Electrospun Polymer Nanofibers Research Articles

Asiaticoside loading into polylactic-co-glycolic acid electrospun nanofibers attenuates host inflammatory response and promotes M2 macrophage polarization.

Polylactic-co-glycolic acid (PLGA) is one of the most promising synthetic materials for tissue engineering due to its excellent biocompatibility, good mechanical properties, and tunable biodegradation time. However, the accumulation of PLGA degradative products could cause significant host inflammatory response, a microenvironment favoring tissue fibrosis that is mainly mediated by M1 subtype macrophage. Drug loading is an emerging technology to modify electrospun nanofibers, and asiaticoside (AS) was demonstrated as an anti-inflammatory drug. This study investigated the potential effect of AS incorporating into PLGA electrospun nanofibers on modulating host inflammatory response. The results showed that AS co-electrospun with PLGA nanofibers could significantly reduce the infiltration of inflammatory cells at the implantation site as opposed to the site of regular PLGA nanofibers. In particular, immunohistochemistry demonstrated decreased M1 macrophage infiltration whereas increased M2 macrophage infiltration in the implantation site of AS-PLGA nanofibers when compared to the PLGA implantation site. In vitro study also revealed that culture of human fibroblasts on PLGA nanofibers resulted in significantly enhanced gene expression of inflammatory cytokines when compared to non-seeded fibroblasts, but these genes were significantly downregulated when seeded on AS-PLGA. Furthermore, culture of macrophage on AS-PLGA led to upregulated M2 marker gene expression and downregulated M1 marker gene expression. Collectively, these results indicate that, AS might be an ideal drug for loading into electrospun polymer nanofibers and thus favoring for tissue regeneration via mediating macrophage polarization.

Quasi-Dynamic Dissolution of Electrospun Polymeric Nanofibers Loaded with Piroxicam.

We investigated and monitored in situ the wetting and dissolution properties of polymeric nanofibers and determined the solid-state of a drug during dissolution. Piroxicam (PRX) was used as a low-dose and poorly-soluble model drug, and hydroxypropyl methylcellulose (HPMC) and polydextrose (PD) were used as carrier polymers for electrospinning (ES). The initial-stage dissolution of the nanofibers was monitored in situ with three-dimensional white light microscopic interferometry (SWLI) and high-resolution optical microscopy. The physical solid-state characterization of nanofibers was performed with Raman spectroscopy, X-ray powder diffraction (XRPD), and scanning electron microscopy (SEM). We showed that PRX recrystallizes in a microcrystalline form immediately after wetting of nanofibers, which could lead to enhanced dissolution of drug. Initiation of crystal formation was detected by SWLI, indicating: (1) that PRX was partially released from the nanofibers, and (2) that the solid-state form of PRX changed from amorphous to crystalline. The amount, shape, and size of the PRX crystals depended on the carrier polymer used in the nanofibers and dissolution media (pH). In conclusion, the present nanofibers loaded with PRX exhibit a quasi-dynamic dissolution via recrystallization. SWLI enables a rapid, non-contacting, and non-destructive method for in situ monitoring the early-stage dissolution of nanofibers and regional mapping of crystalline changes (re-crystallization) during wetting. Such analysis is crucial because the wetting and dissolution of nanofibers can greatly influence the performance of nanofibrous drug delivery systems in pharmaceutical and biomedical applications.

Sustainable progress into batchwise coloration of polyurethane nanofibers by using ultrasonic energy

In this decade, aesthetic potentials of electrospun polymeric nanofibers for advanced apparels have been studied. For the first time, we studied the sustainable aspects in the batchwise dyeing process of electrospun polymeric nanofibers in terms of conserving thermal energy and reducing the wastewater pollution. The nanofibrous mats were prepared using polyurethane (PU) polymer followed by dyeing with disperse dyes by conventional (CN) dyeing method as well as ultrasonic (US)-assisted dyeing method. Potential of savings in thermal energy (1000 kcal), dwell time (40 min) and quantity of disperse dyes (1.5% on the mass of nanofibers) were realized during the US-assisted dyeing method in comparison with the CN dyeing method. Further, total dissolved solids (TDS) and chemical oxygen demand (COD) contents of dyeing effluents demonstrated considerable ecological merits of the US dyeing method in terms of 30% reduction in TDS and 46% reduction in COD contents in comparison with the CN dyeing method. Excellent color strength (K/S) (reached 10) of dyed PU nanofibrous mats were achieved by US-assisted dyeing method in comparison with the K/S (reached 6) with CN dyeing method. Attenuated total reflectance-Fourier transform infra-red (FTIR) spectroscopy, UV–Vis spectrophotometer and Scanning electron microscopy (SEM) analysis were also applied during the study for characterization.

Biodegradable Electrospun Poly(lactic acid) Nanofibers for Effective PM 2.5 Removal

AbstractIn addition to the rapid urbanization and industrialization around the world, air pollution due to particulate matter is a substantial threat to human health. A considerable research effort has been devoted to the development of electrospun polymer nanofibers for air filter applications. Among these new technologies, electrostatic charge‐assisted air filtration is a promising technology for removing small particulate matter (PM). In this investigation, biodegradable electrospun poly(l‐lactic acid) (PLLA) polymer nanofibers are employed for air filter applications. Electrostatic charges generated from the PLLA nanofiber can significantly enhance air filter applications. Compared with a 3M commercial respirator filter, electrospun PLLA fibrous filters exhibit a high efficiency of 99.3%. Even after 6 h of filtration time, the PLLA filtration membrane still exhibits a 15% improvement in quality factor for PM 2.5 particles than the 3M respirator. This is mainly attributed to the electrostatic force generated from the electrospun PLLA nanofibers, which significantly benefit submicron particle absorption. Due to their biodegradability, ease of fabrication, and relatively high efficiency, electrospun PLLA nanofibers show great promise in applications such as air cleaning systems and personal air purifier applications.

Enhanced Spontaneous Emission Rate in a Low-Q Hybrid Photonic-Plasmonic Nanoresonator

In this paper, CdTe quantum dots (QDs)-doped single electrospun polymer nanofibers are partially coated with gold nanoparticles to form distinct hybrid photonic-plasmonic nanoresonators to investig...

Drugs Loaded into Electrospun Polymeric Nanofibers for Delivery

The electrospinning technique is a useful and versatile approach for conversion of polymeric solutions into continuous fibers, ranging from a few micrometers (10-100 μm) to the scale of nanometers (10- 100 nm) in diameters. This technique can be used in a vast number of polymers, in some cases after modifying them to the required properties. The high surface-to-volume ratio of the fibers can improve some processes like cell binding and proliferation, drug loading, and mass transfer processes. One of the most important and studied areas of electrospinning is in the drug delivery field, for the controlled release of active substances ranging from antibiotics and anticancer agents, to macromolecules such as proteins and DNA. The advantage of this method is that a wide variety of low solubility drugs can be loaded into the fibers to improve their bioavailability or to attain controlled release. This review presents an overview of the reported drugs loaded into electrospun polymeric nanofibers to be used as drug delivery systems. These drugs are classified by their applications in pharmacy.

(Invited) Heteronanomat Frameworks As a New Electrode Design for Advanced Lithium-Ion Batteries

Forthcoming smart energy era is in strong pursuit of advanced power sources with reliable electrochemical performances. To date, most research approaches have still relied on traditional synthetic materials and stereotyped electrode architecture (i.e., thickness-directional, simple pile-up of electrode active materials/conductive additives/polymeric binders on top of metallic current collectors), which have posed major obstacles to sustainable progress of the energy storage systems. For example, the presence of electrochemically-inert materials such as metallic current collectors and polymer binders exerts negative influence on volumetric/gravimetric capacity of electrodes. Moreover, the monotonous electrode architecture often gives rise to electrode thickness-dependent irregularity of electronic/ionic conduction pathways and also loss of structural integrity upon external deformation stresses. Here, we demonstrate a new class of heteronanomat-structured electrodes based on carbon nanotubes (CNTs), cellulose nanofibrils and electrospun polymeric nanofibers to resolve the long-standing challenges of conventional electrodes described above. This material/structural uniqueness allows the formation of three-dimensional bicontinuous CNT electron networks and electrolyte conduction channels, in addition to improving the mass loading of electrode active materials and also mechanical flexibility. As a result, the heteronanomat electrodes provide unprecedented advances in the electrochemical performance and shape diversity that lie far beyond those achievable with conventional battery electrode architectures. We envision that the heteronanomat-structured electrode strategy holds a great deal of promise as a reliable and versatile platform technology to open a new route toward advanced lithium-ion batteries. References Sang-Young Lee et al. Adv. Energy Mater. 2017, 1701099.Sang-Young Lee et al. Adv. Funct. Mater. 2015, 25, 6029.Sang-Young Lee et al. Adv. Energy Mater. 2015, 5, 1501194. Figure 1

Characterization of filter media prepared from aligned nanofibers for fine dust screen

ABSTRACTNanofibers for fine dust filters of four structures (random, aligned, orthogonal, and nanofiber net) were prepared by electrospinning method using polymers such as PAN and PA6. While conventional electret filters experienced deterioration problems in fine dust(PM1.0) capture as its surface charge decayed, the electrospun nanofibers prepared contributed to the removal capacity. The filters from aligned fibers showed high quality factors ( q F: filter performance indicator) and filtration efficiency from 22 to 50% depending on particle size than simple electret media at a face velocity of 15.92 cm/s. The fiber structure of nanofiber net (NFN) presented almost absolute collection efficiency, particularly on dust particles smaller than 300 nm. Furthermore, the composite filters which are composed both of a commercial electret mask filters and nanofiber nets effectively enhanced the overall filtration efficiency by 59.46%, resulting in more than 99% for PM1.0. Consequently, electrospun polymer nanofibers offer a promising plausible mask filter material with air permeability. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 48166.

Application of Packed-nanofibers Solid-phase Extraction for Determination of Rhodamine B in Sausage

A method for the determination of Rhodamine B in sausage was developed and validated. After extraction of Rhodamine B with acetonitrile from foodstuffs, a novel electrospun polymer nanofibers packed micro-column was used for cleaning and concentrating of the analyte in the sample. High performance liquid chromatography with fluorescence detection (HPLC-Flu) was used for the determination of Rhodamine B in the sample. The mobile phase was composed of 3.0 g L-1 phosphate buffer and methanol (3:7, volume ratio), and the pH was adjusted to 7. 0 with orthophosphoric acid. The results showed that the standard curve was linear over the validated concentrations range of 2-500 ng g-1, and the limit of detection (LOD) and the limit of quantitation (LOQ) for Rhodamine B spiked samples was 0. 2 ng g-1 and 0. 7 ng g-1, respectively. The average recoveries of Rhodamine B were 90.4% -94.3% for sausage, and the relative standard deviation of the method was from 1.7% to 3.8%. This proposed method was applied to real sample, and there was no Rhodamine B found in sausage.

New Gas-Diffusion Electrode Based on Heterocyclic Microporous Polymer PIM-1 for High-Temperature Polymer Electrolyte Membrane Fuel Cell

Polymer of intrinsic microporosity PIM-1 was used for electrospun polymer nanofiber producing. After pyrolysis, the obtained nanofibers, in a form of entire mat, were used as a support for cathode electrocatalyst for high-temperature polymer electrolyte membrane fuel cell on polymer polybenzimidazole membrane. The material was characterized by the methods of standard contact porosimetry, Raman spectroscopy and scanning electron microscopy. The I-V curves for membrane-electrode assembly suggest a possibility of using the carbon material for electrodes in a fuel cell on polymer membrane.

Recyclable nanoscale zerovalent iron (nZVI)-immobilized electrospun nanofiber composites with improved mechanical strength for groundwater remediation

Nanoscale zero-valent iron (nZVI), as a promising material, has been widely used in groundwater remediation. Membrane-supported nZVI can both avoid nZVI agglomeration for better reactivity and recycle nZVI/contaminants to lower the risk of secondary pollution. However, membrane mechanical strength is a critical property for long-term operation and the regeneration of nZVI membranes. This study tried to use a high molecular weight dual-crosslinking method to improve the mechanical strength of polymeric electrospun nanofiber membranes. Specifically, high molecular weight polyacrylic acid (PAA, Mw = 450,000) was dual-crosslinked by adding polyvinyl alcohol (PVA) as covalent cross-linker (named as M450k) and Fe(II) or Fe(III) as the ionic cross-linker (named as M450k-II and M450k-III). The results indicated that the M450k had better thermal resistance against membrane shrinkage, thus having larger surface areas and more –COOH groups to immobilize more nZVI particles. Besides, M450k-III had the highest tensile strength at 8.5 MPa, 5 times the figure for the mono-crosslinked low molecular weight membrane (M2k). In terms of nZVI immobilization and filtration performance, the Fe(II)-crosslinked membrane had better nZVI immobilization with the highest removal capacity at 463 mg/g while Fe(III)-crosslinked membrane had overwhelming mechanical strength with decent and stable removal capacity under multiple nZVI regenerations over 15 filtration cycles. Generally, the high molecular weight Fe(III)-crosslinked PAA-PVA electrospun nZVI showed better potential for long-term filtration process.

Quantifying Polymer Chain Orientation in Strong and Tough Nanofibers with Low Crystallinity: Toward Next Generation Nanostructured Superfibers.

Advanced fibers revolutionized structural materials in the second half of the 20th century. However, all high-strength fibers developed to date are brittle. Recently, pioneering simultaneous ultrahigh strength and toughness were discovered in fine (<250 nm) individual electrospun polymer nanofibers (NFs). This highly desirable combination of properties was attributed to high macromolecular chain alignment coupled with low crystallinity. Quantitative analysis of the degree of preferred chain orientation will be crucial for control of NF mechanical properties. However, quantification of supramolecular nanoarchitecture in NFs with low crystallinity in the ultrafine diameter range is highly challenging. Here, we discuss the applicability of traditional as well as emerging methods for quantification of polymer chain orientation in nanoscale one-dimensional samples. Advantages and limitations of different techniques are critically evaluated on experimental examples. It is shown that straightforward application of some of the techniques to sub-wavelength-diameter NFs can lead to severe quantitative and even qualitative artifacts. Sources of such size-related artifacts, stemming from instrumental, materials, and geometric phenomena at the nanoscale, are analyzed on the example of polarized Raman method but are relevant to other spectroscopic techniques. A proposed modified, artifact-free method is demonstrated. Outstanding issues and their proposed solutions are discussed. The results provide guidance for accurate nanofiber characterization to improve fundamental understanding and accelerate development of nanofibers and related nanostructured materials produced by electrospinning or other methods. We expect that the discussion in this review will also be useful to studies of many biological systems that exhibit nanofilamentary architectures and combinations of high strength and toughness.

Liquid Phase Selective Hydrogenation of Phenol to Cyclohexanone over Electrospun Pd/PVDF-HFP Catalyst

Cyclohexanone is an important industrial intermediate in the synthesis of materials such as nylons, but preparing it efficiently through one-step hydrogenation of phenol is hindered by over-reduction to cyclohexanol. Using an efficient catalyst can enhance the selectivity of cyclohexanone at high phenol conversion. In this study, catalysts comprised of palladium nanoparticles supported on electrospun PVDF-HFP (polyvinylidene fluoride-co-hexafluoropropylene) nanofibers were prepared using the electrospinning technique. The catalysts were characterized using thermogravimetric analyzer (TGA), scanning electron microscopy (SEM), transmission electron microscope (TEM), and drop shape analyzer (DSA). The prepared catalysts were used to hydrogenate phenol into cyclohexanone in a batch reactor. The Pd/PVDF-HFP catalyst showed a very high product selectivity and high phenol conversion. The conversion of phenol achieved was 98% with 97% cyclohexanone selectivity in 7 h using 15 wt% of palladium (0.0021 moles) relative to phenol (0.0159 moles). The turnover number (TON) and turnover frequency (TOF) values calculated were 7.38 and 1.05 h−1, respectively. This paper presents original research in heterogeneous catalysis using novel electrospun nanofibers. Multiphase hydrogenation of phenol to cyclohexanone over electrospun Pd/PVDF-HFP catalyst has not been reported by any researcher in the literature. This work will also provide a research window for the application of electrospun polymeric nanofibers in multiphase reactions.

Carbon Nanofibers Coated with Silicon/Calcium-Based Compounds for Medical Application

The aim of this work was to develop a method for the manufacture of carbon nanofibers in the form of mats containing silicon and calcium compounds with potential biomedical application. Carbon nanofibers (ECNF) were prepared from the electrospun polyacrylonitrile (PAN) nanofibers. The electrospun polymer nanofibers were heat treated up to 1000°C to obtain carbon nanofibers. The surface of ECNF was covered with a silica-calcium sol (ECNF+Si/Ca) by dip-coating technique followed by the stabilization process. Both types of carbon nanofibers, i.e., the as-received and covered with the sol, were tested to confirm their osteoconductive properties. Biological tests were performed, including genotoxicity, cytotoxicity, and alkaline phosphatase (ALP) activity. Morphology of adhering cells to nanofiber surface was described. The nanofibers were subjected to a bioactivity test in contact with SBF artificial plasma. Biological tests have revealed that the nanofiber-modified ECNF+Si/Ca in contact with osteoblast cells were biocompatible, and the level of cytotoxicity was lower compared to the control. The ALP activity of the modified nanofibers was higher than nonmodified nanofibers and indicates potential applications of such carbon materials in the form of mats as a substrate for bone tissue regeneration.

Fabrication of Electrospun Polymer Nanofibers with Diverse Morphologies.

Fiber structures with nanoscale diameters offer many fascinating features, such as excellent mechanical properties and high specific surface areas, making them attractive for many applications. Among a variety of technologies for preparing nanofibers, electrospinning is rapidly evolving into a simple process, which is capable of forming diverse morphologies due to its flexibility, functionality, and simplicity. In such review, more emphasis is put on the construction of polymer nanofiber structures and their potential applications. Other issues of electrospinning device, mechanism, and prospects, are also discussed. Specifically, by carefully regulating the operating condition, modifying needle device, optimizing properties of the polymer solutions, some unique structures of core–shell, side-by-side, multilayer, hollow interior, and high porosity can be obtained. Taken together, these well-organized polymer nanofibers can be of great interest in biomedicine, nutrition, bioengineering, pharmaceutics, and healthcare applications.

Lightweight and flexible Ni-Co alloy nanoparticle-coated electrospun polymer nanofiber hybrid membranes for high-performance electromagnetic interference shielding

Low-density, flexible and high-performance electromagnetic interference (EMI) shielding materials are urgently required to address the increasingly serious problem of radiation pollution. Ni-Co alloys with intrinsic conductivity and magnetism are good candidates for providing excellent EMI shielding performance. However, their high density and poor flexibility severely restrict their further applications in some specific fields. Herein, lightweight and flexible Ni-Co alloy nanoparticle-coated PAN-PU (P@Ni-Co) nanofiber membrane is fabricated through the combination of the electrospinning technique and the electroless deposition process, and it is employed as an effective EMI shielding material. Due to its remarkable conductivity of 1139.6 S/cm and the satisfactory saturation magnetization value of 49.6 emu/g, P@Ni-Co hybrid membrane with a thickness of 0.180 mm and a density of 0.59 g cm−3 exhibits excellent electromagnetic interference shielding effectiveness (EMI SE) of >68 dB over a wide frequency band (8–26.5 GHz); moreover, the average EMI SE reached as high as 77.8 dB with an absolute EMI shielding effectiveness (SSET) of 7325.8 dB cm2·g−1, which are higher than those for most of the reported EMI shielding materials. Compared to reflection, absorption makes a much larger contribution to the total EMI shielding effectiveness. These results suggest that Ni-Co alloy nanoparticle-coated PAN-PU nanofiber membrane would be very promising for applications as a thinner and lighter EMI shielding material.

A random laser based on electrospun polymeric composite nanofibers with dual-size distribution.

Electrospun fiber-based random lasers are environment-friendly flexible systems in which waveguiding/scattering processes provided by their structure with a broad distribution of diameters are essential elements to generate a suitable lasing mechanism. In this work, we prepared electrospun fibers with dual-size diameter distribution (above and below the critical value for waveguiding), allowing that both optical processes can be established in the polymer network. As a result, random laser emission was observed for the electrospun fibers presenting dual-size diameters with rhodamine 6G as the gain medium, characterizing the combination of waveguiding/scattering as an adequate condition for development of organic nanofibrous random lasers. Degradation assays were also performed in order to evaluate the prolonged use of such random laser systems.

Interface engineering of solution-grown silver nanofiber networks designed as flexible transparent electrodes

Flexible transparent electrodes were fabricated by chemical plating of Ag on electrospun polymer nanofiber templates. Argon plasma treatment and Joule heat-assisted self-welding were exploited to improve the conductivity of the solution-grown Ag nanofibers network.

Recent Patents on Polymeric Electrospun Nanofibers and Their Applications in Drug Delivery.

In the recent years, polymeric nanofibers have gained lots of attention in the area of drug delivery applications. Owing to its simplicity, ease of composition method and high drug loading capacity, it provides various benefits for the therapeutic applications. Nanofibers are useful for the delivery of antibiotics, anticancer drugs, analgesic's agents and various proteins for drug delivery applications. Electrospinning method is widely used method for the preparation of nanofibers, based on their feasibility background for scale-up process from laboratory to the industrial applications. A literature review was conducted to summarize the reported articles as well as patents that have been granted and filed for work related to nanofibers in drug delivery. Efforts have been made to include various types of research undertaken by the researchers for the fabrication of nanofiber and its application in drug delivery system. In this paper, a detailed information is reported about researches and developments related to electrospun polymer nanofibers including its fabrication process, structure, properties, characterization, applications, and patent. Amongst all the patents available, 18 most relevant granted patents and 14 filed patents was summarized in the review article. We expect that these fundamental applications of nanofibers could help the researchers to develop and gain knowledge about nanofibers in drug delivery application.

One- and two-dimensional electrodynamic steering of electrospun polymer nanofibers

Polymer nanofibers, with their specific set of material properties, are favorable for many applications in biomedical engineering (scaffold, stent, or tissue engineering). This application, however, requires the ability to control the manufacturing process together with organization and orientation of the deposited fiber. Electrospinning device parameters leading to a stable fiber extrusion were already found, together with the influence of the individual working parameters on the fiber properties. It was also found that fiber steering via the external electrostatic field, created by auxiliary electrodes, has very limited steering capabilities. In this article, electrodynamic steering of the electrospun polymer nanofiber is discussed, with focus on the macroscopic fiber deposition pattern and microscopic fiber alignment and straightness. Different electric field distributions are examined, and the corresponding fiber collection patterns are demonstrated on a series of experiments. Finally, a mathematical model of a discretized fiber is created. Matching the simulation and experimental results allows for the determination of unknown fiber properties, like the structural damping coefficient or Stokes drag coefficient.