Noncovalent Dispersion and Functionalization of Cellulose Nanocrystals with Proteins and Polysaccharides

Application of cellulose nanocrystals in water treatment membranes: A review

Nanomaterials have brought great changes to human society, and development has gradually shifted the focus to environmentally friendly applications. Cellulose nanocrystals (CNCs) are new one-dimensional nanomaterials that exhibit environmental friendliness and ensure the biological safety of water environment. CNCs have excellent physical and chemical properties, such as simple preparation process, nanoscale size, high specific surface area, high mechanical strength, good biocompatibility, high hydrophilicity and antifouling ability. Because of these characteristics, CNCs are widely used in ultrafiltration membranes, nanofiltration membranes and reverse osmosis membranes to solve the problems hindering development of membrane technology, such as insufficient interception and separation efficiency, low mechanical strength and poor antifouling performance. This review summarizes recent developments and uses of CNCs in water treatment membranes and discusses the challenges and development prospects of CNCs materials from the perspectives of ecological safety and human health by comparing them with traditional one-dimensional nanomaterials.

Nanoengineering and green chemistry-oriented strategies toward nanocelluloses for protein sensing

As one of the most important functional organic macromolecules of life, proteins not only participate in the cell metabolism and gene regulation, they also earnestly protect the body's immunity system, leading to a powerful biological shield and homeostasis. Advances in nanomaterials are boosting the significant progress in various applications, including the sensing and examination of proteins in trace amount. Nanocellulose-oriented protein sensing is at the forefront of this revolution. The inherent feature of high biocompatibility, low cytotoxicity, high specific area, good durability and marketability endow nanocellulose with great superiority in protein sensing. Here, we highlight the recent progress of protein sensing using nanocellulose as the biosensor in trace amount. Besides, various kinds of construction strategies for nanocelluloses-based biosensors are discussed in detail, to enhance the agility and accuracy of clinical/medical diagnostics. Finally, several challenges in the approbatory identification of new approaches for the marketization of biomedical sensing that need further expedition in the future are highlighted.

Recycled Paper Sludge (RPS)-Derived Nanocellulose: Production, Detection and Water Treatment Application

Paper production and recycling result in large amounts of recycled paper sludge (RPS) that is currently being disposed of in very costly and unsustainable practices, raising the importance of developing green solutions for waste management. The use of nanocellulose (NC) as the next generation of materials has gained much attention due to its economic potential. However, there are substantial challenges in NC extraction, detection, and quantification methods. In this study, NC was produced from RPS as a means of converting waste into a resource. The process included a short, 30 min ozonation (21 mg O3/g RPS), which allowed a sufficient delignification and facilitated the following hydrolysis step. Among all tested durations, a 4-h hydrolysis with 64% w/w sulfuric acid resulted in the highest NC production. Fluorescent staining by calcofluor white was used for simple and low-cost detection of NC in-situ. Crude NC showed a significant 63% dye uptake of 0.1 ppm acid red 131 within 30 min. Compared to the standard disposal methods of RPS, its utilization for NC production supports the circular economy concept and significantly contributes to the development of cellulose bio-based nanomaterials for water treatment applications.

Dual topography of laminin corona on gallium arsenide nanowires

Nanowires (NWs) are novel nanomaterials with applications in everything from medical implants to solar cells. With increasing number of applications, it is increasingly likely that organisms are exposed to these materials either intentionally or by accident. It is, therefore, important to study their interactions with biological systems and biomolecules. Upon exposure to biological fluids, nanostructure surfaces are quickly covered by a biomolecule corona. The composition of the corona determines the nanostructure's biological fate. Furthermore, upon adsorption, the protein structure can be affected. In order to study the corona morphology, we used two model proteins, laminin of the extracellular matrix and the immune system enzyme myeloperoxidase. We image the protein corona directly by cryo-TEM and enhance resolution by labeling the corona with activated gold nanoparticles. Three-dimensional imaging of the protein corona further increases the resolution and reveals irregularities in corona topography. By doing so, we identified bimodal distribution of spacing between gold nanoparticles and the NW surface for laminin corona at 58 and 85 nm distance from the NWs' surface. The dual topography of the corona is adding a new complexity of the protein corona surface and its interactions with the surrounding biology.

Adsorption and Assembly of Cellulosic and Lignin Colloids at Oil/Water Interfaces

The surface chemistry and adsorption behavior of submicrometer cellulosic and lignin particles have drawn wide-ranging interest in the scientific community. Here, we introduce their assembly at fluid/fluid interfaces in Pickering systems and discuss their role in reducing the oil/water interfacial tension, limiting flocculation and coalescence, and endowing given functional properties. We discuss the stabilization of multiphase systems by cellulosic and lignin colloids and the opportunities for their adoption. They can be used alone, as dual components, or in combination with amphiphilic molecules for the design of multiphase systems relevant to household products, paints, coatings, pharmaceutical, foodstuff, and cosmetic formulations. This invited feature article summarizes some of our work and that of colleagues to introduce the readers to this fascinating and topical area.

Periodate Oxidation Followed by NaBH4 Reduction Converts Microfibrillated Cellulose into Sterically Stabilized Neutral Cellulose Nanocrystal Suspensions

The periodate oxidation of microfibrillated cellulose followed by a reduction treatment was implemented to produce a new type of sterically stabilized cellulosic nanocrystals, which were characterized at the molecular and colloidal length scales. Solid-state NMR data showed that these treatments led to objects consisting of native cellulose and flexible polyols resulting from the oxidation and subsequent reduction of cellulose. A consistent set of data from dynamic light scattering, turbidimetry, transmission electron microscopy, and small-angle X-ray scattering experiments further showed that stable neutral elongated nanoparticles composed of a crystalline cellulosic core surrounded by a shell of dangling polyol chains were produced. The dimensions of these biosourced nanocrystals could be controlled by the degree of oxidation of the parent dialdehyde cellulose sample. The purely steric origin of the colloidal stability of these nanoparticles is a strong asset for their use under conditions where electrostatics no longer provides colloidal stability.

Multifunctional Stimuli-Responsive Cellulose Nanocrystals via Dual Surface Modification with Genetically Engineered Elastin-Like Polypeptides and Poly(acrylic acid)

Cellulose nanocrystals (CNCs) are promising candidates for a myriad of applications; however, successful utilization of CNCs requires balanced and multifunctional properties, which require ever more applied concepts for supramolecular tailoring. We present here a facile and straightforward route to generate dual functional CNCs using poly(acrylic acid) (PAA) and biosynthetic elastin-like polypeptides (ELPs). We utilize thiol-maleimide chemistry and SI-ATRP to harvest the temperature responsiveness of ELPs and pH sensitivity of PAA to confer multifunctionality to CNCs. Cryo-TEM and light microscopy are used to exhibit reversible temperature response, while atomic force microscopy (AFM) provides detailed information on the particle morphology. The approach is tunable and allows variation of the modifying molecules, inspiring supramolecular engineering beyond the currently presented motifs. The surge of genetically engineered peptides adds further possibilities for future exploitation of the potential of cellulose nanomaterials.

Advanced Materials through Assembly of Nanocelluloses

There is an emerging quest for lightweight materials with excellent mechanical properties and economic production, while still being sustainable and functionalizable. They could form the basis of the future bioeconomy for energy and material efficiency. Cellulose has long been recognized as an abundant polymer. Modified celluloses were, in fact, among the first polymers used in technical applications; however, they were later replaced by petroleum-based synthetic polymers. Currently, there is a resurgence of interest to utilize renewable resources, where cellulose is foreseen to make again a major impact, this time in the development of advanced materials. This is because of its availability and properties, as well as economic and sustainable production. Among cellulose-based structures, cellulose nanofibrils and nanocrystals display nanoscale lateral dimensions and lengths ranging from nanometers to micrometers. Their excellent mechanical properties are, in part, due to their crystalline assembly via hydrogen bonds. Owing to their abundant surface hydroxyl groups, they can be easily modified with nanoparticles, (bio)polymers, inorganics, or nanocarbons to form functional fibers, films, bulk matter, and porous aerogels and foams. Here, some of the recent progress in the development of advanced materials within this rapidly growing field is reviewed.

Crystalline nanocellulose/lauric arginate complexes

As a novel sustainable nanomaterial, crystalline nanocellulose (CNC) possesses many unique characteristics for emerging applications in coatings, emulsions, paints, pharmaceutical formulations, and other aqueous composite systems where interactions with oppositely charged surfactants are commonly employed. Herein, the binding interactions between sulfated CNC and a novel biologically-derived cationic surfactant lauric arginate (LAE) were comprehensively examined. Ionic strength and solution pH are two crucial factors in determining the adsorption of LAE to the CNC surface. Three different driving forces were identified for CNC-LAE binding interactions. Additionally, it was found that the adsorption of LAE to the CNC surface could notably impact the surface potential, aggregation state, hydrophobicity and thermal stability of the CNC. This work provides insights on the binding interactions between oppositely charged CNC and surfactants, and highlights the significance of optimizing the concentration of surfactant required to ionically decorate CNC for its enhanced dispersion and compatibilization in non-polar polymer matrices.

Elastic and pH-Responsive Hybrid Interfaces Created with Engineered Resilin and Nanocellulose

We investigated how a genetically engineered resilin fusion protein modifies cellulose surfaces. We characterized the pH-responsive behavior of a resilin-like polypeptide (RLP) having terminal cellulose binding modules (CBM) and showed its binding to cellulose nanofibrils (CNF). Characterization of the resilin fusion protein at different pHs revealed substantial conformational changes of the protein, which were observed as swelling and contraction of the protein layer bound to the nanocellulose surface. In addition, we showed that employment of the modified resilin in cellulose hydrogel and nanopaper increased their modulus of stiffness through a cross-linking effect.

Recent progress in cellulose nanocrystals: sources and production

Cellulose nanocrystals, a class of fascinating bio-based nanoscale materials, have received a tremendous amount of interest both in industry and academia owing to its unique structural features and impressive physicochemical properties such as biocompatibility, biodegradability, renewability, low density, adaptable surface chemistry, optical transparency, and improved mechanical properties. This nanomaterial is a promising candidate for applications in fields such as biomedical, pharmaceuticals, electronics, barrier films, nanocomposites, membranes, supercapacitors, etc. New resources, new extraction procedures, and new treatments are currently under development to satisfy the increasing demand of manufacturing new types of cellulose nanocrystals-based materials on an industrial scale. Therefore, this review addresses the recent progress in the production methodologies of cellulose nanocrystals, covering principal cellulose resources and the main processes used for its isolation. A critical and analytical examination of the shortcomings of various approaches employed so far is made. Additionally, structural organization of cellulose and nomenclature of cellulose nanomaterials have also been discussed for beginners in this field.

Cellulose nanocrystals by acid vapour: towards more effortless isolation of cellulose nanocrystals

Cellulose nanocrystals (CNCs) are topical in materials science but their full potential is yet to be fulfilled because of bottlenecks in the production: the process consumes huge amounts of water, recycling the strong acid catalyst is difficult, and purification steps are cumbersome, particularly with lengthy dialysis. Production of CNCs with HCl vapour overcomes many of these difficulties but the dispersion of CNCs from the already hydrolysed fibre matrix is a formidable challenge. This study is a fundamental effort to explore very basic means to facilitate CNC dispersion from cotton linter fibres (filter paper), hydrolysed to levelling off degree of polymerization by HCl vapour. The introduction of carboxylic groups on the cellulose crystal surface proved the most efficient method to alleviate dispersion with good yields (ca. 50%) and a provisional possibility to tune the CNC length. By contrast, attempts to directly disperse untreated hydrolysed fibres in various organic solvents and aqueous surfactant solutions were unsuccessful. The results showed that hydrolysis of native cellulose fibres by HCl vapour is indeed a viable method for producing CNCs but it has more potential as a pre-treatment step rather than a full-fledged process on its own.