Single-needle Electrospinning Research Articles

Remarkable Near-Infrared Temperature Sensing Properties of Y3Ga5O12:Cr3+ and Y3Ga5O12:Cr3+/Yb3+ Nanotubes Fabricated via a Single-Needle Electrospinning Technique.

For the first time, nanotubes of Y3Ga5O12:Cr3+ (referred to as YGO:Cr3+) and Y3Ga5O12:Cr3+/Yb3+ (referred to as YGO:Cr3+/Yb3+) were produced via a single-needle electrospinning method. The nanotubes of YGO:Cr3+ and YGO:Cr3+/Yb3+ have outer diameters between 190 and 210 nm, whereas the inner diameter ranges between 70 and 80 nm, and the wall thickness ranges from 50 to 60 nm. The temperature sensitivity of YGO:0.02Cr3+ nanotubes was examined by studying how the Cr3+ lifetime changes with temperature. In the temperature range of 303 to 723 K, the peak values of Sa and Sr were 0.274 and 0.0067 K-1, respectively. Temperature sensing properties of YGO:0.02Cr3+/yYb3+ (y = 0.01, 0.02, and 0.05) nanotubes were evaluated via the FIR technique utilizing nonthermally coupled energy levels. The I970/I708 in the YGO:0.05Cr3+/0.01Yb3+ nanotubes displayed a maximal Sr value of 0.013 K-1 at 633 K, which exceeds that of other Cr3+-doped NIR phosphors previously reported and is promising for high-temperature measurements.

Electric field simulation, structure and properties of nanofiber- coated yarn prepared by multi-needle water bath electrospinning.

To address the issue of low yield in the preparation of nanofiber materials using single-needle electrospinning technology, multi-needle electrospinning technology has emerged as a crucial solution for mass production. However, the mutual interference of multiple electric fields between the needles can cause significant randomness in the morphology of the produced nanofibers. To better predict the influence of electric field distribution on nanofiber morphology, simulation analysis of the multi-needle arrangement was conducted using finite element analysis software. Nanofiber-coated yarn was produced continuously with the core yarn rotating. The water bath was utilized as the receiver of nanofibers on self-made water bath electrospinning equipment. The electric field distribution and mutual interference under seven different needle arrangements was simulated and analyzed by finite element analysis software ANSYS Maxwell. The results indicated that when the needles were arranged diagonally in a staggered pattern and directly above the core yarn, the simulated electric field distribution was relatively uniform, with less mutual interference. The produced nanofibers exhibited a finer diameter and the diameter distribution was more concentrated. In addition, the nanofiber coating showed higher crystallinity and better mechanical properties.&#xD.

Electronic nose based on multiple electrospinning nanofibers sensor array and application in gas classification

To mimic the human olfactory system, an electronic nose (E-nose, also known as artificial olfactory) has been proposed based on a multiple gas sensor array and a pattern recognition algorithm. Detection of volatile organic components (VOCs) has many potential applications in breath analysis, food quality estimation, and indoor and outdoor air quality monitoring, etc. In this study, a facile single-needle electrospinning technology was applied to develop the four different semiconductor metal oxide (MOS) nanofibers sensor arrays (SnO2, CuO, In2O3 and ZnO, respectively). The array shows a smooth surface and constant diameter of nanofiber (average of 150 nm) resulting in high sensitivity to multiple target analyte gases. Five human health related VOCs gases were measured by fabricated E-nose and different response patterns were obtained from four MOS nanofibers sensors. Combined with feature extraction from the response curves, a principal component analysis (PCA) algorithm was applied to reduce the dimension of feature matrix, Thus, the fabricated E-nose system successfully discriminated five different VOCs gases. Real-time and non-invasive gas monitoring by E-nose is very promising for application in human health monitoring, food monitoring, and other fields.

A comparative study on electrospun fibers of cyanobiphenyl liquid crystal homologues

Cyanobiphenyl homologues are important liquid crystals to use in some applications since they exhibit intrinsic properties in a certain temperature interval including room temperature. Recently, generating composites with polymers and liquid crystals by electrospinning has drawn great interest. Here, cyanobiphenyl homologues of chain carbon numbers 5–8 and polyacrylonitrile were spun using single-needle electrospinning for the first time. Morphological, optical, aligning, and thermal properties of spun fibers investigated. The thinnest and thickest fibers were obtained in fibers involving cyanobiphenyl of chain carbon number 5 and 6, respectively considering the scanning electron microscopy images. Also, it was proved that all the cyanobiphenyl members were self-aligned throughout the fibers as a core using polarized optical microscopy. The existence of the cyanobiphenyl homologues in the structure of the fibers was presented by infrared spectroscopy results. In addition, the mass variation depending on temperature and calorimetric measurements were studied. Phase transition temperatures of the bulk cyanobiphenyls and the fibers were compared. The results showed that cyanobiphenyl homologues of chain carbon numbers 5–8 and polyacrylonitrile were able to be spun successfully and the fibers had the potential to be used in applications because the physical properties of the fibers were attractive.

Improving the crashworthiness of CFRP structures by rubbery nanofibrous interlayers

Crashworthiness is the capability of a component to dissipate impact energy throughout its deformation and failure. Composite materials are used to produce crashworthy components to ensure vehicle safety, thanks to their ability to dissipate a high energy amount while maintaining a low weight. The present work investigates the integration of rubbery nanofibers within the laminate interlayers to enhance crush performance. Three different thicknesses (10, 20, and 40 µm) of nanofibrous mats made by nitrile butadiene rubber and polycaprolactone (NBR/PCL) blends were produced by single-needle electrospinning technique and integrated into the laminates during the hand-layup. Mechanical properties of the nano-modified laminates are compared to the reference configuration: the effect of the interlayers is evaluated by Double Cantilever Beam (DCB) and End-Notched Flexure (ENF) interlaminar fracture tests. At the same time, the specific crush energy absorption (SEA) is measured by the compression of self-supporting corrugated specimens. Results show that NBR/PCL nanofibers significantly increase the interlaminar fracture toughness (up to +254% for Mode I and +47% for Mode II), which ultimately helps to improve the total SEA up to +8.2%. The best SEA enhancement is achieved already with a 10 µm nanofibrous membrane while integrating the highest thickness mat has a detrimental effect.

Photothermally Controlled Drug Release of Poly(d,l-lactide) Nanofibers Loaded with Indocyanine Green and Curcumin for Efficient Antimicrobial Photodynamic Therapy

Chronic wound infections with antibiotic-resistant bacteria have become a significant problem for modern healthcare systems since they are often associated with high costs and require profound topical wound management. Successful wound healing is achieved by reducing the bacterial load of the wound and providing an environment that enhances cell growth. In this context, nanofibers show remarkable success because their structure offers a promising drug delivery platform that can mimic the native extracellular matrix and accelerate cell proliferation. In our study, single-needle electrospinning, a versatile and cost-efficient technique, was used to shape polymers into an applicable and homogeneous fleece capable of a photothermally triggered drug release. It was combined with antimicrobial photodynamic therapy, a promising procedure against resistant bacteria. Therefore, poly(d,l-lactide) nanofibers loaded with curcumin and indocyanine green (ICG) were produced for local antimicrobial treatment. The mesh had a homogeneous structure, and the nanofibers showed a smooth surface. Recordings with a thermal camera showed that near-infrared light irradiation of ICG increased the temperature (>44 °C) in the surrounding medium. Release studies confirmed more than 29% enhanced curcumin release triggered by elevated temperature. The antimicrobial activity was tested against the gram-positive strain Staphylococcus saprophyticus subsp. bovis and the gram-negative strain Escherichia coli DH5 alpha. The nanofibers loaded with both photosensitizers and irradiated with both wavelengths reduced the bacterial viability (~4.4 log10, 99.996%) significantly more than the nanofibers loaded with only one photosensitizer (<1.7 log10, 97.828%) or irradiated with only one wavelength (<2.0 log10, 98.952%). In addition, our formulation efficiently eradicated persistent adhered bacteria by >4.3 log10 (99.995%), which was also confirmed visually. Finally, the produced nanofibers showed good biocompatibility, proven by the cellular viability of mouse fibroblasts (L929). The data demonstrate that we have developed a new economic nanofiber formulation, which offers a triggered drug release, excellent antimicrobial properties, and good biocompatibility.

Electrospinning preparation and electrochemical supercapacitor performance of dendrite-like 3D MgCo2O4/C nanofibers

Dendrite-like three-dimensional (3D) MgCo 2 O 4 /C nanofibers were fabricated by using a simple single-needle electrospinning method and adjusting the carbonization temperatures. The dendrite-like 3D MgCo 2 O 4 /C nanofibers are composed of 1D MgCo 2 O 4 /C nanofibers as trunks and secondary carbon nanowires/nanotubes as branches. The diameters of the 1D MgCo 2 O 4 /C nanofiber trunks and carbon nanotube/nanowire branches are approximately 500 nm and 20–40 nm, respectively; the lengths of these branches are approximately 200–500 nm. The dendrite-like 3D MgCo 2 O 4 /C nanofibers possess a large specific surface area of 314.027 g/m 2 and excellent electrochemical performance for supercapacitor owing to their unique structural features. The growth mechanism of the dendrite-like 3D nanofibers was also investigated.

Electrospinning preparation and electrochemical properties of Lu2Ti2O7 nanowires, nanotubes and wire-in-tube architectures for their potential lithium-ion battery applications

Lu2Ti2O7 nanowires, nanotubes, and wire-in-tube architectures were prepared by a simple single-needle electrospinning technique though controlling the environmental humidity. At an atmospheric humidity of 20%, Lu2Ti2O7 nanowires were formed with diameters of about 150 nm. At 40% atmospheric humidity, Lu2Ti2O7 nanotubes and wire-in-tube architectures were obtained. The Lu2Ti2O7 nanotubes have an outer diameter ranging from 80 nm to 200 nm and a wall thickness ranging from 10 to 15 nm. The outer diameter, outer wall thickness, and the embedded wire diameter of the Lu2Ti2O7 wire-in-tube architectures are 100–120, 10–15, and 10–15 nm, respectively. The Lu2Ti2O7 nanotubes and wire-in-tube architectures retain a specific capacity of 167.35 mAh·g−1, while Lu2Ti2O7 nanowires retain that of 143.45 mAh·g−1 at current density of 100 mA·g−1 after 50 charge-discharge cycles as anode materials of a lithium-ion battery. The Lu2Ti2O7 nanotubes and wire-in-tube architectures demonstrate better cycle stability and rate performance than Lu2Ti2O7 nanowires.

Novel ultraporous polyimide-based hollow carbon nanofiber mat: Its polymer-blend electrospinning preparation strategy and efficient dynamic adsorption for ciprofloxacin removal

A novel ultraporous polyimide-based hollow carbon nanofiber mat (CNFM) was facilely fabricated via a polymer-blend electrospinning strategy, which consisted of a simple single-needle electrospinning of two immiscible polymer solutions (polyamide acid/polymethyl methacrylate) (PAA/PMMA) and the subsequent thermal treatment, without involvement of tedious and cost-consuming activation steps. The obtained PP-CNFM-1–1 (PAA:PMMA = 1:1, mass ratio) exhibited well-developed hollow cores along the fiber length, and possesses ultrahigh Brunauer-Emmett-Teller (BET) specific surface area (SBET) of 2327 m2 g-1 and a large total pore volume of 1.26 cm3 g-1, which were superior to many activated CNFMs. The PP-CNFM-1–1 showed high ciprofloxacin (CIP) adsorption capacity of over 700 mg g-1 due to its ultrahigh SBET and abundant pores of 1–3 nm width fitting CIP molecule. Notably, the hollow core of PP-CNFM-1–1, which is similar to molecular channel, was the reason to the excellent CIP adsorption rate and a very short adsorption equilibrium time (<1h). Adsorption mechanism study implied that the pore filling effect and the hydrophobic interaction played the major roles in the adsorption process. The fixed-bed column adsorption study indicated that the PP-CNFM-1–1 had a great application potential for low concentration CIP removal.

Comparative Study of Traditional Single-Needle Electrospinning and Novel Spiral-Vane Electrospinning: Influence on the Properties of Poly(caprolactone)/Gelatin Nanofiber Membranes.

Spiral-vane electrospinning (SVE), a novel needleless electrospinning, was proven effective in obtaining high-throughput production of nanofibers. However, the properties of the electrospun nanofibers produced by SVE remain relatively underexplored, especially in comparison with those made by traditional single-needle electrospinning (SNE). Hence, for the comparative study of SNE and SVE in this study, the difference in the preparation mechanism was first analyzed using numerical simulation, followed by the experimental analysis of the effects of spinneret types on the quality and biocompatibility of electrospun poly(caprolactone)/gelatin (PCL/Gel) nanofibers. The values predicted by the electric field results were consistent with the experimental data, showing that the PCL/Gel nanofibers prepared by SVE have higher yields than SNE. Although the different spinnerets (i.e., needle and spiral vane) had little effect on the surface chemistry, thermal stability, and composition of the PCL/Gel nanofibers, they had great effects on the fiber diameter distribution and mechanical properties in which SVE-electrospun nanofibers have the wider diameter distribution and higher softness. Furthermore, the SVE-electrospun nanofibers were also proven to exhibit good biocompatibility for cell growth of human adipose-derived stem cells (hADSCs) and cell–fiber interactions. Summarily, compared to the traditional SNE, SVE-electrospun nanofibers exhibited many merits including high-throughput yield, good air permeability, and compliance, which provide a facile and effective platform for the improvement of nanofiber applications in biomedical fields (e.g., tissue engineering, cosmetic, and medical textiles).

Self-Assembled NBR/Nomex Nanofibers as Lightweight Rubbery Nonwovens for Hindering Delamination in Epoxy CFRPs.

Still today, concerns regarding delamination limit the widespread use of high-performance composite laminates, such as carbon fiber-reinforced polymers (CFRPs), to replace metals. Nanofibrous mat interleaving is a well-established approach to reduce delamination. However, nanomodifications may strongly affect other laminate thermomechanical properties, especially if achieved by integrating soft materials. Here, this limitation is entirely avoided by using rubbery nitrile butadiene rubber (NBR)/Nomex mixed nanofibers: neither laminate stiffness nor glass-transition temperature (Tg) lowering occurs upon CFRP nanomodification. Stable noncrosslinked nanofibers with up to 60% wt of NBR were produced via single-needle electrospinning, which were then morphologically, thermally, spectroscopically, and mechanically characterized. NBR and Nomex disposition in the nanofiber was investigated via selective removal of the sole rubber fraction, revealing the formation of particular self-assembled structures resembling quasi-core–shell nanofibers or fibril-like hierarchical structures, depending on the applied electrospinning conditions (1.10 and 0.20 mL/h, respectively). Mode I and Mode II loading tests show a significant improvement of the interlaminar fracture toughness of rubbery nanofiber-modified CFRPs, especially GI (up to +180%), while GII enhancement is less pronounced but still significant (+40% in the best case). The two nanofibrous morphologies (quasi-core–shell and fibril-like ones) improve the delamination resistance differently, also suggesting that the way the rubber is located in the nanofibers plays a role in the toughening action. The quasi-core–shell nanofiber morphology provides the best reinforcing action, besides the highest productivity. By contrast, pure Nomex nanofibers dramatically worsen the interlaminar fracture toughness (up to −70% in GI), acting as a release film. The achieved delamination resistance improvements, combined with the retention of both the original laminate stiffness and Tg, pave the way to the extensive and reliable application of NBR/Nomex rubbery nanofibrous mats in composite laminates.

Rubbery-Modified CFRPs with Improved Mode I Fracture Toughness: Effect of Nanofibrous Mat Grammage and Positioning on Tanδ Behaviour.

Carbon Fiber Reinforced Polymers (CFRPs) are widely used where high mechanical performance and lightweight are required. However, they suffer from delamination and low damping, severely affecting laminate reliability during the service life of components. CFRP laminates modified by rubbery nanofibers interleaving is a recently introduced way to increase material damping and to improve delamination resistance. In this work, nitrile butadiene rubber/poly(ε-caprolactone) (NBR/PCL) blend rubbery nanofibrous mats with 60 wt% NBR were produced in three different mat grammages (5, 10 and 20 g/m2) via single-needle electrospinning and integrated into epoxy CFRP laminates. The investigation demonstrated that both mat grammage and positioning affect CFRP tanδ behaviour, evaluated by dynamic mechanical analysis (DMA) tests, as well as the number of nano-modified interleaves. Double cantilever beam (DCB) tests were carried out to assess the mat grammage effect on the interlaminar fracture toughness. Results show an outstanding improvement of GI,R for all the tested reinforced laminates regardless of the mat grammage (from +140% to +238%), while the effect on GI,C is more dependent on it (up to +140%). The obtained results disclose the great capability of NBR/PCL rubbery nanofibrous mats at improving CFRP damping and interlaminar fracture toughness. Moreover, CFRP damping can be tailored by choosing the number and positioning of the nano-modified interleaves, besides choosing the mat grammage.

Boosting total oxidation of propane over CeO2@Co3O4 nanofiber catalysts prepared by multifluidic coaxial electrospinning with continuous grain boundary and fast lattice oxygen mobility

A one-dimensional (1D) core-shell of Co-Ce oxide has been prepared by multifluidic coaxial electrospinning method and evaluated for the total oxidation of propane (C3H8). Activity and morphological characterizations show that the CeO2@Co3O4 nanofiber catalyst, of which the core is CeO2 and the shell is Co3O4, exhibits excellent oxidation activity. The exposed Co3O4 grown on the outside of the fibers can rapidly react with C3H8 while CeO2 with high oxygen storage capacity in the inside is conductive to the enhanced oxidation rate. Besides, the continuous grain boundary provides a fast mass transfer channel for lattice oxygen, and rich oxygen vacancies favor the mobility of active oxygen species. In situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTs) confirms that the CeO2@Co3O4 catalyst have a faster rate of C3H8 adsorption and better oxidation activity with respect to the counterpart using a single-needle electrospinning method. Moreover, the CeO2@Co3O4 catalyst displays excellent thermal stability, and strong resistance against 5 vol% H2O and 5 vol% CO2 at both 300 and 400 °C. Our strategy can give some new insights into morphological engineering to promote active oxygen mobility via the construction of one-dimensional core-shell of metal oxides for catalytic oxidation of VOCs.

On-line dissolution analysis of multiple drugs encapsulated in electrospun nanofibers.

Electrospun nanofiber is a very attractive material which can be used as the support to form multiple-drug dosage. Understanding the dissolution process of different active drug ingredients released from electrospun fibers is of great importance to control and evaluate the quality of medicated nanofibers. Here we present the first study of on-line automatic analysis of dissolution of multiple drugs in electrospun fiber mats. Single-needle electrospinning technology is utilized to combine polymers, hydrophilic polyvinylpyrrolidone (PVP) and hydrophobic polycaprolactone (PCL) as carrier to load three poorly water-soluble non-steroidal anti-inflammatory drugs (paracetamol, nimesulide, and ibuprofen). The loading of the drugs in PVP/PCL electrospun fibers are characterized by various techniques, including scanning electron microscopy, X-ray diffraction, Fourier infrared spectroscopy and differential scanning calorimetry. The in vitro dissolution is investigated by our home-made portable analyzer, which can simultaneously on-line determine multiple drugs released from the nanofibers by a single step. The analysis shows a wide linear detection range of the drugs with limit-of-detection (LOD) down to μg/mL-level. The dissolution profiles of three ingredients in nanofibers can be monitored every thirty seconds from the beginning to the end in the entire dissolution process from only one HSCE run. The kinetic information of the dissolution, including the dissolution curve, characteristic dissolution time and dissolution efficiency, is obtained and evaluated for different dissolution media, drug loading content and the ratio of PVP/PCL. Our study provides a promising method for rapid and accurate dissolution testing of nanofiber-based drugs, and would extend the applications of separation techniques in pharmaceutical analysis.

Needleless electrospinning system with wire spinneret: an alternative way to control morphology, size, and productivity of nanofibers

Electrospinning is a versatile method to produce nanofibers. Electrospun nanofibers have been extensively used in many industrial applications such as wound dressing, sensor, protective clothing, and filters. However, producing nanofibers efficiently through a single-needle electrospinning technique is still challenging. In this study, a system of needleless electrospinning with a wire spinneret was utilized to produce Polyvinylpyrrolidone (PVP) nanofibers. Process parameters comprised concentration of solution, applied voltage, flow rate of solution, collection distance, and diameter of the wire spinneret were altered to examine morphology, diameter, and productivity of the produced fibers. SEM images showed that morphology of the produced fibers was affected by concentration of PVP solution. Moreover, diameter of the produced fibers could be varied by controlling the process parameters. Our needleless electrospinning system has proved to be more productive in producing fibers than the single-needle electrospinning system.

A new method for preparing needle-free cylindrical nozzle nanofibers

Aiming at the traditional single-needle electrospinning technology, a novel system for the efficient production of multi-production nanofibers through electrospinning is reported. The polymer solution is delivered to the liquid tank, and when the applied voltage exceeds a certain value, a plurality of nozzles is formed. In this paper, the electric field distribution of pinhole cylindrical spinneret structure is studied by simulating the electric field intensity with finite element software. The diameter and yield of the nanofibers were investigated by varying the center electrode voltage and the annular collector radius. The results show that the diameter and productivity of nanofibers are affected by the electric field intensity around the spinneret. Increasing the applied voltage and collecting distance has some significant effect on the diameter of nanofibers. The diameter of nanofibers increases with the concentration of the solution. The maximum yield of nanofibers is 3.1 g/h. It is noteworthy that this method not only greatly improves productivity but also significantly reduces the influence of solvent evaporation during electrospinning. This spinning method provides support for large-scale production of nanofibers in the future. This will be conducive to the further development of electrospinning, increase production, and more accurate control.

Preparation and characterization of naftifine-loaded poly(vinyl alcohol)/sodium alginate electrospun nanofibers

In this study, naftifine (a topical antifungal drug) loaded poly(vinyl) alcohol (PVA)/sodium alginate (SA) nanofibrous mats were prepared using the single-needle electrospinning technique. The produced nanofibers were crosslinked with glutaraldehyde (GTA) vapor. The morphology and diameter of the electrospun nanofibers were studied by scanning electron microscopy (SEM). SEM images showed the smoothness of the nanofibers and indicated that the fiber diameter increased with crosslinking and drug loading. Atomic force microscopy (AFM) images confirmed the uniform production of the scaffolds, and elemental mapping via energy dispersive X-ray spectroscopy (EDS) showed the uniform distribution of the drug within the nanofibers. An attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy study demonstrated that naftifine has sufficient secondary interactions with the polymer blend. The crosslinking treatment decreased the burst drug release effectively and the release mechanism followed Korsmeyer-Peppas Super Case-II transport. Overall, these findings suggest the potential use of naftifine-loaded PVA/SA nanofibers as a topical antifungal drug delivery system.

Large-Scale and Rapid Preparation of Nanofibrous Meshes and Their Application for Drug-Loaded Multilayer Mucoadhesive Patch Fabrication for Mouth Ulcer Treatment.

Electrospinning provides a simple and convenient method to fabricate nanofibrous meshes. However, the nanofiber productivity is often limited to the laboratory scale, which cannot satisfy the requirements of practical application. In this study, we developed a novel needleless electrospinning spinneret based on a double-ring slit to fabricate drug-loaded nanofibrous meshes. In contrast to the conventional single-needle electrospinning spinneret, our needless spinneret can significantly improve nanofiber productivity due to the simultaneous formation of multiple jets during electrospinning. Curcumin-loaded poly(l-lactic acid) (PLLA) nanofiber meshes with various concentrations and on the large scale were manufactured by employing our developed needleless spinneret-based electrospinning device. We systematically investigated the drug release behaviors, antioxidant properties, anti-inflammatory attributes, and cytotoxicity of the curcumin-loaded PLLA nanofibrous meshes. Furthermore, a bilayer nanofibrous composite mesh was successfully generated by electrospinning curcumin-loaded PLLA solution and diclofenac sodium loaded poly(ethylene oxide) solution in a predetermined time sequence, which revealed potent antibacterial properties. Subsequently, novel mucoadhesive patches were assembled by combining the bilayer composite nanofibrous meshes with (hydroxypropyl)methyl cellulose based mucoadhesive film. The multilayered mucoadhesive patch has excellent adhesion properties on the porcine buccal mucosa. Overall, our double-ring slit spinneret can provide a novel method to rapidly produce large-scale drug-loaded nanofibrous meshes to fabricate mucoadhesive patches. The multiple-layered mucoadhesive patches enable the incorporation of multiple drugs with different targets of action, such as analgesic, anti-inflammatory, and antimicrobial compounds, for mouth ulcer or other oral disease treatments.

Anchoring Pt on surface/bulk of LaCoO3 nanotubes via one step of coaxial electrospinning for efficient total propane oxidation

The effect of location sites of platinum (Pt) nanoparticles on LaCoO3 support for complete catalytic oxidation of propane (C3H8) was investigated. Pt nanoparticles were anchored on the surface, bulk and surface/bulk of LaCoO3 by using three different loading methods: incipient-wetness impregnation, single-needle electrospinning and coaxial electrospinning, respectively, followed by a simple 300 °C H2 reduction process. The obtained catalysts were systematically characterized. It turns out that one step synthesis of coaxial electrospun Pt/LaCoO3 nanotubes with both surface and bulk Pt species exhibits a relatively more efficient catalytic activity, where surface Pt favors the reduction of Co3+ to Co2+ and bulk Pt accelerates that of Co2+ to Co0. Meanwhile, Co species are active sites for C3H8 oxidation despite Pt loading, but the enhanced redox property and oxygen mobility upon Pt loading are crucial for the Mars-van Krevelen mechanism obeyed total C3H8 oxidation. Additionally, good thermal stability is found over coaxial electrospun Pt/LaCoO3, removing propane at a temperature of 450 °C over 48 h without a significant decrease in propane conversion. The addition of water vapor has a little inhibition effect on the catalytic activity under the reaction condition. Such route of Pt anchoring will provide an effective means for designing highly efficient perovskite based catalysts with low precious loadings for total oxidation reaction.

Scaled-Up Production and Tableting of Grindable Electrospun Fibers Containing a Protein-Type Drug.

The aims of this work were to develop a processable, electrospun formulation of a model biopharmaceutical drug, β-galactosidase, and to demonstrate that higher production rates of biopharmaceutical-containing fibers can be achieved by using high-speed electrospinning compared to traditional electrospinning techniques. An aqueous solution of 7.6 w/w% polyvinyl alcohol, 0.6 w/w% polyethylene oxide, 9.9 w/w% mannitol, and 5.4 w/w% β-galactosidase was successfully electrospun with a 30 mL/h feeding rate, which is about 30 times higher than the feeding rate usually attained with single-needle electrospinning. According to X-ray diffraction measurements, polyvinyl alcohol, polyethylene oxide, and β-galactosidase were in an amorphous state in the fibers, whereas mannitol was crystalline (δ-polymorph). The presence of crystalline mannitol and the low water content enabled appropriate grinding of the fibrous sample without secondary drying. The ground powder was mixed with excipients commonly used during the preparation of pharmaceutical tablets and was successfully compressed into tablets. β-galactosidase remained stable during each of the processing steps (electrospinning, grinding, and tableting) and after one year of storage at room temperature in the tablets. The obtained results demonstrate that high-speed electrospinning is a viable alternative to traditional biopharmaceutical drying methods, especially for heat sensitive molecules, and tablet formulation is achievable from the electrospun material prepared this way.