Recent advances in cotton fabric-based photocatalytic composites for the degradation of organic contaminants

Cotton is one of the oldest and most widely used natural fibers in the world. It enables a wide range of applications due to its excellent moisture absorption, thermal insulation, heat resistance, and durability. Benefiting from current developments in textile technology and materials science, people are constantly seeking more comfortable, more beautiful and more versatile cotton fabrics. As the second skin of body, clothing not only provides the basic needs of wear but also increases the protection of body against different environmental stimuli. In this article, a comprehensive review is proposed regarding research activities of systematically summarise the development and research of cotton fabric-based photocatalytic composites for the degradation of organic contaminants in the area of self-cleaning, degradation of gaseous contaminants, pathogenic bacteria or viruses, and chemical warfare agents. Specifically, we begin with a brief exposition of the background and significance of cotton fabric-based photocatalytic composites. Next, a systematical review on cotton fabric-based photocatalytic composites is provided according to their mechanisms and advanced applications. Finally, a simple summary and analysis concludes the current limitations and future directions in these composites for the degradation of organic contaminants.

Soft Gel Filler Embedded Elastomer with Surfactant Improved Interface for Dielectric Elastomer Actuators

Stretchable materials are the foundation of dielectric actuators (DEAs) for artificial muscle. However, the inadequate dielectric constant of stretchable materials has always greatly limited the performance of artificial muscle. Recently, soft fillers have been proposed to improve the dielectric property and preserve the stretchability for softness, aiming to avoid the stiffening effect of traditional rigid fillers. As composites, an amount of interfacial region is generated, which remarkably affects composites' performance from dielectrics to mechanics. Herein, we demonstrate that the size effect, interfacial binding, and compatibility have a great impact on soft filler doped composites. Particularly, according to the liquid characteristics of soft fillers, we explore an interfacial modification method using surfactants. Composite breakdown strength is thus enhanced 2.2-fold from that in the control group due to the reduction of mismatch between fillers and matrix. Moreover, surfactants alleviate the well-known stiffening effect in small fillers. The area strain of the composites reaches 10.3 ± 0.4% at a low electric field of 7 MV/m, and a soft micropump is successfully assembled. These findings demonstrate a unique and combined interfacial influence of soft filler doped elastomer, which promotes the advancements of the dielectric elastomer artificial muscle.

Fibrous Zr-MOF Nanozyme Aerogels with Macro-Nanoporous Structure for Enhanced Catalytic Hydrolysis of Organophosphate Toxins

Metal-organic frameworks (MOFs) with Lewis acid catalytic sites, such as zirconium-based MOFs (Zr-MOFs), comprise a growing class of phosphatase-like nanozymes that can degrade toxic organophosphate pesticides and nerve agents. Rationally engineering and shaping MOFs from as-synthesized powders into hierarchically porous monoliths is essential for their use in emerging applications, such as filters for air and water purification and personal protection gear. However, several challenges still limit the production of practical MOF composites, including the need for sophisticated reaction conditions, low MOF catalyst loadings in the resulting composites, and poor accessibility to MOF-based active sites. To overcome these limitations, a rapid synthesis method is developed to introduce Zr-MOF nanozyme coating into cellulose nanofibers, resulting in the formation of processable monolithic aerogel composites with high MOF loadings. These composites contain Zr-MOF nanozymes embedded in the structure, and hierarchical macro-micro porosity enables excellent accessibility to catalytic active sites. This multifaceted rational design strategy, including the selection of a MOF with many catalytic sites, fine-tuning the coating morphology, and the fabrication of a hierarchically structured monolithic aerogel, renders synergistic effects toward the efficient continuous hydrolytic detoxification of organophosphorus-based nerve agent simulants and pesticides from contaminated water.

Applications of waste polyethylene terephthalate (PET) based nanostructured materials: A review

While polyethylene terephthalate (PET) has enjoyed widespread use, a large volume of plastic waste has also been produced as a result, which is detrimental to the environment. Traditional treatment of plastic waste, such as landfilling and incinerating waste, causes environmental pollution and poses risks to public health. Recycling PET waste into useful chemicals or upcycling the waste into high value-added materials can be remedies. This review first provides a brief introduction of the synthesis, structure, properties, and applications of virgin PET. Then the conversion process of waste PET into high value-added materials for different applications are introduced. The conversion mechanisms (including degradation, recycling and upcycling) are detailed. The advanced applications of these upgraded materials in energy storage devices (supercapacitors, lithium-ion batteries, and microbial fuel cells), and for water treatment (to remove dyes, heavy metals, and antibiotics), environmental remediation (for air filtration, CO2 adsorption, and oil removal) and catalysis (to produce H2, photoreduce CO2, and remove toxic chemicals) are discussed at length. In general, this review details the exploration of advanced technologies for the transformation of waste PET into nanostructured materials for various applications, and provides insights into the role of high value-added waste products in sustainability and economic development.

Fluorine-free nanoparticle coatings on cotton fabric: comparing the UV-protective and hydrophobic capabilities of silica vs. silica-ZnO nanostructures

Robust, hydrophobic woven cotton fabrics were obtained through the sol-gel dip coating of two different nanoparticle (NP) architectures; silica and silica-ZnO. Water repellency values as high as 148° and relatively low tilt angles for fibrous fabrics (12°) were observed, without the need for fluorinated components. In all cases, this enhanced functionality was achieved with the broad retention of water vapor permeability characteristics, i.e., less than 10% decrease. NP formation routes indicated direct bonding interactions in both the silica and silica-ZnO structures. The physico-chemical effects of NP-compatibilizer (i.e., polydimethoxysilane (PDMS) and n-octyltriethoxysilane (OTES) at different ratios) coatings on cotton fibres indicate that compatibilizer-NP interactions are predominantly physical. Whenever photoactive ZnO-containing additives were used, there was a minor decrease in hydrophobic character, but order of magnitude increases in UV-protective capability (i.e., UPF > 384); properties which were absent in non-ZnO-containing samples. Such water repellency and UPF capabilities were stable to both laundering and UV-exposure, resisting the commonly encountered UV-induced wettability transitions associated with photoactive ZnO. These results suggest that ZnO-containing silica NP coatings on cotton can confer both excellent and persistent surface hydrophobicity as well as UV-protective capability, with potential uses in wearables and functional textiles applications.

4-Electron redox enabled by a perylene diimide containing side-chain amines for efficient organic cathode development

A perylene diimide containing side-chain amines (PDIN) was studied as an organic cathode for application in lithium batteries, showing a high capacity of 174 mA h g-1. The chemical structures, experimental results, and calculation analyses verify that PDIN performed a 4-electron redox reaction jointly involving its CO and side-chain amine groups. This study promotes the development of organic cathodes with multi-electron redox reactions.

A Cross-Plane Design for Wearable Thermoelectric Generators with High Stretchability and Output Performance

Stretchable wearable thermoelectric (TE) generators (WTEGs) without compromising output performance for real wearables have attracted much attention recently. Herein, a 3D thermoelectric generator with biaxial stretchability is constructed on the device level. Ultraflexible inorganic Ag/Ag2 Se strips are sewn into the soft purl-knit fabric, in which the thermoelectric legs are aligned in the direction of vertical heat flux. A stable and sufficient temperature gradient of 5.2 °C across the WTEG is therefore achieved when contacted with the wrist at a room temperature of 26.3 °C. The prepared TEG generates a high power density of 10.02 W m-2 at a vertical temperature gradient of 40 K. Meanwhile, the reliable energy harvesting promises a variation of less than 10% under the biaxial stretching up to 70% strain via leveraging the combined effects of the stretchability of knit fabric and geometry of TE strips. The knit fabric-supported TEG enables a seamless conformation to the skin as well as efficient body heat harvesting, which can provide sustainable energy to low power consumption wearable electronics.

Guanidine-containing double-network silks with enhanced tensile and antibacterial property

The bacterial infection of surgical wounds results in prolonged hospitalization and even death of patients, calling for antibacterial function in modern suture products. To tackle this challenge, cationic guanidine-containing copolymer was synthesized, exhibiting antibacterial potency over 5 log reduction against both Gram-positive S. aureus and Gram-negative E. coli. Furthermore, we developed a double-network silk suture by integrating a guanidine-containing copolymer network into the silk fibroin network. This suture exhibited biocidal activity against S. aureus and E. coli, and superior strength compared to the commercial product in both dry and wet conditions. These results may bring general benefits to public health and medical equipment sustainability.

Platelet-rich plasma-loaded bioactive chitosan@sodium alginate@gelatin shell-core fibrous hydrogels with enhanced sustained release of growth factors for diabetic foot ulcer healing

The ability of autologous platelet-rich plasma (PRP) gel to promote rapid wound healing without immunological rejection has opened new avenues for the treatment of diabetic foot wounds. However, PRP gel still suffers from the quick release of growth factors (GFs) and requires frequent administration, thus resulting in decreased wound healing efficiency, higher cost as well as greater pain and suffering for the patients. In this study, the flow-assisted dynamic physical cross-linked coaxial microfluidic three-dimensional (3D) bio-printing technology, combined with the calcium ion chemical dual cross-linking method was developed to design PRP-loaded bioactive multi-layer shell-core fibrous hydrogels. The prepared hydrogels exhibited outstanding water absorption-retention capacity, good biocompatibility as well as a broad-spectrum antibacterial effect. Compared with clinical PRP gel, these bioactive fibrous hydrogels displayed a sustained release of GFs, reducing the administration frequency by 33 % availably during the wound treatment, but more prominent therapeutic effects such as effective reduced inflammation, in addition to promoting the growth of granulation tissue and angiogenesis, the formation of high-density hair follicles, and the generation of regular ordered and high-density collagen fiber network, which suggested great promise as exceptional candidates for treatment of diabetic foot ulcer in clinical settings.

Terahertz polarization and chirality modulation induced by asymmetry inversion combining chiral metasurface and liquid crystal anisotropy

We experimentally demonstrate a dynamic terahertz (THz) chiral device based on a composite structure of anisotropic liquid crystals (LCs) sandwiched between a bilayer metasurface. The device supports the symmetric mode and antisymmetric mode under the incidence of left- and right-circular polarized waves, respectively. The different coupling strengths of the two modes reflect the chirality of the device, and the anisotropy of the LCs can change the coupling strength of the modes, which brings tunability to the chirality of the device. The experimental results show that the circular dichroism of the device can be dynamically controlled from 28 dB to -32 dB (i.e., inversion regulation) at approximately 0.47 THz and from -32 dB to 1 dB (i.e., switching regulation) at approximately 0.97 THz. Moreover, the polarization state of the output wave is also tunable. Such flexible and dynamic manipulation of THz chirality and polarization might build an alternative pathway for complex THz chirality control, high-sensitivity THz chirality detection, and THz chiral sensing.

Large-area ultra-thin GO nanofiltration membranes prepared by a pre-crosslinking rod coating technique

In existing separation membranes, it is difficult to quickly produce large-area graphene oxide (GO) nanofiltration membranes with high permeability and high rejection, which is the bottleneck of industrialization. In this study, a pre-crosslinking rod-coating technique is reported. A GO-P-Phenylenediamine (PPD) suspension was obtained by chemically crosslinking GO and PPD for 180 min. After scraping and coating with a Mayer rod, the ultra-thin GO-PPD nanofiltration membrane with an area of 400 cm² and a thickness of 40 nm was prepared in 30 s. The PPD formed an amide bond with GO to improve its stability. It also increased the layer spacing of GO membrane, which could improve the permeability. The prepared GO nanofiltration membrane had a 99 % rejection rate for dyes such as methylene blue, crystal violet, and Congo red. Meanwhile, the permeation flux reached to 42 LMH/bar, which was 10 times that of the GO membrane without PPD crosslinking, and it still maintained excellent stability under strongly acidic and basic conditions. This work successfully solved the problems of GO nanofiltration membranes, including the large-area fabrication, high permeability and high rejection.

Biomimetic three-layer hierarchical scaffolds for efficient water management and cell recruitment

Taking inspiration from the structures of roots, stems and leaves of trees in nature, a biomimetic three-layered scaffold was designed for efficient water management and cell recruitment. Using polycaprolactone (PCL) and polyacrylonitrile (PAN) as raw materials, radially oriented nanofiber films and multistage adjustable nanofiber films were prepared through electrospinning technology as the base skin-friendly layer (roots) and middle unidirectional moisture conductive material (stems), the porous polyurethane foam was integrated as the outer moisturizing layer (leaves). Among which, radially oriented nanofiber films could promote the directional migration of fibroblasts and induce cell morphological changes. For the spatially hierarchically nanofiber films, the unidirectional transport of liquid was effectively realized. While the porous polyurethane foam membrane could absorb 9 times its weight in biofluid and retain moisture for up to 10 h. As a result, the biomimetic three-layered scaffolds with different structures can promote wound epithelization and drain biofluid while avoiding wound inflammation caused by excessive biofluid, which is expected to be applied in the field of skin wounds.

Improving Generalizability of Spectral Reflectance Reconstruction Using L1-Norm Penalization

Spectral reflectance reconstruction for multispectral images (such as Weiner estimation) may perform sub-optimally when the object being measured has a texture that is not in the training set. The accuracy of the reconstruction is significantly lower without training samples. We propose an improved reflectance reconstruction method based on L1-norm penalization to solve this issue. Using L1-norm, our method can provide the transformation matrix with the favorable sparse property, which can help to achieve better results when measuring the unseen samples. We verify the proposed method by reconstructing spectral reflection for four types of materials (cotton, paper, polyester, and nylon) captured by a multispectral imaging system. Each of the materials has its texture and there are 204 samples in each of the materials/textures in the experiments. The experimental results show that when the texture is not included in the training dataset, L1-norm can achieve better results compared with existing methods using colorimetric measure (i.e., color difference) and shows consistent accuracy across four kinds of materials.

Charge-controllable mussel-inspired magnetic nanocomposites for selective dye adsorption and separation

Magnetic polydopamine (PDA) nanocomposites were prepared with a facile and sustainable synthetic method. The as-synthesized polymer-based hybrid composites inherited the intrinsic adhesiveness contributed by catechol and amino moieties of PDA as well as the magnetic property of Fe₃O₄. With the unique properties of PDA, the surface charges of Fe₃O₄@PDA could be easily tuned by pH for smart adsorption-desorption behaviors. Four commercially available dyestuffs including crystal violet, rhodamine B, direct blue 71 and orange G with different structures and surface charges in solution were selected to investigate the adsorption ability and universality of Fe₃O₄@PDA in wastewater treatment. It was found that the nanocomposites could successfully adsorb these cationic and anionic dyes under suitable pH conditions. This confirmed the ability of the nanoadsorbents for the removal of common textile dyes. The dispersed magnetic nanoadsorbents also demonstrated the ease of collection from dye mixtures, and the possibility of reusing them for several cycles. Selective dye separation was found to be achievable via simple charge control without large consumption of organic solvent and energy. These bio-inspired nanocomposite adsorbents have shown high potential in wastewater treatment and selective recovery of dye waste, especially for wastewater containing ionic dyes.

Environmentally Benign Biosynthesis of Hierarchical MOF/Bacterial Cellulose Composite Sponge for Nerve Agent Protection

The fabrication of MOF polymer composite materials enables the practical applications of MOF-based technology, in particular for protective suits and masks. However, traditional production methods typically require organic solvent for processing which leads to environmental pollution, low-loading efficiency, poor accessibility, and loss of functionality due to poor solvent resistance properties. For the first time, we have developed a microbial synthesis strategy to prepare a MOF/bacterial cellulose nanofiber composite sponge. The prepared sponge exhibited a hierarchically porous structure, high MOF loading (up to ≈90 %), good solvent resistance, and high catalytic activity for the liquid- and solid-state hydrolysis of nerve agent simulants. Moreover, the MOF/ bacterial cellulose composite sponge reported here showed a nearly 8-fold enhancement in the protection against an ultra-toxic nerve agent (GD) in permeability studies as compared to a commercialized adsorptive carbon cloth. The results shown here present an essential step toward the practical application of MOF-based protective gear against nerve agents.

A multifunctional 3D dressing unit based on the core-shell hydrogel microfiber for diabetic foot wound healing

The healing mechanism of diabetic foot wounds is very complicated, and it is difficult for a single-function medical dressing to achieve good therapeutic effects. We propose a simple coaxial biological 3D printing technology, which uses one-step 3D deposition to continuously produce multifunctional medical dressings on the basis of core-shell hydrogel fibers. These dressings have good biocompatibility, controlled drug-release performance, excellent water absorption and retention, and antibacterial and anti-inflammatory functions. In vivo experiments with type 2 diabetic rats were performed over a 14-day period to compare the performance of the multifunctional 3D dressing with a gauze control; the multifunctional 3D dressing reduced inflammation, effectively increased the post-healing thickness of granulation tissue, and promoted the formation of blood vessels, hair follicles, and highly oriented collagen fiber networks. Therefore, the proposed multifunctional dressing is expected to be suitable for clinical applications for healing diabetic foot wounds.

Novel and Sustainable Colorants Developed via Incorporating Azo Chromophores into Dopamine Molecules

Inspired by the application of dopamine as an "anchor" and UV absorber, novel sustainable colorants with biscatecholic structure were synthesized through a simple incorporation of simple azo chromophores with dopamine. Their structures were confirmed using MS and NMR analyses, and their application on textile materials was investigated. Compared to the simple azo chromophores with almost no coloring ability on fabrics, the biscatecholic colorants could color different fabrics effectively, mainly through self-polymerization only in the presence of a trace amount of organic base at room temperature, which is environmentally friendly in terms of saving resources and alleviating chemical pollution. Meanwhile, the UV resistance of colored fabrics was enhanced significantly, showing the advantage of protecting wearers from UV damage.

Circadian humidity fluctuation induced capillary flow for sustainable mobile energy

Circadian humidity fluctuation is an important factor that affects human life all over the world. Here we show that spherical cap-shaped ionic liquid drops sitting on nanowire array are able to continuously output electricity when exposed to outdoor air, which we attribute to the daily humidity fluctuation induced directional capillary flow. Specifically, ionic liquid drops could absorb/desorb water around the liquid/vapor interface and swell/shrink depending on air humidity fluctuation. While pinning of the drop by nanowire array suppresses advancing/receding of triple-phase contact line. To maintain the surface tension-regulated spherical cap profile, inward/outward flow arises for removing excess fluid from the edge or filling the perimeter with fluid from center. This moisture absorption/desorption-caused capillary flow is confirmed by in-situ microscope imaging. We conduct further research to reveal how environmental humidity affects flow rate and power generation performance. To further illustrate feasibility of our strategy, we combine the generators to light up a red diode and LCD screen. All these results present the great potential of tiny humidity fluctuation as an easily accessible anytime-and-anywhere small-scale green energy resource.

Droplet generators convert mechanical movements of droplets into small-scale electricity. Here, Tang et al. report a humidity-driven power generator by utilizing daily humidity fluctuation in atmosphere enabling continuous generation of electricity upon moisture absorption and desorption cycles.

Immobilized Regenerable Active Chlorine within a Zirconium-Based MOF Textile Composite to Eliminate Biological and Chemical Threats

The most recent global health crisis caused by the SARS-CoV-2 outbreak and the alarming use of chemical warfare agents highlight the necessity to produce efficient protective clothing and masks against biohazard and chemical threats. However, the development of a multifunctional protective textile is still behind to supply adequate protection for the public. To tackle this challenge, we designed multifunctional and regenerable N-chlorine based biocidal and detoxifying textiles using a robust zirconium metal-organic framework (MOF), UiO-66-NH₂, as a chlorine carrier which can be easily coated on textile fibers. A chlorine bleaching converted the amine groups located on the MOF linker to active N-chlorine structures. The fibrous composite exhibited rapid biocidal activity against both Gram-negative bacteria (E. coli) and Gram-positive bacteria (S. aureus) with up to a 7 log reduction within 5 min for each strain as well as a 5 log reduction of SARS-CoV-2 within 15 min. Moreover, the active chlorine loaded MOF/fiber composite selectively and rapidly degraded sulfur mustard and its chemical simulant 2-chloroethyl ethyl sulfide (CEES) with half-lives less than 3 minutes. The versatile MOF-based fibrous composite designed here has the potential to serve as protective cloth against both biological and chemical threats.

A Facile and Scalable Method of Fabrication of Large-Area Ultrathin Graphene Oxide Nanofiltration Membrane

With their ultrafast water transport and excellent molecule sieving properties, graphene oxide (GO)-based membranes show great potential in the membrane filtration field for water purification and molecular separation. However, the inability of uniform GO membranes to be produced on an industrial scale and their nonenvironmentally friendly reduction treatment are the bottleneck preventing their industrial applications. Herein, we report a scalable ultrathin uniform GO membrane fabrication technique. Ultrathin GO membranes with a large area of 30 × 80 cm² and a thickness of a few nanometers were uniformly and facilely fabricated using a continuous process combining Mayer rod-coating and a short-time, high-power UV reduction. The interlayer spacing of the GO membrane could be effectively reduced and regulated to improve the salt rejection rate. The fabricated membrane showed superior water permeability of over 60.0 kg m^-2 h^-1 and a high separation efficiency of over 96.0% for a sodium sulfate (Na₂SO₄) solution. It also exhibited excellent mechanical stability under various harsh crossflow conditions. More importantly, the fabrication method developed here can be scaled up using a roll-to-roll industrial production process, which successfully solves the problem currently faced by GO membrane researchers and makes the industrial usage of GO membrane a reality.

Mussel-Inspired Design of a Self-Adhesive Agent for Durable Moisture Management and Bacterial Inhibition on PET Fabric

Functional textiles with advanced moisture management can enhance human comfort and physiological health. However, conventional wet finishing processes used for textiles are usually highly polluting and exhibit poor fastness. Inspired by the strong underwater adhesion properties of mussels based on cation-π interaction, a novel superhydrophilic polymeric molecule with strong cohesion and adhesion property is designed on a poly(ethylene terephthalate) (PET) fabric. The cation-π hydrophilic agent (CPHA) can efficiently transform the hydrophobic PET fabric to a superhydrophilic one, and its superhydrophilicity can withstand 150 home laundry cycles. In addition, the cationic moieties in the CPHA self-adhere to the PET fabric without any finishing auxiliary that would cause pollution. Due to its strong adhesion, CPHA can be applied to one side of the PET fabric via spray coating and curing to form a Janus hydrophobic/superhydrophilic fabric capable of diode-like one-way sweat transportation (with forward transportation capability of 1115% and backward transportation capability of -1509%). Moreover, the Janus fabric inhibits bacterial growth and invasion, while simultaneously preserving the inner ecological healthy balance of the skin's microflora. This work opens up a pathway to develop adhesives in textile wet processing for more diverse, smarter applications, e.g., quick-dry sportswear, protective suits, or air-conditioning fabrics.

Single-Ion Conducting Double-Network Hydrogel Electrolytes for Long Cycling Zinc-Ion Batteries

As one of the promising alternatives of lithium-ion batteries, zinc-ion batteries (ZIBs) have received growing interest from researchers due to their good safety, eco-friendliness, and low cost. Nevertheless, aqueous ZIBs are still a step away from practical applications due to the nonuniform deposition of Zn and parasitic side reactions, which cause capacity fading and even short circuit. To tackle these problems, here we introduce a single-Zn-ion conducting hydrogel electrolyte (SIHE), P(ICZn-AAm), synthesized with iota carrageenan (IC) and acrylamide (AAm). The SIHE manifests single Zn²⁺ conductivity via the abundant sulfates fixed on the IC polymer backbone, delivering a high Zn²⁺ transference number of 0.93. It also exhibits outstanding ionic conductivity of 2.15 × 10^-3 S cm^-1 at room temperature. The enhanced compatibility at the electrode-electrolyte interface was verified by the stable Zn striping/plating performance along with a homogenous and smooth Zn deposition layer. It is also found that the passivation of the Zn anode can be effectively prohibited due to the lack of free anions in the electrolyte. The practical performance of the SIHE is further investigated with Zn-V₂O₅ batteries, which showed a stable capacity of 271.6 mA h g^-1 over 150 cycles at 2 C and 127.5 mA h g^-1 over 500 cycles at 5 C.

Microfluidic-directed biomimetic Bulbine torta-like microfibers based on inhomogeneous viscosity rope-coil effect

Helical structures are attracting increasing attention owing to their unique typical physical and chemical properties. However, it remains a challenge to construct atypical helical structures at the microscale. This paper proposes a continuous spinning method with a microfluidic-chip-based spinning device to engineer atypical helical microfibers. The strategy causes polymer fluid to form the biomimetic Bulbine torta (BT)-like shape with the aid of the inhomogeneous viscosity rope-coil effect. In particular, the structure parameter of the BT microfibers could be optimized through the synchronous regulation of the microfluidic flow and reaction kinetics, and the obtained microfibers exhibit ultrahigh strain sensitivity, indicating great promise as exceptional candidates for constructing ideal strain sensors. In addition, single- and double-hollow BT microfibers are also prepared by introducing the core flow channel into the microfluidic chip and demonstrate high structural similarity to irregular blood vessels (e.g. varicose veins), which is promising for the actual application of blood vessel tissue engineering.

Bifunctional Regenerated Cellulose/Polyaniline/Nanosilver Fibers as a Catalyst/Bactericide for Water Decontamination

For antagonizing urgent water pollution and increasing environmental consciousness, the integration of renewable resources and nanotechnologies has become a trend to improve water quality in the ecosystem. Here, we designed a green route to fabricate regenerated cellulose fibers (CFs) with 3D micro- and nanoporous structures in NaOH/urea aqueous solvent systems via a scalable wet-spinning procedure as support materials for nanoparticles (NPs). Modification of CFs with polyaniline@Ag nanocomposites through in situ reduction of the silver ion with aqueous aniline led to enhanced pollutant removal efficiency of functional cellulose-based fibers (FCFs), demonstrating both rapid hydrogenation catalytic performance for the reduction of p-nitrophenol and high antibacterial properties for in-flow water purification. Most importantly, the hierarchically porous structures of FCFs not only provided carrier space but also formed a limiting domain guaranteeing the homogeneity of FCFs even with a Ag NP content as high as 36.47 wt %. The prepared functional fibers show good behavior in in-flow water purification, representing significant advancement in the use of biomass fibers for catalytic and bactericidal applications in liquid media.

Neuro-perceptive discrimination on fabric tactile stimulation by Electroencephalographic (EEG) spectra

The precise evaluation of sensory perceptions during fabric-skin interactions is still poorly understood in neuroscience. This study aims to investigate the cortical sensory response to fabric stimuli with different textiles by Electroencephalographic (EEG) spectral intensities, and evaluate the relationships between EEG frequency bands, traditional subjective questionnaires, and the materials' physical properties. Twelve healthy adult participants were recruited to test three fabrics with different textile compositions of 1) cotton, 2) nylon, and 3) polyester and wool. The physical properties of the fabrics were quantitatively evaluated by a Fabric Touch Tester (FTT). Subjects were invited to rate the sensory perception of the fabric samples via a subjective questionnaire and objective EEG recording. Significant differences in the EEG relative spectral power of Theta and Gamma bands were acquired in response to the different fabric stimuli (P<0.05). The Theta and Gamma powers demonstrated a significant correlation with the most of the subjective sensations evaluated by questionnaire and the fabrics' physical properties by FTT (P<0.05). The EEG spectral analysis could feasibly be used for the discrimination of fabric stimuli with different textile compositions and further indicates sensory perceptions during fabric stimulation. This finding may provide evidence for further exploratory research of sensory perceptions via EEG spectral analysis, which could be applied to the study of brain generators of skin tactility in future prostheses and the automatic detection of sensory perception in industries.

Polymorphic calcium alginate microfibers assembled using a programmable microfluidic field for cell regulation

Effectively guiding and accurately controlling cell adhesion and growth on the surfaces of specific morphological materials are key issues and hot research topics for optimizing biomaterials. Herein, novel polymorphic alginate microfibers formed through microfluidic spinning technology in a single microchip are presented. Through programming the flow and reaction kinetics in microchannels, other than self-modified micromorphic channel geometry, polymorphic microfibers with precisely tuned curvature-adjustable morphology can be obtained. Finite element (FE) simulations of the flow field (unidirectional fluid-solid coupling) proved the efficacy of the proposed control strategy. Moreover, the specific disordered-ordered cell arrangements showed a linear relationship between bioinspired alginate microfibers with different curvatures and the orientation angle of L929 cells, and diversified growth morphologies, including oblate ellipse, star, tree and strip shapes, occurred on the customizable interface curvature of the calcium alginate microfibers, providing a paradigm for using specific structured natural biomedical materials for cell regulation. This work represents a new design concept for manufacturing polymorphic fibrous biomedical materials through a unique marriage of the fields of green chemistry, hydromechanics, and biomaterials, which should be very useful for guiding the controllable construction of alginate materials for use in structural materials for biomedical and engineering purposes.

Growing Poly(norepinephrine) Layer over Individual Nanoparticles To Boost Hybrid Perovskite Photocatalysts

To address the poor stability of lead halide perovskite nanoparticles (NPs), monodisperse methylammonium lead bromide (MAPbBr₃, M-PE) NPs were successfully encapsulated with a thin layer (10 nm) of poly(norepinephrine) (PNE) by in situ polymerization. The PNE layer endowed M-PE NPs with high structural stability against severe environmental conditions. Furthermore, the chemical interaction between M-PE and PNE facilitates the construction of the core@shell composite, as well as contributes to the enhanced light-harvesting capacity and improved photoelectronic conversion efficiency in photocatalytic activity. The encapsulated NP M-PE@PNE with a band gap of 2.04 eV degraded the organic pollutant of malachite green by 81% in less than 2 h under visible light, which was 4.5 times higher than pristine M-PE NPs. This work provides a practical approach to stabilize and boost the MAPbX₃ photocatalyst and carries enormous potential in wide engineering applications.

Simultaneous fire safety enhancement and mechanical reinforcement of poly(lactic acid) biocomposites with hexaphenyl (nitrilotris(ethane-2,1-diyl))tris(phosphoramidate)

Poly(lactic acid) (PLA) is an important bioplastic polymer with wide engineering applications, but has relatively low tensile strength and high susceptibility to flames. This manuscript reports the synthesis of a new cyclo-phosphorus-nitrogen flame retardant (FR) - hexaphenyl (nitrilotris(ethane-2,1-diyl))tris(phosphoramidate) (HNETP) for concurrent FR and tensile strength enhancement. ¹H, ¹³C Nuclear Magnetic Resonance and Fourier Transform Infra-red spectra showed that HNETP was successfully synthesized. The FR properties of PLA/HNETP composites were investigated, and the peak heat release rate (PHRR) reduced by ˜ 51.3%, total heat released (THR) ˜ 43.1%, and carbon monoxide (CO) production by ˜ 46.5% with 3 wt% HNETP loading. The fire performance index increased by ˜ 65.8%, while the fire growth index decreased by ˜ 56.7%. The tensile strength and the Young's Modulus improved to ˜ 67.4 and ˜ 87.8% respectively. A significant increase in limiting oxygen index (LOI) (32.5%) was attained with a V-0 rating in the vertical burning test. TG-IR study showed considerable reduction in pyrolysis gaseous products by the PLA/HNETP composites compared to PLA. Insignificant changes were observed in the glass transition and the melting temperature of PLA and PLA/HNETP biocomposites.

Integration of Metal-Organic Frameworks on Protective Layers for Destruction of Nerve Agents under Relevant Conditions

Metal-organic frameworks (MOFs) are promising candidates for the catalytic hydrolysis of nerve agents and their simulants. Though highly efficient, bulk water and volatile bases are often required for hydrolysis with these MOF catalysts, preventing real-world implementation. Herein we report a generalizable and scalable approach for integrating MOFs and non-volatile polymeric bases onto textile fibers for nerve agent hydrolysis. Notably, the composite material showed similar reactivity under ambient conditions compared to the powder material in aqueous alkaline solution. This represents a critical step toward a unified strategy for nerve agent hydrolysis in practical settings, which can significantly reduce the dimensions of filters and increase the efficiency of protective suits.

Scalable and Template-Free Aqueous Synthesis of Zirconium-Based Metal-Organic Framework Coating on Textile Fiber

Organophosphonate-based nerve agents, such as VX, Sarin (GB), and Soman (GD), are among the most toxic chemicals to humankind. Recently, we have shown that Zr-based metal-organic frameworks (Zr-MOFs) can effectively catalyze the hydrolysis of these toxic chemicals for diminishing their toxicity. On the other hand, utilizing these materials in powder form is not practical, and developing scalable and economical processes for integrating these materials onto fibers is crucial for protective gear. Herein, we report a scalable, template-free, and aqueous solution-based synthesis strategy for the production of Zr-MOF-coated textiles. Among all MOF/fiber composites reported to date, the MOF-808/polyester fibers exhibit the highest rates of nerve agent hydrolysis. Moreover, such highly porous fiber composites display significantly higher protection time compared to that of its parent fabric for a mustard gas simulant, 2-chloroethyl ethyl sulfide (CEES). A decreased diffusion rate of toxic chemicals through the MOF layer can provide time needed for the destruction of the harmful species.

Facile and Scalable Coating of Metal-Organic Frameworks on Fibrous Substrates by a Coordination Replication Method at Room Temperature

Coating of metal-organic frameworks (MOFs) on flexible substrates is a crucial technology for applications such as purification/separation, sensing, and catalysis. In this work, a facile coordination replication strategy was developed to coat various MOFs onto flexible fibrous materials where a dense layer of an insoluble precursor template, such as a layered hydroxide salt, was first deposited onto a fiber substrate via a mild interfacial reaction and then rapidly transformed into a MOF coating in a ligand solution at room temperature. Spatiotemporal harmonization of solid precursor dissolution and MOF crystallization enabled precise replication of the precursor layer morphology to form a continuous MOF coating composed of intergrown crystals. The resulting flexible, highly robust, and processable fibrous MOF/textile composites demonstrated tremendous potential for industrially relevant applications such as continuous removal of the organosulfur compound dibenzothiophene from simulated gasoline and ammonia capture. This rapid, versatile, eco-friendly, and scalable MOF coating process at room temperature gives rise to new possibilities for preparing MOF-coated functional materials.

Nature-Inspired Windmill for Water Collection in Complex Windy Environments

Nature-inspired water collection technology has been well-recognized as an effective solution for relieving water shortage hardships, and yet remains challenging when being used in an actual natural environment. In this work, we have successfully developed a promising water-collecting windmill that can be used in complex windy environments, by taking integrative inspiration from the liquid-manipulation strategies adopted by rice leaves, cacti, Nepenthes pitcher plants, and butterflies. The unique directional grooves on the blade surface with ridge-like walls with a shape gradient, combined with a molecular slippery layer, are crucial for not only water deposition but also directional drainage in water collection. Besides, the engineering design of rotatable blades turns the adverse effect of strong winds into a positive one, along with the nature-inspired surface topography and physicochemical property. Such a novel windmill has shown unprecedented water-collecting performance in a static environment, in strong wind, and in intermittent wind. Furthermore, the windmill can sense the wind-blowing direction and adjust its facing direction accordingly to ensure maximum utilization of wind power. It is believed that this work will bring a broad guiding significance to the design of smart water-harvesting materials and devices for application in more complex situations.

Fully Controllable Design and Fabrication of Three-Dimensional Lattice Supercapacitors

Supercapacitors have been proven to be a superior candidate for energy storage systems. Yet, most of them are of an approximately two-dimensional structure, without taking full advantage of the spatial superiority to load more mass of active materials. Moreover, three-dimensional (3D) sponge electrodes may hinder ion transmission due to the significant variations in porous structures. In this work, fully controllable 3D lattice supercapacitors with the ordered porous structures were fabricated for the first time via using 3D printing technology. To increase the mass loading capacity, active materials, including metal films, carbon nanomaterials, and transition-metal sulfides, were hierarchically loaded onto the surface of the lattice substrate by using electroless plating, dip-coating, and electrodeposition methods. The as-fabricated CoNi₂S₄/Ni/octet-truss lattice (OTL) electrode demonstrates a high capacitance until up to 1216 F g^-1 (KOH electrolyte). The lattice asymmetric all-solid-state supercapacitors, composed of CoNi₂S₄/Ni/OTL as anode and carbon materials/Ni/OTL as cathode, display the highest specific capacitance of 23.5 F g^-1, a 10.6 Wh kg^-1 energy density at the 2488.3 W kg^-1 power density, and a robustness (77.3% capacitance retention after 1800 cycles). We expect that the design and fabrication method for the fully controllable 3D lattice supercapacitor with hierarchical activating materials can open a door to develop 3D supercapacitors.

Normalized Total Gradient: A New Measure for Multispectral Image Registration

Image registration is a fundamental issue in multispectral image processing, and is challenged by two main characteristics of multispectral images. First, the regional intensities can be essentially different between band images. Second, the local contrasts of two difference band images are inconsistent or even reversed. Conventional measures can align images with different regional intensity levels, but may fail in the circumstance of severe local intensity variation. In this paper, a new measure called normalized total gradient is proposed for multispectral image registration. The measure is based on the key assumption (observation) that the gradient of the difference between two aligned band images is sparser than that between two misaligned ones. A registration framework, which incorporates image pyramid and global/local optimization, is further introduced for affine transform. Experimental results validate that the proposed method is not only effective for multispectral image registration, but also applicable to general unimodal/multimodal image registration tasks. It performs better than or comparable to the existing methods, both quantitatively and qualitatively.

Effect of graphene oxide inclusion on the optical reflection of a silica photonic crystal film

In this study, the inclusion of graphene oxide in silica photonic crystals was found to affect optical reflectance intensity and reflectance peak broadening. The quantitative relationship between weight percentage and the reflected light intensity and corresponding wavelength shift of light GO-decorated photonic crystals was studied, providing a useful parameter in the rational design of antireflection coatings for GO-based photonic crystal films. Comparison of the experimental results with a pure SiO₂ particle film shows that a SiO₂ particle surface layer incorporated with a fixed graphene oxide weight percentage results in broadening of the peak and a decrease in reflectance intensity. The percentage of the reduction in reflectance intensity is a function of particle size, as indicated by the structured color film surface, demonstrating the possibility of estimating the effect of different graphene oxide inclusion percentages on the antireflection properties of photonic crystal films.

In this study, the inclusion of graphene oxide in silica photonic crystals was found to affect optical reflectance intensity and reflectance peak broadening.

Flexible Slippery Surface to Manipulate Droplet Coalescence and Sliding, and Its Practicability in Wind-Resistant Water Collection

A flexible slippery membrane (FSM) with tunable morphology and high elastic deformability has been developed by infusing perfluoropolyether (PFPE) into a fluorinated-copolymer-modified thermoplastic polyurethane (TPU) nanofiberous membrane. To immobilize PFPE in TPU matrix, we synthesized a fluorinated-copolymer poly(DFMA-co-IBOA-co-LMA) with low surface energy, high chemical affinity to PFPE, adequate flexibility, and strong physical adhesion on TPU. Upon external tensile stress, the as-prepared FSM can realize a real-time manipulation of water sliding and coalescence on it. Furthermore, it exhibits the ability to preserve the captured water from being blown away by strong wind, which ensures the water collection efficiency in windy regions.

Bidirectional texture function image super-resolution using singular value decomposition

The bidirectional texture function (BTF) is widely employed to achieve realistic digital reproduction of real-world material appearance. In practice, a BTF measurement device usually does not use high-resolution (HR) cameras in data collection, considering the high equipment cost and huge data space required. The limited image resolution consequently leads to the loss of texture details in BTF data. This paper proposes a fast BTF image super-resolution (SR) algorithm to deal with this issue. The algorithm uses singular value decomposition (SVD) to separate the collected low-resolution (LR) BTF data into intrinsic textures and eigen-apparent bidirectional reflectance distribution functions (eigen-ABRDFs) and then improves the resolution of the intrinsic textures via image SR. The HR BTFs can be finally obtained by fusing the reconstructed HR intrinsic textures with the LR eigen-ABRDFs. Experimental results show that the proposed algorithm outperforms the state-of-the-art single-image SR algorithms in terms of reconstruction accuracy. In addition, thanks to the employment of SVD, the proposed algorithm is computationally efficient and robust to noise corruption.

Spectral bidirectional texture function reconstruction by fusing multiple-color and spectral images

Spectral bidirectional texture function (BTF) is essential for accurate reproduction of material appearance due to its nature of conveying both spatial and spectral information. A practical issue is that the acquisition of raw spectral BTFs is time-consuming. To resolve the limitation, this paper proposes a novel framework for efficient spectral BTF acquisition and reconstruction. The framework acquires red-green-blue (RGB) BTF images and just one spectral image. The full spectral BTFs are reconstructed by fusing the RGB and spectral images based on nonnegative matrix factorization (NMF). Experimental results indicate that the accuracy of spectral reflectance reconstruction is higher than that of existing algorithms. With the reconstructed spectral BTFs, the material appearance can be reproduced with high fidelity under various illumination conditions.

Constructing safe and durable antibacterial textile surfaces using a robust graft-to strategy via covalent bond formation

Recently zwitterionic materials have been widely applied in the biomedical and bioengineering fields due to their excellent biocompatibility. Inspired by these, this study presents a graft-to strategy via covalent bond formation to fabricate safe and durable antibacterial textile surfaces. A novel zwitterionic sulfobetaine containing triazine reactive group was specifically designed and synthesized. MTT assay showed that it had no obvious cytotoxicity to human skin HaCaT cells as verified by ca. 89.9% relative viability at a rather high concentration of 0.8 mg·mL⁻¹. In the evaluation for its skin sensitization, the maximum score for symptoms of erythema and edema in all tests were 0 in all observation periods. The sulfobetaine had a hydrophilic nature and the hydrophilicity of the textiles was enhanced by 43.9% when it was covalently grafted onto the textiles. Moreover, the textiles grafted with the reactive sulfobetaine exhibited durable antibacterial activities, which was verified by the fact that they showed antibacterial rates of 97.4% against gram-positive S. aureus and 93.2% against gram-negative E. coli even after they were laundered for 30 times. Therefore, the titled zwitterionic sulfobetaine is safe to human for healthcare and wound dressing and shows a promising prospect on antibacterial textile application.

Beads-on-String Structured Nanofibers for Smart and Reversible Oil/Water Separation with Outstanding Antifouling Property

It is challenging to explore a unified solution for the treatment of oily wastewater from complex sources. Thus, membrane materials with flexible separation schemes are highly desired. Herein, we fabricated a smart membrane by electrospinning TiO2 doped polyvinylidene fluoride (PVDF) nanofibers. The as-formed beads-on-string structure and hierarchical roughness of the nanofibers contribute to its superwetting/resisting property to liquids, which is desirable in oil/water separation. Switched simply by UV (or sunlight) irradiation and heating treatment, the smart membrane can realize reversible separation of oil/water mixtures by selectively allowing water or oil to pass through alone. Most importantly, the as-prepared nanofiber membrane possesses outstanding antifouling and self-cleaning performance resulting from the photocatalytic property of TiO2, which has practical significance in saving solvents and recycling materials. This work provides a route for fabricating cost-effective, easily scaled up, and recyclable membranes for on-demand oil/water separation in versatile situations, which can be of great usage in the new green separation technology.

Graphene oxide-enhanced sol-gel transition sensitivity and drug release performance of an amphiphilic copolymer-based nanocomposite

We report the fabrication of a highly sensitive amphiphilic copolymer-based nanocomposite incorporating with graphene oxide (GO), which exhibited a low-intensity UV light-triggered sol-gel transition. Non-cytotoxicity was observed for the composite gels after the GO incorporation. Of particular interest were the microchannels that were formed spontaneously within the GO-incorporated UV-gel, which expedited sustained drug release. Therefore, the present highly UV-sensitive, non-cytotoxic amphiphilic copolymer-based composites is expected to provide enhanced photothermal therapy and chemotherapy by means of GO's unique photothermal properties, as well as through efficient passive targeting resulting from the sol-gel transition characteristic of the copolymer-based system with improved sensitivity, which thus promises the enhanced treatment of patients with cancer and other diseases.

Fast Multispectral Imaging by Spatial Pixel-Binning and Spectral Unmixing

Multispectral imaging system is of wide application in relevant fields for its capability in acquiring spectral information of scenes. Its limitation is that, due to the large number of spectral channels, the imaging process can be quite time-consuming when capturing high-resolution (HR) multispectral images. To resolve this limitation, this paper proposes a fast multispectral imaging framework based on the image sensor pixel-binning and spectral unmixing techniques. The framework comprises a fast imaging stage and a computational reconstruction stage. In the imaging stage, only a few spectral images are acquired in HR, while most spectral images are acquired in low resolution (LR). The LR images are captured by applying pixel binning on the image sensor, such that the exposure time can be greatly reduced. In the reconstruction stage, an optimal number of basis spectra are computed and the signal-dependent noise statistics are estimated. Then the unknown HR images are efficiently reconstructed by solving a closed-form cost function that models the spatial and spectral degradations. The effectiveness of the proposed framework is evaluated using real-scene multispectral images. Experimental results validate that, in general, the method outperforms the state of the arts in terms of reconstruction accuracy, with additional 20× or more improvement in computational efficiency.

Antibacterial modification of an injectable, biodegradable, non-cytotoxic block copolymer-based physical gel with body temperature-stimulated sol-gel transition and controlled drug release

Biomaterials are being extensively used in various biomedical fields; however, they are readily infected with microorganisms, thus posing a serious threat to the public health care. We herein presented a facile route to the antibacterial modification of an important A-B-A type biomaterial using poly (ethylene glycol) methyl ether (mPEG)- poly(ε-caprolactone) (PCL)-mPEG as a typical model. Inexpensive, commercial bis(2-hydroxyethyl) methylammonium chloride (DMA) was adopted as an antibacterial unit. The effective synthesis of the antibacterial copolymer mPEG-PCL-∼∼∼-PCL-mPEG (where ∼∼∼ denotes the segment with DMA units) was well confirmed by FTIR and (1)H NMR spectra. At an appropriate modification extent, the DMA unit could render the copolymer mPEG-PCL-∼∼∼-PCL-mPEG highly antibacterial, but did not largely alter its fascinating intrinsic properties including the thermosensitivity (e.g., the body temperature-induced sol-gel transition), non-cytotoxicity, and controlled drug release. A detailed study on the sol-gel-sol transition behavior of different copolymers showed that an appropriate extent of modification with DMA retained a sol-gel-sol transition, despite the fact that a too high extent caused a loss of sol-gel-sol transition. The hydrophilic and hydrophobic balance between mPEG and PCL was most likely broken upon a high extent of quaternization due to a large disturbance effect of DMA units at a large quantity (as evidenced by the heavily depressed PCL segment crystallinity), and thus the micelle aggregation mechanism for the gel formation could not work anymore, along with the loss of the thermosensitivity. The work presented here is highly expected to be generalized for synthesis of various block copolymers with immunity to microorganisms. Light may also be shed on understanding the phase transition behavior of various multiblock copolymers.

Durable Antibacterial and Nonfouling Cotton Textiles with Enhanced Comfort via Zwitterionic Sulfopropylbetaine Coating

A rapid, environment-friendly, and cost-effective finishing method has been developed for cotton textiles by using zwitterionic NCO-sulfopropylbetaine as the antibacterial finishing agent through covalent bond. The sulfopropylbetaine-finished cotton textile exhibits durable broad-spectrum antibacterial and nonfouling activity, improved mechanical properties, and enhanced comfort.

Biomimetic Water-Collecting Fabric with Light-Induced Superhydrophilic Bumps

To develop an efficient water-collecting surface that integrates both fast water-capturing and easy drainage properties is of high current interest for addressing global water issues. In this work, a superhydrophobic surface was fabricated on cotton fabric via manipulation of both the surface roughness and surface energy. This was followed by a subsequent spray coating of TiO2 nanosol that created light-induced superhydrophilic bumps with a unique raised structure as a result of the interfacial tension of the TiO2 nanosol sprayed on the superhydrophobic fiber surface. These raised TiO2 bumps induce both a wettability gradient and a shape gradient, synergistically accelerating water coalescence and water collection. The in-depth study revealed that the quantity and the distribution of the TiO2 had a significant impact on the final water collection efficiency. This inexpensive and facilely fabricated fabric biomimicks the desert beetle's back and spider silk, which are capable of fog harvesting without additional energy consumption.

A novel graphene oxide-based fluorescent nanosensor for selective detection of Fe(3+) with a wide linear concentration and its application in logic gate

A graphene oxide-based fluorescent nanosensor AGO has been designed and synthesized by covalent grafting allylamine onto GO surface. In aqueous media, AGO displays a highly selective and sensitive discrimination of Fe(3+) from Fe(2+) and other metal ions through electron transfer-induced fluorescence quenching. The quenching of AGO fluorescence is linearly proportional to Fe(3+) concentration in a wide range of 0-120 μM (correlation coefficient R(2)=0.9994). Moreover, AGO can be used to construct a combinational three-input logic gate to discriminate Fe(3+) and Fe(2+). The logic gate works well in intracellular fluorescence imaging, which shows a potential as a promising platform for biosensing analysis.