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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]

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]

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]

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]

A novel three-dimensional construct was designed to serve as a substitute for the natural meniscus tissue, and tested in vitro. The design consisted of mats of aligned collagen micro/nanofibers, entrapped within a macroporous poly(l-lactic acid)/poly(lactic acid-co-glycolic acid) foam coated with Ca+2-cross-linked alginic acid. Fibrochondrocytes derived from human meniscus were tested in vitro to study cell attachment and proliferation. After a 21-day culture, the cells populating the constructs were shown to produce extracellular matrix components specific for fibrocartilages, such as collagen Types I and II and aggrecan. Coating the foam with alginate increased the compressive modulus of the collagen-containing constructs (from 320 to 381 kPa, after 21 days of incubation with fibrochondrocytes) but decreased cell attachment and proliferation, as well as aggrecan production. Collagen fibers substantially increased the tensile modulus of the cell-seeded constructs (from 0.98 to 1.71 MPa for uncoated and from 0.67 to 1.32 MPa for coated samples). All constructs produced extracellular matrix components specific for fibrocartilages. These findings indicate that these constructs have potential for use as meniscus substitutes. [ABSTRACT FROM AUTHOR]

Novel polypyrrole (PPy) micro/nanofibers were synthesized via a self-assembly process by using 4-hydroxy-3-[(4-sulfo-1-naphthalenyl) azo]-1-naphthalenesulfonic acid (Acid Red B) as dopant and ferric chloride (FeCl3) as oxidant. Experimental conditions, including the concentration of the dopant, reaction temperature and stirring state have been investigated for their influences on the morphology of the synthesized PPy micro/nanofibers. The products were characterized by scanning electron microscopy, transmission electron microscopy and Fourier-transform infrared spectroscopy. The formation mechanism of micro/nanofibers was studied. It is believed that the micelles formed by the dopant and pyrrole monomer act as templates during the synthesis process. Two functions of aggregation and synthesis are proposed in the reaction system simultaneously, and the morphologies of micro/nanofibers are the co-operations of these two functions. The maximum conductivity value of the PPy micro/nanofibers was 8.56 S cm−1 [ABSTRACT FROM AUTHOR]

This review aims at providing an examination of the central polymeric systems that have been tested by the Solution Blow Spinning Technique (SBS). The SBS is an on-demand micro/nanofibrous material forming technique that uses simple instrumentation, thus making its research substantial. Although other studies had already presented the SBS parameters and their correlations with fiber morphology, it's still unclear for polymeric researchers which systems have already been tested, therefore some questions remain unanswered, such as: "which polymers have been used most in the art?", "which solvents have promoted the fiber formation?", "which additives or particles were tested for composite polymer fibers?", "for which applications have the fibers been targeted?", "what adaptations have been investigated to overcome the challenges of the process?". Seventy-nine articles related to polymeric fibers produced by SBS, reported from January 2010 to May 2019, were chosen among four databases, using precise keywords. The principal findings of these articles were presented and reviewed, using additional references as support. From this study, polymeric researchers will have access to the current SBS state-of-the-art, being able to try new polymer-solvents combinations, as well as to solve the existing process inconveniences. [ABSTRACT FROM AUTHOR]