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Hydrogen is regarded as an ideal energy carrier to cope with the energy crisis and environmental problems due to its high energy density, cleanliness, and renewability. Although there are several primary methods of industrial hydrogen production, hydrogen evolution reaction (HER) is an efficient, eco-friendly, and sustainably green method for the preparation of hydrogen which has attracted considerable attention. However, this technique is characterized by slow reaction kinetics and high energy potential owing to lack of electrocatalysts with cost-effective and high performance which impedes its scale-up. To address this issue, various studies have focused on electrospun micro/nanofiber-based electrocatalysts for HER due to their excellent electron and mass transport, high specific surface area, as well as high porosity and flexibility. To further advance their development, recent progress of highly efficient HER electrospun electrocatalysts is reviewed. Initially, the characteristics of potential high-performance electrocatalysts for HER are elucidated. Subsequently, the advantages of utilizing electrospinning technology for the preparation of electrocatalysts are summarized. Then, the classification of electrospun micro/nanofiber-based electrocatalysts for HER are analyzed, including metal-based electrospun electrocatalyst (noble metals and alloys, transition metals, and alloys), metal–non-metal electrocatalysts (metal sulfide-based electrocatalysts, metal oxide-based electrocatalysts, metal phosphide-based electrocatalysts, metal nitride-based electrocatalysts, and metal carbide-based electrocatalysts), metal-free electrospun micro/nanofiber-based electrocatalysts, and hybrid electrospun micro/nanofiber-based electrocatalysts. Following this, enhancement strategies for electrospun micro/nanofiber-based electrocatalysts are discussed. Finally, current challenges and the future research directions of electrospun micro/nanofiber-based electrocatalysts for HER are concluded. [ABSTRACT FROM AUTHOR]

Smart wound dressings capable of detecting, monitoring, and regulating complicated dynamic healing processes hold tremendous potential in wound healing and tissue reconstruction. Micro/nanofiber‐based materials are regarded as one of the most promising candidates to develop smart wound dressings owing to their remarkable features including architectural mimicry of extracellular matrix, tunability in structural assembly, and diversity in functionality. Herein, the latest progress of smart micro/nanoscale fiber‐based materials in terms of composition engineering, structural design, and applications in wound management is comprehensively reviewed. This work begins with the advances in smart fibers including stimuli‐responsive fibers, shape memory fibers, and conductive fibers. Then, the structural design of fiber‐based materials from conventional 2D fibrous membrane to emerging 3D fibrous sponge/hydrogel is thoroughly discussed. Furthermore, the applications of smart micro/nanofibrous materials as wound dressings in stimuli‐responsive drug delivery, biomechanical stimulation, electrical stimulation, and wound monitoring are highlighted. Finally, the article offers perspectives on the existing challenges and future directions of smart fibrous materials for wound management. [ABSTRACT FROM AUTHOR]

The rapid development and popularization of smart and portable electronic devices have led to increasingly related electromagnetic pollution affecting human health and equipment safety. Thus, designing high‐performance electromagnetic interference (EMI) shielding materials with lightweight, flexible, and easy preparation is urgent. The intrinsic physiochemical properties of electrospun micro/nanofibers provide an attractive potential to ease and accelerate the next‐generation EMI shielding materials. Here, a detailed review of the electrospun EMI shielding materials is established. First, this article outlines the shielding mechanism of EMI shielding materials obtained via electrospinning. Then, the affecting factors of electrospinning process conditions on the resulting EMI shielding micro/nanofibers are discussed. Next, diverse fillers that contribute to the EMI shielding efficiency of electrospun materials are demonstrated. Finally, the conclusion and prospects are introduced, hopefully contributing to assisting with more comprehensive and rational designs of high‐performance electrospun fiber‐based EMI shielding for various applications. Priority measures and future directions are suggested for the future development of electrospun EMI shielding materials. [ABSTRACT FROM AUTHOR]

In recent years, piezoelectric nanogenerators have become more attractive than triboelectric nanogenerators due to their more excellent durability in high dust or humidity. Therefore, increasing their output is the subject of many studies. Here the focus is on electrodes of acoustic micro/nanofiber nanogenerators for the first time. Compared to other works here, introducing a new electrode is the aim, and it should be cheap and does not result in lower outputs. Here, for the first time, graphene spin-coated ink was used for a polyacrylonitrile-based acoustic nanogenerator, which gave the output of 60 mV. The results of the acoustic tests were compared with the in situ synthesis of nickel nanoparticles on the layer using graphene spin-coated screen ink and conductive tape, which had the highest outputs of 0, 60 and 120 mV. Additionally, the best way for increasing the output of piezoelectric acoustic nanogenerators is to make composites. Up to now the highest piezoelectric effect is for PAN and its composites have not been investigated yet. Here, as a first step of doing work in this field, I used a copolymer of PAN, because PAN is not a good polymer for doping and it needs functional groups.

Polylactic acid (PLA) micro/nanofiber fabrics with good biodegradability and biocompatibility have wide applications in the medical protective field. However, the poor flexibility, high brittleness, and insufficient mechanical properties of PLA micro/nanofiber fabrics remain challenging. Herein, a polylactic acid/polyethylene glycol (PLA/PEG) micro/nanofiber fabric with aligned fibers was successfully prepared by an inexpensive and straightforward post-drafting melt blown process. The experimental results showed that PEG can reduce the Tg of PLA, improve the mobility of PLA molecular chains, reduce the complex viscosity of PLA/PEG blends, and play a role in plasticization. The PLA/PEG micro/nanofiber fabrics had an aligned micro/nanofibrous structure, and the average fiber diameter was easily adjusted from 10.7 to 4.9 μm by tailoring the melt blown process parameters, i.e., die temperature and hot air temperature. Moreover, the breaking tensile strength increased from 45.06 to 78.73 N in the machine direction (MD), while it increased from 11.87 to 21.89 N in the cross direction (CD), which means that the breaking tensile strength was enhanced significantly by adjusting the die temperature and hot air temperature. Furthermore, the prepared samples showed a high softness score of 82.7, a large synthetic blood contact angle of 125.7°, and an excellent bursting strength of 58.5 N. These PLA/PEG micro/nanofiber fabrics with aligned fibers are ideal candidates for medical protective applications such as surgical gowns, protection suits, masks, and medical bandages. [ABSTRACT FROM AUTHOR]

Biosensors are analytical tools that can be used as simple, real-time and effective devices in clinical diagnosis, food analysis, and environmental monitoring. In the last years, electrospun nanofiber's engineering has emerged as a possible strategy to improve the performance of biosensor devices. These nanostructures present a high surface-to-volume ratio, interconnected porous structure, low barrier to diffusion, and adjustable surface functionality. Additionally, nanofibers have also been demonstrated to work efficiently as platforms to immobilize biomolecules, providing a suitable microenvironment to biologically active molecules, which is beneficial for biosensing performance. This review aims to highlight the different strategies (e.g., adsorption, covalent binding, entrapment, and imprinting) for immobilizing functional receptors onto nanofibers surface for the development of specific and sensitive (bio)chemical assays, which can be used for a wide range of applications. The attractive features of electrospun nanofibers and the biorecognition elements properties are also presented and discussed. Finally, the current challenges and future opportunities for the design of nanofiber-based biosensing interfaces are also addressed.

Four amino acid-based polyorganophosphazenes were synthesized and characterized by 1H NMR, 31P NMR and GPC. Individually, the synthesized polyorganophosphazenes were blended with two commonly used biocompatible polymers, poly (methyl methacrylate) (PMMA) and polylactic-co-glycolic acid (PLGA) to fabricate anticancer drug loaded micro/nanofibers and microspheres. The nature of side groups, blend composition and drug contents were particularly found significant to adjust the surface morphology, hydrolytic degradation and drug loading/release behavior of microspheres. Moreover, higher in vitro drug release rate was observed in acidic medium. Collectively, our findings suggest that amino acid-based polyorganophosphazenes blend' systems may provide a therapeutic strategy for cancers. [ABSTRACT FROM AUTHOR]

Micro/nanofiber-based face masks are recommended as personal protective equipment (PPE) against particulate matter (PM), especially PM 0.3 . Ensuring thermal comfort in daily use face masks is essential in many situations. Here, radiative thermal management is introduced into face masks to elevate the user comfort. An interlayered poly(lactic acid) (PLA) micro/nanofibrous filter effectively captures PM 0.3 (99.69%) with minimal pressure drop (49 Pa). Thermal regulation is accomplished by controlling the mid-infrared (MIR) emissivity of the face mask's outer surface. Cooling face masks feature cotton nonwovens with high MIR emissivity (90.7%) for heat dissipation, while warming face masks utilize perforated Al/PE films with minimal MIR emissivity (10.7%) for warmth retention. Skin temperature measurements indicate that the skin covered by the cooling face mask could be 1.1 °C lower than that covered by the 3M face mask, while the skin covered by the warming face mask could be 1.3 °C higher than that covered by the 3M face mask.

SiO2/polystyrene porous micro/nanofibers with superhydrophobic and superoleophilic properties were prepared by facile electrospinning method. The spindle-beads-on-string structured fibers were found to be more hydrophobic than those without the beads. The doping of nano-SiO2 endowed the fibers with porous structure, and thus further increased the water contact angle from 139° to 153°. Simultaneously, the oil contact angle of 0° was obtained. The superhydrophobic-superoleophilic micro/nanofibers could selectively absorb oil from water within eight seconds. The oil sorption process followed pseudo-first order kinetic model. The absorption mechanism was proved to be physical encapsulation by Fourier transform infrared technique. The maximum sorption capacity for highly viscous silicone oil was up to 122.7 g/g. It is higher than many recently reported values. The porous micro/nanofibers exhibit significant value in oil-water separation. [ABSTRACT FROM AUTHOR]

BACKGROUND Mosquitoes are hematophagous insects of major public health concern, serving as vectors of many diseases. Available products for personal protection against mosquitoes lack adequate efficacy and in most cases need to be reapplied or replaced frequently. In recent years, the encapsulation of the active repellents in various matrices has arisen as an alternative method for the development of new‐generation repellent systems. The aim of the present study was to explore the potential of functional micro/nanofibrous matrices as systems for the sustained release of the highly volatile insect‐repellent citronella oil. RESULTS: Micro/nanofibrous single‐ and triple‐layer systems incorporating citronella oil as the active agent were developed via the electrospinning technique using the low‐cost, non‐toxic, biodegradable polymers cellulose acetate and polyvinylpyrrolidone. All the micro/nanofiber systems produced exhibited prolonged release of citronella oil and a high repellent activity in laboratory bioassays against the mosquito Aedes albopictus for at least 4 weeks. CONCLUSION: Considering the high volatility of the embedded repellent, the present study demonstrates the strong potential of the micro/nanofibrous matrices to act as carriers of highly volatile repellents for an effective and sustained protection from mosquitoes. © 2019 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

An optical micro/nanofiber (MNF) is a quasi-one-dimensional free-standing optical waveguide with a diameter close to or less than the vacuum wavelength of light. Combining the tiny geometry with high-refractive-index contrast between the core and the surrounding, the MNF exhibits favorable optical properties such as tight optical confinement, strong evanescent field, and large-diameter-dependent waveguide dispersion. Meanwhile, as a quasi-one-dimensional structure with extraordinarily high geometric and structural uniformity, the MNF also has low optical loss and high mechanical strength, making it favorable for manipulating light on the micro/nanoscale with high flexibility. Over the past two decades, optical MNFs, typically being operated in single mode, have been emerging as a miniaturized fiber-optic platform for both scientific research and technological applications. In this paper, we aim to provide a comprehensive overview of the representative advances in optical MNFs in recent years. Starting from the basic structures and fabrication techniques of the optical MNFs, we highlight linear and nonlinear optical and mechanical properties of the MNFs. Then, we introduce typical applications of optical MNFs from near-field optics, passive optical components, optical sensors, and optomechanics to fiber lasers and atom optics. Finally, we give a brief summary of the current status of MNF optics and technology, and provide an outlook into future challenges and opportunities. [ABSTRACT FROM AUTHOR]

New systems for the controlled release of 1,7-dioxaspiro[5.5]undecane and ( Z)-7-tetradecenal, the sex pheromones of olive fruit fly, Bactrocera oleae, and olive moth, Prays oleae, respectively, were developed utilizing electrospun micro/nanofiber matrices from inexpensive, biodegradable polymers, namely polycaprolactone, cellulose acetate and polyhydroxybutyrate. The incorporation of the pheromones in 5, 10 and 20% w/w in the electrospinning polymer blends allowed for the production of fiber mats with variable loading levels and release rates, ensuring however in all cases the release of pheromones for more than 16 weeks. Laboratory bioassays and field trapping tests showed that the fiber mats obtained from electrospinning of polyhydroxybutyrate solution containing 5% w/w 1,7-dioxaspiro[5.5]undecane and polycaprolactone solution containing 5% w/w ( Z)-7-tetradecenal were almost twice as effective in attracting B. oleae and P. oleae males, respectively, in comparison to the positive controls used. [ABSTRACT FROM AUTHOR]

Cationic mesa-tetra(4-pyridyl) porphine (TPyP)-graphene oxide (GO) hybrid structures have been synthesized by ionic self-assembly. The different aggregated structures shape were obtained through electrostatic and π–π stacking interactions, as indicated by redshift of porphyrin Soret band throughout the pH range of 1.5–9.1, fluorescence quenching, Raman spectra and Energy dispersive X-ray spectroscopy. A strong fluorescence quenching of the cationic porphyrin in the presence of graphene indicated that efficient electron or energy transfer occurred from the excited state of the cationic porphyrin to graphene. The investigation revealed a three-dimensional fiber structures formation under the acid conditions and leaf-like structures of the TPyP/GO assemblies under the alkaline conditions of the solution. The fibers morphology and cross-section was determined quantitatively by Scanning force microscopy; this revealed a diameter of the fibers up to hundreds of nanometers and the lengh up to hundreds of micrometers. The electrical properties of the fibers were investigated by spreading resistance and current–voltage characteristics measurements using Atomic Force Microscopy (AFM) with conductive cantilevers. The current–voltage characteristics fit to the Poole–Frenkel emission mechanism in the case of TPyP/GO sheets and Schottky emission dominate in the nanofibers case. This new graphene material shows a potential for energy, sensing and photonic applications. [ABSTRACT FROM AUTHOR]

Drug-eluting medical textiles have recently gained great attention to be used in different applications due to their cost effectiveness and unique physical and chemical properties. Using various fiber production and textile fabrication technologies, fibrous constructs with the required properties for the target drug delivery systems can be designed and fabricated. This review summarizes the current advances in the fabrication of drug-eluting medical textiles. Different fiber production methods such as melt-, wet-, and electro-spinning, and textile fabrication techniques such as knitting and weaving are explained. Moreover, various loading processes of bioactive agents to obtain drug-loaded fibrous structures with required physicochemical and morphological properties, drug delivery mechanisms, and drug release kinetics are discussed. Finally, the current applications of drug-eluting fibrous systems in wound care, tissue engineering, and transdermal drug delivery are highlighted., (© 2021 The Authors. Macromolecular Bioscience published by Wiley-VCH GmbH.)