PEO Fibers Research Articles

DNA data storage in electrospun and melt-electrowritten composite nucleic acid-polymer fibers

Incorporating biomolecules as integral parts of computational systems represents a frontier challenge in bio- and nanotechnology. Using DNA to store digital data is an attractive alternative to conventional information technologies due to its high information density and long lifetime. However, developing an adequate DNA storage medium remains a significant challenge in permitting the safe archiving and retrieval of oligonucleotides. This work introduces composite nucleic acid-polymer fibers as matrix materials for digital information-bearing oligonucleotides. We devised a complete workflow for the stable storage of DNA in PEO, PVA, and PCL fibers by employing electrohydrodynamic processes to produce electrospun nanofibers with embedded oligonucleotides. The on-demand retrieval of messages is afforded by non-hazardous chemical treatment and subsequent PCR amplification and DNA sequencing. Finally, we develop a platform for melt-electrowriting of polymer-DNA composites to produce microfiber meshes of programmable patterns and geometries.

Shape-memory performance of electrospun thermoplastic polyurethane/polyethylene oxide blend fibrous membranes with diverse morphological structures

The present study aimed at exploring the effect of morphological structure design on shape-memory effect (SME) of thermoplastic polyurethane/polyethylene oxide (TPU/PEO) blend electrospun fibrous membranes (EFMs), that were fabricated by co-spinning, dual-jet spinning, and layer-by-layer spinning, respectively. Tunable shape-memory performances of co-spun EFMs were realized by simply varying the blend ratio of TPU and PEO in individual fiber. By comparison, the sample containing 50 wt% PEO showed the best SME due to the rich blend interface in individual fiber and the sufficient fusion points between fibers, both of which promoted the synergistic effect between two components in optimizing SME. As turning the TPU/PEO co-spun fibers into well-separated TPU and PEO fibers by dual-jet electrospinning, the interaction channels were reduced to only the fusion points between fibers, leading to the simultaneous decrease of shape-fixity and -recovery ratios. After assembling the TPU and PEO fibers into a sandwich-structured structured EFM, the SME was further degraded due to the few diffusion points between fibers located at the layer interface. This work provides a good guidance for developing high-performance shape-memory EFMs.

Centrifugally spun poly(ethylene oxide) fibers rival the properties of electrospun fibers

AbstractCentrifugal force spinning (CFS), also known as centrifugal spinning, forcespinning, or rotary jet spinning, provides considerably higher production rates than electrospinning (ES), but the more widespread use of CFS as an alternative depends on the ability to produce fibers with robust thermal and mechanical properties. Here, we report the CFS of poly(ethylene oxide) (PEO) fibers made using a spinning dope formulated with acetonitrile (AcN) as the volatile solvent, and we describe the thermal and mechanical properties of the centrifugally‐spun fibers. Even though the formation, diameter, and morphology of electrospun and centrifugally‐spun PEO fibers are relatively well‐studied, the article presents three crucial contributions: the pioneering use of PEO solutions in AcN as spinning dope, characterization of crystallinity and mechanical properties of the centrifugally‐spun PEO fibers, and a comparison with the corresponding properties of electrospun fibers. We find that fiber formation occurrs for the chosen CFS conditions if polymer concentration exceeds the entanglement concentration, determined from the measured specific viscosity. Most significantly, the centrifugally spun PEO fibers display crystallinity, modulus, elongation‐at‐break, and fiber diameter that rival the properties of electrospun PEO fibers reported in the literature.

Non-Woven Textiles Formed from Contact Drawn Poly(ethylene oxide) Fibers Provide Tunable Filtration and Virucidal Properties via Entrapment of Silver Nanoparticles

Filtering facepiece respirators (FFRs) protect wearers from inhalation of fine particulates and help prevent transmission of airborne viruses. Here, an FFR material is produced by successive deposition of contact drawn poly(ethylene oxide) (PEO) fibers. Fibers are formed by immersing an array of pins in a highly viscous precursor solution of PEO and then rapidly removing the pins such that polymer entanglement occurs, forming multiple liquid bridges that rapidly dry as they extend. Tunable filtration is achieved by varying the number of PEO fiber elongation cycles. Placing the PEO textiles between two woven cotton cloths provides structural support and additional filtration capacity, achieving a maximum filtration efficiency of 95% with a corresponding initial pressure drop of 281 Pa. The entrapment of silver nanoparticles in the PEO fibers imparts virucidal properties to PEO-based textiles, as demonstrated by inactivation of a human coronavirus HCoV-OC43 and influenza A virus inoculum. The ability to tune filtration efficiency to application needs and provide advanced function through entrapment of active materials represents a versatile tool for limiting exposure to airborne particulates and pathogens.

A New Generation of Electrospun Fibers Containing Bioactive Glass Particles for Wound Healing.

Chitosan fibers blended with polyethylene oxide (CHIT_PEO) and crosslinked with genipin were fabricated by electrospinning technique. Subsequently, CHIT_PEO bioactive glass composite electrospun mats were fabricated with the aim to achieve flexible structures with adequate mechanical properties and improved biological performance respect to CHIT_PEO fibers, for potential applications in wound healing. Three different compositions of bioactive glasses (BG) were selected and investigated: 45S5 BG, a Sr and Mg containing bioactive glass (BGMS10) and a Zn-containing bioactive glass (BGMS_2Zn). Particulate BGs (particles size < 20 μm) were separately added to the starting CHIT_PEO solution before electrospinning. The two recently developed bioactive glasses (BGMS10 and BGMS_2Zn) showed very promising biological properties in terms of bioactivity and cellular viability; thus, such compositions were added for the first time to CHIT_PEO solution to fabricate composite electrospun mats. The incorporation of bioactive glass particles and their distribution into CHIT_PEO fibers were assessed by SEM and FTIR analyses. Furthermore, CHIT_PEO composite electrospun mats showed improved mechanical properties in terms of Young’s Modulus compared to neat CHIT_PEO fibers; on the contrary, the values of tensile strain at break (%) were comparable. Biological performance in terms of cellular viability was investigated by means of WST-8 assay and CHIT_PEO composite electrospun mats showed cytocompatibility and the desired cellular viability.

Wet‐Spinning of Biocompatible Core–Shell Polyelectrolyte Complex Fibers for Tissue Engineering

AbstractPolyelectrolyte complex fibers (PEC fibers) have great potential with regard to biomedical applications as they can be fabricated from biocompatible and water‐soluble polyelectrolytes under mild process conditions. The present publication describes a novel method for the continuous fabrication of PEC fibers in a water‐based wet‐spinning process by interfacial complexation within a core–shell spinneret. This process combines the robustness and flexibility of nonsolvent‐induced phase separation (NIPS) spinning processes conventionally used in the membrane industry with the complexation between oppositely charged polyelectrolytes. The produced fibers demonstrate a core–shell structure with a low‐density core and a highly porous polyelectrolyte complex shell of ≈800 μm diameter. In the case of chitosan and polystyrene sulfonate (PSS), mechanical fiber properties could be enhanced by doping the PSS with poly(ethylene oxide) (PEO). The resulting CHI/PSS‐PEO fibers present a Young modulus of 3.78 GPa and a tensile strength of 165 MPa, which is an excellent combination of elongation at break and break stress compared to literature. The suitability of the CHI/PSS‐PEO fibers as a scaffold for cell culture applications is verified by a four‐day cultivation of human HeLa cells on PEO‐reinforced fibers with a subsequent analysis of cell viability by fluorescence‐based live/dead assay.

Evaluating the protective role of carrier microparticles in preserving protein secondary structure within electrospun meshes

AbstractDirect incorporation of proteins into electrospun meshes using approaches such as blend electrospinning can promote adverse interactions with hydrophobic polymers, organic solvents and high voltage, potentially leading to loss of protein activity. However, pre‐encapsulation within a protective carrier phase can preserve protein conformation by avoiding exposure to harsh processing conditions. In this study, bovine serum albumin (BSA) was loaded within cellulose microparticles (MPs) and the BSA‐loaded MPs were dispersed in a solution of poly(ethylene oxide) (PEO). Particle‐mesh composites were created using a sacrificial fiber/co‐electrospinning approach in which the BSA/MP/PEO solution was simultaneously electrospun against a poly(caprolactone) (PCL) solution. Post‐fabrication, sacrificial PEO fibers were selectively dissolved by treatment with ethanol. Microscopy, weight loss analysis and FTIR spectroscopy together confirmed selective dissolution of PEO fibers and the retention of BSA‐loaded MPs within the PCL network without significant loss of either the MPs or the protein. Circular dichroism spectroscopy and intrinsic fluorescence measurements on BSA extracted from the co‐electrospun meshes indicated minimal disruption to secondary structure, although partial sheet induction was observed. In contrast, direct exposure of BSA to four commonly used electrospinning solvents resulted in a large decrease in helical content and significant induction of sheets, revealing significant changes to the secondary structure. In summary, our results demonstrate the protective role of MPs in minimizing adverse effects of electrospinning on the secondary structure of incorporated protein.

Flow-Induced Formation of Thin PEO Fibers in Water and Their Stability After the Strain Release

Recently, we have shown that a tensile stress applied to chains of poly(ethylene oxide) (PEO) in water reduces the solubility and leads to phase separation of PEO chains from water with the formation of a two-phase region. In this work, we further elucidate the generic mechanism behind strain-induced phase transitions in aqueous PEO solutions with concentrations of 50-60 wt % by performing all-atom molecular dynamics simulations. In particular, we study the stability of oriented PEO fibers after removing stretching forces. We found that the size of the PEO bundle increased with time, which is associated with the dissolution of PEO chains on the fiber surface due to the reformation of hydrogen bonds between the outer PEO molecules and water. For precise characterization of the fibers, the scattering patterns (small- and wide-angle X-ray spectra) for configurations taken at different relaxation times are calculated. The tendency of the oligomer chains to be peeled off from the surface of the bundle eventually might lead to a complete dissolution of the PEO fiber. We conclude that either entanglement constraints or a quick drying process are necessary to conserve the fiber structure in a quiescent state. The scattering results show that external strain induced a liquid-liquid phase separation first. On long time scales, this can be a precursor for crystallization of the fiber.

Fabrication and properties of carboxymethyl chitosan/polyethylene oxide composite nonwoven mats by centrifugal spinning

Carboxymethyl chitosan/polyethylene oxide (CMCS/PEO) mixed composition nonwoven mats with the average mat basis weight of 34.53–49.63 g/m2 were prepared by centrifugal spinning from homogeneous aqueous solution for potential use as wound dressings. The weight fraction composition of CMCS/PEO investigated was 40/60 to 60/40. The CMCS/PEO fibers were found to have normally distributed, monomodal, average diameters ranging from 1.91 μm (55 % CMCS) to 3.22 μm (50 % CMCS). Addition of CMCS to PEO (40 % CMCS) resulted in appearance of a wide angle x-ray diffraction (WXRD) peak at 18.9°. The CMCS and PEO fibers were demonstrated by differential scanning calorimetry and WXRD to be mixtures of the two paracrystalline polymers. The composite nonwoven mats with 60 % weight of CMCS demonstrated Log2 reduction at 24 h against Staphylococcus aureus inoculation (104 cfg/mL).

Elaboration and characterization of P3HT–PEO–SWCNT fibers by electrospinning technique

In the present work, we report the preparation by the electrospinning technique and the characterization of poly(3-hexylthiophene)–polyethylene oxide–single wall carbon nanotubes (P3HT–PEO–SWCNT) fibers. The SWCNT concentration into the P3HT–PEO matrix is varied from 0.2 to 1%. Optical, electrical, thermal, and morphological properties of the P3HT–PEO–SWCNT fibers are determined. The incorporation of the SWCNT into the P3HT–PEO polymer matrix is determined by SEM, EDS analysis, TEM, FTIR, and Raman. The optical properties are analyzed by the determination of photoluminescence and photoresponse. The stability and degradation temperature of the fibers are determined by TGA. The morphology of the P3HT–PEO–SWCNT fibers depends on the SWCNT concentration, in all cases non-beaded fibers are obtained. It is found that the SWCNT incorporating into the P3HT–PEO fibers increases the conjugation length of P3HT chains. Charge transfer from P3HT to SWCNT is corroborated by photoluminescence and Raman. The P3HT–PEO–SWCNT fibers obtained in this work exhibit interesting optoelectronic properties that could be useful for device applications.

Intensity dependent nonlinear absorption switching behavior of electrospun meta-nitroaniline nanofiber

The present work reports the study on nonlinear absorbing behavior of optically nonlinear m-nitroaniline (mNA) organic molecules properly oriented in the core of a polymeric fiber such as Poly (methyl methacrylate) (PMMA) and Poly (ethylene Oxide) (PEO) free standing films synthesized by electrospinning technique for the first time. The nonlinear absorption nature of the nanofibers is investigated by intensity dependent Z scan technique (532 nm, 10 Hz, 5ns). We observed an unusual nonlinear switching behavior in mNA- PMMA nanofiber from reverse saturable absorption (RSA) to saturable absorption (SA) through a peculiar W-pattern for an increase in pulse energy, whereas intensity dependent SA behavior is seen clearly in mNA–PEO polymer matrix. The identified nonlinear absorption of mNA –PMMA and mNA -PEO fibers can be of interest for various optical applications such as switching, optical sensors, etc. The normalized transmittance versus input fluence graph confirms the potential possibility of using the prepared fibers as optical switches at higher intensity. And mNA – PMMA fiber matrix at low intensities exhibits an optical limiting behavior, implying that the material to be a potential candidate for laser safety devices. Demonstrated fiber matrix free standing films are of potential use as it finds direct application in laser photonic devices.

Microfluidics-Based On-Demand Generation of Nonwoven and Single Polymer Microfibers.

In this work, we present a microfluidics-based microfiber fabrication method with the ability to control both the fiber size and the extent of coiling of the generated fiber. This latter feature allows on-demand generation of both nonwoven and single fiber within the same device, broadening the scope of application of the fabricated fibers. Using a hybrid poly(dimethylsiloxane) (PDMS)-glass microfluidic device, we implement a coflowing solvent removal technique to generate poly(ethylene oxide) (PEO) fibers. Characterization of fibers by Fourier transform infrared (FTIR) spectroscopy and differential scanning calorimetry (DSC) confirms the production of solvent-free, pure PEO fibers. Control over fiber size using both inner and outer liquid flow rates is demonstrated by scanning electron microscopy (SEM) imaging. More crucially, we employ a complementary flow toward the downstream end of the fiber solidification region to control the extent of coiling of the generated fiber. By simple variation of the complementary flow, we induce a transition from a nonwoven fiber to a single fiber. The presented technique is expected to broaden the scope of microfluidics as a tool for the continuous generation of microfibers with a wider range of applications than the existing microfluidics techniques.

Fabrication of microgrooved scaffolds using near-field electrospinning-assisted lithography (NFEAL)

A simple patterning process combining near-field electrospinning (NFE) and template lithography, called near-field electrospinning-assisted lithography (NFEAL), was developed to prepare polymeric scaffolds with microgroove patterns for potential use in biomedical applications. NFE enabled the deposition of poly (ethylene oxide) (PEO) fibers at a desired position. The diameters of the deposited PEO fibers could be controlled over a range of 0.5–20μm by adjusting the NFE parameters such as voltage, distance, feed rate, and translation speed. The preparation of PEO fibers with 1 and 3μm diameters using NFE, followed by the deposition of polystyrene (PS) and removal of the fiber template, created free-standing PS scaffolds with microgroove patterns. The width of the microgroove was similar to the diameter of the PEO fibers. The depth of the microgroove was also dependent on the dimensions of the PEO fibers; microgrooves of depth 64.49±11.5nm and 216.68±62.9nm were fabricated from PEO fibers of diameters 1 and 3μm, respectively. When C2C12 cells were cultured on the microgrooved scaffolds, they showed enhanced elongation or alignment along the microgrooved scaffolds, especially, for the microgroove (1μm) with a smaller width.

Effect of Thermal Treatment on Crystallinity of Poly(ethylene oxide) Electrospun Fibers.

Post-process thermal treatment of electrospun fibers obtained from poly(ethylene oxide) (PEO) water and methanol solutions was examined. PEO fibers from methanol solution showed larger diameters as observed by scanning electron microscopy. Fibers both from water and methanol solutions exhibited a significant dimensional stability and surface cracking during the specific exposure time after thermal treatments at 40, 50, and 60 °C. Changes in crystallinity after the thermal treatment were studied by wide-angle X-ray diffraction. The kinetics of secondary crystallization were positively influenced by the as-processed level of the amorphous phase and temperature of thermal treatment. Samples treated at 60 °C were degraded by thermooxidation within the time.

Characterization of mechanically reinforced electrospun dextrin‐polyethylene oxide sub‐microfiber mats

Dextrin and dextrin‐polyethylene oxide (DEX/PEO) fibers in the submicron range were produced by electrospinning of single and blend polymer solutions. The morphology, intermolecular interactions, and mechanical properties of dextrin microfibers with and without PEO were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, X‐ray diffraction, nuclear magnetic resonance spectroscopy, and uniaxial tensile testing. Spectroscopic results confirmed hydrogen bond formation, evidencing dextrin as a molecular entanglement source for fiber mechanical reinforcement. The uniaxial tensile tests demonstrated a synergistic mechanical reinforcement effect that varied with blend composition. Equal weight ratio blends supported a maximum tensile strength with a high elastic modulus and demonstrated to be more elastic and resistant to breaking, even than pristine PEO fibers. Moreover, elastic moduli of blend fiber mats were found to lie within the value range for human skin, thus providing the DEX/PEO meshes with potential applicability as skin tissue scaffolds. This synthesis approach proved the feasible and inexpensive fabrication process of natural‐synthetic polymer hybrid fibers that combine the biocompatibility, biodegradability, and encapsulating capability of dextrin with the mechanical strength and flexibility of PEO for the development of scaffolds for tissue engineering and topical drug delivery applications in skin wound healing. POLYM. ENG. SCI., 59:1778–1786, 2019. © 2019 Society of Plastics Engineers

Study on microstructure and mechanical properties of polydiacetylene composite biosensors

ABSTRACT10,12‐Pentacosadiynoic acid (PCDA) monomers were mixed with polyurethane (PU) or poly(ethylene oxide) (PEO) and the mixtures were electrospun to obtain composite nanofibers that were then photopolymerized via ultraviolet radiation, resulting polydiacetylene (PDA) in the nanofibers. The PDA demonstrated color‐changing properties in the presence of Escherichia coli, which exhibited potential for developing flexible colorimetric biosensors for medical textiles. Phase separation was found in the PEO–PDA fibers, resulting in amorphous PEO accumulation at the fiber surface. In contrast, the PU–PDA fibers demonstrated a homogeneous microstructure throughout the fibers. Tensile test results suggested a molecular orientation in the PU–PDA fibers that significantly improved the mechanical properties of the fibers. The presence of PDA in the matrix polymer reduced the overall strength and breaking elongation of both composite nanofibers in comparison to 100% PEO and PU fibers. A single PU–PDA fiber showed significantly higher stiffness and modulus than a single PEO–PDA fiber. Force–distance curve analysis suggested that the PU–PDA fibers exhibited an elastic deformation. In a comparison, the PEO–PDA fibers were brittle and showed low modulus. The results of structural and mechanical properties suggest that the PU–PDA nanofibers are a promising composite for developing nonadherent, durable, and flexible colorimetric biosensors used in medical textiles. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47877.

Electrostatic alignment of electrospun PEO fibers by the gap method increases individual fiber modulus in comparison to non-aligned fibers of similar diameter

Studies on the alignment, physical and mechanical properties of individual electrospun fibers provide insight to their formation, production and optimization. Here we measure the alignment, diameter and modulus of individual fibers formed using the electrostatic gap method. We find electrostatic alignment produces fibers with a smaller diameter than their nonaligned counterparts have. Therefore, due to the dependence of fiber modulus on diameter aligned fibers have a higher modulus. Furthermore, we show that aligned and nonaligned fibers of the similar diameter have different moduli. Aligned fibers have a modulus 1.5 to 2 times larger than nonaligned fibers of the similar diameter.

Electric field distribution and initial jet motion induced by spinneret configuration for molecular orientation in electrospun fibers

Understanding the molecular orientation of electrospun fibers is a key challenge for tailoring fiber properties. The studies of electric field distribution, and the motion of the initial portion of the polymer jet, are of interest for clarifying molecular orientation in fibers during electrospinning. In this work, we study the impact of electric field distribution and the initial jet motion induced by two kinds of spinneret configurations, referred to as a needle configuration and a hole configuration, on molecular orientation in electrospun PEO fibers. Using FE-SEM, FTIR and WAXD techniques, the fiber diameter and molecular orientation of the fibers prepared with the needle electrospinning system and the hole electrospinning system are characterized. To explore jet stretching and chain orientation during the spinning process, electric field simulation and high-speed photography are performed to obtain the electric field characteristics and to measure the initial jet velocities for the needle and the hole systems. Our results reveal the higher electric field strength around the spinneret and the larger initial jet velocities, which depend on the spinneret configuration, result in the higher degree of molecular orientation in fibers.

Raman spectroscopy of individual poly(ethylene oxide) electrospun fibers: Effect of the collector on molecular orientation

Electrospun fibers are complex polymeric materials with a typical diameter of a few hundred nanometers that are often frozen in out-of-equilibrium states due to the fast solvent evaporation and high elongational forces during the process. Their molecular orientation, and the parameters affecting it, is a critical (although challenging) parameter to characterize because it allows improving and tuning many properties. In this paper, we characterize molecular orientation of poly(ethylene oxide) (PEO) fibers produced with the three most common collectors by applying our recently developed Raman spectroscopy methodologies to probe individual fibers. Results reveal an extremely high orientation in all PEO fibers and, surprisingly, the absence of any effect of the collector on molecular orientation. This contrasts with reports by several other research groups in the context of studies on bundles of fibers, as well as with our WAXD results on the same fibers. It is concluded that studies on bundles composed of thousands of imperfectly aligned fibers lead to a systematic underestimation of the orientation and to apparent results that prevent us from drawing clear conclusions on the molecular impact of processing parameters when they generate different levels of macroscopic alignment. This work highlights how Raman spectroscopy helps to overcome one of the major challenges in the field, the characterization of individual fibers, to reach a better understanding and control of electrospun fibers properties.

Alignment and Diameter of Electrospun PEO Fibers

The method of electro-spinning fibers is useful, due to the extreme similarities to fibers in the body, and knowledge about electrospun fiber properties can be implemented in such research areas as tissue engineering, tissue scaffolding, and intracellular matrices. Here we report the alignment and diameter determination of PEO fibers following research by Liu and Dzenis (2008 Nanotechnology). We used a two-collector plate method to align fibers and examined the diameter and alignment of fibers formed from various percentages of PEO and working distances from tip to collector, holding the collector plate separation fixed. We found the greatest fiber alignment using a working distance of 40 cm from tip to collector. An 8% PEO in water solution with a working distance of 40 cm formed aligned fibers with an average angle of deviation from the alignment direction of 1.9 +/- 1.2 degrees and the narrowest distribution. The smallest angle and narrowest distribution of angles was also seen with a working distance of 40 cm using 6 % PEO in water. The diameter of electrospun PEO fibers showed a subtle non-significant increase in diameter as working distance increased from 20 cm to 40 cm. However, the diameter was significantly dependent on the PEO concentration with 8 % PEO producing fibers with diameters of 245 nm +/- 50 nm and 6 % PEO producing fibers with diameters of 181 nm +/- 40 nm.In the future we will use these result to compare the mechanical properties of individual aligned electrospun fibers with their nonaligned counterpart.