Coaxial Electrospinning Process Research Articles

Core-shell nanofibers based on microalgae proteins/alginate complexes for enhancing survivability of probiotics

In this study, a novel one-step coaxial electrospinning process is employed to fabricate shell-core structure fibers choosing Chlorella pyrenoidosa proteins (CP) as the core material. These nanofibers, serving as the wall material for probiotic encapsulation, aimed to enhance the stability and antioxidant activity of probiotics in food processing, storage, and gastrointestinal environments under sensitive conditions. Morphological analysis was used to explore the beads-on-a-string morphology and core-shell structure of the electrospun fibers. Probiotics were successfully encapsulated within the fibers (7.97 log CFU/g), exhibiting a well-oriented structure along the distributed fibers. Compared to free probiotics and uniaxial fibers loaded with probiotics, encapsulation within microalgae proteins/alginate core-shell structure nanofibers significantly enhanced the probiotic cells' tolerance to simulated gastrointestinal conditions (p < 0.05). Thermal analysis indicated that microalgae proteins/alginate core-shell structure nanofibers displayed superior thermal stability compared to uniaxial fibers. The introduction of CP resulted in a 50 % increase in the antioxidant capacity of probiotics-loaded microalgae proteins/alginate nanofibers compared to uniaxial alginate nanofibers, with minimal loss of viability (0.8 log CFU/g) after 28 days of storage at 4 °C. In summary, this dual-layer carrier holds immense potential in probiotic encapsulation and enhancing their resistance to harsh conditions.

All‐organic shell–core PVDF/PMMA composite fiber films with enhanced piezoelectric performance for flexible sensing and energy harvesting

AbstractThe demand for self‐powered sensing technology and energy harvesting system necessitates high‐performance and flexible piezoelectric materials. This paper presents a novel approach utilizing coaxial electrospinning to fabricate all‐organic PVDF/PMMA piezoelectric fiber films with a shell–core structure. The resulting fiber films, cut into 2 × 2 cm2 square pieces and hot‐pressed every three pieces, demonstrate enhanced piezoelectric properties while retaining high flexibility. The interaction between the CO bonds in the PMMA polymer and the CH2 in PVDF promotes the arrangement of F atoms in PVDF, enhancing the content of the piezoelectric active phase. Additionally, the coaxial electrospinning process fosters vertically oriented hydrogen bonds between PVDF and PMMA, augmenting cross‐linking and improving mechanical properties. Notably, when the PVDF to PMMA layer volume ratio is 5:1, the piezoelectric coefficient (|d33|) of the composite fiber film exhibits a significant 60% increase from 10 pC N−1 in neat PVDF to 16 pC N−1. This research holds substantial promise for applications in self‐powered sensing and energy harvesting piezoelectric materials.

Coaxial electrospinning of polycaprolactone – A design of experiments approach

Coaxial electrospinning is a commonly used technique in pharmaceutical sciences that allows producing polymeric nano- or microfibers with core-shell structure. In addition to process parameters such as voltage and flow rate of the polymer solutions, the properties of such fibers are influenced by solution properties including the total polymer concentration and the polymer ratio between fiber core and shell. As these parameters are typically changed empirically during development of electrospinning methods, there is a lack of structured studies that determine the optimal settings for the production of homogeneous, mechanically stable fibers. Therefore, we used a design of experiments approach to systematically address the coaxial electrospinning process of polycaprolactone, a polymer for biomaterials applied to the skin, for instance in the form of patches for wound healing or the treatment of skin cancer. We set out to investigate the influence of different process parameters on the fiber morphology (diameter and size distribution) as well as their mechanical properties as these properties are decisive determinants for handling and pharmaceutical efficacy of such patches. The investigated process parameters were the polymer concentration in the electrospinning solution and the ratio of polymer between fiber core and shell. We additionally investigated the impact of the presence of the model drug hydrocortisone in the fiber core on the electrospinning outcome and the drug release. The experiments revealed that the fiber diameter increases with increasing total polymer concentration, correlating with a narrower fiber size distribution. In addition, our results show that a higher ratio of polymer content in core and shell leads to more mechanically stable fibers (higher tensile strength, higher Young’s modulus). Taken together, the results obtained in this study contribute to a better understanding of the electrospinning process of polycaprolactone.

Small-diameter vascular graft composing of core-shell structured micro-nanofibers loaded with heparin and VEGF for endothelialization and prevention of neointimal hyperplasia

Despite the significant progress made in recent years, clinical issues with small-diameter vascular grafts related to low mechanical strength, thrombosis, intimal hyperplasia, and insufficient endothelialization remain unresolved. This study aims to design and fabricate a core-shell fibrous small-diameter vascular graft by co-axial electrospinning process, which will mechanically and biologically meet the benchmarks for blood vessel replacement. The presented graft (PGHV) comprised polycaprolactone/gelatin (shell) loaded with heparin-VEGF and polycaprolactone (core). This study hypothesized that the shell structure of the fibers would allow rapid degradation to release heparin-VEGF, and the core would provide mechanical strength for long-term application. Physico-mechanical evaluation, in vitro biocompatibility, and hemocompatibility assays were performed to ensure safe in vivo applications. After 25 days, the PGHV group released 79.47 ± 1.54% of heparin and 86.25 ± 1.19% of VEGF, and degradation of the shell was observed but the core remained pristine. Both the control (PG) and PGHV groups demonstrated robust mechanical properties. The PGHV group showed excellent biocompatibility and hemocompatibility compared to the PG group. After four months of rat aorta implantation, PGHV exhibited smooth muscle cell regeneration and complete endothelialization with a patency rate of 100%. The novel core-shell structured graft could be pivotal in vascular tissue regeneration application.

Polar, catalytic, volume-tolerant CoSe2/carbon tubes for enhanced performance sulfur host in Li-S battery

The low sulfur utilization and notorious polysulfides shuttling of Li-S battery (LSBs) largely limit the practical implementation as an effective energy storage system. Herein, we designed a coaxial electrospinning process to prepare cobaltous selenide/carbon tube (CoSe2/CTs) with hollow tubular structures to hold sulfur activity for the cathode of LSBs. This CoSe2/CTs material with superior hollow tubular structures and high specific surface area is able to tolerate the sulfur volume expansion/contraction and make the intimate contact with sulfur at the micro level. Moreover, the uniformly dispersed CoSe2 on the CTs both as catalysts and trappers can significantly facilitate the reaction kinetics in the LSBs and chemically immobilize lithium polysulfides. In order to optimize the CoSe2/CTs/S cathode, we investigated the effects of the Co concentration and carbon tube porosities on batteries performance to achieve the satisfactory discharge specific capacity and a long duration at a high current density. We believe that our method can provide a significant strategy to prepare Co-based cathodes and enhance the performance of LSBs.

Polarity-dominated chitosan biguanide hydrochloride-based nanofibrous membrane with antibacterial activity for long-lasting air filtration

Facemasks play a significant role as personal protective equipment during the COVID-19 pandemic, but their longevity is limited by the easy dissipation of electrostatic charge and the accumulation of bacteria. In this study, nanofibrous membranes composed of polyacrylonitrile and chitosan biguanide hydrochloride (PAN@CGH) with remarkable antibacterial characteristics were prepared through the coaxial electrospinning process. Particulate matter could be efficiently captured by the fibrous membrane, up to 98 % or more, via polarity-dominated forces derived from cyano and amino groups. As compared commercial N95 masks, the PAN@CGH was more resistant to a wider variety of disinfection protocols. Additionally, the nanofibrous membrane could kill >99.99 % of both Escherichia coli and Staphylococcus aureus. Based on these characteristics, PAN@CGH nanofibrous membrane was applied to facial mask, which possessed an excellent and long-lasting effect on the capture of airborne particles. This work may be one of the most promising strategies on designing high-performance face masks for public health protection.

Conversion of Animal-Derived Protein By-Products into a New Dual-Layer Nanofiber Biomaterial by Electrospinning Process

The aim of this study was to design a dual-layer wound dressing as a new fibrous biomaterial based on the valorization of animal-derived proteins. The first layer was fabricated by the deposition of poly(ethylene oxide) (PEO) loaded with keratin hydrolysate (KH) via a mono-electrospinning process onto a poly(lactic acid) (PLA) film, which was used as a support. The second layer consisted of encapsulating a bovine collagen hydrolysate (CH) into poly(vinyl pyrrolidone) (PVP) through a coaxial electrospinning process, which was added onto the previous layer. This assemblage was characterized by electronic microscopy for morphology and the controlled release of KH. In vitro biocompatibility was evaluated on the L929 (NCTC) murine fibroblasts using quantitative MTT assay and qualitative cell morphological examination after Giemsa staining. Additionally, in vivo biocompatibility methods were used to assess the impact of the biomaterial on white Swiss mice, including the evaluation of hematological, biochemical, and immunological profiles, as well as its impact on oxidative stress. The results revealed a nanofibrous structure for each layer, and the assembled product demonstrated antioxidant activity, controlled release of KH, a high degree of in vitro biocompatibility, negligible hematological and biochemical changes, and minimal impact of certain specific oxidative stress parameters compared to the use of patches with textile support.

Preparation and Characterization of Nano-Silver-Loaded Antibacterial Membrane via Coaxial Electrospinning.

The coaxial electrospinning process has been widely used in the biomedical field, and its process parameters affect product quality seriously. In this paper, the influence of key process parameters of coaxial electrostatic spinning (solution concentration, electrospinning voltage, acceptance distance and liquid supply velocity) on the preparation of a membrane with Chitosan, Polyethylene oxide and nano-silver as the core layer and Polycaprolactone as the shell layer was studied. The optimal combination of key process parameters was obtained by using an orthogonal test, scanning electron microscope, transmission electron microscope and macro-characterization diagram. The results showed that the coaxial electrospun membrane had good mechanical properties (tensile strength is about 2.945 Mpa), hydrophilicity (the water contact angle is about 72.28°) and non-cytotoxicity, which was conducive to cell adhesion and proliferation. The coaxial electrospun membrane with nano-silver has an obvious inhibitory effect on Escherichia coli and Staphylococcus aureus. In summary, the coaxial electrospun membrane that we produced is expected to be used in clinical medicine, such as vascular stent membranes and bionic blood vessels.

Bimetallic ZIFs-derived electrospun carbon nanofiber membrane as bifunctional oxygen electrocatalyst for rechargeable zinc-air battery

The recharged zinc-air battery (ZAB) has drawn significant attention owing to increasing requirement for energy conversion and storage devices. Fabricating the efficient bifunctional oxygen catalyst using a convenient strategy is vitally important for the rechargeable ZAB. In this study, the bimetallic ZIFs-containing electrospun (ES) carbon nanofibers membrane with hierarchically porous structure was prepared by coaxial electrospinning and carbonization process, which was expected to be a bifunctional electrocatalyst for ZABs. Owing to the formed dual single-atomic sites of Co–N4 and Zn–N4, the obtained ES-Co/Zn-CNZIF exhibited the preferable performance toward oxygen reduction reaction (ORR) with E1/2 of 0.857 V and JL of 5.52 mA cm−2, which were more than Pt/C. Meanwhile, it exhibited a marked oxygen evolution reaction (OER) property with overpotential of 462 mV due to the agglomerated metallic Co nanoparticles. Furthermore, the ZAB based on the ES-Co/Zn-CNZIF carbon nanofibers membranes delivered peak power density of 215 mW cm−2, specific capacity of 802.6 mA h g−1, and exceptional cycling stability, far larger than Pt/C+RuO2-based ZABs. A solid-state ZAB based on ES-Co/Zn-CNZIF showed better flexibility and stability with different bending angles.

A Sequential Electrospinning of a Coaxial and Blending Process for Creating Double-Layer Hybrid Films to Sense Glucose.

This study presents a glucose biosensor based on electrospun core-sheath nanofibers. Two types of film were fabricated using different electrospinning procedures. Film F1 was composed solely of core-sheath nanofibers fabricated using a modified coaxial electrospinning process. Film F2 was a double-layer hybrid film fabricated through a sequential electrospinning and blending process. The bottom layer of F2 comprised core-sheath nanofibers fabricated using a modified process, in which pure polymethacrylate type A (Eudragit L100) was used as the core section and water-soluble lignin (WSL) and phenol were loaded as the sheath section. The top layer of F2 contained glucose oxidase (GOx) and gold nanoparticles, which were distributed throughout the polyvinylpyrrolidone K90 (PVP K90) nanofibers through a single-fluid blending electrospinning process. The study investigated the sequential electrospinning process in detail. The experimental results demonstrated that the F2 hybrid film had a higher degradation efficiency of β-D-glucose than F1, reaching a maximum of over 70% after 12 h within the concentration range of 10-40 mmol/L. The hybrid film F2 is used for colorimetric sensing of β-D-glucose in the range of 1-15 mmol/L. The solution exhibited a color that deepened gradually with an increase in β-D-glucose concentration. Electrospinning is flexible in creating structures for bio-cascade reactions, and the double-layer hybrid film can provide a simple template for developing other sensing nanomaterials.

Electrospun Core-Sheath Fibers with a Uniformly Aligned Polymer Network Liquid Crystal (PNLC).

Electrospun polymer-liquid crystal (PLC) fibers have potential applications such as wearable sensors and adaptive textiles because of their rapid response and high flexibility. However, existing PLC fibers only have a narrow responsive range and poor resistance to heat and chemicals. Herein, a new type of PLC fiber is prepared by using a coaxial electrospinning process. The core solution is 4'-pentyl-4-biphenylcarbonitrile (5CB), and the sheath solution is a mixture containing 13 wt % PVP and 10 wt % reactive mesogen (RM). After UV exposure of the fibers, 5CB in the core and RM diffusing from the core are cross-linked into an LC polymer. The fibers have a highly uniform morphology with an average diameter of 3.2 ± 0.5 μm, and mesogens inside the fibers align unidirectionally with the long axis of the fibers. The fibers show a broad phase-transition temperature range between 13.5 and 155.5 °C and have a response time of less than 10 s. The temperature range can also be controlled by adjusting components in the electrospun fibers and UV exposure time. The core-sheath fibers prepared in such a manner exhibit excellent heat and chemical resistance with reversible optical responses. Moreover, when the fibers are exposed to volatile organic compounds (VOCs) such as toluene, the fibers show a rapid optical response to toluene vapor within 25 s. This study demonstrates that the fibers are potentially useful for preparing flexible temperature and chemical sensors.

Unique Fiber Morphologies from Emulsion Electrospinning—A Case Study of Poly(ε-caprolactone) and Its Applications

The importance of electrospinning to produce biomimicking micro- and nano-fibrous matrices is realized by many who work in the area of fibers. Based on the solubility of the materials to be spun, organic solvents are typically utilized. The toxicity of the utilized organic solvent could be extremely important for various applications, including tissue engineering, biomedical, agricultural, etc. In addition, the high viscosities of such polymer solutions limit the use of high polymer concentrations and lower down productivity along with the limitations of obtaining desired fiber morphology. This emphasizes the need for a method that would allay worries about safety, toxicity, and environmental issues along with the limitations of using concentrated polymer solutions. To mitigate these issues, the use of emulsions as precursors for electrospinning has recently gained significant attention. Presence of dispersed and continuous phase in emulsion provides an easy route to incorporate sensitive bioactive functional moieties within the core-sheath fibers which otherwise could only be hardly achieved using cumbersome coaxial electrospinning process in solution or melt based approaches. This review presents a detailed understanding of emulsion behavior during electrospinning along with the role of various constituents and process parameters during fiber formation. Though many polymers have been studied for emulsion electrospinning, poly(ε-caprolactone) (PCL) is one of the most studied polymers for this technique. Therefore, electrospinning of PCL based emulsions is highlighted as unique case-study, to provide a detailed theoretical understanding, discussion of experimental results along with their suitable biomedical applications.

Fabrication of core-shell structured cobalt nanoparticle/carbon nanofiber as a bifunctional catalyst for the oxygen reduction/evolution reactions

One-dimensional (1D) catalysts composed of non-precious metal nanoparticles (NPs) and carbon materials exhibit characteristics that make them attractive for electrochemical applications. However, metal NPs with catalytic activity are mostly buried in the carbon material, significantly limiting the surface catalytic reaction. In the present study, a 1D core-shell structured catalyst was designed to secure enhanced number of active sites by placing cobalt NPs on the surface of the catalyst. The proposed 1D core–shell-structured Co NP/carbon nanofiber, Co-CSNF, was realized by facile coaxial electrospinning process followed by the two-step heat treatment process. Through the position control of cobalt nanoparticles, the Co-CSNF showed improved catalyst performance in both ORR and OER compared to Co NP/carbon nanofiber electrospun with a single nozzle (Co-NF). The Co-CSNFs showed excellent oxygen reduction performance with a 4 electron path and a half-wave potential (E1/2) of 0.86 V to RHE, and achieved a low oxygen evolution reaction of 322 mV (@10 mA cm−2 at 1.0 M KOH). It was demonstrated that the Co-CSNF-based zinc–air battery (ZAB) exhibited a lower discharge and charge overpotential than the ZAB with Pt/C+IrO2 with a stable cycling time of 366 h.

Encapsulation of β-carotene into food-grade nanofibers via coaxial electrospinning of hydrocolloids: Enhancement of oxidative stability and photoprotection

Εncapsulation of β-carotene in two different food hydrocolloid matrices, pure pullulan (PUL) and its blend with whey protein isolate (WPI) at a weight ratio of WPI:PUL 30:70, via coaxial electrospinning, was investigated. Τhe encapsulation efficiency of β-carotene in the generated WPI:PUL (30:70 w/w) and PUL nanofibers has reached up to ∼90% and ∼95%, respectively. Among the various operating parameters examined, the factor which had the greatest impact on encapsulation efficiency was the oil-β-carotene solution (core material) flow rate. More uniform thread-like nanofibers were obtained using pure pullulan as wall material, while the WPI:PUL (30:70 w/w) blend resulted in formation of nanostructures with bead-shaped morphologies periodically along the fiber axis. The β-carotene degradation kinetics followed an apparent first-order reaction model, showing highest values of the rate constants at an intermediate water activity level (aw = 0.53) for all matrices and storage temperatures (25 °C, 35 °C, 45 °C) examined. The degradation kinetics did not seem to be directly related with the molecular mobility of the fiber polymeric components (i.e., physical state of the amorphous wall material), as β-carotene losses were evident even at temperatures below their glass transition temperatures ( T g ). The electrospun WPI:PUL nanofibers were more suitable as carriers in delaying oxidation of β-carotene under different storage temperatures, a w levels and exposure to UV–Vis irradiation, compared to pure PUL. Overall, the coaxial electrospinning process using the mixture of WPI:PUL (30:70 w/w) as an encapsulation vehicle appears to be an effective technique to fabricate functional foods or dietary supplements enriched with β-carotene. • β-carotene was encapsulated through coaxial electrospinning for food applications. • β-carotene can be effectively encapsulated in WPI:PUL (30:70) and PUL nanofibers. • β-carotene solution flow rate had the greatest impact on encapsulation efficiency. • Both encapsulation structures showed improved stability at low humidity environments. • Electrospun WPI:PUL (30:70) nanofibers were more effective than PUL ones.

Novel polycaprolactone (PCL)-type I collagen core-shell electrospun nanofibers for wound healing applications.

Type I collagen (Col_1) is one of the main proteins present in the skin extracellular matrix, serving as support for skin regeneration and maturation in its granulation stage. Electrospun materials have been intensively studied as the next generation of skin wound dressing mainly due to their high surface area and fibrous porosity. However, the electrospinning of collagen-based solutions causes degradation of its structure. In this work, a coaxial electrospinning process was proposed to overcome this limitation. The production of mats of polycaprolactone (PCL)-Col_1/PVA (collagen/poly(vinyl alcohol)) composed of core-shell nanofibers was investigated. PCL solution was used as the core solution, while Col_1/PVA was used as the shell solution. PVA was used to improve the processability of collagen, while PCL was employed to improve the mechanical properties and morphology of Col_1/PVA fibers. The morphology and the cytotoxicity of the fibers were highly dependent on the processing parameters. Defect-free core-shell nanofibers were obtained with a shell/core flow rates ratio=4, flight distance of 12 cm, and an applied voltage of 16 kV. Using this strategy, the triple helix structure characteristic of the collagen molecule was preserved. Moreover, the common post-processing of solvent removal could be suppressed, simplifying the manufacturing processing of these biomaterials. The nanostructured mats showed no cytotoxicity, high liquid absorption, structural stability, hydrophilic character, and collagen release capacity, making them a potential novel dressing for skin damage regeneration, in special in the case of chronic wounds treatment, in which exogenous collagen delivery is necessary.

An innovative and facile strategy to construct GdF3:Eu3+@Void@SiO2 nanowire-in-nanotube structured nanofibers with photoluminescence-magnetism Bi-functionality

An innovative and facile approach has been designed to construct non-shattering GdF3:Eu3+@void@SiO2 nanowire-in-nanotube structured nanofibers (NSN) via a new technique combining electrospinning and fluorination strategy efficiently for the first time. The average diameters of the outer tubes and inner wires of GdF3:Eu3+@void@SiO2 NSN are 403 ± 36 nm and 157 ± 20 nm, respectively. GdF3:Eu3+@void@SiO2 NSN simultaneously possess excellent luminescent and paramagnetic properties, which are suitable for many applications such as light-emitting devices, lasers and planar waveguides, biomedical therapy and drug delivery. Nanowire-in-nanotube structured nanofibers possess large length-diameter ratio, their peculiar void-space structures make them have promising applications in biotherapy, energy storage, sensors, catalysts, etc. A series of conditional experiments including GdF3:Eu3+/SiO2 composite nanofibers, GdF3:Eu3+ nanofibers, and GdF3:Eu3+@SiO2 nanomaterials with different morphologies have been performed to validate the success of the synthesis technology. The fabrication technique has some advantages over other methods, for example, simple and convenient, high-efficient, economical, and without introducing organics. More importantly, the approach can overcome the drawback of synthesizing complexity used by template-assisted means and coaxial electrospinning process, etc. This strategy is a universal technology for the construction of nanowire-in-nanotube structured multifunctional nanomaterials, and extends the application fields of electrospinning technology.

Preparation of Linalool/Polycaprolactone Coaxial Electrospinning Film and Application in Preserving Salmon Slices.

A linalool/polycaprolactone (LL/PCL) antibacterial film was prepared by using a coaxial electrospinning process, and its physical and chemical properties were characterized. The antibacterial film was formed into an active antibacterial gasket, and its effect on salmon preservation was analyzed. The results show that the LL/PCL nanofiber membrane had a well-developed microstructure, and the fiber surface was smooth and uniform. The diameter of the fibers in the PCL membrane without the core material (linalool) was 113.92 ± 23.74 nm. In contrast, the diameter of the coaxial nanofiber membrane with linalool increased, and the diameter of the LL/PCL membranes with 20% and 40% linalool was 220.62 ± 44.01 and 232.22 ± 56.27 nm, respectively. The hydrophobicity and water vapor permeability were enhanced, whereas the tensile strength and elongation at break decreased slightly, while the thermal stability did not differ significantly with the incorporation of linalool. Analysis of the sustained release of linalool showed that the LL/PCL coaxial fiber membranes could release linalool into the reaction system for a long time. The LL/PCL nanofiber film was used to create an antibacterial active gasket for salmon preservation experiments. Sensory evaluation and analyses of the total bacterial count, total volatile basic nitrogen (TVB-N), thiobarbituric acid reactive substances (TBARS), pH, texture (hardness, elasticity, chewiness, and viscoelasticity), water distribution change, and aroma using an electronic nose were used to determine the quality of salmon. It was found that food-grade tinfoil and the PCL gasket had no significant effect on the freshness of salmon, while the active antibacterial gasket samples containing linalool could decrease the rate of decay salmon and effectively prolong the shelf-life of salmon by releasing linalool.

Core‐Shell Nanofibers of Polyvinyl Alcohol/Polylactic Acid Containing TiO2 Nanotubes for Natural Sunlight Driven Photocatalysis

AbstractHighly stable and efficient coaxial electrospun fibers of polyvinyl alcohol (PVA) and polylactic acid (PLA) nanocomposite filled with titanium dioxide (TiO2) nanotubes areaccomplished for natural sunlight‐driven photocatalytic dye degradation. The coaxial electrospinning process generates well‐defined concentric cylinder‐like morphology, with the polymeric core and sheath phases, with TiO2 present only in the outer phases. The nanofibers are characterized for their coaxial morphology and the distribution of TiO2 in the sample is monitored through EDAX studies. Coaxial electrospinning process influences the polymeric structural and functional performances, regulates the crystallization kinetics, and ensures the entanglement of TiO2 nanopowders without allowing them to leach out. Photodecomposition of Rhodamine B and methylene blue dye are observed by the UV–visible studies and ≈80% and ≈85% degradation is achieved respectively after 8 h. A higher efficiency of degradation is achieved for the TiO2 nanocomposites, due to the photocatalytic activity of the TiO2 semiconductors, and also because of its presence in the sheath phase. The efficiency of dye degradation is correlated with the mechanical and dynamic mechanical properties of the fibers and with the typical fiber morphology and spinning mechanism. While the dye molecules get trapped in the porous sites of composite fibers, the TiO2 radicals initiates the photocatalysis process. The current technology is promising in manipulating flexible, durable, and environmentally friendly polymer nanocomposite fibers for industrial wastewater purification.

MOF–derived hollow porous ZnFe2O4/AgCl/Ag/C nanotubes with magnetic–dielectric synergy as high–performance photocatalysts for hydrogen evolution reaction

The design of unique structures for semiconductor photocatalysts is one of the most effective approach to stimulate their performance toward solar–to–chemical energy conversion. Herein, an interesting scheme has been introduced to produce hollow porous ZnFe2O4/AgCl/Ag/C nanotubes on the PDA@PANI nanofibers by a simple combined PANI capturing–PDA embedding–in situ graphitization process. In a first step, PDA@PANI were first prepared via a coaxial electrospinning process, followed by PANI capturing transition metal ions (Zn2+ and Fe2+) with the assistance of 2,5–dihydroxy–1,4–benzenedicarboxylic acid to convert these metal ions into PDA@PANI@MOF–74–Zn/Fe through thermal treatment. Then, AgCl cubes and Ag NPs were synthesized via in–situ embedding with various active groups of the PDA and its reducibility. At last, after calcination of the PDA@PANI@MOF–74–Zn/Fe/AgCl/Ag, ZnFe2O4/AgCl/Ag/C nanotubes with uniform distribution of graphitic carbon were successfully fabricated. Benefiting from the novel hollow porous structure, the obtained ZnFe2O4/AgCl/Ag/C exhibited outstanding H2 evolution activity (e.g., 7524 µmol h−1 g−1) and high stability without engaging any cocatalyst, which is among the highest reported for ZnFe2O4–based materials with different morphologies and nanostructures.

Surface Functionalization of PEO Nanofibers Using a TiO2 Suspension as Sheath Fluid in a Modified Coaxial Electrospinning Process

Surface Functionalization of PEO Nanofibers Using a TiO2 Suspension as Sheath Fluid in a Modified Coaxial Electrospinning Process