Reactive Dyeing of Electrospun Cellulose Nanofibers by Pad-steam Method

Based on the functional properties of electrospun cellulose nanofibers(CNF), scientists are showing substantial interest to enhance the aesthetic properties. However, the lower color yield has remained a big challenge due to the higher surface area of nanofibers. In this study, we attempted to improve the color yield properties of CNF by the pad-steam dyeing method. Neat CNF was obtained by deacetylation of electrospun cellulose acetate(CA) nanofibers. Three different kinds of reactive dyes were used and pad-steam dyeing parameters were optimized. SEM images revealed smooth morphology with an increase in the average diameter of nanofibers. FTIR results showed no change in the chemical structure after dyeing of CNF. Color fastness results demonstrated excellent ratings for reactive dyes, which indicate good dye fixation properties and no color loss during the washing process. The results confirm that the pad-steam dyeing method can be potentially considered to improve the aesthetic properties of CNF, which can be utilized for functional garments, such as breathable raincoats and disposable face masks.     

Synthesis of Poly（N-vinylpyrrolidone） Nanofibers Containing Gold Nanoparticles via Electrospinning Technique

Poly(N-vinylpyrrolidone)(PVP)nanofibers containing gold nanoparticles were prepared by electrospinning method.This simple route was used to prepare composites on a large scale,and the syntheses are simple.The optical property of gold nanoparticles in PVP aqueous solution was investigated by UV-Visible absorption spectra.The morphology of the fibers and the distribution of particles were characterized by transmission electron microscopy.The structure of the composite was characterized by Fourier transform infrared spectroscopy.     

Hydrothermal Synthesis of Ce-doped ZnO Heterojunction Supported on Carbon Nanofibers with High Visible Light Photocatalytic Activity

Ce/ZnO decorated carbon nanofibers(CNFs) heteroarchitectures(Ce/ZnO/CNFs) have been synthesized using electrospinning technique followed hydrothermal method, which have a high visible light photocatalytic activity. The samples were characterized by means of SEM, FTIR and XRD. The photocatalytic performance of Ce/ZnO/CNFs was tested with the methylene blue in the presence of visible light irradiation. In this work, we have analyzed the effects of Ce doping amount, initial methylene blue(MB) concentration and dosage of Ce/ZnO/CNFs on photocatalytic efficiency of the composite. The results showed that the photocatalyst containing 1.0% Ce in molarity(CZC1) obtained by autoclaving at 150℃ has the best photocatalytic degradation of MB than other as-synthesized samples. Ce/ZnO/CNFs catalysts exhibit a good stability and reusability, which would be an economical and environmentally friendly photocatalyst for various practical applications.     

Electrospun Polyaniline/Poly(ethylene oxide) Composite Nanofibers Based Gas Sensor

Camphor‐10‐sulfonic acid (HCSA) doped polyaniline (PANI)/poly(ethylene oxide) (PEO) composite nanofibers with different compositions (12 to 52 wt.% of PANI) were synthesized by an electrospinning method and their properties including optical, electrical and sensing were systematically investigated. FT‐IR shows that an increase of IR absorbance ratios of aromatic C? C stretching vibration of benzenoid rings of PANI to C? O? C symmetric vibrational modes of PEO confirmed that the PANI content in nanofiber mats increased proportionally with increase in PANI content in electrospinning solution. The band gap of PANI was determined to be 2.5 eV using UV‐Vis spectroscopy. The electrical conductivities of the nanofibers increased with an increase in the PANI content in the nanofibers. Additionally, the sensitivity toward NH₃ increased as the PANI content increased, but branched nanofibers reduced sensing response. The humidity sensitivity changed from positive to negative as the PANI content increased. The electron transport mechanism was studied by measuring the temperature dependence electrical resistivity. The negative temperature coefficient of resistance revealed a semiconducting behavior for the PANI/PEO nanofibers. The activation energy, calculated by Arrhenius plot, increased as the PANI content decreased. The power law indicated that electrons were being transported in a three dimensional matrix, and the longer hopping distance required more hopping energy for electron transport.     

Electrochemical Evaluation of Titanium (IV) Oxide/Polyacrylonitrile Electrospun Discharged Battery Coals as Supercapacitor Electrodes

The TiO₂ nanoparticles are electrospun with polyacrylonitrile (PAN) polymer solution onto the discharged battery coal (DBC) electrode and the results are evaluated as a supercapacitor. The morphology and chemical composition of the synthesized TiO₂ nanoparticles and PAN+TiO₂ nanocomposite fibers were characterized by Scanning electron microscopy, thermogravimetry and FTIR analysis. Supercapacitor measurements and electrochemical characterizations of the electrodes examined by cyclic voltammetry and electrochemical impedance spectroscopy. Electrochemical measurements showed that the best current value was obtained from PAN and TiO₂ coated DBC. The performances of both PAN and PAN+TiO₂ coated DBC electrodes were investigated as supercapacitors. PAN+TiO₂/DBC showed the best specific capacitance value of 156.00 F g⁻¹ and PAN/DBC showed 74.93 F g⁻¹. In addition, PAN+TiO₂/DBC exhibited reliable stability performance over 2000.00 cycles.     

红外光谱法研究LB膜中的分子取向

The structure information of orientation and packing of molecular chains can be obtained from infrared transmission and reflection-absorbance (RA) spectra. In the present paper, on the basis of Umemura et al., their FORTRAN program of minicomputer was developed and can be run on 486 personal computer. By comparison of infrared transmission and RA intensities, surface enhancement factors and molecular orientation angle were calculated using the above program, and the influence of complex refractive index, angle of incidence, and thickness of LB film were discussed. These results are consistent with that of Umemura et al.     

聚(ε-己内酯)薄膜结晶形貌及分子取向研究

用匀胶机通过溶液铸膜方法在硅片和铝箔基板上分别制备具有不同厚度的聚(ε-己内酯)(PCL)薄膜. 通过原子力显微镜(AFM)和偏光衰减全反射傅里叶红外光谱(ATR-FTIR)对薄膜中PCL的结晶形貌、 片晶生长方式及分子链取向进行了研究. AFM结果表明, 在200 nm或更厚的薄膜中, PCL主要以侧立(edge-on)片晶的方式生长; 对于厚度小于200 nm的薄膜, PCL片晶更倾向于以平躺(flat-on)的方式生长. 这种片晶生长方式的改变在硅片和铝箔基板上都表现出同样的倾向. 此外, 在15 nm或更薄的薄膜中, PCL结晶由通常的球晶结构变为树枝状晶体. 偏光ATR-FTIR结果表明, 当膜厚小于200 nm时, 薄膜结晶中PCL分子链沿垂直于基板表面方向取向, 并且膜越薄, 取向程度越高, 与AFM的观测结果一致.     

Molecular Orientation and Structural Characterization of Ultrathin Films of C12AzoNaph(1,4)C6N-SDS Studied by FT-IR and NIR-SERS Spectroscopies

IntroductionAzobenzene- containing long- chain fatty acidsand their ammonium amphiphiles have recentlyaroused a great interest of some researchersbecause of their promising photochromicproperties[1— 6 ] . In order to understand theinteresting physical properties the LB films withazo chromophores show,a structure- functionrelationship of the films must be explored.Thusfar,infrared spectroscopy has been usedextensively for the investigations of molecularaggregation,orientation and structuralch…     

Effect of Gate Electric Field on Single Organic Molecular Devices (cited: 3)

Based on the first-principles computational method and elastic scattering Green's function theory, we have investigated the effect of gate electric field on electronic transport properties of a series of single organic molecular junctions theoretically. The numerical results show that the molecular junctions that have redox centers and relatively large dipole moments parallel gate direction can respond to the gate electric field remarkably. The current-voltage properties of 2,5-dimethyl-thiophene-dithiol present N-channel-metal-oxide-semiconductor-like characteristics. Its distinct current-voltage properties can be understood from the evo-lution of eigenvalues, coupling energies, and atomic charges with gate electric field.     

Electrospun Mesoporous Poly(Styrene‐Block‐Methyl‐ Methacrylate) Nanofibers as Biosensing Platform: Effect of Fibers Porosity on Sensitivity

The present work demonstrates the use of mesoporous nanofibers for the enhanced analytical performance of electrochemical biosensor. By exploiting the phase separation property of the block copolymers, a simple three‐step process was used to generate the porosity in the nanofibers. Here we present the effect of the porosity on the sensing ability of the electrospun PS‐b‐PMMA nanofibers. The functional groups present on the nanofiber surface were characterized using DPV. The nanofibers modified electrode showed a large decrease in the oxidation current with the increase in the pH from 4.2 to 6.8 for the anionic redox couple whereas the change in the current is negligible for a neutral redox couple, this suggested the presence of ‐COOH groups. A one‐step process was used for the immobilization of biotin. There were about 35.5 % and 66.6 % decrease in the redox current for the as‐spun and porous nanofibers after functionalization respectively which indicate the presence of a high amount of active sites in the porous nanofibers. Finally, the sensor response was studied using streptavidin (1μg/ml–1fg/ml) as a model analyte. CV studies showed a 2.7‐fold increase whereas DPV showed a 6‐fold increase in the sensitivity for the porous nanofibers as compared to the as‐spun nanofibers.     

Molecular Imprinting Fibrous Membranes of Poly（ acrylonitrile-co-acrylic acid） Prepared by Electrospinning

Introduction Overthepastfewdecades,molecularimprinting hasbeendescribedasatechnologyforpreparing“mo leculardoors”whichcanbematchedto“template keys”.Ithasbeenfoundtobeasimpleandeffective approachtointroducespecificrecognitionsitesintosyn theticpolymers…     

Enhanced Mechanical Properties of Poly(arylene sulfide sulfone)Membrane by Co-electrospinning with Poly(m-xylene adipamide)

The mechanical properties of poly(arylene sulfide sulfone)(PASS) electrospun membrane were significantly enhanced by coelectrospinning with semi-aromatic nylon poly(m-xylene adipamide)(MXD6), another engineering plastic with high thermal stability and good mechanical properties. The tensile strength of PASS membrane increased with increased incorporation of MXD6, and was tripled when 20%MXD6 was incorporated. The mechanism of the mechanical property improvement is the existence of hydrogen bonding interaction between PASS and MXD6 and between adjacent fibers at the intersections. Thermal properties of the PASS/MXD6 membranes were evaluated by differential scanning calorimetry(DSC) and thermogravimetric analysis(TGA), which showed that the membranes could be stably utilized up to180 °C without any change in appearance and without decomposition. Contact angle measurements of all the membranes showed hydrophobic character. To demonstrate the potential applications of PASS/MXD6 blend membranes, their oil absorption capacities were evaluated with three oils of different viscosities, which proved that the PASS/MXD6 membranes are better absorbents than commercial non-woven polypropylene fibers. Therefore, PASS/MXD6 fibrous membranes produced by electrospinning have a great potential in practical applications.     

Aligned Poly(ε‐caprolactone) Nanofibers Guide the Orientation and Migration of Human Pluripotent Stem Cell‐Derived Neurons,Astrocytes, and Oligodendrocyte Precursor Cells In Vitro

Stem cell transplantations for spinal cord injury (SCI) have been studied extensively for the past decade in order to replace the damaged tissue with human pluripotent stem cell (hPSC)‐derived neural cells. Transplanted cells may, however, benefit from supporting and guiding structures or scaffolds in order to remain viable and integrate into the host tissue. Biomaterials can be used as supporting scaffolds, as they mimic the characteristics of the natural cellular environment. In this study, hPSC‐derived neurons, astrocytes, and oligodendrocyte precursor cells (OPCs) are cultured on aligned poly(ε‐caprolactone) nanofiber platforms, which guide cell orientation to resemble that of spinal cord in vivo. All cell types are shown to efficiently spread over the nanofiber platform and orient according to the fiber alignment. Human neurons and astrocytes require extracellular matrix molecule coating for the nanofibers, but OPCs grow on nanofibers without additional treatment. Furthermore, the nanofiber platform is combined with a 3D hydrogel scaffold with controlled thickness, and nanofiber‐mediated orientation of hPSC‐derived neurons is also demonstrated in a 3D environment. In this work, clinically relevant materials and substrates for nanofibers, fiber coatings, and hydrogel scaffolds are used and combined with cells suitable for developing functional cell grafts for SCI repair.

     

红外光谱结合线阵列检测技术研究聚合物分散液晶膜分子取向

采用偏振红外光谱和变温红外光谱研究聚合物分散液晶膜中液晶分子取向随外加电场及温度的变化.利用线阵列检测技术表征了聚合物与液晶界面处的成分分布.结果表明,线阵列检测技术能够快速而直观地给出成分分布图,通过该成分分布图可以解释PDLC在温度场作用下分子取向的变化.     

Single DNA Condensation Induced by Hexammine Cobalt with Molecular Combing

We investigated the interaction between DNA and hexammine cobalt III [Co(NH₃)₆]³⁺ by a simple molecular combing method and dynamic light scattering. The average extension of ?λ-DNA-YOYO-1 complex is found to be 20.9 μm, about 30% longer than the contour length of the DNA in TE buffer (10 mmol/L Tris, 1 mmol/L EDTA, pH=8.0), due to bis-intercalation of YOYO-1. A multivalent cation, hexammine cobalt, is used for DNA condensation. We find that the length of DNA-[Co(NH₃)₆]³⁺ complexes decrease from 20.9 μm to 5.9 μm as the concentration of the [Co(NH₃)₆]³⁺ vary from 0 to 3 μmol/L. This observation provides a direct visualization of single DNA condensation induced by hexammine cobalt. The results from the molecular combing studies are supported by dynamic light scattering investigation, where the average hydrodynamic radius of the DNA complex decreases from 203.8 nm to 39.26 nm under the same conditions. It shows that the molecular combing method is feasible for quantitative conformation characterization of single bio-macromolecules.     

液晶离聚物--分子设计与热性能

综述了液晶离聚物的分子设计与液晶热性能的关系,一般主链液晶,离子在链中浓度增加,玻璃化温度（Ｔｇ）和熔点（Ｔｍ）下降,离子在端基,对Ｔｇ和Ｔｍ影响不大;离子对侧链淮晶的影响,取决于主链的柔顺性和离子在链中的位置等。一般情况下,无论对主链还是侧链液晶离聚物,随着离子在链中浓度增加,液晶相向各向同性液体转化温度（Ｔｉ）降低。     

Improved mechanical property and biocompatibility of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) for blood vessel tissue engineering by blending with poly(propylene carbonate)

Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx) and poly(propylene carbonate) (PPC) were blended by solvent casting method into films at various weight ratios in order to obtain materials with properties more suitable for blood vessel tissue engineering than pure PHBHHx alone. FTIR and XRD analysis indicated the crystal structure of PHBHHx was not altered but the crystallinity was reduced by the interfusion of PPC. Mechanical properties of the films were improved significantly by blending with PPC. A lower elastic modulus and a higher elongation at break were obtained with the increase of PPC content. Wettability, fibronectin adsorption and adhesion of rabbit aorta smooth muscle cells (RaSMCs) on blend films were similar to or better than that on PHBHHx film. All these results showed promises of PHBHHx/PPC blended materials as scaffold material for blood vessel tissue engineering.     

Molecular Size and Morphology of Single Chains of Poly(sulfobetaine methacrylate)

The effects of the concentration of sodium chloride in an aqueous solution(c_NaCl) and the temperature on the molecular size of poly(sulfobetaine methacrylate)(PSBMA) were studied via viscometry and dynamic light scattering(DLS). The morphology of single-chain PSBMA was determined by atomic force microscopy(AFM). The results demonstrate that the hydrodynamic diameter of PSBMA can be expressed as a continuous function of c_NaCl, with the molecular size of PSBMA increasing and eventually approaching an asymptotic value with increasing c_NaCl. The molecular size of PSBMA at a lower c_NaCl(0.04 mol/L) increases with increasing temperature, which is the opposite of the temperature effect at a higher c_NaCl(2.0 mol/L). Therefore, the internal structure of PSBMA chains in solutions with a low salt concentration differs from that in solutions with a high salt concentration. In addition, the morphology of single chains of PSBMA appears to be spherical, containing 89% void space, and the apparent size of the dried chains is almost identical to that in solution.     

Electrospun poly(l‐lactide) nanofibers coated with mineral trioxide aggregate enhance odontogenic differentiation of dental pulp stem cells

A combination of bioceramics and nanofibrous scaffolds holds promising potential for inducing of mineralization in connective tissues. The aim of the present study was to investigate the attachment, proliferation and odontogenic differentiation of dental pulp stem cells (DPSC) on poly(l ‐lactide) (PLLA) nanofibers coated with mineral trioxide aggregate (MTA). Polymeric scaffolds were fabricated via the electrospinning method and their surface was coated with MTA. DPSC were isolated from dental pulp and their biological behavior was evaluated on scaffolds and the control group using MTT assay. Alkaline phosphatase (ALP) activity, biomineralization and the expression of odontogenic genes were analyzed during odontogenic differentiation. Isolated DPSC showed spindle‐shaped morphology with multi‐lineage differentiation potential and were positive for CD73, CD90 and CD105. MTA‐coated PLLA (PLLA/MTA) exhibited nanofibrous structure with average fiber diameter of 756 ± 157 nm and interconnected pores and also suitable mechanical properties. Similar to MTA, these scaffolds were shown to be biocompatible and to support the attachment and proliferation of DPSC. ALP activity transiently peaked on day 14 and was significantly higher in PLLA/MTA scaffolds than in the control groups. In addition, increasing biomineralization was observed in all groups with a higher amount in PLLA/MTA. Odontogenic‐related genes, DSPP and collagen type I showed a higher expression in PLLA/MTA on days 21 and 14, respectively. Taken together, MTA/PLLA electrospun nanofibers enhanced the odontogenic differentiation of DPSC and showed the desired characteristics of a pulp capping material.     

Electrospun microfibrous poly(styrene-alt-maleic anhydride)/poly(styrene-co-maleic anhydride) mats tailored for enzymatic remediation of waters polluted by endocrine disruptors

Novel bicomponent microfibrous mats containing targeted amount of reactive maleic anhydride groups were prepared by electrospinning of mixed solutions of poly(styrene-alt-maleic anhydride) and poly(styrene-co-maleic anhydride). Then, amino-functionalized P(St-alt-MA)/P(St-co-MA) mats were obtained by reaction with p-phenylenediamine. ATR-FTIR and XPS spectroscopy were used to characterize pristine and modified P(St-alt-MA)/P(St-co-MA) mats. On the next step, laccase from Trametes versicolor was covalently attached onto the modified mats; the average amount of immobilized enzyme was 40 ± 0.7 mg/g mat. The catalytic activity of the immobilized enzyme was studied in respect to bisphenol A (BPA) endocrine disruptor. The optimum activity of the immobilized enzyme was reached at maximum flow rate of 1.3 mL/s. After 90 min the BPA concentration was reduced by 60% and the catalytic activity of microfibrous mats remained stable for about 30 successive reuses. In addition, the relative activity of laccase immobilized on the microfibrous mats was displayed in a broader pH range as compared to that of the free one.