Synthetic helical peptides on nanofibers to activate cell-surface receptors and synergistically enhance critical-sized bone defect regeneration.

More than 500,000 bone grafting procedures are performed annually in the USA. Considering the significant limitations of available bone grafts, we previously invented a phase-separation technology to generate nanofibrous poly(l-lactic acid) (PLLA) scaffolds that mimic the bone matrix collagen in nanofiber geometry and enhance bone regeneration. Here we report the development of nanofibrous scaffolds with covalently attached synthetic peptides that mimic native collagen peptides to activate the two main collagen receptors in bone cells, discoidin domain receptor 2 (DDR2) and ß1 integrins. We synthesized a PLLA-based graft-copolymer to enable covalent peptide conjugation via a click reaction. Using PLLA and the graft-copolymer, we developed 3D scaffolds with interconnected pores and peptides-containing nanofibers to activate DDR2 and ß1 integrins of osteogenic cells. The degradation rate and mechanical properties of the scaffolds are tunable. The peptides-decorated nanofibrous scaffolds demonstrated 7.8 times more mineralized bone regeneration over the control scaffolds without the peptides in a critical-sized bone defect regeneration model after 8 weeks of implantation, showing a synergistic effect of the two peptides. This study demonstrates the power of scaffolds to mimic ECM at both nanometer and molecular levels, activating cell surface receptors to liberate the innate regenerative potential of host stem/progenitor cells.

The revealing of the Cyto-genotoxic properties (Allium and MTT) and the effect of chicken meat quality of characterized zein-eugenol nanofibers.

Electrospun zein-based eugenol nanofibers (ZEnF) with diameters (148.19-631.52 nm) were fabricated. Thermal degradation was found as <15 % until 300 °C while the nanofiber diffraction pattern presented three main peaks among the 5o and 45o positions. ZEnF was not only evaluated as non-toxic to cells but also possessed anticancer characteristics revealing with the MCF-7 cell line at 800 µg/mL (reduction: 18.08 %) and 1600 µg/mL (reduction: 41.64 %). Allium tests revealed that ZEnF did not have any adverse impact on the health status (chromosomes-DNA) of exposed organisms. Following the nanofiber coating for chicken meat parts (thigh and breast), it was observed up to 1.25 log CFU/g limitation in total viable bacteria counts (p < 0.05). The sensory score (difference: 3.64 in 10 points scoring on the 6th day of the cold storage) and odor score of chicken meat samples were found to be as higher than control samples (p < 0.05).

Temperature-sensitive poly(N-isopropylacrylamide)/polylactic acid/lemon essential oil nanofiber films prepared via different electrospinning processes: Controlled release and preservation effect.

To develop an optimized controlled-release system based on temperature-sensitive poly(N-isopropylacrylamide) (PNIPAAm) nanofibers, we prepared three types of temperature-controlled preservative films. These films were composed of PNIPAAm, polyvinyl alcohol (PVA), polylactic acid (PLA), and lemon essential oil (LEO), and were fabricated using uniaxial, coaxial, and layered spinning techniques. The nanofiber films obtained by layered spinning exhibited a sandwich structure, demonstrating superior physical barrier properties, mechanical strength, and thermal resistance. Fourier-transform infrared spectroscopy confirmed the hydrogen bonding interaction between the polylactic acid/lemon essential oil and PNIPAAm layers. LEO release tests showed that PNIPAAm functions as a temperature-responsive switch, suppressing LEO release below and promoting it above the critical solution temperature. After a sustained release at 40 °C for 5 days, the layered film maintained significant antibacterial activity, effectively extending the shelf life of blackberries to 4 days. Considering its physical barrier, mechanical, and sustained-release properties, the layered film derived from PNIPAAm shows great potential as an intelligent temperature-controlled cling film to effectively extend the freshness of perishable products.

Poly (lactic acid) electrospun nanofiber membranes: Advanced characterization for biomedical applications with drug loading performance studies.

Traditional dressings have shortcomings such as poor moisture absorption and easy to adhere, making the development of new dressings crucial. In this work, a PLA/PVP crosslinked drug-loaded nanofiber membrane was prepared through electrospinning and ultraviolet crosslinking, with poly (lactic acid) (PLA), polyvinylpyrrolidone (PVP), and salicylic acid (SA) as starting materials. The results demonstrated that the inclusion of PVP notably boosted the viscosity and conductivity of the blend spinning solution. The roughness of the fabricated fiber was elevated, and the diameter of the fibers was more uniform. Additionally, the incorporation of PVP not only enhanced the porosity of the fiber membrane but also effectively decreased its contact angle. Notably, when the PVP content reached 40 %, the contact angle underwent a substantial reduction, decreasing significantly from 125.4° to 82.2°. The SA drug-loaded fiber membrane exhibited a notable bacteriostatic effect against Escherichia coli and Staphylococcus aureus, with its release behavior adhering to Fick's diffusion law. In the cell viability experiment, the cell proliferation rate increased from 94 % to 129 % after 3 days. This shows that the prepared membrane has good antibacterial effect and cell compatibility, which provides a theoretical basis for the construction of a new medical dressing.

Supported Supramolecular Hydrogel Nanoarchitectonics for Tunable Biocatalytic Flow Activity.

Enzymatically-active polyelectrolyte multilayers containing n layers of phosphatase (APn-PEM) induce the formation of supported biocatalytic supramolecular hydrogels when brought in contact with the precursor tripeptide Fmoc-FFpY (Fmoc = N-fluorenylmethyloxycarbonyl; F = Phenylalanine; Y = Tyrosine; p = phosphate group). APn-PEM triggers the spatially-localized hydrogelation reaching 2, 17 and 350 µm of thickness for n = 1, 2 and 3, respectively. As observed by cryo scanning electron microscopy, a dense nanofibrous network underpinning the hydrogel shows parallelly orientated Fmoc-FFY peptide-based fibrils, perpendicular to the substrate. For the gel generated by the AP3-PEM, fluorescence confocal microscopy images show that during the peptide self-assembly, some enzymes are distributed in the hydrogel, preferentially located in few dozens of micrometers above the substrate. In addition, a self-assembly growth rate of 5 µm min-1 is determined when the hydrogelation starts. Through transmission electron microscopy immuno-labelling experiments on self-assemblies generated in solution, we observe that AP are decorating the Fmoc-FFY nanofibers. It is observed both a long-term stability and a higher biocatalytic activity of the so AP-encapsulated hydrogel compared to the bare APn-PEM. This bioactivity can be tuned by the number n in batch and under continuous flow conditions. To illustrate the versatility of this enzyme-supported strategy, multi-catalytic transformations in continuous flow conditions have been successfully carried out using supported supramolecular hydrogel.

A bio-based, self-healable, conductive rubber film with oxidized cellulose nanofiber segregated network.

Rubber composites are indispensable in all areas of our daily lives. However, the formation of permanent crosslinked networks in rubber materials makes it difficult to recycle, resulting in a non-negligible waste of resources. In this paper, a vulcanization-free, fully bio-sourced rubber composite was prepared by using oxidized natural rubber (oNR) and oxidized cellulose nanofibers (TOCFs). TOCFs are selectively dispersed between the latex particles to form a segregated network. Meanwhile, the formation of hydrogen-bonding between oxygenated polar groups of oNR and abundant hydroxyl and carboxyl groups of TOCFs improves their interfacial interactions. This special structure promotes strain-induced crystallization (SIC) behavior of oNR matrix, giving its tensile strength up to 14.7 MPa. Furthermore, the oNR/TOCFs film shows excellent self-healing efficiency (96 %) at 40 °C for 5 h. The hygroscopicity of the TOCFs segregated network can turn the oNR/TOCFs film to be a conductive film by regulating the absorbed water content. The film has high conductivity (0.05 S/m) at a water content of 8.99 wt%, and the resistance change (RV/R0) can be varied between 1-5.9 × 10-6 at a water content range of 0-8.99 wt%, which makes it have potential for a wide range of humidity monitoring applications.

Regulation of Osteogenic Differentiation of hBMSCs by the Overlay Angles of Bone Lamellae-like Matrices.

Oriented fibers in bone lamellae are recognized for their contribution to the anisotropic mechanical performance of the cortical bone. While increasing evidence highlights that such oriented fibers also exhibit osteogenic induction to preosteoblasts, little is known about the effect of the overlay angle between lamellae on the osteogenic differentiation of bone marrow-derived mesenchymal stem cells (BMSCs). In this study, bone lamellae-like fibrous matrices composed of aligned core-shell [core: polycaprolactone (PCL)/type I collagen (Col I) + shell: Col I] nanofibers were seeded with human BMSCs (hBMSCs) and then laid over on each other layer-by-layer (L-b-L) at selected angles (0 or 45°) to form three-dimensional (3D) constructs. Upon culture for 7 and 14 days, osteogenic differentiation of hBMSCs and mineralization within the lamellae assembly (LA) were characterized by real-time PCR, Western blot, immunofluorescent staining for osteogenic markers, and alizarin red staining for calcium deposition. Compared to those of random nanofibers (LA-RF) or aligned fibers with the overlay angle of 45° (LA-AF-45), the LA of aligned fibers at a 0° overlay angle (LA-AF-0) exhibited a noticeably higher osteogenic differentiation of hBMSCs, i.e., elevated gene expression of OPN, OCN, and RUNX2 and protein levels of ALP and RUNX2, while promoting mineral deposition as indicated by alizarin red staining and mechanical testing. Further analyses of hBMSCs within LA-AF-0 revealed an increase in both total and phosphorylated integrin ß1, which subsequently increased total focal adhesion kinase (FAK), phosphorylated FAK (p-FAK), and phosphorylated extracellular signal kinase ERK1/2 (p-ERK1/2). Inhibition of integrin ß1 and ERK1/2 activity effectively reduced the LA-AF-0-induced upregulation of p-FAK and osteogenic markers (OPN, OCN, and RUNX2), confirming the involvement of integrin ß1-FAK-ERK1/2 signaling. Altogether, the overlay angle of aligned core-shell nanofiber membranes regulates the osteogenic differentiation of hBMSCs via integrin ß1-FAK-ERK1/2 signaling, unveiling the effects of anisotropic fibers on bone tissue formation.

Tannic Acid Film Based on One-Dimensional Supramolecular Self-Assembly for Electrical Conductivity and Oil-Water Separation.

Tannic acid is widely regarded as one of the most promising natural polyphenolic compounds. However, current research predominantly focuses on the utilization of its phenolic hydroxyl groups, with limited exploration of the functional potential of its aromatic structure. Herein, one-dimensional nanofibers based on supramolecular self-assembly were successfully prepared through the simple alkylation reaction of tannic acid and the π-π stacking of aromatic structures. These fibers, with lengths reaching tens of micrometers and an average height of 10 nm, were clearly observed using SEM and AFM. A film with excellent electrical conductivity (σ = 37.9 µS/cm) was fabricated by vacuum filtering the organic suspension of these fibers, which was 100-fold higher than that of the TA film. Additionally, the hydrophobic and lipophilic properties of Bn-TA were further investigated through oil-water separation experiments, where the Bn-TA membrane displayed excellent separation efficiency and durability, maintaining stable performance over multiple cycles. This strategy presents opportunities for the high-value utilization of tannic acid.

Bioinspired Hydrophobicity via Temperature-Induced Phase Separation of Beeswax: A Pathway for Developing Cellulose Nanofiber-Based Adsorbents for the Removal of Conventional Tetracycline Tablets.

Cellulose nanofiber-based aerogels (CNFAs) hold immense promise across diverse fields, but their innate hydrophilicity and structural fragility in water have constrained their utility in water purification. This study introduces a green approach to induce hydrophobicity into CNFAs via thermally induced phase separation (TIPS) of beeswax, which was adhered to the nanofiber by hydrogen bonding and hydrophobic-hydrophobic interactions. The fabricated aerogel was characterized by using FTIR, SEM, XRD, TGA, contact angle, BET, and compression test. The resulting beeswax cellulose nanofiber-based aerogels (BCNFAs) possess a highly porous structure and extremely low density, enabling the aerogels to self-float and facilitate practical applications and recycling. Due to these remarkable characteristics, BCNFAs had excellent adsorption capacity within 10 min to effectively remove tetracycline (TC) from water with an adsorption capacity of 31.6 mg/g. The demonstrated methodology to induce hydrophobicity in CNFAs via TIPS of beeswax on CNFAs could be an eco-friendly and scalable approach for the fabrication of robust BCNFAs without using any toxic chemicals. So far, this is the first report on to make robust hydrophobic CNFAs by employing TIPS of beeswax while maintaining the porosity of CNFAs, which is highly desirable for effective TC tablet adsorption from water in the present context. The demonstrated work has commercial potential as it focuses on the practical utility of the modified aerogel for adsorbing conventional tetracycline tablets, rather than exclusively targeting the pharmaceutical ingredient alone.

Spin-coating ANF based multilayer symmetric composite films for enhanced electromagnetic interference shielding and thermal management.

The demand for flexible composite films with electromagnetic interference (EMI) shielding capabilities is rapidly increasing. Balancing high EMI performance with flexibility and portability has become a critical research focus in practical applications. In this study, an optimized strategy for aramid nanofibers (ANF) films was developed using spin-coating and sol-gel techniques. The resulting film features a smooth surface and excellent mechanical properties. ANF, initially an insulator, was transformed into a conductor through the in-situ polymerization of ion-doped polypyrrole (PPy). Leveraging a multilayer structural strategy, we prepared a symmetric composite film, ANF@PPy-(TA-MXene)-AgNWs-(TA-MXene)-ANF@PPy (PMA), using vacuum-assisted filtration and lamination hot pressing. This film, composed of ANF@PPy (PA) as the matrix, tannic acid (TA) modified MXene, and silver nanowires (AgNWs) as fillers, exhibited multiple shielding mechanisms as electromagnetic wave (EMW) passed through its various layers. This multilayer configuration provides significant flexibility in EMW shielding. Moreover, TA-modified MXene expands the lamellar spacing, enhancing the scattering efficiency of EMWs within the film, and serves as a medium connecting the upper and lower layers. This results in the efficient integration of the multilayer structure, synergistically improving both EMI shielding performance and mechanical properties. When the ratio of PA/MXene/AgNWs was 1:3:1, the film demonstrated optimal properties, including an EMI shielding effectiveness of 70.2 dB, thermal conductivity of 4.62 W/(m•K), and tensile strength of 50.2 MPa. Due to the exceptional EMI shielding and thermal properties of the PMA composite film, it holds great potential for applications in artificial intelligence, wearable heaters, and military equipment.

Iron metal-organic framework nanofiber membrane for the integration of electro-Fenton and effective continuous treatment of pharmaceuticals in water.

In this study, an iron metal-organic framework (Fe-MOF) was synthesized and immobilized by electrospinning technique with the objective of obtaining a membrane composed of nanofibers of this material (Fe-MOF nanofiber membrane). The characterization performed by XRD, TEM, SEM, EDS mapping and FTIR confirmed the correct synthesis of Fe-MOF as well as its correct retention in the elaborated membranes. The usefulness and effectiveness of the Fe-MOF nanofiber membrane as a catalyst for the electro-Fenton process was evaluated by performing sulfamethoxazole degradation tests. Different parameters such as the effect of intensity (25 and 100 mA), the effect of the drug initial concentration (10-50 mg/L) and the reusability of membranes were studied. Then, the degradation of a drug mixture formed by sulfamethoxazole and antipyrine was evaluated, reaching a degradation of 92.10 % and 87.43 % respectively for each drug in 4 h at 25 mA. In addition, the identification of reactive oxygen species was ascertained by scavenger assays. The study of degradation products was also carried out and their toxicity was predicted by ECOSAR program, concluding that the environmental toxicity would disappear with mineralization. Finally, given the good results obtained in batch tests, the behavior of the process was studied in a system that works continuously, achieving a stable degradation of 83.10 % in the case of treatment with a mixture of drugs. This confirmed the stability of the Fe-MOF nanofiber membrane, as well as, its catalytic activity, making it suitable for long-term treatments.

Optical Micro/Nanofiber Enabled Multiaxial Force Sensor for Tactile Visualization and Human-Machine Interface.

Tactile sensors with capability of multiaxial force perception play a vital role in robotics and human-machine interfaces. Flexible optical waveguide sensors have been an emerging paradigm in tactile sensing due to their high sensitivity, fast response, and antielectromagnetic interference. Herein, a flexible multiaxial force sensor enabled by U-shaped optical micro/nanofibers (MNFs) is reported. The MNF is embedded within an elastomer film topped with a dome-shaped protrusion. When the protrusion is subjected to vector forces, the embedded MNF undergoes anisotropic deformations, yielding time-resolved variations in light transmission. Detection of both normal and shear forces is achieved with sensitivities reaching 50.7 dB N-1 (14% kPa-1) and 82.2 dB N-1 (21% kPa-1), respectively. Notably, the structural asymmetry of the MNF induces asymmetrical optical modes, granting the sensor directional responses to four-directional shear forces. As proof-of-concept applications, tactile visualizations for texture and relief pattern recognition are realized with a spatial resolution of 160 µm. Moreover, a dual U-shaped MNF configuration is demonstrated as a human-machine interface for cursor manipulation. This work represents a step towards advanced multiaxial tactile sensing.

Yarn-Based Degradable Janus PPDO Fabric for Multifunctional Applications.

The growing high standard of people's wear has put forward requirements for fabrics, and multifunctional fabrics have been developed precisely in response to the requirements of the times. However, the incineration of waste fabrics produces a large amount of pollutants, resulting in a massive waste of resources and environmental pollution. Herein, the degradable nanofiber yarns (NYs) with self-cleaning properties were fabricated by in situ growth of SiO2 nanoparticles on the surface of the electrospun poly(p-dioxanone) (PPDO) NYs using the Stöber method. Then, the PPDO NYs were blended with carbon fibers and the PPDO/SiO2 NYs with themselves to form the Janus PPDO fabrics, respectively. The Janus PPDO fabric offered asymmetric wettability and dual personal thermal management properties. The PPDO/C side of the Janus PPDO fabric provided 65.8 °C at 1.5 V or 58.5 °C under one sunlight intensity for radiative heating. The PPDO/SiO2 side exhibited high solar reflectivity (81.8%) and mid-infrared (MIR) emissivity (99.1%), which reduced the skin temperature by 4.6 °C, resulting in radiative cooling. Moreover, the Janus PPDO fabrics display an excellent electromagnetic interference (EMI) shielding performance (53.3 dB). Therefore, yarn-based degradable Janus fabric has a promising future in multifunctional wearable products.

Optimizing the Production of Bacterial Cellulose Nanofibers and Nanocrystals Through Strategic Fiber Pretreatment.

Bacterial cellulose (BC) has unique properties such as high tensile strength, high crystallinity, and high purity. The fiber length of BC causes different attributes. Therefore, the degradation of BC has been studied extensively. In this study, the fibers of BC were rearranged via a DMAc-LiCl solvent and BC was degraded in the wet state. Two different degradation methods were applied: milling with liquid nitrogen and autoclave treatment. The degraded BCs were characterized by FTIR, TEM, AFM, TGA, and XRD. The solvent helps to align the fibers, making them more crystalline. The degraded BCs had a lower crystalline ratio than untreated BC, due to increased hydrogen bonding during degradation in the wet state. Degradation with an autoclave produced two different degraded BCs: nanofibrils and spherical nanocrystals, with and without solvent pretreatment, respectively. The nanofibril lengths were between 312 and 700 nm depending on the applied method, and the spherical nanocrystal size was 56 nm. The rearrangement via solvent causes an important difference in the degradation of BC. Nanofibrils and nanocrystals can be obtained, depending on the rearrangement of fibers before the degradation process.

Bacterial cellulose nanofiber reinforced self-healing hydrogel to construct a theranostic platform of antibacterial and enhanced wound healing.

In order to promote wound healing, self-healing hydrogels with moisturizing property are employed as wound dressing. In this study, bacterial cellulose nanofibers (BCN) with high mechanical strength are used as reinforcement to improve the mechanical properties of self-healing hydrogels. A multifunctional self-healing hydrogel has been constructed by incorporating natural biomass, including Ag hybrid bacterial cellulose nanofiber (Ag-BCN), resveratrol (Res), and carbon nanodots (CNDs). The results of in vitro experiments demonstrate that the mechanical strength of the hybrid hydrogel was increased by 6 times with the addition of Ag-BCN, which also offers excellent antibacterial efficiency (S. aureus 99.99 % and E. coli 99.68 %). The hydrogel with CNDs can observe the healing process of the crack in real time and realize the controlled release of Res through photothermal effect. Moreover, the results of animal model experiments indicate that the prepared hydrogel could reduce the infection of the wound, effectively shorten the progress of wound healing (from 21d to 14 d). All the results imply that the prepared hydrogel has great promise in the application of skin wound healing.

Experimental and Numerical Investigation of Slip Effect on Nanofiber Filter Performance at Low Pressures.

Nanofiber filters are widely used in air filtration applications due to their superior performance over microfiber filters. Velocity slip around nanofibers has been identified as a key factor contributing to their high figure of merit, yet its impact on filter performance, especially particle collection efficiency, remains unclear due to the difficulty in isolating the slip effect as the sole variable. This study combines experimental and simulation methods to investigate the slip effect by adjusting the air molecule mean free path, rather than varying fiber size as done in previous studies. Filter media with mean fiber sizes ranging from 16.2 to 0.084 µm are utilized. An image-based regression method is developed to address the challenge of determining the solidity of thin nanofiber layers. The results show that the slip effect is enhanced as the testing pressure decreases, reducing pressure drop by less than 15% for microfiber filters and over 50% for nanofiber filters ≈100 nm. The enhanced slip effect at low pressures (i.e., relatively low pressure compared to the ambient environment) significantly improves filtration efficiency, especially for particles larger than 100 nm. It also proposes semi-empirical equations for predicting filter performance in slip and transition flow regimes.

A separable double-layer self-pumping dressing containing astragaloside for promoting wound healing.

Some skin wounds often have many exudate. Ordinary single layer electrospunning nanofiber wound dressings often don't have enough capacity to absorb them. Therefore, a separable double layer electrospunning nanofiber dressing was developed in this work. The dressing had a separable feature that allowed the upper layer to be separated and removed after it had absorbed a significant amount of wound exudate. This dressing consisted of an upper layer of super hydrophilic sodium polyacrylate nanofibers and a bottom layer of 3D-structure coaxial nanofibers with encapsulated Astragaloside (AS). The results showed that nanofibers had better morphology. The water absorption rate, water vapor transmission rate and free radical scavenging rate of the double-layer dressings were 1461.71 ±â€¯39.72 %, 1193.63 ±â€¯134 g·m-2·day-1, and 63.35 ±â€¯3.65 %, respectively. The double-layer nanofiber dressing achieved 65.69 ±â€¯2.62 % and 75.10 ±â€¯6.26 % inhibition against Staphylococcus aureus and Escherichia coli, respectively. The double-layer dressing had proliferative, migratory, and adhesive effects on L929 fibroblasts. And the double-layer dressing resulted in a 96.78 ±â€¯1.0 % wound healing rate in rats after giving a 14 days treatment. Therefore, the 3D-structure separable double-layer wound dressing designed and prepared in this study was effective in promoting wound healing.

Electric field simulation, structure and properties of nanofiber- coated yarn prepared by multi-needle water bath electrospinning.

To address the issue of low yield in the preparation of nanofiber materials using single-needle electrospinning technology, multi-needle electrospinning technology has emerged as a crucial solution for mass production. However, the mutual interference of multiple electric fields between the needles can cause significant randomness in the morphology of the produced nanofibers. To better predict the influence of electric field distribution on nanofiber morphology, simulation analysis of the multi-needle arrangement was conducted using finite element analysis software. Nanofiber-coated yarn was produced continuously with the core yarn rotating. The water bath was utilized as the receiver of nanofibers on self-made water bath electrospinning equipment. The electric field distribution and mutual interference under seven different needle arrangements was simulated and analyzed by finite element analysis software ANSYS Maxwell. The results indicated that when the needles were arranged diagonally in a staggered pattern and directly above the core yarn, the simulated electric field distribution was relatively uniform, with less mutual interference. The produced nanofibers exhibited a finer diameter and the diameter distribution was more concentrated. In addition, the nanofiber coating showed higher crystallinity and better mechanical properties. .

LDH nanoparticles-doped cellulose nanofiber scaffolds with aligned microchannels direct high-efficiency neural regeneration and organized neural circuit remodeling through RhoA/Rock/Myosin II pathway.

Spinal cord injury (SCI) triggers interconnected malignant pathological cascades culminating in structural abnormalities and composition changes of neural tissues and impairs spinal cord tissue function. Cellulose nanofibers (CNF) have considerable potential in mimicking tissue microstructure for nerve regeneration, but the effectiveness of CNF in repairing SCI remains poorly understood. In this study, we designed a Mg-Fe layered double hydroxide (LDH)-doped cellulose nanofiber (CNF) scaffold with aligned intact microchannels and homogeneously distributed pores (CNF-LDH), loaded with retinoic acid and sonic hedgehog (CNF-LDH-RS) for neuroregeneration. The aligned microchannel structure and chemical cues in the scaffold were designed further to enhance the differentiation of neural stem cells towards neurons and promote axon growth while inhibiting differentiation to astrocytes. Transplanting the scaffolds into a completely transected SCI mice model dramatically improved behavioral and electrophysiological outcomes underpinned by robust neuronal regeneration, significant axonal growth and orderly neural circuit remodeling. RNA-seq analysis revealed the pivotal roles of the RhoA/Rock/Myosin II pathway and neuroactive ligand-receptor interaction pathway in SCI repair by CNF-LDH-RS. Particularly, Myosin II emerged as a key gene for functional recovery, and its effect on negative regulation of axon growth was suppressed by the scaffolds, resulting in a distinctly oriented growth of the axons along the microchannel structure. The results indicate that CNF-LDH scaffolds rationally combined with physical and biochemical cues create promising tissue-engineered substrates to facilitate the repair of spinal cord injury.

Wood Cell Wall Nanoengineering toward Anisotropic, Strong, and Flexible Cellulosic Hydrogel Sensors.

Achieving highly ionic conductive hydrogels from natural wood remains challenging owing to their insufficient surface area and low number of active sites on the cell wall. This study proposes a viable strategy to design a strong and anisotropic wood-based hydrogel through cell wall nanoengineering. By manipulating the microstructure of the wood cell wall, a flexible cellulosic hydrogel is achieved through Schiff base bonding via the polyacrylamide and cellulose molecular chains. This results in excellent flexibility and mechanical properties of the wood hydrogel with tensile strengths of 22.3 and 6.1 MPa in the longitudinal and transverse directions, respectively. Moreover, confining aqueous salt electrolytes within the porous structure gives anisotropic ionic conductivities (19.5 and 6.02 S/m in the longitudinal and transverse directions, respectively). The wood-based hydrogel sensor has a favorable sensitivity and a stable working performance at a low temperature of -25 °C in monitoring human motions, thereby demonstrating great potential applications in wearable sensor devices.