Hierarchical Fibrous Structure Research Articles

Universal architecture and defect engineering dual strategy for hierarchical antimony phosphate composite toward fast and durable sodium storage

Antimony (Sb)-based anode materials are feasible candidates for sodium-ion batteries (SIBs) due to their high theoretical specific capacity and excellent electrical conductivity. However, they still suffer from volume distortion, structural collapse, and ionic conduction interruption upon cycling. Herein, a hierarchical array-like nanofiber structure was designed to address these limitations by combining architecture engineering and anion tuning strategy, in which SbPO4−x with oxygen vacancy nanosheet arrays are anchored on the surface of interwoven carbon nanofibers (SbPO4−x@CNFs). In particular, bulky PO43− anions mitigate the large volume distortion and generate Na3PO4 with high ionic conductivity, collectively improving cyclic stability and ionic transport efficiency. The abundant oxygen vacancies substantially boost the intrinsic electronic conductivity of SbPO4, further accelerating the reaction dynamics. In addition, hierarchical fibrous structures provide abundant active sites, construct efficient conducting networks, and enhance the electron/ion transport capacity. Benefiting from the advanced structural design, the SbPO4−x@CNFs electrodes exhibit outstanding cycling stability (1000 cycles at 1.0 A g−1 with capacity decay of 0.05% per cycle) and rapid sodium storage performance (293.8 mA h g−1 at 5.0 A g−1). Importantly, systematic in-/ex-situ techniques have revealed the “multi-step conversion-alloying” reaction process and the “battery-capacitor dual-mode” sodium-storage mechanism. This work provides valuable insights into the design of anode materials for advanced SIBs with elevated stability and superior rate performance.

Optimizing Protein Fiber Spinning to Develop Plant-Based Meat Analogs via Rheological and Physicochemical Analyses.

The substitution of meat products in the human diet with plant-based analogs is growing due to environmental, ethical, and health reasons. In this study, the potential of fiber-spinning technology was explored to spin protein fiber mimicking the structural element of meat muscle for the purpose of developing plant-based meat analogs. Overall, this approach involved extruding fine fibers and then assembling them into hierarchical fibrous structures resembling those found in whole muscle meat products. Considering the nutritional facts and to help build muscle fiber, soy protein, polysaccharide (pectin, xanthan gum, or carrageenan), plasticizer (glycerol), and water were used in the formulations to spin into fibers using an extruder with circular orifice dies. Extrudability and thermal and rheological properties were assessed to characterize the properties of the spun fiber. The extrusion trials showed that the presence of the polysaccharides increased the cohesiveness of the fibers. The properties of the fibers produced also depended on the temperature used during extrusion, varying from pasty gels to elastic strands. The extrudability of the fibers was related to the rheological properties (tan δ) of the formulations. This study demonstrated that fiber-spinning technology can be used to produce fibrous materials from plant-derived ingredients. However, the formulation and operating conditions must be optimized to obtain desirable physicochemical and functional attributes in the fibers produced.

Bioinspired and dual-functional nanocellulose aerogels for water disinfection and heavy metal removal

Treating water resources contaminated by pathogenic microorganisms and heavy metals is a great challenge because of the difficulties in developing efficient strategies for water treatment. Traditional adsorbent materials have the drawbacks of high cost, low adsorption efficiency, secondary pollution creation, and a lack of adaptability in removing a wide variety of pollutants. In this study, inspired by the hierarchical fibrous structure and antibacterial property of the natural silkworm cocoon, we developed a guanidine-functionalized sericin/nanocellulose aerogel (GSNA) with a biomimetic skeletal architecture, which holds great promise for achieving hybrid water disinfection and heavy metal removal. The nanocellulose (CNC) fibers integrated into a robust building block with an interconnected structure and mechanical stability. The grafted polyhexamethylene biguanide (PHMB) endows the biomimetic aerogel with exceptional bactericidal activity (7 log reduction against Escherichia coli within 30 min). Benefiting from the abundant surface functional groups on sericin and CNC-PHMB, the obtained aerogel also exhibits superior heavy metal adsorption capacity (571.5 mg/g for Cu). These compelling merits enable the aerogel to disinfect water and remove heavy metal ions simultaneously as a membrane filter. The synthesized GSNA can be a promising candidate for water disinfection and purification because of its facile preparation, cost-effectiveness, and environmentally friendly characteristics.

Silk Fibroin/Wool Keratin Composite Scaffold With Hierarchical Fibrous and Porous Structure.

The present study describes a silk microfiber reinforced meniscus scaffold (SMRMS) with hierarchical fibrous and porous structure made from silk fibroin (SF) and wool keratin (WK) using electrospinning and freeze-drying technology. This study focused on the morphology, secondary structure, mechanical properties and water absorption properties of the scaffold. The cytotoxicity and biocompatibility of SMRMS were assessed in vivo and in vitro. The scaffold showed hierarchical fibrous and porous structure, hierarchical pore size distribution (ranges from 50µm to 650µm), robust mechanical properties (compression strength can reach at 2.8MPa) and stable biodegradability. A positive growth condition revealed by in vitro cytotoxicity testing indicated that the scaffold was not hazardous to cells. In vivo assessments of biocompatibility revealed that only a mild inflammatory reaction was present in implanted rat tissue. Meniscal scaffold made of SF/WK composite shows a potential application prospect in meniscal repair engineering field with its development. This article is protected by copyright. All rights reserved.

Molecular Tuning of a Benzene-1,3,5-Tricarboxamide Supramolecular Fibrous Hydrogel Enables Control over Viscoelasticity and Creates Tunable ECM-Mimetic Hydrogels and Bioinks.

Traditional synthetic covalent hydrogels lack the native tissue dynamics and hierarchical fibrous structure found in the extracellular matrix (ECM). These dynamics and fibrous nanostructures are imperative in obtaining the correct cell/material interactions. Consequently, the challenge to engineer functional dynamics in a fibrous hydrogel and recapitulate native ECM properties remains a bottle-neck to biomimetic hydrogel environments. Here,the molecular tuning of a supramolecular benzene-1,3,5-tricarboxamide (BTA) hydrogelator via simple modulation of hydrophobic substituents is reported. This tuning results in fibrous hydrogels with accessible viscoelasticity over 5 orders of magnitude, while maintaining a constant equilibrium storage modulus. BTA hydrogelators are created with systematic variations in the number ofhydrophobic carbon atoms, and this is observed to control the viscoelasticity and stress-relaxation timescales in a logarithmic fashion. Some of theseBTA hydrogels are shear-thinning, self-healing, extrudable, and injectable, and can be 3D printed into multiple layers. These hydrogels show high cell viability for chondrocytes and human mesenchymal stem cells, establishing their use in tissue engineering applications. This simple molecular tuning by changing hydrophobicity (with just a few carbon atoms) provides precise control over the viscoelasticity and 3D printability in fibrillar hydrogels and can be ported onto other 1D self-assembling structures. The molecular control and design of hydrogel network dynamics can push the field of supramolecular chemistry towardthe design of new ECM-mimicking hydrogelators for numerous cell-culture and tissue-engineering applications and give access towardhighly biomimetic bioinks for bioprinting.

Hierarchical fibrous collagen/poly(ε-caprolactone) structure fabricated with a 3D-printing process for tissue engineering applications

Hierarchical scaffolds have been extensively used in various tissue engineering applications as they can provide unique biofunctional properties, including biophysical cues, to successfully accomplish preferred cell attachment, growth, and differentiation depending on the target tissues. In this study, we propose a new strategy for fabricating hierarchical structures consisting of microfibrous collagen/poly(ε-caprolactone) (PCL) bundles obtained using a 3D printing process supplemented with a unique bioink, plasma treatment, and collagen coating process. To obtain the hierarchical fibrous PCL structure, we used an alginate matrix hydrogel to form a microfibrous bundle of dispersed PCL components using elongational and shear stresses within a printing nozzle. By controlling various mixture ratios of alginate and PCL, processing temperature, pneumatic pressure, and nozzle moving speeds, a stable hierarchical structure consisting of PCL microfibers was obtained. To demonstrate the feasibility of hierarchical PCL-based structures coated with type I collagen, we investigated whether the construct affects the alignment and differentiation of myoblasts. The hierarchical fibrous biocomposite constructs presented a higher degree of myogenic activity than the control, which was fabricated using normal printing/collagen coating processes. Furthermore, the hierarchical PCL structures were further elaborated using 10 × simulated body fluid (SBF) resulting in a scaffold consisting of a hydroxyapatite (HA) layer. The hierarchical collagen/PCL/HA structures were evaluated with the aim of obtaining a functional scaffold that could efficiently induce osteogenesis to the human adipose stem cells (hASCs). These in vitro results suggest that the fibrous composite structure can provide enhanced osteogenic activity compared to the normally printed control (collagen/PCL/HA).

Performance of Cu/ZnO Nanosheets on Electrospun Al2O3 Nanofibers in CO2 Catalytic Hydrogenation to Methanol and Dimethyl Ether

The synthesis of methanol and dimethyl ether (DME) from carbon dioxide (CO2) and green hydrogen (H2) offers a sustainable pathway to convert CO2 emissions into value-added products. This heterogeneous catalytic reaction often uses copper (Cu) catalysts due to their low cost compared with their noble metal analogs. Nevertheless, improving the activity and selectivity of these Cu catalysts for these products is highly desirable. In the present study, a new architecture of Cu- and Cu/Zn-based catalysts supported on electrospun alumina nanofibers were synthesized. The catalysts were tested under various reaction conditions using high-throughput equipment to highlight the role of the hierarchical fibrous structure on the reaction activity and selectivity. The Cu or Cu/ZnO formed a unique structure of nanosheets, covering the alumina fiber surface. This exceptional morphology provides a large surface area, up to ~300 m2/g, accessible for reaction. Maximal production of methanol (~1106 gmethanolKgCu-1∙h-1) and DME (760 gDMEKgCu-1∙h-1) were obtained for catalysts containing 7% wt. Cu/Zn with a weight ratio of 2.3 Zn to Cu (at 300 °C, 50 bar). The promising results in CO2 hydrogenation to methanol and DME obtained here point out the significant advantage of nanofiber-based catalysts in heterogeneous catalysis.

A novel semi-dry method for rapidly synthesis ZnO nanorods on SiO2@PTFE nanofiber membrane for efficient air cleaning

Particulate matter including dust and airborne microorganisms has severe effect on indoor air quality and thus be injurious to human health. In this research, inspired by corals, a tentacle-like ZnO nanorods (NRs) decorated SiO 2 @PTFE nanofibers was prepared by a novel semi-dry method combining rapid dipping and solid-phase drying process. The controllable growth of ZnO nanostructures can be achieved by adjusting the numbers of dipping cycles. It may be the most simple and effective way to prepare sufficiently crystallized ZnO nanostructures at relatively facile conditions without high temperature calcination and any pressure vessels. The obtained ZnO NRs-SiO 2 @PTFE nanofiber membrane (NFM) with a hierarchical fibrous structure possesses uniform pore structure (average pore size 0.92 μm), high gas permeance (626.4 m 3 ∙m −2 ∙h −1 ∙kPa −1 ), and a superior filtration property (99.997% for 0.3 μm particulates). Moreover, the active ZnO with enhanced specific surface also exhibits good antibacterial property with sterilization rate of 99.67% and 99.93% for E. coli and B. subtilis , respectively. The ZnO growth mechanism and air cleaning principle including dust filtration and bacteria sterilization were analyzed by the corresponding experiments. This work provides a new insight into the dual-function air cleaning membrane preparation via a mild and simple reaction conditions, energy efficient and environment friendly strategy. • A facile semi-dry method for preparing ZnO NRs decorated SiO 2 @PTFE NFMs. • The corals tentacle-like ZnO NRs help to capture and deactivate microorganisms. • The membrane exhibits excellent filtration property with low pressure drop. • The method is energy saving and environment friendly for scale up application.

Mechanical properties of an interpenetrating network poly(vinyl alcohol)/alginate hydrogel with hierarchical fibrous structures.

Bioinspired hierarchical fibrous structures were constructed in an interpenetrating poly(vinyl alcohol, PVA)/alginate hydrogel network to improve its mechanical properties. The interpenetrating hydrogel network with hierarchical fibrous structures was prepared by combining the confined drying method and freeze–thaw method. First, Ca2+ cross-linked alginate formed a nano–micro hierarchical fibrous structure via the confined drying method. Then, PVA that was uniformly distributed among the Ca2+–alginate chains was cross-linked by hydrogen bonding via the freeze–thaw method, further dividing the hierarchical fibers into finer fibers. The results of a tensile test demonstrated that both the tensile stress and fracture energy improved by more than double after the introduction of 2 wt% PVA, achieving a combination of high strength (∼12.9 MPa), high toughness (∼13.2 MJ m−3) and large strain (∼161.4%). Cyclic tensile tests showed that a hysteresis loop existed on the loading–unloading curves of the hydrogel along the fibrous directions, and a good self-recovery property emerged after resting for a period of time. The hydrogel with hierarchical fibrous structures constructed by alginate and PVA can be employed in biomedical applications in the future.

Engineered Myoblast-Laden Collagen Filaments Fabricated Using a Submerged Bioprinting Process to Obtain Efficient Myogenic Activities.

The skeletal muscle tissue comprises a hierarchical fibrous structure with fully aligned myofibers. To obtain a unique aligned engineering construct for regenerating muscle tissue, we adopted a submerged bioprinting process. Here, 3 wt % collagen and 6 wt % alginate solutions were used as a matrix cell-encapsulating bioink and supporting solution in the printing bath, respectively. By manipulating the processing parameters (various alginate weight fractions in the bath, nozzle moving speed, and hydrostatic pressure), cell-laden filaments (∼50 μm in diameter) were successfully fabricated. They presented a high degree of alignment of the fibrillated collagen and meaningful initial viability (∼90%) of the C2C12 myoblasts. In vitro cellular responses indicated that fully aligned F-actin filaments of myoblasts were developed, resulting in a high degree of alignment/formation of myotubes, compared to that in the controls (>100 μm diameter of cell-laden filaments). Furthermore, the expression levels of various myogenic genes (Myod1, Myh2, and Myog) were measured using a reverse transcription polymerase chain reaction on day 21 of the cell culture, and the results showed that the cell-laden filaments with a small diameter had considerably greater gene expression levels (2.2-8-fold) than those with a relatively large diameter. Thus, the printing process described herein can provide a new potential biofabricating platform to obtain cell-laden engineering constructs for various tissues.

Regional variations in discrete collagen fibre mechanics within intact intervertebral disc resolved using synchrotron computed tomography and digital volume correlation

Many soft tissues, such as the intervertebral disc (IVD), have a hierarchical fibrous composite structure which suffers from regional damage. We hypothesise that these tissue regions have distinct, inherent fibre structure and structural response upon loading. Here we used synchrotron computed tomography (sCT) to resolve collagen fibre bundles (∼5μm width) in 3D throughout an intact native rat lumbar IVD under increasing compressive load. Using intact samples meant that tissue boundaries (such as endplate-disc or nucleus-annulus) and residual strain were preserved; this is vital for characterising both the inherent structure and structural changes upon loading in tissue regions functioning in a near-native environment. Nano-scale displacement measurements along >10,000 individual fibres were tracked, and fibre orientation, curvature and strain changes were compared between the posterior-lateral region and the anterior region. These methods can be widely applied to other soft tissues, to identify fibre structures which cause tissue regions to be more susceptible to injury and degeneration. Our results demonstrate for the first time that highly-localised changes in fibre orientation, curvature and strain indicate differences in regional strain transfer and mechanical function (e.g. tissue compliance). This included decreased fibre reorientation at higher loads, specific tissue morphology which reduced capacity for flexibility and high strain at the disc-endplate boundary. Statement of significanceThe analyses presented here are applicable to many collagenous soft tissues which suffer from regional damage. We aimed to investigate regional intervertebral disc (IVD) structural and functional differences by characterising collagen fibre architecture and linking specific fibre- and tissue-level deformation behaviours. Synchrotron CT provided the first demonstration of tracking discrete fibres in 3D within an intact IVD. Detailed analysis of regions was performed using over 200k points, spaced every 8 μm along 10k individual fibres. Such comprehensive structural characterisation is significant in informing future computational models. Morphological indicators of tissue compliance (change in fibre curvature and orientation) and fibre strain measurements revealed localised and regional differences in tissue behaviour.

Facile preparation of cellulose hydrogel with Achilles tendon-like super strength through aligning hierarchical fibrous structure

The extreme mechanical strength of fibrous connective tissues in the human body, such as ligaments and tendons, has always been challenging for hydrogel scientists. Here, we created extremely strong, purely cellulose-based hydrogels (DCC-E gels). The fracture stress and Young’s modulus of the gels were improved to the level of an Achilles tendon even at their equilibrium swollen state. To make DCC-E gels, regenerated cellulose gels were first prepared with ethanol as the anti-solvent. DCC-E gels were then prepared by applying Drying in Confined Condition method, where regenerated cellulose gels were prestretched and dried while their length was fixed. Although strength improvement of materials is typically only achieved at the expense of toughness, a significant increase in strength was achieved while maintaining high levels of toughness. The high strength and toughness of the DCC-E gels were realized by optimizing the cellulose fibril arrangement from nanoscale to macroscale, which was done by selection of an appropriate solvent used for cellulose regeneration. Parallel aggregated fibrous structures observed in the DCC-E gels are thought to play a central role in the enhancement of both toughness and strength. This study can assist in expanding the application of biopolymer-based hydrogels in tissue engineering and soft electronics.

Durable Antibacterial and Antifungal Hierarchical Silver-Embedded Poly(vinylidene fluoride-co-hexafluoropropylene) Fabricated Using Electrospinning

The aim of this study was to demonstrate the use of electrospinning to produce hierarchical fibrous structures for antibacterial and antifungal applications. Silver nanoparticles (Ag NPs) are produ...

<i>In situ</i> Tracking of Individual Collagen Fibre Bundles in Intact Loaded Intervertebral Discs Exposes Damage-Susceptible Collagen Organisations

Many soft tissues, such as the intervertebral disc (IVD), have a hierarchical fibrous composite structure which suffers from regional damage. We hypothesise that clinical injury patterns in these tissues occur in localised regions where there is an integrated requirement for both marked compliance and significant load transfer. Here we used synchrotron computed tomography (sCT) to resolve collagen fibre bundles (~5μm width) in 3D throughout an intact native rat lumbar IVD under increasing compressive load. Using intact samples meant that tissue boundaries (such as endplate-disc or nucleus-annulus) and residual strain were preserved; this is vital for characterising both the inherent structure and structural changes upon loading in tissue regions functioning in a near-native environment. Nano-scale displacement measurements along >10,000 individual fibres were tracked, and fibre orientation, curvature and strain changes were compared between the failure-prone posterior-lateral region and the more robust anterior region. These methods can be widely applied to other soft tissues, to identify fibre structures which cause tissue regions to be more susceptible to injury and degeneration. Our results demonstrate for the first time that highly-localised changes in fibre orientation, curvature and strain indicate differences in regional strain transfer and mechanical function (e.g. tissue compliance), correlating directly with locations clinically at risk of damage. This included decreased fibre reorientation at higher loads, specific tissue morphology which reduced capacity for flexibility and high strain at the disc-endplate boundary.

Polypropylene/Polyvinyl Alcohol/Metal-Organic Framework-Based Melt-Blown Electrospun Composite Membranes for Highly Efficient Filtration of PM2.5.

Particulate matter 2.5 (PM2.5) has become a public hazard to people’s lives and health. Traditional melt-blown membranes cannot filter dangerous particles due to their limited diameter, and ultra-fine electrospinning fibers are vulnerable to external forces. Therefore, creating highly efficient air filters by using an innovative technique and structure has become necessary. In this study, a combination of polypropylene (PP) melt-blown and polyvinyl alcohol (PVA)/zeolite imidazole frameworks-8 (ZIF-8) electrospinning technique is employed to construct a PP/PVA/ZIF-8 membrane with a hierarchical fibrous structure. The synergistic effect of hierarchical fibrous structure and ZIF-8 effectively captures PM2.5. The PP/PVA composite membrane loaded with 2.5% loading ZIF-8 has an average filtration efficacy reaching as high as 96.5% for PM2.5 and quality factor (Qf) of 0.099 Pa−1. The resultant membrane resists 33.34 N tensile strength and has a low pressure drop, excellent filtration efficiency, and mechanical strength. This work presents a facile preparation method that is suitable for mass production and the application of membranes to be used as air filters for highly efficient filtration of PM2.5.

Effects of node with discontinuous hierarchical fibers on the tensile fracture behaviors of natural bamboo

Bamboo is widely planted in the world and many species of bamboo are intensively used as sustainable bio-composite materials in the construction of houses, pavilions, furniture and bridges, etc. The bamboo nodes play an important role on natural bamboo's strength. This paper is focused on the structure-property-fracture relations of the natural Moso bamboo with node. The inner structures are characterized by optical and scanning electron microscopy (SEM), which indicated that bamboo node has coarser fiber bundles, higher volumes of fibers and 3D woven hierarchical fibrous structures. Though the fibers on the out and inner skins of node are discontinuous, it has higher strength than internodes samples. There are three kinds of fracture behaviors within bamboo node during the tensile fracture process as detected by acoustic emission (AE), which are matrix (parenchyma cells) failure, fiber dissociation and fiber breakage. The AE results indicated bamboo node has much lower volumes of fracture behaviors, higher proportions of fiber dissociation and matrix failure due to its hierarchical fibrous woven structure. The strengthening effects within bamboo node are concluded as coarse fiber bundles, high volumes of fibers, fiber pull-out and crack deflections.

Harnessing electrospun nanofibers to recapitulate hierarchical fibrous structures of meniscus.

The meniscus has complex biomechanical functions endowed by the hierarchical fibrous structure of its extracellular matrix (ECM), which plays a central role in protecting the knee joint. However, it is challenging to recapitulate the ECM structure of the meniscus. Herein, we used electrospinning to prepare various scaffolds with distinct nanofibrous structures to approximate that of the heterogeneous ultrastructure of meniscus ECM. Our results showed that adjusting the deposition manner of nanofibers during electrospinning could effectively manipulate the architectures of resulting scaffolds. This approach led to electrospun scaffolds with random or aligned fibrous structures that reassemble the surface or superficial layers of the meniscus. We also showed that assembly of electrospun nanofibers into yarn-like configurations replicates the circumferentially aligned fibrous bundles of the inner part of the meniscus. These scaffolds exhibited distinct fibrous anisotropies and mechanical properties. In vitro studies indicated good cytocompatibility of scaffolds, especially, the yarn scaffold supported considerable meniscus cell infiltration. The meniscus cells, in turn, enhanced the mechanical properties of scaffolds. Taken together, these data imply that electrospun scaffolds may have potential in enhancing meniscus repair and regeneration.

Lamellar Bilayer to Fibril Structure Transformation of Tough Photonic Hydrogel under Elongation

Synthetic hydrogels possessing both macroscopic anisotropic structure and toughness, which are analogous to the load-bearing bio-tissues such as muscles and tendons, are rarely available. Studying the molecular mechanism of tough and anisotropic hydrogel under deformation is beneficial to understand the load-deformation functions of soft bio-tissues. In this work, the deformation-induced structure transformation of a macroscopically anisotropic and tough hydrogel has been investigated to understand the role of structure evolution for enhanced toughness. At rest, the hydrogel possesses a well-defined hierarchical structure in which self-assembled nanometer thick lamellar bilayers are alternatively stacked in hundred nanometer thick hydrogel matrixes. Stretching along the lamellar direction induces structure transformation from lamellar bilayers to hierarchical fibrous structures aligned along the deformation axis. The generated hierarchical structures consist of micrometer thick fiber bundles made from nanometer thick fibrils analogous to tropo-collagen bundles or microfibrils of the tendon. The fibrous structure formed at large elongation is associated with damage and rupture of the bilayers, which underpins the molecular mechanism of the unique mechanical behaviors of the tough lamellar hydrogel.

Flexural deformation and fracture behaviors of the sandwich turtle rib bones with hierarchical woven fibers

Turtle rib is a kind of bio-composites with excellent fracture resistance and toughness, whose composition and structure were characterized by X-ray diffraction (XRD), Raman spectroscopy and scanning electron microscopy (SEM), which indicated that the turtle rib has woven hierarchical fibrous and sandwich structure. With the aid of acoustic emission (AE), bi-spectrum estimation analysis and Wavelet, the damage behaviors during the flexural fracture process of the ribs can be summarized as three categories: breakage of the mineralized collagen fibers, collagen fiber debonding and organic matrix failure. Sandwich specimens have higher proportions of fiber debonding AE signals, which is consistent with the hierarchical fracture morphology. The AE signal distributions implied that the fracture dynamics of turtle rib bones drive the materials into a self-organized criticality (SOC). The woven hierarchical fibrous and sandwich structure can delay the damage avalanches, certainly making a contribution to the ribs' fracture toughness.

Cladophora Cellulose: Unique Biopolymer Nanofibrils for Emerging Energy, Environmental, and Life Science Applications.

Because of its natural abundance, hierarchical fibrous structure, mechanical flexibility, potential for chemical modification, biocompatibility, renewability, and abundance, cellulose is one of the most promising green materials for a bio-based future and sustainable economy. Cellulose derived from wood or bacteria has dominated the industrial cellulose market and has been developed to produce a number of advanced materials for applications in energy storage, environmental, and biotechnology areas. However, Cladophora cellulose (CC) extracted from green algae has unprecedented advantages over those celluloses because of its high crystallinity (>95%), low moisture adsorption capacity, excellent solution processability, high porosity in the mesoporous range, and associated high specific surface area. The unique physical and chemical properties of CC can add new features to and enhance the performance of nanocellulose-based materials, and these attributes have attracted a great deal of research interest over the past decade. This Account summarizes our recent research on the preparation, characterization, functionalization, and versatile applications of CC. Our aim is to provide a comprehensive overview of the uniqueness of CC with respect to material structure, properties, and emerging applications. We discuss the potential of CC in energy storage, environmental science, and life science, with emphasis on applications in which its properties are superior to those of other nanocellulose forms. Specifically, we discuss the production of the first-ever paper battery based on CC. This battery has initiated a rising interest in the development of sustainable paper-based energy storage devices, where cellulose is used as a combined building block and binder for paper electrodes of various types in combination with carbon, conducting polymers, and other electroactive materials. High-active-mass and high-mass-loading paper electrodes can be made in which the CC acts as a high-surface-area and porous substrate while a thin layer of electroactive material is coated on individual nanofibrils. We have shown that CC membranes can be used directly as battery separators because of their low moisture content, high mesoporosity, high thermal stability, and good electrolyte wettability. The safety, stability, and capacity of lithium-ion batteries can be enhanced simply by using CC-based separators. Moreover, the high chemical modifiability and adjustable porosity of dried CC papers allow them to be used as advanced membranes for environmental science (water and air purification, pollutant adsorption) and life science (virus isolation, protein recovery, hemodialysis, DNA extraction, bioactive substrates). Finally, we outline some concluding perspectives on the challenges and future directions of CC research with the aim to open up yet unexplored fields of use for this interesting material.