Nanofibrous wound dressing material by electrospinning method

Abstract

Wound dressings are very useful materials for accelerating the wound healing process. In this study, nanofibrous wound dressings were produced from blending solution of Poly-lactic acid(PLA)/Chitosan(C)/Starch(S)/Zinc oxide(Z) by electrospinning method. Morphology, chemical interaction, mechanical, water uptake and weight loss tests were performed on each samples. Moreover, the biocompatibility of primary dermal fibroblast (ATCC, PCS-201-012) on prepared wound dressings was investigated with MTT assays in vitro, and the samples were found suitable for cell viability and proliferation. These results suggest that produced nanofibrous wound dressings can be promising candidate for wound dressing applications.     

新型环境友好型热塑材料聚羟基烷酸的研究进展

在对聚羟基烷酸（PHAs）的结构和性质介绍的基础上,从实际工业应用的角度综述了国内外近年有关它的生物合成、提取及应用中取得的成果与存在的问题,展望了这一新材料的发展趋势与应用前景。     

利用有机废水生产聚羟基烷酸(PHAs)的进展

聚羟基烷酸（PHAs,polyhydroxyalkanoates）是由微生物经β-羟基烷酸聚合而成的一类高分子化合物的总称,它具有优良的生物可溶性、生物可降解性、光学活性、压电性等品质。本文综述了近年来利用有机废水生产PHAs的研究进展。     

Polylactide (PLA)-Based Electrospun Fibrous Materials Containing Ionic Drugs as Wound Dressing Materials: A Review

The effect of the electrospinning process parameters on the morphology, alignment, and self-organization of the fibers into bundles and/or yarns are outlined. The fabrication of polylactide materials containing ionic drugs by electrospinning is emphasized. The main approaches used for the preparation of electrospun drug-loaded materials: electrospinning of a mixed solution containing the polymer(s) and the drug(s) or dual spinneret electrospinning of separate drug-containing solutions are compared. The latter approach allows the obtaining of drug-loaded fibrous materials while avoiding the drug interaction. The potential application of the obtained materials containing ionic drugs as wound dressings is outlined.     

A facile method to prepare ZrC nanofibers by electrospinning and pyrolysis of polymeric precursors

Zirconium carbide (ZrC) is one of the most attractive ultra-high temperature ceramics due to its excellent properties. ZrC nanofibers were fabricated via electrospinning and pyrolysis of a novel polymeric precursor, Polyzirconosaal (PZSA), with the addition of polyvinylpyrrolidone (PVP) as the spinning aid. The polymer PZSA was prepared from the chemical reaction between Polyzirconoxane (PZO) and Salicyl alcohol. The as-spun PZSA/PVP fibers were converted to ZrC nanofibers with a diameter ~200 nm after carbothermal reduction at 1300 °C in argon. The obtained ZrC nanofibers maintained its excellent fibrous morphology. The microstructures exhibited that nanoscale ZrC particles dispersed in the fibers containing free carbon. The average crystallite size of ZrC particles using Scherrer method was 42 nm. The obtained ZrC nanofibers were characterized by XRD, SEM and TEM. The current material would be particularly useful for applications such as catalyst support, filters, gas storage, supercapacitors, and phase change material support in thermal management systems.     

Chemical characterization of medium‐chain‐length polyhydroxyalkanoates (PHAs) recovered by enzymatic treatment and ultrafiltration

BACKGROUND: Medium‐chain‐length polyhydroxyalkanoates (PHAs) are biodegradable polyesters accumulated intracellularly as energy resources by bacterial species such as Pseudomonas putida. The most popular method for PHA recovery is solvent extraction using trichloromethane (chloroform) and methyl alcohol (methanol). An alternative method is enzymatic treatment, which eliminates usage of these hazardous solvents. This research focuses on the characterization of PHAs recovered by enzymatic treatments and ultrafiltration. Comparisons are made with conventional solvent extracted PHA. RESULTS: The purity of PHA in water suspension recovered by enzymatic treatments as analyzed by gas chromatography was 92.6%. Enzymatically recovered PHA was comparable to conventional solvent‐extracted PHA, which had a purity of 95.5%. PHA was further characterized for functional group analysis, structural composition analysis and molecular weight determination. It was found that the molecular weight of the PHA recovered by enzymatic treatment was less than solvent‐extracted PHA, probably due to degradation of the lipopolysaccharide layer. However, functional group and structural composition analyses showed similar results for PHA recovered by both methods. CONCLUSION: PHAs recovered through enzymatic digestion treatment have good comparability with solvent‐extracted PHAs. Thus enzymatic digestion has great potential as an alternative recovery method. Copyright © 2007 Society of Chemical Industry     

Preparation of photochromic poly(vinylidene fluoride-co-hexafluoropropylene) fibers by electrospinning

Photochromic poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-co-HFP) fibers were prepared by electrospinning from a solution of copolymer and ester-functionalized nitrospiropyran (SPEST) molecules. The surface and internal features of the electrospun (ES) fibers were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and wide-angle X-ray diffraction (WAXD). The strong segregation of fluorine-rich groups on the fiber surface, which occurs during and/or after the electrospinning process, is driven by the lower surface tension for fluorine-rich groups and leads to encapsulation of SPEST predominantly near the core of the fibers, as confirmed by both X-ray photoelectron spectroscopy (XPS) and dynamic water contact angle (CA) measurements. The photochromic behavior of the spiropyran is preserved in the polymeric fibers, as confirmed by steady-state absorption and emission spectroscopy. Both isomeric forms of the photochrome in SP-PVDF-co-HFP were emissive, an effect that is thought to be due to the steric and/or electrostatic restrictions on the ring-opening reaction imposed by the fiber.     

静电纺丝制备生物医用敷料研究进展

介绍了静电纺丝的原理以及静电纺丝纤维膜作为医用敷料的优点;综述了国内外静电纺丝制备医用敷料的研究进展,包括用于体外创伤护理、皮肤再生和具有定向药物释放功能的静电纺丝医用敷料。指出静电纺丝纳米纤维医用敷料作为一种高科技的功能性敷料,具有良好的发展前景。     

Helical peanut-shaped poly(vinyl pyrrolidone) ribbons generated by electrospinning

This paper describes the preparation and understanding of helical peanut-shaped ribbons of poly(vinyl pyrrolidone) (PVP) by a magnetic field-assisted electrospinning method. The relative humidity is found to significantly influence the morphology of PVP fibers. The morphology changed from straight rods to helical ribbons as relative humidity decreased. The percentage of helical ribbons increased dramatically as well. At the same time, the cross-section of electrospun fibers changed from circle, to ellipse, and to peanut shape. Formation of helical ribbons is attributed to the synergistic interaction of bending instability and rigidity of the polymers during the electrospinning process. These fibers had different mechanical properties and the helical ribbons were shown to have the largest ultimate elongation.     

Fluorescent core-sheath fibers by electrospinning of a phenyleneethynylene/poly(styrene-co-maleimide) blend

Ultrafine fluorescent fibers were prepared by electrospinning of a phenyleneethynylene oligomer mixed in DMF with a poly(styrene-co-maleimide) (PSM). The microscopic characterization by SEM reveals that the fibers are smooth and entangled one to the others forming a non-woven mat with an average diameter of 490 nm. By TEM, a core-sheath type structure is observed which derives from phase segregation between the PSM interacting with the oligomer and the excess of PSM that acts as matrix, as supported by XRD and DSC analysis. The membranes are fluorescent emitting at 420 nm, in the blue region, a high energy light, opening the possibility of their application in optoelectronic devices such as fluorescent sensors. Preliminary assays have been performed for the detection of sodium ions.     

In_2O_3纳米陶瓷纤维无纺布的静电纺丝制备及气敏特性研究

采用溶胶-凝胶法结合静电纺丝技术制备了直径20~60 nm的超细氧化铟(In2O3)纳米陶瓷纤维及纳米陶瓷纤维无纺布。采用XRD,IR,SEM,HR-TEM,TGA等分析方法对纳米纤维的形貌和显微结构进行了表征,并研究了其气敏特性。由700℃下煅烧的该超细In2O3纳米纤维所制备的气敏元件具有较好的反应和选择性,对甲醛气体表现出较快的响应和恢复速度。     

Synthesis, characterization, and electrospinning of zwitterionic poly(sulfobetaine methacrylate)

Poly(sulfobetaine methacrylate) (PSBMA) can be potentially utilized in filtration and wound dressing applications for which nanofibers structures are highly desirable. In this work, a series of PSBMAs with different molecular weights were synthesized, characterized, and electrospun into nanofibers. The polymer molecular weight was controlled by varying the amount of redox initiators in the free radical polymerization of SBMA, with the highest molecular weight achieved at an intermediate initiator concentration. From the intrinsic viscosity measurements, the Mark-Houwink parameters for PSBMA (at 21 °C in 0.2 M NaCl solution) was determined as a = 0.4071 and k = 2.06 × 10⁻³. Thermogravimetric (TGA) analysis shows that the PSBMAs were thermally stable up to at least 250 °C. Fourier transform infrared (FTIR) spectra indicate major structural changes of both polymer backbone and pendant groups by thermal degradation. Results from differential scanning calorimetry (DSC), TGA, and FTIR characterizations all demonstrate the existence of water strongly bound in PSBMA. DSC analysis also indicates different degrees of crystallinity for the PSBMAs of different sizes. Viscosity of the PSBMA solutions, a critical parameter for electrospinning, increased with the solution concentration and the polymer molecular weight. For the electrospinning of PSBMA, it was found that high solution concentration and high molecular weight favored the formation of smooth fibers while low solution concentration or low molecular weight led to the formation of beaded fibers or beads. Fiber diameters ranging from 200 to 570 nm were achieved by controlling solution concentration and polymer molecular weight. The characterization data and electrospinning results were finally correlated to explore the relationships between fiber formation, viscosity, molecular weight, and concentration.     

Stability and phase behavior of the poly(ethylene oxide)-urea complexes prepared by electrospinning

The poly(ethylene oxide)-urea binary system forms a stable (α) complex that can be melt-quenched into a mixture of urea and a second (β) complex with a different stoichiometry. Our results confirm that this mixture is metastable, but that the β-α solid-solid transition is much slower than previously reported. In contrast with the melt-quenched mixture, we observe for the first time that the pure β complex, prepared by electrospinning, is thermodynamically stable up to its melting temperature. This melting is incongruent and leads to the formation of the crystalline α complex and liquid PEO. A phase diagram is drawn over the complete composition range and allows interpreting the formation of the various out-of-equilibrium mixtures observed experimentally. This work also demonstrates an interesting new possibility of electrospinning: the direct preparation of thermodynamically stable compounds that are otherwise inaccessible because of the formation of kinetically frozen products.     

静电纺丝制备中空纳米纤维/纳米管研究进展

介绍了静电纺丝的制备原理和制备中空纳米纤维/纳米管的方法,简述了静电纺丝制备中空纳米纤维/纳米管的影响因素;对目前静电纺丝制备中空纳米纤维/纳米管的研究进展情况进行阐述,并对其在光催化、传感器和电池方面的应用加以介绍。     

Ultra-fine polyelectrolyte fibers from electrospinning of poly(acrylic acid)

Ultra-fine polyelectrolyte fibers have been generated from electrospinning of poly(acrylic acid) in aqueous and DMF solutions. The fiber diameters ranged from 80 to 500 nm and increased with increasing solution concentrations and electrospinning voltages. The fibers generated from the aqueous solutions were more homogeneous in sizes, especially when NaCl or NaOH was added. Higher voltages in electrospinning of the aqueous solutions also resulted in fibers with larger heat capacity in the glass transition region, and higher dehydration temperatures. These polyelectrolyte fibers could be rendered water-insoluble by incorporating β-cyclodextrin (at 20 wt% of PAA) in the aqueous solution, then heat-induced crosslinking was performed at 140 °C for 20 min. The resulting hydrogel fibers showed strongly pH-responsive swelling behaviors.     

Preparation and characterization of polyketone (PK) fibrous membrane via electrospinning

In this study, the aliphatic polyketone (PK) fibrous membrane was successfully prepared from the solution by electrospinning process at room temperature. As solvents for PK polymer, the mixed solvents of trifluoroacetic acid (TFA) and dichloromethane (MC) were used. Electrospun PK fibrous membrane was characterized by scanning electron microscope (SEM), wide angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC), Fourier transform infrared spectrophotometer (FT-IR), and Raman spectroscopy, and compared to the corresponding cast PK film. The crystal structures of electrospun PK fiber and solvent cast PK film were characterized by WAXD. The result indicated that the crystal structure of cast PK film was assigned to α-form, while the crystal structure of PK fibrous membrane corresponded to β-form, which was attributed to fast crystallization during electrospinning process. Accordingly, the crystallinity of electrospun PK fibrous membrane was lower than that of solvent cast PK film. To confirm further these crystalline structures, FT-IR and Raman spectroscopy were employed.     

Thermal and structural characterization of nanofibers of poly(vinyl alcohol) produced by electrospinning

Poly(vinyl alcohol) (PVOH) was obtained from the alkaline hydrolysis of poly(vinyl acetate) (PVAc). Nonwoven membranes (mats) of PVOH nanofibers were produced by electrospinning of solutions of PVOH in water with and without aluminum chloride. The concentration of the PVOH/water solution was 12.4% w/v. The morphology of the mats was analyzed by scanning electron microscopy (SEM). The thermal properties and the degree of crystallinity of the nanofibers were measured by differential scanning calorimetry (DSC); the crystal structure of the mats was evaluated by wide‐angle X‐ray diffraction. The best nanofibers were obtained by electrospinning the PVOH/water solution with aluminum chloride (45% w/v) in which an electrical field of 3.0 kV/cm was applied. It was observed that the addition of the aluminum chloride and the increase in the applied electrical field decreased the number‐average nanofibers diameters. The mats without aluminum chloride had higher melting temperatures and higher degrees of crystallinity than the mats with the salt. The crystal structure of the mats was found to be monoclinic; however, the mats were neither highly oriented nor have a high degree of crystallinity. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Characterization of nano-structured poly(ε-caprolactone) nonwoven mats via electrospinning

Nano-structured poly(ε-caprolactone) (PCL) nonwoven mats were prepared by electrospinning process. In this study, three types of solution were used. One dissolved in only methylene chloride (MC), the second dissolved in mixture of MC and N,N-dimethylformamide (DMF), the third dissolved in mixture of MC and toluene. MC, toluene and DMF are a good, poor, and nonsolvent for PCL, respectively. For the MC only, electrospun fibers had very regular diameter of about 5500 nm, but electrospinng is not facilitated. For the mixture of MC and DMF, electrospinning is certainly enhanced as well as fiber diameter decreased dramatically as increasing DMF volume fraction. It was due to high electric properties of solution such as dielectric constant and conductivity. Whereas, as increasing toluene volume fraction, electrospinning is strictly restricted due to very high viscosity and low conductivity. As the results, it has regarded that solution properties is one of the important parameter in electrospinning. Properties such as conductivity, surface tension, viscosity and dielectric constant of the PCL solutions prepared from three types of solvent system were studied. The morphology, crystallinity and mechanical properties of electrospun PCL nonwoven mats were characterized by scanning electron microscopy (SEM), wide angle X-ray diffraction (WAXD) and universal testing method (UTM), respectively.     

Corona discharge from electrospinning jet of poly(ethylene oxide) solution

Corona discharges from electrospinning jets were observed and photographed at the tip of the Taylor cone, and in a cylindrical region around the jet, a few millimeters below the tip. The corona discharge was also faintly visible to a dark adapted eye. At the position at which the cylindrical corona discharge became apparent, typical conditions were a jet diameter of 30 μm, an applied potential of 12 kV, and a calculated radial electric field of 400 kV/cm, The calculated electric field required to create a corona in air around a metal wire of the same diameter, calculated from Peek's empirical formula, was only about 200 kV/cm. The cross sectional shape of some segments of the electrospun fibers had two or three lobes. The lobes often separated, and formed smaller fibers.     

One-step fabrication of branched poly(vinyl alcohol) nanofibers by magnetic coaxial electrospinning

Branching has been emerging in 3-D interconnecting building blocks. Branched and hyperbranched poly(vinyl alcohol) (PVA) nanofibers were fabricated by coaxially electrospinning two-liquids under an alternating magnetic field in a facile manner. Both the PVA nanofiber trunks with diameter of 100–200 nm and the PVA nanofiber branches with diameter of 10–30 nm were formed in a single step. The length and the morphology of the branched PVA nanofibers could be controlled through a rational design of the magnetic field. The facile technique may readily be extended to prepare 3-D branched nanofibers from other materials such as various polymers and polymer–ceramic materials. Moreover, the multifunctional and multicomponent materials with branched nanostructure could be expected by using the magnetic coaxial electrospinning technique. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012