Hyperbranched Polymer Induced Antibacterial Tree-Like Nanofibrous Membrane for High Effective Air Filtration.

The air filtration materials with high efficiency, low resistance, and extra antibacterial property are crucial for personal health protection. Herein, a tree-like polyvinylidene fluoride (PVDF) nanofibrous membrane with hierarchical structure (trunk fiber of 447 nm, branched fiber of 24.7 nm) and high filtration capacity is demonstrated. Specifically, 2-hydroxypropyl trimethyl ammonium chloride terminated hyperbranched polymer (HBP-HTC) with near-spherical three-dimensional molecular structure and adjustable terminal positive groups is synthesized as an additive for PVDF electrospinning to enhance the jet splitting and promote the formation of branched ultrafine nanofibers, achieving a coverage rate of branched nanofibers over 90% that is superior than small molecular quaternary ammonium salts. The branched nanofibers network enhances mechanical properties and filtration efficiency (99.995% for 0.26 µm sodium chloride particles) of the PVDF/HBP-HTC membrane, which demonstrates reduced pressure drop (122.4 Pa) and a quality factor up to 0.083 Pa-1 on a 40 µm-thick sample. More importantly, the numerous quaternary ammonium salt groups of HBP-HTC deliver excellent antibacterial properties to the PVDF membranes. Bacterial inhibitive rate of 99.9% against both S. aureus and E. coli is demonstrated in a membrane with 3.0 wt% HBP-HTC. This work provides a new strategy for development of high-efficiency and antibacterial protection products.

Breathable Metal-Organic Framework Enhanced Humidity-Responsive Nanofiber Actuator with Autonomous Triboelectric Perceptivity.

Autonomous object manipulation and perception with environmental factor-triggered and self-powered actuation is one of the most attractive directions for developing next-generation soft robotics with a smart human-machine-environment interface. Humidity, as a sustainable energy source ubiquitous in the surrounding environment, can be used for triggering smart grippers. In this work, it is proposed that by contacts between the gripper and objects upon humidity-induced actuation, real-time distinguishable triboelectric signals can be generated to realize the humidity-driven object manipulation and identification. Herein, a thermo-modified electrospun polyvinylpyrrolidone/poly(acrylic acid)/MIL-88A (T-PPM) nanofibrous film with micro-to-nano cross-scale porosity is developed, and a bilayer humidity-responsive actuator (T-HRA) was designed, mimicking the tamariskoid spikemoss to enhance the humidity-driven actuation. The breathing effect of MIL-88A and hierarchical porous structure of the T-PPM facilitate moisture diffusion and offer huge actuation (2.41 cm-1) with a fast response (0.084 cm-1 s-1). For autonomous object manipulation perception, T-PPM was verified as a tribo-positive material located between paper and silk. Accordingly, the T-HRA was demonstrated as a smart soft gripper that generates a different electric signal upon contact with objects of different material. This work proposes a concept of soft robots that are interactive with the environment for both autonomous object manipulation and information acquisition.

Silk fibroin fibers-based shape memory membrane with Janus wettability for multitiered wearable protection.

Realizing breathable shape memory fiber-based material with antibacterial and waterproof performances is important for multitiered wearable protection to address the increasing concerns of air pollution. Herein, using an alternating electrospinning-electrospraying technology, we develop a fiber-based membrane with Janus wettability based on a silk fibroin nanofibers-substrate (SFNFs), a polyurethane nanospheres-top layer (PUNSs), and a middle layer of PU nanofibers-mat with in-situ grown silver nanoparticles (PUNFs-AgNPs), which serves separately for skin contact, a self-cleaning physical barrier to resist external aerosol/bacteria (PM2.5 filtration efficiency ~ 98.1%), and a bio-barrier that can sterilize harmful particles and inhibit bacteria proliferation (> 95%). This breathable Janus film (SFNFs/PUNFs-AgNPs/PUNSs, SPAP) with an antibacterial filter shows shape memory stretchability enabled by the thermoplastic PU component, which is mechanically adaptive to human body for wearable protection. This work presents a breathable wearable material for air-filtration and anti-bacteria, promising for applications such as wound dressings, medical masks, protection suits, and multifunctional filters. Graphical abstract: An alternating electrospinning-electrospraying technology was proposed to achieve a silk fibroin-based antibacterial membrane with Janus wettability, as well as good skin affinity and breathability, which serves well as physical and bio-barriers for water resistance, PM2.5 filtration (~98.1%) and bacteria inhibition (efficiency of 95%). This shape memory Janus membrane can adapt mechanically to human body curvatures for functional wearable protections. Supplementary Information: The online version contains supplementary material available at 10.1557/s43578-022-00805-w.

Elastic Fibers/Fabrics for Wearables and Bioelectronics.

Wearables and bioelectronics rely on breathable interface devices with bioaffinity, biocompatibility, and smart functionality for interactions between beings and things and the surrounding environment. Elastic fibers/fabrics with mechanical adaptivity to various deformations and complex substrates, are promising to act as fillers, carriers, substrates, dressings, and scaffolds in the construction of biointerfaces for the human body, skins, organs, and plants, realizing functions such as energy exchange, sensing, perception, augmented virtuality, health monitoring, disease diagnosis, and intervention therapy. This review summarizes and highlights the latest breakthroughs of elastic fibers/fabrics for wearables and bioelectronics, aiming to offer insights into elasticity mechanisms, production methods, and electrical components integration strategies with fibers/fabrics, presenting a profile of elastic fibers/fabrics for energy management, sensors, e-skins, thermal management, personal protection, wound healing, biosensing, and drug delivery. The trans-disciplinary application of elastic fibers/fabrics from wearables to biomedicine provides important inspiration for technology transplantation and function integration to adapt different application systems. As a discussion platform, here the main challenges and possible solutions in the field are proposed, hopefully can provide guidance for promoting the development of elastic e-textiles in consideration of the trade-off between mechanical/electrical performance, industrial-scale production, diverse environmental adaptivity, and multiscenario on-spot applications.

Silk Fabric Decorated with Thermo-Sensitive Hydrogel for Sustained Release of Paracetamol.

Paracetamol is a safe and widely used antipyretic and analgesic drug, however, with the drawbacks of gastrointestinal first-pass effect and short intervals of administration. Transdermal drug delivery system can effectively avoid the liver metabolism caused by excess oral ingestion of paracetamol. Herein, a silk fabric-based medical dressing decorated by a thermo-responsive hydrogel for sustained release of paracetamol is proposed. Genipin as a bio-safe cross-linker is applied to assist gelation of a thermo-responsive hydrogel system coupled with chitosan and glycerol-phosphate disodium salt around body temperature (37 °C), as well as densifying the microporous gel to improve mechanical strength. The in situ sol-gel transition enabled hydrogel well penetrate and coat the silk fabric, forming a hierarchical hydrogel structure capable of prolonging the sustained release of drug to 12 h, twice as long as a blank fabric. The silk fabric with a thin gel coating maintains a good water vapor transmission rate, compatible for skin contact application. The drug release properties can be tuned by regulating the genipin content and fabric braiding structure. The silk fabric dressing exhibits temperature-dependent instant release behavior within the first 2 h. The sustained release mechanism of paracetamol well matches with the Korsmeyer-Peppas model in a non-Fickian diffusion.

Construction of Hierarchical NiCo2O4@Ni-MOF Hybrid Arrays on Carbon Cloth as Superior Battery-Type Electrodes for Flexible Solid-State Hybrid Supercapacitors.

Metal-organic frameworks (MOFs) have been considered as a class of promising electrode materials for supercapacitors owing to their large surface area, rich porosity, and variable redox sites; however, direct application of pristine MOFs in energy storage has been largely hindered by their poor electrical conductivity and stability issues. In this work, we demonstrate a facile two-step approach to address the controlled growth of Ni-MOF arrays on the surface of NiCo2O4 nanowires by modulating the formation reaction of MOFs. By taking advantage of the intriguing merits from the NiCo2O4 core and Ni-MOF shell as well as their synergistic effects, the optimized NiCo2O4@Ni-MOF hybrid electrode exhibits boosted electrochemical performance, in terms of high specific capacity (208.8 mA h/g at 2 mA/cm2) and good rate capability. In addition, the assembled flexible solid-state HSC device based on the optimized NiCo2O4@Ni-MOF and activated carbon as the cathode and anode achieves a maximum energy density of 32.6 W h/kg at a power density of 348.9 W/kg without sacrificing its outstanding cycling performance (nearly 100% retention over 6000 cycles at 8 mA/cm2) and mechanical stability, outperforming most recently reported MOF-based HSC devices in an aqueous electrolyte. Our work demonstrates the possibility of exploiting novel MOF-based hybrid arrays as battery-type electrodes with enhanced electrochemical properties, which exhibits great potential in flexible energy storage devices.

Interlaced NiMn-LDH nanosheet decorated NiCo2O4 nanowire arrays on carbon cloth as advanced electrodes for high-performance flexible solid-state hybrid supercapacitors.

The development of flexible energy storage devices for portable and wearable electronics has aroused increasing interest. In this work, three-dimensional hierarchical NiCo2O4@NiMn-LDH nanowire/nanosheet arrays have been successfully fabricated on carbon cloth through a facile hydrothermal and calcination synthetic method. Benefiting from the sophisticated hybrid nanoarchitectures with desirable structure and components, the optimized NiCo2O4@NiMn-LDH hybrid electrode is found to deliver a remarkable specific capacity of 278 mA h g-1 at 2 mA cm-2 and a good rate capability of 89.1% retention at 20 mA cm-2. Detailed analysis of the reaction kinetics for the hybrid electrode clearly indicates the dominant diffusion-controlled contribution to the total capacity. In addition, a flexible solid-state hybrid supercapacitor is assembled by taking NiCo2O4@NiMn-LDH and activated carbon as the cathode and anode, respectively, which manifests a maximum energy density of 47 W h kg-1 at a power density of 357 W kg-1 as well as an excellent long-term cycling stability (95.6% retention after 5000 cycles over 8 mA cm-2). Our work demonstrates the great potential of this core/shell hybrid nanostructure as an advanced battery-type electrode for high-performance flexible energy storage devices.

One-Step Synthesis of Ag@TiO2 Nanoparticles for Enhanced Photocatalytic Performance.

Polyamide network polymers (PNP) modified TiO2 nanoparticles (NPs) were decorated with Ag NPs in hydrothermal gel method, forming one-step synthesized photocatalysts, Ag@TiO2 NPs. The effect of PNP and the amount of Ag NPs added were investigated in this work. PNP acted as a nanocage to prevent TiO2 aggregation and capture Ag accurately, which could effectively control product sizes and improve dispersibility in solvents. Simultaneously, TiO2 NPs modified with Ag NPs exhibited remarkable photocatalytic effects. One-step synthesis simplified the experimental process and avoided the agglomeration of silver ions during the secondary reaction, achieving the purpose of uniform distribution at a specific location of TiO2 NPs. The prepared Ag@TiO2 NPs-0.5 could remove 79.49% of Methyl Orange (MO) after 3 h of ultraviolet light irradiation, which was 2.7 times higher than the reaction rate of pure TiO2 NPs. It also exhibited good photoactivity under Visible light conditions. Moreover, the mineralization rate of MO over the Ag@TiO2 NPs-0.5 could be up to 72.32% under UV light and 47.08% under Visible light irradiation, which revealed that the prepared catalysts could effectively degrade most of the MO to CO2 and H2O. The samples also demonstrated the excellent stability and easy recyclability with over 90% of the original catalytic level for MO degradation. The photocatalysts studied also exerted broad application prospects such as photovoltaic hydrogen production, electronic sensors and biomedicine.

Cellulose/polymer/silica composite cotton fiber based on a hyperbranch-mesostructure system as versatile adsorbent for water treatment.

The present study describes the preparation of a hybrid cellulose-based adsorbent (HM-cotton) containing a dot-plane composite adsorption system. The dot-plane adsorption structure is formed by the plane of hyperbranched polymer (HBP) layer distributed by the functional mesoporous nanoparticle (CA-MSN) dots, fabricating hyperbranch-mesostructure system via self-assembly. The resultant adsorbent HM-cotton was characterized, and the adsorption mechanism for dyes and metal ions was also discussed in detail. The results show that the adsorption data is fitted to Pseudo-second-order kinetic model and Langmuir isotherm model, and owing to the dot-plane system possessing functional mesostructure of CA-MSNs with large surface area and substantial adsorption sites from HBP macromolecules, HM-cotton exhibits versatile, highly-efficiency and sustainable adsorption properties for dyes such as CR and MB, and metal ions such as Fe3+ and Cu2+ from aqueous media. The saturated adsorption capacities are 243.7, 165.4, 143.8 and 119.1mg/g for CR, MB, Fe3+ and Cu2+, respectively.

Sodium alginate/graphene oxide aerogel with enhanced strength-toughness and its heavy metal adsorption study.

Ordered porous sodium alginate/graphene oxide (SAGO) aerogel was fabricated by in situ crosslinking and freeze-drying method. GO, as reinforcing filler, can be easily incorporated with SA matrix by self-assembly via hydrogen bonding interaction. Compared with pure SA aerogel, the as-prepared SAGO exhibited excellent mechanical strength and elasticity, and the compression strength of SAGO can reach up to 324 kPa and remain 249 kPa after five compression cycles when 4 wt% GO was added, which were considered significant improvements. SEM result presents that the addition of GO obviously improves the porous structures of aerogel, which is beneficial for the enhancement of strength-toughness and adsorbability. As a consequence, the adsorption process of SAGO is better described by pseudo-second-order kinetic model and Langmuir isotherm, with maximum monolayer adsorption capacities of 98.0 mg/g for Cu2+ and 267.4 mg/g for Pb2+, which are extremely high adsorption capacities for metal ions and show far more promise for application in sewage treatment.

Antibacterial cotton fabric grafted with silver nanoparticles and its excellent laundering durability.

In order to fabricate antibacterial cotton fabric with excellent antibacterial property and laundering durability, amino functional silver nanoparticles (Ag NPs) were prepared by one-step reaction with amino-terminated hyperbranched polymer (HBP-NH(2)) and grafted on the oxidized cotton fabric subsequently. The synthesized amino functional Ag NPs and Ag NPs grafted oxidized cotton fabric (Ag-GOCF) were characterized which indicated that the average size of Ag NPs was 10.8 nm with narrow size distribution and the Ag NPs have been grafted on the cotton fabric. 99.43% and 99.45% bacterial reduction rates were obtained for Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) respectively in case the cotton fabric was treated with 10 mg/L Ag NPs solution to produce Ag-GOCF with 149.88 mg/kg Ag content. After 50 washing cycles, the Ag content of this Ag-GOCF was maintained at 116.08 mg/kg with its antibacterial activity at over 96% reduction level.