreases, indicating that XG molecules have no time to laterally rearrange before new XG molecules adsorb.
Nanosized composite rods 300 nm in length and 20 nm in width were produced by deposition of 22–77 wt% of a c-axis-oriented hydroxyapatite (HA) on cellulose nanocrystals (CNCs). The CNCs functionalized with sulphonic groups were covered with the HA nanocrystals through controlled nucleation and growth under a moderately supersaturated condition in a solution system based on a simulated body fluid. Water-resistant transparent coatings 2–4 μm thick were obtained via evaporation-induced assembly of CNC–HA nanocomposites by casting their suspension on a glass substrate and the subsequent growth of HA nanocrystals by vapour hydrothermal treatment. The composite coatings exhibited improved mechanical strength compared to that of crustacean exoskeletons, and potential for bone regeneration.
Nanocellulose fibrils are ubiquitous in nature and nanotechnologies but their mesoscopic structural assembly is not yet fully understood. Here we study the structural features of rod-like cellulose nanoparticles on a single particle level, by applying statistical polymer physics concepts on electron and atomic force microscopy images, and we assess their physical properties via quantitative nanomechanical mapping. We show evidence of right-handed chirality, observed on both bundles and on single fibrils. Statistical analysis of contours from microscopy images shows a non-Gaussian kink angle distribution. This is inconsistent with a structure consisting of alternating amorphous and crystalline domains along the contour and supports process-induced kink formation. The intrinsic mechanical properties of nanocellulose are extracted from nanoindentation and persistence length method for transversal and longitudinal directions, respectively. The structural analysis is pushed to the level of single cellulose polymer chains, and their smallest associated unit with a proposed 2 × 2 chain-packing arrangement.
This research explores the properties of bionanocomposite films prepared by binding recombinant resilin-like protein (res) consisting of the exon 1 resilin sequence from Drosophila melanogaster engineered to include a cellulose binding domain (CBD), to cellulose nanocrystals (CNCs). The optimal binding of res-CBD to CNCs was 1:5 by mass, and the resulting res-CBD-CNCs remained colloidally stable in water. Res-CBD-CNCs were solvent cast into transparent, free-standing films, which were more hydrophobic than neat CNC films, with water contact angles of 70-80° compared to 35-40° for the latter. In contrast to the multi-domain orientation typical of chiral nematic CNC films, res-CBD-CNC and CBD-CNC films exhibited long-range, uniaxial orientation that was apparently driven by the CBD moiety. Glycerol was studied as an additive in the films to determine whether the addition of a wet component to solvate the recombinant protein improved the mechanical properties of the res-CBD-CNC films. In comparison to the other films, res-CBD-CNC films were more elastic with added glycerol, demonstrating a range of 0.5-5 wt% (i.e., the films responded more elastically to a given strain and/or were less plastically deformed by a given mechanical load), but became less elastic with added glycerol between 0.5-5 wt%. Overall, films made of res-CBD-CNCs plus 0.5 wt% glycerol displayed improved mechanical properties compared to neat CNC films, and with an increase in toughness of 150% and in elasticity of 100%.
This article surveys progress in both fundamental and applied research related to cellulosic liquid crystals, mainly of chiral nematic order. These liquid crystals are divided into two different classes, namely cellulosic macromolecules and cellulose nanocrystals (CNCs), depending on the mesogenic constituent. We start with a review of the fundamental and chiroptical characteristics of molecular liquid crystals of representative cellulose derivatives and then discuss recent efforts on the design and construction of functional material systems (such as stimuli-sensitive optical media and novel hybrids with minerals). These systems make use of the liquid crystalline molecular assembly of cellulosics. The survey of the other class of cellulosic liquid crystals deals with colloidal suspensions of CNCs obtained by acid hydrolysis of native cellulose fibers. Following the review of fundamental aspects related to the isotropic–anisotropic phase separation behavior of CNC suspensions, attention is directed to current applications of free-standing colored films, polymer composites reinforced with CNCs as mesofiller, and inorganic hybridizations using CNC chiral nematics as template. Some comments and the outlook for future explorations are also offered.
The use of cellulose nanocrystals (CNCs) in optical materials has been extensively studied. Key in most applications reported to date is the chiral nematic ordering of CNCs. Here, we demonstrate that random packing of silicated CNCs can also yield materials with interesting optical properties, i.e., highly porous, ultra-low refractive index coatings. Needle-shaped CNCs with an aspect ratio of 25 were extracted from Avicel, and subsequently covered with a silica layer. In one single dip coating step, highly porous coatings of CNC-silica core-shell particles were deposited on glass slides and silicon wafers. The lowest refractive index achieved was 1.03, which corresponds to a porosity of 94%; the thickness of these coatings ranged from 101 nm to 239 nm. The substrates, coated with a layer of CNC-silica core-shell particles, were heated to 450 °C for two hours. Cellulose was removed through pyrolysis, which resulted in porous coatings of sub-micron sized hollow silica rods. The porosity increase generated through pyrolysis of cellulose, however, was largely compensated by the decrease in packing porosity due to shrinkage of the coating.
Bacterial cellulose (BC) is considered a promising three-dimensional (3D) nanofibrous scaffold for tissue engineering. To further improve its biological behavior, BC scaffold was modified by the creation of macropores and the immobilization of collagen (COL) on the surface. The creation of macropores was performed by laser perforation technique and the immobilization of collagen was achieved by solution immersion and subsequent crosslinking. The asprepared macroporous BC/COL nanocomposite (denoted as mBC/COL) was characterized by SEM, FTIR, contact angle measurement, and dynamic mechanical analysis, and its cell behavior was evaluated by MTT assay. SEM and FTIR confirmed the presence of collagen coating and patterned macropores (300 μm). Although the presence of macropores and collagen reduced its storage modulus and hydrophilicity, mBC/COL exhibited sufficient stiffness and wettability. More importantly, preliminary cell studies demonstrated that mBC/COL exhibited improved biological activity over BC and BC/COL due to the co-existence of macropores and collagen.
Open image in new window
Oriented films were prepared from aqueous suspensions of cellulose nanocrystal (CNC; microfibril fragment of sulfuric acid-hydrolyzed cotton) by a shearing method. Rotating glass vials each containing a 3–4 wt% CNC/water suspension under evaporation resulted in formation of translucent films of CNC per se. Structural characterization of the dry films was carried out by use of X-ray diffractometry and optical and scanning electron microscopy. The orientation pattern of CNCs in the films was much affected by pH condition of the starting suspensions; that is, the longitudinal axes of CNCs aligned preferentially perpendicular to the shear direction (SD) in the acidic condition of pH = 2.0, while an ordinary orientation of CNCs aligning parallel to SD was observed in the neutral condition of pH = 6.7 (adjusted with NaOH addition to the acidic suspension, however). To interpret the two distinct orientation patterns, first, it was inspected whether a mesomorphic ordered phase arrived or not in the two sheared and dried suspensions, different from each other in the counterions of surface-sulfated CNCs. As to the orientation development from the suspension of pH = 2, it was particularly assumed that the arising nematic planar domains would have been rolled up into a transversely extended body with the director perpendicular to SD. For the two film preparations, the orientation parameter of the longitudinal axis of CNC was quantified by WAXD intensity measurements, and the data were compared with those for other CNC-oriented materials such as CNC/polymer composites synthesized by immobilizing CNC suspensions via magnetic field application.
Photonic crystals incorporating with plasmonic nanoparticles have recently attracted considerable attention due to their novel optical properties and potential applications in future subwavelength optics, biosensing and data storage device. Here we demonstrate a free-standing chiral plasmonic film composed of entropy-driven self-co-assembly of gold nanoparticles (GNPs) and rod-like cellulose nanocrystals (CNCs). The CNCs-GNPs composite films not only preserve the photonic ordering of the CNCs matrix, but also retain the plasmonic resonance of GNPs, leading to a distinct plasmon-induced chiroptical activity and a strong resonant plasmonic-photonic coupling which confirms by the stationary and ultrafast transient optical response. Switchable optical activity can be obtained by either varying the incidence angle of lights, or by taking advantage of the responsive feature of the CNCs matrix. Notably, an angle-dependent plasmon resonance in chiral nematic hybrid film has been observed for the first time, which differs drastically from that of the GNPs embed in three-dimensional photonic crystals, revealing a close relation with the structure of the host matrix. The current approach for fabricating device-scale, macroscopic chiral plasmonic materials from abundant CNCs with robust chiral nematic matrix may enable the mass production of functional optical metamaterials.
Natural high performance materials inspire to pursue ordered hard/soft nanocomposite structures at high fractions of reinforcements and with balanced molecular interactions. Herein, we develop a facile, waterborne self-assembly pathway to mimic the multiscale cuticle structure of the crustacean armor by combining hard reinforcing cellulose nanocrystals (CNC) with soft poly(vinyl alcohol) (PVA). We show iridescent CNC nanocomposites with cholesteric liquid crystal structure, in which different helical pitches and photonic bandgaps can be realized by varying the CNC/PVA ratio. We further show that multilayered crustacean-mimetic materials with tailored periodicity and layered cuticular structure can be obtained by sequential preparation pathways. The transition from a cholesteric to a disordered structure occurs for a critical polymer concentration. Correspondingly, we find a transition from stiff and strong mechanical behavior to materials with increasing ductility. Crack propagation studies using scanning electron microscopy visualize the different crack growth and toughening mechanisms inside cholesteric nanocomposites as a function of the interstitial polymer content for the first time. Different extents of crack deflection, layered delamination, ligament bridging and constrained microcracking can be observed. Drawing of highly plasticized films sheds light on the mechanistic details of the transition from a cholesteric/chiral nematic to a nematic structure. The study demonstrates how self-assembly of biobased CNCs in combination with suitable polymers can be used to replicate a hierarchical biological structure, and how future design of these ordered multifunctional nanocomposites can be optimized by understanding mechanistic details of deformation and fracture.
Cellulose nanocrystals (CNCs) were modified through a one-step 1,1′-carbonyldiimidazole (CDI)-mediated coupling with 1-(3-aminopropyl)imidazole (APIm). The CNC-APIm prepared could be readily dispersed into carbonated water. Subsequent sparging of N2 into the dispersion gave rise to the formation of aggregates. This dispersion/aggregation cycle was reproducible by alternatively sparging CO2/N2 into the CNC-APIm aqueous dispersion, indicating that the chemically bonded imidazole groups on the CNC surface were stable and could respond to the CO2 stimulus in an effective and repeatable manner. Moreover, above certain concentrations (around 5.5–10 mg/ml) the CNC-APIm dispersion could be gelled in the presence of N2 while subsequent sparging CO2 could break the gel and regenerate a low viscosity CNC-APIm dispersion. This dispersion-gelation conversion was reversible by alternatively switching between sparging CO2 and N2. To our knowledge, the present work is the first report of CO2-switchable CNCs.
In search for induced chiral plasmonic activity, cholesteric films formed by cellulose nanocrystals have attracted great interest as potential hosts for plasmonic nanoparticles. Circular dichroism (CD) spectra of the composite films exhibit two peaks, one of which is ascribed to the cholesteric host and the other one - to plasmonic chiroptical activity of the plasmonic nanoparticles. Here we report the results of comprehensive studies of extinction and CD properties of composite films formed by different types of cellulose nanocrystals and different types of plasmonic nanoparticles. We show that the second peak in the CD spectra acquired using CD spectrometers appears as the result of the local reduction of the CD signal of the host material, due to excessive absorption by the nanoparticles, and thus it cannot be interpreted as induced plasmonic chiroptical activity. Instead, we propose an alternative way to measure CD spectra of plasmonic cholesteric films by using Mueller matrix transmission ellipsometry. The results of this study are important for ongoing research in the field of chiral plasmonics and for the optical characterization of a broad range of chiral nematic nanostructured materials.
This paper reports on a simple and green approach to fabricate cellulose nanocrystal@polyrhodanine (CNC@PR) core–sheath nanoparticles. Polymerization of rhodanine on the surface of negatively charged CNC was achieved using ferric chloride as the initiator and oxidant. The coating conditions were optimized by varying the ratio of CNC and monomer as well as the concentration of oxidant. Antimicrobial tests were performed using Escherichia coli (Gram negative) and Bacillus subtilis (Gram positive) as model bacteria and the minimum inhibitory concentrations were determined by plate colony counting methods. Rod-like CNC@PR nanoparticles exhibited promising antimicrobial properties, comparable to spherical nanocomposite particles. This may be attributed to the lower percolation threshold for rod-like nanoparticles resulting from the higher aspect ratio. By taking advantage of the nanosize effects, the core–sheath material can be a potential candidate for antimicrobial applications, such as food-packaging, antimicrobial additives and antimicrobial surfaces or coatings.
Chemically cross-linked cellulose nanocrystal aerogels represent a versatile and universal substrate on which to prepare lightweight hybrid materials. In situ incorporation of polypyrrole nanofibers, polypyrrole-coated carbon nanotubes, and manganese dioxide nanoparticles in the aerogels gives flexible 3D supercapacitor devices with excellent capacitance retention, low internal resistance, and fast charge-discharge rates.
© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Nanofibrillar cellulose is a very promising innovation with diverse potential applications including high quality paper, coatings and drug delivery carriers. The production of nanofibrillar cellulose on an industrial scale may lead to increased exposure to nanofibrillar cellulose both in the working environment and the general environment. Assessment of the potential health effects following exposure to nanofibrillar cellulose is therefore required. However, as nanofibrillar cellulose primarily consists of glucose moieties, detection of nanofibrillar cellulose in biological tissues is difficult. We have developed a simple and robust method for specific and sensitive detection of cellulose fibers, including nanofibrillar cellulose, in biological tissue, using a biotinylated carbohydrate binding module (CBM) of beta-1,4-glycanase (EXG:CBM ) from the bacterium Cellulomonas fimi. EXG:CBM was expressed in Eschericia coli, purified and biotinylated. EXG:CBM was shown to bind quantitatively to five different cellulose fibers including four different nanofibrillar celluloses. Biotinylated EXG:CBM was used to visualize cellulose fibers by either fluorescence- or horse radish peroxidase (HRP) -tagged avidin labeling. The HRP-EXG:CBM complex was used to visualize cellulose fibers in both cryopreserved and paraffin embedded lung tissue from mice dosed by pharyngeal aspiration with 10-200 µg/mouse. Detection was shown to be highly specific and the assay appeared very robust. The present method represents a novel concept for the design of simple, robust and highly specific detection methods for detection of nanomaterials, which are otherwise difficult to detect.
Natural rubber/cellulose nanocrystals (NR/CNCs) form true biocomposites from renewable resources and are demonstrated to show significantly improved thermo-mechanical properties and reduced stress-softening. The nanocomposites were prepared from chemically functionalized CNCs bearing thiols. CNCs served both as reinforcing and cross-linking agents in the NR matrix, and the study was designed to prove the crosslinking function of modified CNCs. CNCs were prepared from cotton and the cross-linkable mercapto-groups were introduced onto the surface of CNCs by esterification. Nanocomposite films were prepared by dispersing the modified CNCs (m-CNCs) in NR matrix by solution casting. The cross-links at the filler-matrix (m-CNCs-NR) interface were generated by photochemically initiated thiol-ene reactions as monitored by real-time FTIR analysis. The synergistic effects of reinforcement and chemical cross-linking at the m-CNCs-NR interface on structure, thermo-mechanical and stress-softening behavior were investigated. Methods included field emission scanning electron microscopy (FE-SEM), swelling tests, dynamic mechanical analysis, and tensile tests. Compared to biocomposites from NR with unmodified CNCs, the NR/m-CNCs nanocomposites showed 2.4-fold increase in tensile strength, 1.6-fold increase in strain-to-failure, and 2.9-fold increase in work-of-fracture at 10 wt% of m-CNCs in NR.
Injectable hyaluronic acid (HA)-based hydrogels comprise a promising class of materials for tissue engineering and regenerative medicine applications. However, their limited mechanical properties restrict the potential range of application. In this study, cellulose nanocrystals (CNCs) were employed as nanofillers in a fully biobased strategy for the production of reinforced HA nanocomposite hydrogels. Herein we report the development of a new class of injectable hydrogels composed of adipic acid dihydrazide-modified HA (ADH-HA) and aldehyde-modified HA (a-HA) reinforced with varying contents of aldehyde-modified CNCs (a-CNCs). The obtained hydrogels were characterized in terms of internal morphology, mechanical properties, swelling and degradation behaviour in the presence of hyaluronidase. Our findings suggest that the incorporation of a-CNCs in the hydrogel resulted in a more organized and compact network structure and led to stiffer hydrogels (maximum storage modulus, E', of 152.4 kPa for 0.25 wt.% a-CNCs content) with improvements of E' up to 135% comparatively to unfilled hydrogels. In general, increased amounts of a-CNCs led to lower equilibrium swelling ratios and higher resistance to degradation. The biological performance of the developed nanocomposites was assessed towards human adipose derived stem cells (hASCs). HA-CNCs nanocomposite hydrogels exhibited preferential cell supportive properties in in vitro culture conditions due to higher structural integrity and potential interaction of microenvironmental cues with CNC's sulphate groups. hASCs encapsulated in HA-CNCs hydrogels demonstrated ability to spread within the volume of gels and exhibited pronounced proliferative activity. Together, these results demonstrate that the proposed strategy is a valuable toolbox for fine tuning the structural, biomechanical and biochemical properties of injectable HA hydrogels, expanding their potential range of application in the biomedical field.
2,2,6,6-Tetramethylpiperidine-1-oxyl (TEMPO)-oxidized cellulose nanofibrils (TOCNs) and poly(acrylamide) (PAM) with sodium carboxylate groups (TOCN-COONa and PAM-COONa, respectively) were converted to TOCN and PAM with protonated carboxyl groups (TOCN-COOH and PAM-COOH, respectively). Transparent and flexible PAM-COOH/TOCN-COOH, PAM-COONa/TOCN-COOH, and PAM-COOH/TOCN-COONa composite films were prepared by mixing aqueous PAM-COOH or PAM-COONa solutions and aqueous TOCN-COOH or TOCN-COONa dispersions with various PAM/TOCN weight ratios, and successive casting/drying of the mixtures. In all cases, the Young’s modulus and tensile strength of the composite film were highest when the PAM content of the composite film was in the range 10-25 %. PAM therefore has the potential to reinforce TOCN films, irrespective of the sodium carboxylate groups or protonated carboxyl groups of TOCN or PAM. Although the FT-IR spectra of the PAM-COOH/TOCN-COOH composite films with various PAM/TOCN weight ratios indicated the formation of hydrogen bonds between PAM-COOH and TOCN-COOH, the formation of these hydrogen bonds could not explain the reinforcing effect achieved by PAM addition to TOCN-COOH. Because the TOCN elements form nematic-ordered or self-aligned domain structures in aqueous dispersions, PAM molecules at the corresponding PAM contents are probably present around the boundary regions of TOCN domains, and fill or cover the defects present between the TOCN domains.
Ru nanoparticles were synthesized from RuCl3 under mild H2 pressure within a suspension of cellulose nanocrystals. X-ray photoelectron spectroscopy and transmission electron microscopy revealed that the small Ru(0) nanoparticles (3.3 ± 1 nm) were deposited onto their cellulosic support. This hybrid proved to be a highliy efficient arene hydrogenation catalysts operational at 4 bars and room temperature.
Cellulose nanocrystals (CNCs) are entering the marketplace as new high-strength nanoadditives from renewable resources. These high aspect ratio particles have potential applications as rheological modifiers, reinforcing agents in composites, coatings, and porous materials. In this work, chemically cross-linked CNC aerogels were prepared based on hydrazone cross-linking of hydrazide and aldehyde-functionalized CNCs. The resulting aerogels were ultralightweight (5.6 mg/cm3) and highly porous (99.6%) with a bimodal pore distribution (mesopores <50 nm and macropores >1 μm). Chemically cross-linked CNC aerogels showed enhanced mechanical properties and shape recovery ability, particularly in water, compared to previous reports of physically cross-linked CNC aerogels. Specifically, the aerogel shape recovered more than 85% after 80% compression, even after 20 compress and release cycles. These CNC aerogels can absorb significant amounts of both water (160 ± 10 g/g of aerogel) and dodecane (72 ± 5 g/g of aerogel) with cyclic absorption capacity. We demonstrate that CNC aerogels can be used as superabsorbents and for oil/water separations and they may also find application as insulating or shock-absorbing materials. The cross-linking technology developed here presents new ways to design CNC networked structures and suggests an alternate route to incorporate CNCs into matrix materials, such as epoxies and foams.
Cellulose nanocrystal (CNC) reinforced polycarbonate (PC) nanocomposites were obtained by melt extrusion. Highly concentrated CNC/PC masterbatch was first prepared using a dis-solution/precipitation process which was then diluted by extrusion. Water from the CNC aqueous dispersion was exchanged to pyridine. PC was dissolved in this suspension and the mixture was precipitated in water. Two different methodologies were adopted for the PC matrix. In the first one, PC was submitted to the same dissolution/precipitation process than masterbatch, whereas in the second approach, the PC pellets were directly mixed with the solid masterbatch capsules. The structural, thermal and mechanical properties of ensuing nanocomposite materials were investigated.
In this study, we developed a pH-responsive shape-memory polymer nanocomposite by blending poly(ethylene glycol)-poly(?-caprolactone)-based polyurethane (PECU) with functionalized cellulose nanocrystals (CNCs). CNCs were functionalized with pyridine moieties (CNC-C6H4NO2) through hydroxyl substitution of CNCs with pyridine-4-carbonyl chloride and with carboxyl groups (CNC-CO2H) via 2, 2, 6, 6-tetramethyl-1-piperidinyloxy (TEMPO) mediated surface oxidation, respectively. At high pH value the CNC-C6H4NO2 had attractive interactions from the hydrogen bonding between pyridine groups and hydroxyl moieties; at low pH value the interactions reduced or disappeared due to the protonation of pyridine groups which are a Lewis base. The CNC-CO2H responded to pH variation in an opposite manner. The hydrogen bonding interactions of both CNC-C6H4NO2 and CNC-CO2H can be readily disassociated by altering pH values, endowing the pH-responsiveness of CNCs. When these functionalized CNCs were added in PECU polymer matrix to form nanocomposite network which was confirmed with rheological measurements, the mechanical properties of PECU were not only obviously improved but also the pH-responsiveness of CNCs could be transferred to the nanocomposite network. The pH-sensitive CNCs percolation network in polymer matrix served as the switch units of shape-memory polymers (SMPs). Furthermore, the modified CNCs percolation network and polymer molecular chains also had strong hydrogen bonding interactions among hydroxyl, carboxyl, pyridine moieties and isocyanate groups, which could be formed or destroyed through changing pH value. The shape memory function of the nanocomposite network was only dependent on the pH variation of environment. Therefore, this pH-responsive shape-memory nanomposite could be potentially developed into a new smart polymer material.
Cellulose nanocrystal-stabilized graphene (GR-CNC) was produced by liquid phase exfoliation of graphite assisted by cellulose nanocrystals (CNC), a recently reported method that allows stabilization of resulting graphene flakes in aqueous dispersions. Using a simple and environmentally friendly process, GR-CNC was incorporated into poly(vinyl alcohol) (PVA) aqueous solutions to obtain PVA-based nanocomposites (GR-CNC/PVA) by a casting method. For comparison purposes, two reference materials were also prepared following the same procedure: CNC/PVA and GR-T/PVA, where graphene was stabilized by an organic surfactant, Triton X-100 (T). At 1wt% nanofiller loading, GR-CNC/PVA exhibited superior mechanical properties (improvements in tensile strength and Young’s modulus were about 20% and 50%, respectively, compared with neat PVA) than CNC/PVA (4% increase in tensile strength and 19% in Young’s modulus) and GR-T/PVA (where a decrease in mechanical properties was observed), suggesting the synergistic reinforcing effect of CNC and graphene (GR). This significant reinforcement found for GR-CNC/PVA is attributed to the strong interaction between PVA and GR-CNC.
Improvement of the mechanical and thermal properties of cellulose triacetate (CTA) films is required without sacrificing their optical properties. Here, poly(ethylene glycol) (PEG)-grafted cellulose nanofibril/CTA nanocomposite films were fabricated by casting and drying methods. The cellulose nanofibrils were prepared by 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-mediated oxidation, and amine-terminated PEG chains were grafted onto the surfaces of the TEMPO-oxidized cellulose nanofibrils (TOCNs) by ionic bonds. Because of the nanosize effect of TOCNs with a uniform width of ~3 nm, the PEG-TOCN/CTA nanocomposite films had high transparency and low birefringence. The grafted PEG chains enhanced the filler-matrix interactions and crystallization of matrix CTA molecules, resulting that the Young's modulus and toughness of CTA film were significantly improved by PEG-grafted TOCN addition. The coefficient of thermal expansion of the original CTA film was mostly preserved even with the addition of PEG-grafted TOCNs. These results suggest that PEG-TOCNs are applicable to the reinforcement for transparent optical films.
A series of reactive GAP (glycidyl azide polymer)/PTPB (propargyl-terminated polybutadiene) nanocomposites reinforced by alkynylated cellulose nanocrystals (ACNC) were synthesized from the Huisgen click chemistry. High-efficiency substitution (more than 80%) of the hydroxyl groups by alkynyl groups on the surface of CNC was realized through the esterification reaction between the alkynylated anhydride compound and the cellulose nanocrystals. The covalent bonding from the alkynyl groups of ACNC and the azide groups of GAP was proved by Fourier transform infrared spectroscopy, which indicated the possible participation of the click reactions among the ACNC, GAP, and PTPB components in the composites. The nanoreinforcing effect of rigid ACNC in the GAP/PTPB matrix and the strong interfacial interaction through the covalent grafting between the nanoparticles and matrix significantly improved the mechanical properties of the prepared nanocomposites. In comparison with the neat GAP/PTPB (GP2) material, the tensile strength, Young’s modulus, and elongation at break of the GP2/ACNC-1.0 nanocomposite (containing only 1.0 wt% ACNC) were increased by 103.3%, 100.0% and 12.4%, respectively. This study is a promising attempt to develop advanced polymeric composites reinforced with biomass-based nanoparticles with the simultaneous improvement of the strength, modulus and toughness.
Exploration of environment-friendly light-emitting devices with extremely low-weight has been a trend in recent decades for modern digital technology. Herein, we describe a simple suction filtration method to develop a transparent and photoluminescent nanocellulose (NC) paper, which contains ZnSe quantum dot (QD) with high quantum yield as a functional filler. ZnSe QD can be dispersed uniformly in NC, and a quite low coefficient of thermal expansion is determined for resultant composite paper, suggesting its good dimension stability. These results indicate the meeting of NC with ZnSe QD can bring a brilliant future during the information age.
Nanocomposites of polymethylmethacrylate (PMMA) and cellulose were made by a solution casting method using acetone as the solvent. The nanofiber networks were prepared using three different types of cellulose nanofibers: (i) nanofibrillated cellulose (NFC), (ii) cellulose nanocrystals (CNC) and (iii) bacterial cellulose from nata de coca (NDC). The loading of cellulose nanofibrils in the PMMA varied between 0.25 and 0.5wt%. The mechanical properties of the composites were evaluated using a dynamic mechanical thermal analyzer (DMTA). The flexural modulus of the nanocomposites reinforced with NDC at the 0.5wt% loading level increased 23% compared to that of pure PMMA. The NFC composite also exhibited a slightly increased flexural strength around 60MPa while PMMA had a flexural strength of 57MPa. The addition of NDC increased the storage modulus (11%) compared to neat PMMA at room temperature while the storage modulus of PPMA/CNC nanocomposite containing 0.25 and 0.5wt% cellulose increased about 46% and 260% to that of the pure PMMA at the glass transition temperature, respectively. Thermogravimetric analysis (TGA) indicated that there was no significant change in thermal stability of the composites. The UV-vis transmittance of the CNF nanocomposites decreased by 9% and 27% with the addition of 0.25wt% CNC and NDC, respectively. This work is intended to spur research and development activity for application of CNF reinforced PMMA nanocomposites in applications such as: packaging, flexible screens, optically transparent films and light-weight transparent materials for ballistic protection.
Copyright © 2015 Elsevier Ltd. All rights reserved.
. Co-assembly of nanoparticles with different size- and shape-dependent properties is a promising approach to the design and fabrication of functional materials and devices. This paper reports the results of a detailed investigation of the formation and properties of free-stranding composite films formed by the co-assembly of cellulose nanocrystals and shape-isotropic, plasmonic gold nanoparticles. The effect of gold nanoparticle size, surface charge and concentration on the structural and optical properties of the composite films has been studied. The composite films retained photonic crystal and chiroptical activity properties. The size and surface charge of gold nanoparticles had a minor effect on the structure and properties of the composite films, while the concentration of gold nanoparticles in the composite material played a more significant role, and can be used to fine-tune the optical properties of materials derived from cellulose nanocrystals. These findings significantly broaden the range of nanoparticles that can be used for producing nanocomposite materials based on cellulose nanocrystals. The simplicity of film preparation, the abundance of cellulose nanocrystals and the robust, free-standing nature of the composite films, offer highly advantageous features and pave the way for the generation of functional materials with coupled optical properties. .
Carbon nanotubes have excellent penetrability and encapsulation efficiency in the field of drug/gene delivery. It was reported that due to their excellent physico-chemical properties, biocompatible rod-like cellulose nanocrystals (CNCs) were expected to replace carbon nanotubes. In this work, CNCs from natural cotton wool were functionalized with disulfide bonds-linked poly(2-(dimethylamino)-ethyl methacrylate) (PDMAEMA) brushes for effective biomedical applications. A range of CNC-graft-PDMAEMA vectors (termed as CNC-SS-PDs) with various molecular weights of PDMAEMA were synthesized. Under reducible conditions, PDMAEMA chains can be easily cleaved from CNCs. The gene condensation ability, reduction sensitivity, cytotoxicity, gene transfection, and in vivo antitumor activities of CNC-SS-PDs were investigated in detail. The CNC-SS-PDs exhibited good transfection efficiencies and low cytotoxicities. The needle-like shape of CNCs had an important effect on enhancing transfection efficiency. The antitumor effect of CNC-SS-PD was evaluated by a suicide gene/prodrug system (cytosine deaminase/5-fluorocytosine, CD/5-FC) in vitro and in vivo. This research demonstrates that the functionalization of CNCs with redox-responsive polycations is an effective method to develop novel gene delivery systems.
Poly (amidoamine) (PAMAM) dendrimers have found promising applications in biomedicine and in the encapsulation of inorganic nanoparticles. G6 PAMAM dendrimer-grafted cellulose nanocrystals (CNC-PAMAM) were prepared via a simple carbodiimide-mediated amidation process and they displayed pH-responsive and fluorescent characteristics as confirmed by zeta potential, transmittance, isothermal titration calorimetry (ITC), and fluorescence spectroscopy. Stable aqueous dispersions of CNC-PAMAM were obtained at pH⩽4 and pH⩾10, driven by electrostatic repulsion from positive charge and negative charge respectively. However, large aggregates were formed at pH values from 5 to 9 due to electrostatic attraction. In addition, strong blue fluorescent emission was observed, and the fluorescent behaviour of CNC-PAMAM was influenced by the formation of aggregates. The pH-responsive and fluorescent properties of CNC-PAMAM may be suitable for their applications in pH-responsive nanodevices, fluorescent-based pH sensors, optical markers, and nanoreactors for the encapsulation of inorganic nanoparticles.
Copyright © 2015 Elsevier Inc. All rights reserved.
The present work deals with the elaboration of nanobiocomposite composed of a cellulose derivative matrix reinforced by cellulose nanocrystals. First, thermoplastic cellulose matrix was obtained by cellulose esterification with lauroyl chloride. Cellulose nanocrystals (NCC), as reinforcement, were obtained by sulfuric acid hydrolysis of cellulose and characterized by AFM. Surface of cellulose nanocrystals (NCC) was then modified by lauroyl chloride in toluene (non swelling solvent), before being used as reinforcing elements in nanobiocomposite. Both cellulose modification and NCC surface modification were proved by different characterizations techniques: FT-IR, contact angle measurements, elemental analysis and thermogravimetric analysis (TGA). Successful surface modification has been shown with rather high degree of substitution (DS). Structural changes of NCC were checked by X-ray Diffraction analyses. Nanocomposites with surface modified and unmodified cellulose nanocrystals as reinforcements were elaborated by casting process. Thermal post-treatment has been performed to “melt” the cellulose derivatives interface. Homogenous nanocomposite films were obtained by film casting process when NCC was grafted, whereas unmodified NCC did not yield the same result. Thermal and mechanical properties were performed with DMA. When NCCs were grafted and thermopressed with the matrix, positive results were obtained proving the efficiency of this new compatibilization process by interface “melting”.
Introduction of active groups on the surface of bacterial cellulose (BC) nanofibers is one of the promising routes of tailoring the performance of BC scaffolds for tissue engineering. This paper reported the introduction of aldehyde groups to BC nanofibers by 2,2,6,6-tetramethylpyperidine-1-oxy radical (TEMPO)-mediated oxidation and evaluation of the potential of the TEMPO-oxidized BC as tissue engineering scaffolds. Periodate oxidation was also conducted for comparison. Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) analyses were carried out to determine the existence of aldehyde groups on BC nanofibers and the crystallinity. In addition, properties relevant to scaffold applications such as morphology, fiber diameter, mechanical properties, and in vitro degradation were characterized. The results indicated that periodate oxidation could introduce free aldehyde to BC nanofibers and the free aldehyde groups on the TEMPO-oxidized BC tended to transfer to acetal groups. It was also found that the advantageous 3D structure of BC scaffolds remained unchanged and that no significant changes in morphology, fiber diameter, tensile structure and in vitro degradation were found after TEMPO-mediated oxidation while significant differences were observed upon periodate oxidation. The present study revealed that TEMPO-oxidation could impart BC scaffolds with new functions while did not degrade their intrinsic advantages.
Ethylene-co-vinyl acetate rubber/nanocrystalline cellulose (EVA/NCC) nanocomposites were prepared by solution mixing and static vulcanization in the presence of peroxide. The gel content and crosslink density of the nanocomposites were decreased with increasing NCC loading. However, mechanical properties of the EVA were considerably enhanced, e.g. the tensile strength and the storage modulus were increased by around 75% and 50%, respectively, when 2 phr of the NCC was incorporated. Such significant reinforcement is ascribed to a uniform dispersion of the NCC, the formation of NCC network and the strong EVA-NCC interactions as confirmed by morphology observation (SEM and AFM) and dynamic mechanical thermal analysis (DMA). Moreover, the presence of the NCC did not compromise obviously the optical clarity and the thermal decomposition temperature of the EVA. The highly reinforced ethylene-co-vinyl acetate rubber with high transparence may broaden its application range.
In the present work, a novel composite material formed by bacterial cellulose (BC) networks and graphene oxide (GO) nanosheets was synthesized by a sonochemical method. The BC and as-prepared BC/GO composites were characterized by several techniques including Scanning Electron Microscopy (SEM), Fourier-transform infrared (FTIR) spectra, ultraviolet-visible (UV-vis) absorption spectra, thermogravimetric analyses (TG) and X-ray diffraction (XRD). SEM images showed that the morphologies of composites became more compact than BC. FTIR, UV, TG and XRD confirmed the existence of GO in the composites. Moreover, HEK 293 cells were cultivated, and both the biocompatibility of the materials and the cell viability were demonstrated. Meanwhile, the anti-bacterial performances of BC/GO composites were evaluated with Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), which frequently cause medically associated infections. The experimental results showed that the BC/GO composites have excellent anti-bacterial activities, thus confirming its utility as a potential biomaterial in biomedical applications. Furthermore, the anti-bacterial behavior had been well explained by the extended DLVO theory.
The oxidation of cellulose nanocrystal (CNC) by sodium periodate can generate aldehyde functions for crosslinking reactions or for further modification, which can extend the range of applications of CNC. In this paper, the effects of reaction conditions during the periodate oxidation of CNC, such as oxidant concentration, pH, temperature and oxidation time on the oxidized CNC yield and the aldehyde content, were investigated and an optimized reaction condition was identified. The generation of aldehyde groups on the CNC was confirmed by Fourier transform infrared spectroscopy analysis, and the decreased crystalline index was observed by X-ray diffraction. The transmission electron microscope observation showed the morphological changes of CNC after the oxidation. The oxidized CNC was used as a strength additive to paper, and the results showed that the dry tensile index was 32.6 % higher than the control sample, and the wet tensile index was reached to 3.08 N.m/g, at the oxidized CNC dosage of 1.2 %.