Bacterial Cellulose Nanofibers Research Articles

Stabilization of Pickering emulsions with bacterial cellulose nanofibrils (BCNFs) fabricated by electron beam irradiation

Bacterial cellulose (BC) had been considered as a promising Pickering stabilizer for its non-toxicity, high purity, and biocompatibility. The electron beam irradiation (EBI) technology had gained significant attention in the field of cellulose degradation due to its operational convenience and mild reaction conditions. Pickering emulsions using BC degraded by EBI as Pickering stabilizers were successfully prepared. Irradiated bacterial cellulose nanofibers (IBCNFs) exhibited a high aspect ratio(30–80 μm in length and 21–109 nm in width) and high absolute zeta potential (-50 mV). The optimal emulsification performance of IBCNFs was observed at an irradiation dosage of 100 kGy (IBC-100). The emulsions based on IBC-100 achieved an EI value of 96.15 ± 0.19%, while those based on IBC-500 obtained an EI value of 59.93 ± 1.47%. Stable Pickering emulsions were prepared when the concentration of IBC-100 stabilizer exceeded 0.3 wt% with a fixed oil phase of 30%, or when the rapeseed oil phase was below 50% while maintaining a fixed suspension of 0.5 wt% IBCNFs. Confocal laser scanning microscopy (CLSM) demonstrated that IBCNFs facilitated the formation of a dense interfacial layer at the oil-water interface and formed a three-dimensional network within the water phase. Which effectively hindered the aggregation and flocculation between individual oil droplets. Furthermore, rheological findings demonstrated that emulsions possessed primarily exhibited properties of elasticity, and their gel strength could be enhanced by adjusting the irradiation dosages of IBCNFs. Moreover, environmental stability experiments indicated that IBCNFs-based emulsions exhibited exceedingly high temperature (20–80 °C) and pH tolerance (4–12). Flocculation occurred under high acid (pH = 2) conditions and at high ionic levels (≥ 40 mM NaCl), without causing disruption to the emulsion droplet structure. This study provided an innovative approach to preparing cellulose nanofibers with high aspect ratio, which could be utilized as emulsion stabilizers. The study also demonstrated that Pickering emulsions based on IBCNFs exhibit excellent stability and rheological properties. IBCNFs have promising potential to serve as a natural Pickering emulsifier for stabilizing oil-in-water emulsions in various food applications, cosmetic and pharmaceutical formulations.

Hierarchical and reconfigurable interfibrous interface of bioinspired Bouligand structure enabled by moderate orderliness.

Introducing natural Bouligand structure into synthetics is expected to develop high-performance structural materials. Interfibrous interface is critical to load transfer, and mechanical functionality of bioinspired Bouligand structure yet receives little attention. Here, we propose one kind of hierarchical and reconfigurable interfibrous interface based on moderate orderliness to mechanically reinforce bioinspired Bouligand structure. The interface imparted by moderate alignment of adaptable networked nanofibers hierarchically includes nanofiber interlocking and hydrogen-bonding (HB) network bridging, being expected to facilitate load transfer and structural stability through dynamic adjustment in terms of nanofiber sliding and HB breaking-reforming. As one demonstration, the hierarchical and reconfigurable interfibrous interface is constructed based on moderate alignment of networked bacterial cellulose nanofibers. We show that the resultant bioinspired Bouligand structural material exhibits unusual strengthening and toughening mechanisms dominated by interface-microstructure multiscale coupling. The proposed interfibrous interface enabled by moderate orderliness would provide mechanical insight into the assembly of widely existing networked nanofiber building blocks toward high-performance macroscopic bioinspired structural assemblies.

All-in-one tissue adhesive hydrogels for topical wound care

An adhesive tissue sealant that enables rapid formation of new granulation tissue while leading to additional synthesis of extracellular matrix (ECM) to promote tissue regeneration is strongly required in the clinical field. This study presents an all-in-one wound care hydrogel sealant that generates cohesion in response to pH change while adhering stably to tissue. To fulfill this, we employ an injectable boronic acid-conjugated alginate (Al-BA) aqueous sol phase that turns into a soft viscoelastic hydrogel gel phase at physiological pH conditions, thus filling in wounds of any size or depth. Positively charged bacterial cellulose nanofibers ((+)BCNF) are incorporated to reinforce this gel. Compared to the only Al-BA adhesive, the resulting Al-BA/(+)BCNF adhesive hydrogel exhibits substantial adhesion strength while retaining the wound closure even with external mechanical perturbation such as stretching, bending and twisting. Furthermore, in vitro and in vivo wound healing evaluations revealed that fibrous (+)BCNF provides favorable microenvironment for cell migration and proliferation similar to collagen fibers, promoting wound healing and skin regeneration.

The effect of poly(ethylene glycol) on the properties of poly (lactic acid)/silane-modified bacterial cellulose nanocomposites

ABSTRACT This study aimed to investigate the impact of poly (ethylene glycol) (PEG) on the properties of nanocomposites consisting of polylactic acid (PLA) and 3-aminopropyltriethoxysilane-modified bacterial cellulose (MBC) nanofibers. Differential scanning calorimetry (DSC) studies indicated that the presence of PEG enhanced the chain mobility of PLA during crystallization, thereby enabling the MBC to act as efficient nucleation agents. Furthermore, DSC and X-ray diffraction (XRD) analyses provided evidence for the formation of two distinct crystal structures, namely α and α,’ as well as various spherulitic dimensions. Finally, the toughening of PLA was occurred by adding PEG to PLA and ternary nanocomposites.

Impact of Metal Salt Oxidants and Preparation Technology on Efficacy of Bacterial Cellulose/Polypyrrole Flexible Conductive Fiber Membranes.

In this study, we investigated the preparation and characterization of flexible conductive fiber membranes (BC/PPy) using different metal salt oxidants on bacterial cellulose (BC) and pyrrole (Py) in the in situ polymerization and co-blended methods, respectively. The effects of these oxidants, namely, ferric chloride hexahydrate (FeCl3·6H2O) and silver nitrate (AgNO3), on the structural characterization, conductivity, resistance value and thermal stability of the resulting materials were assessed by scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). A comparative study revealed that the BC/PPy conductive fiber membrane prepared using FeCl3·6H2O as the oxidant had a resistance value of 12 Ω, while the BC/PPy conductive fiber membrane prepared using AgNO3 as the oxidant had an electrical resistance value of 130 Ω. The conductivity of the same molar ratio of BC/PPy prepared using FeCl3·6H2O as an oxidant was 10 times higher than that of the BC/PPy prepared using AgNO3 as an oxidant. Meanwhile, the resistance values of the conductive fiber membranes prepared from BC and PPy by the co-blended method were much higher than the BC/PPy prepared by in situ polymerization. SEM and XPS analyses revealed that when FeCl3·6H2O was used as the oxidant, the Fe-doped polypyrrole conductive particles could form uniform and dense conductive layers on the BC nanofiber surfaces. These two metal salt oxidants demonstrated differences in the binding sites between PPy and BC.

DNA-Directed Assembly of Hierarchical MOF-Cellulose Nanofiber Microbioreactors with "Branch-Fruit" Structures.

Assembling metal-organic frameworks (MOFs) into ordered multidimensional porous superstructures promises the encapsulation of enzymes for heterogeneous biocatalysts. However, the full potential of this approach has been limited by the poor stability of enzymes and the uncontrolled assembly of MOF nanoparticles onto suitable supports. In this study, a novel and exceptionally robust Ni-imidazole-based MOF was synthesized in water at room temperature, enabling in situ enzyme encapsulation. Based on this MOF platform, we developed a DNA-directed assembly strategy to achieve the uniform placement of MOF nanoparticles onto bacterial cellulose nanofibers, resulting in a distinctive "branch-fruit" structure. The resulting hybrid materials demonstrated remarkable versatility across various catalytic systems, accommodating natural enzymes, nanoenzymes, and multienzyme cascades, thus showcasing enormous potential as universal microbioreactors. Furthermore, the hierarchical composites facilitated rapid diffusion of the bulky substrate while maintaining the enzyme stability, with ∼3.5-fold higher relative activity compared to the traditional enzyme@MOF immobilized in bacterial cellulose nanofibers.

Hybrid nanocomposite wound dressings by a novel nanorod vitamin-B3-Ag metal-organic framework and bacterial cellulose nanofibers

This paper presents a novel nanorod metal-organic framework made of silver nods configured within nicotinic acid (vitamin-B3) linkers (AgNA) aimed at wound healing applications. X-ray diffraction analysis indicated that the synthesized AgNA MOFs comprised of zigzag chains of silver (I) nicotinate with orthorhombic crystal structure. Electron microscopy showed nanorod structures for the MOFs with uniform dimensions and element distribution. By seeding the AgNA MOFs into the bacterial cellulose (BC) nanofibers, an innovative BC-xAgNA nanocomposite was fabricated for wound dressing applications. MTT assay demonstrated improved biocompatibility for the BC-AgNA nanocomposites up to more than 116% cell viability. The Acridine Orange staining showed more than 87% of live/dead cells ratio for the prepared wound dressings. The fibroblast cells attached on the BC-AgNA nanocomposite exhibited expanded morphologies with long filopodia. The in vitro cellular scratch analysis demonstrated excellent wound healing by more than of 96% wound closure rate of the wound cured with the BC-AgNA nanocomposite. Evaluating the BC-xAgNA nanocomposites revealed their appropriate antibacterial activities against different bacterial strains. Synergistic wound healing effects corresponding to vitamin-B3, Ag, and BC nanofibers were observed. The results confirmed that the designed BC-AgNA nanocomposite can potentially be considered for wound healing and damaged tissue regeneration.

Tailored lipid crystallization in confined microparticle domains through alkyl chains infiltration from cellulose nanofiber surfactants

Through this study, we show that hydrophobically modified cellulose nanofibers can substantially influence the subcell crystallization of ceramide-based lipids within confined particle domains. We demonstrate that C18 alkyl chain-conjugated bacterial cellulose nanofibers (BCNFC18) can armor ceramide (Cer)/stearyl alcohol (SA) lipid crystal phases to form ceramide-based lipid microparticles (CerMPs). X-ray diffraction measurements revealed that by armoring CerMPs with BCNFC18, lipid crystal structures could be changed from the β subcell to β’ subcell. Less generation of β subcells within a densely packed lipid crystal structure is critically important to confine the growth of Cer/SA lipid crystals within a microparticle domain. By performing energy calculations and interfacial rheology analysis, we found that the alkyl chains of BCNFC18 infiltrated the CerMP peripheries. We demonstrate through this study that the alkyl chains of BCNFC18 can associate with the highly crystalline Cer/SA crystal phase of a lipid, thereby strengthening the interface between the lipid and the BCNFC18. The study findings highlight the importance of engineering nanoscale fiber surfactants capable of alkyl chain infiltration. These surfactants can be used to prepare crystallizable active ingredients in a feasible and diverse manner for applications in the pharmaceutical, food, and cosmetic industries.

Effect of TEMPO-oxidized bacterial cellulose nanofibers stabilized Pickering emulsion of cinnamon essential oil on structure and properties of gelatin composite films

Pure gelatin film often exhibits high hydrophilicity and a lack of antibacterial activity, hindering its practical application in the field of food preservation. To address these issues, we incorporated 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO)-oxidized bacterial cellulose (TOBC) nanofibers stabilized cinnamon essential oil (CEO) Pickering emulsions into the gelatin matrix to develop active food packaging films. The study revealed that the good distribution of emulsion droplets in the film matrix. While with increasing Pickering emulsion proportion, the microstructures of composite films were more heterogeneous, showing some pores or cavities. In addition, the insertion of TOBC-stabilized CEO emulsions could improve the elongation at break (EAB), water-resistance, UV blocking ability, and antibacterial activity of film, but reduced its tensile strength (TS) and water vapor barrier properties (WVP). Notably, the film prepared with 4 % TOBC-stabilized CEO Pickering emulsion demonstrated enhanced preservation of strawberries. Overall, the as-prepared gelatin-based active composite films have considerable potential for food packaging.

Using bacterial cellulose to bridge covalent and physical crosslinks in hydrogels for fabricating multimodal sensors

Network optimization is vital for the polysaccharide based hydrogels with multiple crosslinks. In this study, we developed a ‘two-step’ strategy to activate synergistic effect of chemical and physical crosslinks using a poly (vinyl alcohol) (PVA)/bacterial cellulose (BC) hydrogel as a template. The BC nanofibers, on the one hand, acted as nucleating agents, participating in the crystallization of PVA, and on the other hand, were also involved in the formation of boronic ester bond, anchored with the PVA chains via chemical bonding. Therefore, the existence of BC nanofibers, as ‘bridge’, linked the crystalline regions and amorphous parts of PVA together, associating the two characteristic crosslinks, which was conducive to load transfer. The mechanical properties of resultant hydrogels, including the tensile elongation and strength, as well as fracture toughness, were significantly improved. Moreover, the dually cross-linked hydrogels possessed ionic conductivity, which was sensitive to the tensile deformation and environmental temperature. This study clarifies a unique role of BC nanofibers in hydrogels, and proposes an effective approach to construct multiple networks in the nanocellulose reinforced PVA hydrogels.

Calcium crosslinked macroporous bacterial cellulose scaffolds with enhanced in situ mineralization and osteoinductivity for cranial bone regeneration

The inherent biological inertness and lack of three-dimensional (3D) macroporous structures greatly hinder the use of pristine bacterial cellulose (BC) as a tissue engineering scaffold for bone regeneration. To address this issue, we developed a simple and effective strategy to fabricate a BC-based scaffold with excellent bioactivity and macroporous structure by crosslinking short-cut BC nanofibers using Ca2+. The Ca2+ crosslinked macroporous BC scaffold (MPBC@Ca) presents better structural stability due to the enhanced cellulose hydration. Importantly, the Ca2+ on the surface of BC nanofibers can serve as an active nucleation site to accelerate the deposition of hydroxyapatite (HAp), which is beneficial for the construction of biomimetic bone tissue extracellular matrix (ECM) microenvironment. The HAp-deposited MPBC@Ca scaffolds (HAp-MPBC@Ca) with biomimetic ECM microenvironment have excellent cytocompatibility and enhanced osteogenic differentiation of stem cells in vitro. Furthermore, the results of in vivo tests revealed that the HAp-MPBC@Ca scaffold has favorable osteoinductivity and accelerates cranial bone tissue regeneration. This study proposes a novel strategy to improve the bioactivity of BC and presents the great potential of biomimetic ECM microenvironment BC-based scaffold for repairing large cranial bone defects.

Coupling iron-based zeolitic imidazolate Framework-8 and cellulose nanofiber for efficient peroxymonosulfate oxidation

The development of biocompatible Fenton-like catalysts with outstanding activities and stabilities, using low-cost sustainable bio-sourced materials, has garnered significant attention, yet remains a substantial challenge. In this study, we successfully constructed monodispersed iron anchored on a 3D porous N-doped carbon substrate (CNF@Fe-NC) via one-step annealing of Fe-based zeolitic imidazolate frameworks (ZIFs) and bacterial cellulose nanofibers (CNFs) as highly efficient peroxide-activation catalysts. Due to abundant micropores and mesopores in the interconnected CNF support and ZIFs, even after annealing, the obtained catalysts have a specific surface area of up to 739.4 m2/g. Owing to monodispersed Fe-Nx species and abundant nanofibrous structure, CNF@Fe-NC exhibited outstanding catalytic stability and superior activity for peroxymonosulfate (PMS) activation toward organic contaminant oxidation, outperforming the benchmark Fenton system. Surface Fe-Nx sites and CNF defects could adsorb negatively charged PMS to produce nonradical CNF@Fe-NC-PMS* complexes and high-valent iron oxo species (FeV = O), rather than radicals and 1O2, for eliminating pollutants. The strong iron − support electronic interaction and abundant π-conjugation in the CNF support facilitated the efficient adsorption and activation of PMS and the uniformly dispersed Fe species in CNF@Fe-NC improved atom-utilization efficiency. This study provides a clue to design biocompatible cellulosic-based Fenton-like catalysts for the removal of organic contaminants.

Orange peel-like triboelectric nanogenerators with multiscale micro-nano structure for energy harvesting and touch sensing applications

With the continuous advancements in technology, triboelectric nanogenerators (TENGs) have gained significant traction as efficient harnessers of low-frequency mechanical energy to meet the escalating energy demands. Notably, employing solid polymer electrolyte (SPE) as a contact layer or optimizing the microstructural composition of the surface material represents a prevalent strategy for augmenting the output performance of TENGs. However, the fabrication of numerous microstructures poses significant challenges, particularly in terms of incorporating environmentally harmful materials. Moreover, the utilization of triboelectric nanogenerators is further constrained by limitations associated with electrode materials. Although various techniques are available for producing transparent and stretchable electrodes for such generators, these procedures can be intricate and necessitate the use of hazardous chemicals. In this study, we exploit Poly(vinyl alcohol) (PVA) and natural bacterial cellulose (BC) nanofibers to fabricate contact layers with OP structures characterized by micron-scale domes and nanoscale microcracks. The electrodes were fabricated using BC hydrogel and ionic liquids(ILs). Under the action of hydrogen bond topological network, a multi-scale structure is formed comprising of a molecular-scale interlacing network of hydrogen bonds and a nanoscale fiber skeleton, which synergistically confer the ionic gel with remarkable tensile strength and high ionic conductivity (up to 83.51mS/cm). The resulting OP-TENG exhibited an output open-circuit voltage of 280 V, a short-circuit current of 24μA, and a maximum power density of 5.6 W m−2, enabling it to illuminate up to 303 LEDs. A SSEM-TENG was devised by stacking two single electrode mode TENGs on top of each other using a single wire. This innovative design holds great potential for applications in wearable motion monitoring, high-precision writing stroke recognition, and low-frequency mechanical energy harvesting.

Poly(methyl methacrylate)/ bacterial cellulose nanofiber nanocomposites prepared by solution casting method and its reinforcement study

Poly(methyl methacrylate)/ bacterial cellulose nanofiber nanocomposites prepared by solution casting method and its reinforcement study

Insights into controlling bacterial cellulose nanofiber film properties through balancing thermodynamic interactions and colloidal dynamics

Proposed mechanistic model: balancing electrokinetic and thermodynamic factors in CNF colloid to film transition.

Intrinsic lithiophilic carbon host derived from bacterial cellulose nanofiber for dendrite-free and long-life lithium metal anode

Intrinsic lithiophilic carbon host derived from bacterial cellulose nanofiber for dendrite-free and long-life lithium metal anode

Silk fibroin/polyacrylamide-based tough 3D printing scaffold with strain sensing ability and chondrogenic activity

Cartilage tissue plays an important role in our life activities. The poor self-repair capacity makes cartilage tissue engineering an urgent clinical demand. Among them, the development of tissue engineering scaffolds with both biomimetic features and microenvironment signal sensing abilities could significantly promote the development of cartilage tissue engineering. While most of the reported cartilage scaffolds have no intelligent sensing features. Herein, a ternary composite 3D printing scaffold with both strain sensing ability and desired mechanical property was developed, by using regenerated silk fibroin (RSF) and polyacrylamide (PAM) as main matrixes, and oxidized bacterial cellulose nanofibers (OBC) as filler. Then, the mechanical property, strain sensing ability and corresponding ectopic chondrogenic activity of the RSF/PAM/OBC 3D printing scaffold were comprehensively investigated and verified through in vitro and in vivo studies. Results showed that the RSF/PAM/OBC (OBC-6.3 wt%) scaffold owns effective strain sensing property and desired ectopic chondrogenesis capabilities in the subcutaneous microenvironment. It could be used for reliable monitoring the joint movements, related motion amplitudes, and also promoting the cartilage specifical genes expression. These features not only confirmed the great potential of these smart scaffolds for applications in tissue reconstruction and mechanical stimulus monitoring of the corresponding tissue microenvironment, but also proved the possibility of employing various 3D printing scaffolds as flexible bioelectronics.

High-performance electro-responsive ionic soft actuators based on polypyrrole coated functional carboxylated bacterial cellulose nanofibers for bioinspired applications

High-performance electro-responsive ionic soft actuators based on polypyrrole coated functional carboxylated bacterial cellulose nanofibers for bioinspired applications

Flexible, ultrathin and integrated nanopaper supercapacitor based on cationic bacterial cellulose

Cellulose composite nanopaper is extensively employed in flexible energy storage systems owing to their light weight, good flexibility and high specific surface area. Nevertheless, achieving flexible and ultrathin nanopaper supercapacitors with excellent electrochemical performance remains a challenge. Herein, surface cationization of bacterial cellulose (BC) nanofibers was conducted using 2,3-epoxypropyltrimethylammonium chloride (EPTMAC). Anion-doped polypyrrole (PPy) was incorporated onto the surface of the cationic bacterial cellulose (BCE) nanofibers by an interfacial electrostatic self-assembly process. The obtained PPy@BCE electrode exhibited excellent electrochemical performance, including an areal capacitance of 3988 mF cm−2 at 1.0 mA cm−2 and a capacitance retention of 97 % after 10,000 cycles. A laminated paper-forming strategy was adopted to design and fabricate all-in-one integrated flexible supercapacitors (IFSCs) using PPy@BCE nanopaper as electrodes and BC nanopaper as a separator. The IFSCs showed superior areal capacitance (3669 mF cm−2 at 1 mA cm−2), high energy density (193.7 μWh cm−2 at a power density of 827.3 μW cm−2), and outstanding mechanical flexibility (with no significant capacitance attenuation after repeatedly bending for 1000 times). The present strategy paves a way for the large-scale production of paper-based energy storage devices.

Fibrous Conductive Metallogels with Hybrid Electron/Ion Networks for Boosted Extreme Sensitivity and High Linearity Strain Sensor.

Fibrous strain sensing materials with both high sensitivity and high linearity are of significant importance for wearable sensors, yet they still face great challenges. Herein, a photo-spun reaction encapsulation strategy is proposed for the continuous fabrication of fibrous strain sensor materials (AMGF) with a core-sheath structure. Metallogels (MOGs) formed by bacterial cellulose (BC) nanofibers and Ag nanoparticles (AgNPs), and thermoplastic elastomers (TPE) are employed as the core and sheath, respectively. The in situ ultraviolet light reduction of Ag+ ensured AgNPs to maintain the interconnections between the BC nanofibers and form electron conductive networks (0.31 S m-1 ). Under applied strain, the BC nanofibers experience separation, bringing AMGF a high sensitivity (gauge factor 4.36). The concentration of free ions in the MOGs uniformly varies with applied deformation, endowing AMGF with high linearity and a goodness-of-fit of 0.98. The sheath TPE provided AMGF sensor with stable working life (>10000 s). Furthermore, the AMGF sensors are demonstrated to monitor complex deformations of the dummy joints in real-time as a wearable sensor. Therefore, the fibrous hybrid conductive network fibers fabricated via the photo-spun reaction encapsulation strategy provide a new route for addressing the challenge of achieving both high sensitivity and high linearity.