Currently, most of the materials for oil–water separation membranes are limited to fluorine-based polymers with low surface energy. However, it is not biodegradable and requires large amounts of organic and toxic solvents in the membrane manufacturing process. Therefore, interest in the development of a new eco-friendly oil–water separation membrane that does not cause secondary pollution and exhibits selective wettability characteristics in water or oil is increasing. The biopolymeric nanofibrous membranes inspired by fish skin can provide specific underwater oleophobicity, which is effective for excellent oil–water separation efficiency and prevention of secondary contamination. Fish gelatin, which is highly soluble in water and has a low gelation temperature, can be electrospun in an aqueous solution and has the same polar functional groups as the hydrophilic mucilage of fish skin. In addition, the micro/nanostructure of fish skin, which induces superoleophobicity in water, introduces a bead-on-string structure using the Rayleigh instability of electrospinning. The solubility of fish gelatin in water was removed using an eco-friendly crosslinking method using reducing sugars. Fish skin-mimicking materials successfully separated suspended oil and emulsified oil, with a maximum flux of 2086 Lm−2 h−1 and a separation efficiency of more than 99%. The proposed biopolymeric nanofibrous membranes use fish gelatin, which can be extracted from fish waste and has excellent biodegradability with excellent oil–water separation performance. In addition, polymer material processing, including membrane manufacturing and crosslinking, can be realized through eco-friendly processes. Therefore, fish skin-inspired biopolymeric membrane is expected to be a promising candidate for a sustainable and effective oil–water separation membrane in the future.
Electrospinning is a simple and versatile method to produce nanofiber filters. However, owing to bending instability that occurs during the electrospinning process, electrospinning has frequently produced a non-uniform-thickness nanofiber filter, which deteriorates its air filtration. Here, an adaptive electrospinning system based on reinforcement learning (E-RL) was developed to produce uniform-thickness nanofiber filters. The E-RL accomplished a real-time thickness measurement of an electrospun nanofiber filter by measuring the transmitted light through the nanofiber filter using a camera placed at the bottom of the collector and converting it into thickness using the Beer–Lambert law. Based on the measured thickness, the E-RL detected the non-uniformity of the nanofiber filter thickness and manipulated the movable collector to alleviate the non-uniformity of the thickness by a pre-trained reinforcement learning (RL) algorithm. For the training of the RL algorithm, the nanofiber production simulation software based on the empirical model of the deposition of the nanofiber filter was developed, and the training process of the RL algorithm was repeated until the optimal policy was achieved. After the training process with the simulation software, the trained model was transferred to the adaptive electrospinning system. By the movement of the collector under the optimal strategy of RL algorithm, the non-uniformity of such nanofiber filters was significantly reduced by approximately five times in standard deviation and error for both simulation and experiment. This finding has great potential in improving the reliability of electrospinning process and nanofiber filters used in research and industrial fields such as environment, energy, and biomedicine.
Micro- and nano-fibers of shape memory polymers (SMP) offer multiple advantages like high specific surface area, porosity, and intelligence, and are suitable for biomedical applications. In this study, biodegradable poly (p-dioxanone) (PPDO) materials were incorporated to improve the brittleness of shape memory polylactic acid (PLA), and plasticizers were used to reduce the transition temperature of SMP composites such that their transitions could be induced close to body temperature. Furthermore, an electrostatic spinning technology was applied to prepare SMP fibers with wrinkled structures and regulate their microstructures and morphologies such that the intelligent transition of wrinkled and smooth morphologies can be achieved on the fiber surface. The application of this controllable-morphology fiber membrane in intelligent controlled drug release and scar inhibition after Ahmed Glaucoma Valve (AGV) implantation was also studied. The drug release from the stretched and deformed drug-loaded fiber membranes was faster than those from membranes with the original shape. This membrane with micro- and nano-fibers had good anti-scarring effects that improved after drug loading. The achievement of intelligent controlled drug release and the evident anti-scarring effects of the membrane broaden the application of SMP fibers in the biomedical field.
Yarn-based batteries with the dual functions of wearable and energy storage have demonstrated promising potential in wearable energy textiles. However, it is still an urgent problem to construct efficient and flexible electrodes while optimize the configuration of yarn-based batteries to maintain excellent electrochemical performance under different mechanical deformations. Herein, NiCo2S4−x nanotube arrays with tunable S-vacancies are constructed on carbon yarn (CY) (NiCo2S4−x@CY) by a facile hydrothermal strategy. The aqueous zinc-ion batteries (ZIBs) with NiCo2S4−x@CY as cathodes exhibit exceptional discharge capacity (271.7 mAh g−1) and outstanding rate performance (70.9% capacity retention at 5 A g−1), and reveal a maximum power density of 6,059.5 W kg−1 and a maximum energy density of 432.2 Wh kg−1. It is worth noting that the tunable S-vacancies promote the surface reconfiguration and phase transitions of NiCo2S4−x, thereby enhancing the conductivity and charge storage kinetics. The high reactivity and cycling stability of NiCo2S4−x@CY can be related to the discharge products of S-doped NiO and CoO. Furthermore, flexible stretchable yarn-based ZIBs with wrapped yarn structures are constructed and exhibit excellent tensile stability and durability under a variety of mechanical deformations. As a proof of concept, the ZIBs integrated into the fabric show excellent electrochemical performance even in response to simultaneous stretching and bending mechanical deformations. The proposed strategy provides novel inspiration for the development of highly efficient and economical yarn-based ZIBs and wearable energy textiles.
Insufficient bionic performance is a structural obstacle and makes urethral repair unobtainable. To overcome this challenge, we mimicked the urethral matrix and applied two electrospinning techniques to build a double-layer sponge tube of nanofibers and nanoyarns. Intriguingly, silk fibroin (SF) and vitamin B5 (VitB5) could be introduced to increase the elasticity of the outer layer and reduce the hydrophobicity to further improve mesenchymal cell proliferation. Systematic experiments validated the bionic structure, biocompatibility, and exosome delivery capacity in this scaffold. We achieved scarless urethral repair by delivering the bioactive growth factors from adipose-derived stem cell exosomes by physical absorption. Biological regeneration of the urethra can be accomplished with continuous epithelium in animals. Furthermore, bioinformatics studies revealed that the expression of cell proliferation and fibrotic genes (e.g., Wnt7a, cfa-miR-574) was responsible for the biological regeneration of the adipose-derived stem cells exosomes (ADSC-exos) by delivering poly l-lactide-co-caprolactone/SF/VitB5 bilayer sponge (PSVBS) via reduced fibrosis gene expression, as well as improved epithelial formation and blood vessel formation. Therefore, the PSVBS design appeared to be an instructive approach for urethral and other tubular organ regeneration.
TOC figure: The electrospun double-layer sponge fabricated by electrospinning simulated the microstructure of the urethra. The sponge can deliver the exosomes through a physical absorption style. The P(LLA-CL)/SF/VitB5 bilayer sponge has great potential to promote vascular regeneration and wound healing and can effectively inhibit fibrosis.
Flexible wearable ultraviolet (UV) shielding, monitoring and warning devices have important applications in civil and military fields. However, most flexible wearable UV devices show unsatisfactory performance due to their poor stability and easy failure at large strains. Herein, inspired by tree rings, we engineered a hierarchical composite nanofibrous helix with an alternately stacked Archimedes spiral structure via a cost-effective strategy. Based on a photo-electricity-acoustic energy conversion system, we fabricated an all-in-one device exhibiting strain-insensitive UV protection at 0–500% strain for UV shielding as well as strain-sensitive UV monitoring at 500–1500% strain for UV early warning. Compared with previously reported common nanofibrous membrane devices, the as-prepared composite nanofibrous helix shows great advantages in terms of stability and UV protection, especially at large strains. Furthermore, the helix demonstrates multiple functions of wear resistance, antibacterial properties, biodegradation and knittability. This versatile strategy holds great promise for wearable electronics and multifunctional devices.