Study on the properties of the electrospun silk fibroin/gelatin blend nanofibers for scaffolds

Silk fibroin (SF)/gelatin blend nanofibers membranes as scaffolds were fabricated successfully via electrospinning with different composition ratios in formic acid. The formation of intermolecular hydrogen bonds and the conformational transition of SF provided scaffolds with excellent mechanical properties. FTIR and DTA analysis showed the SF/gelatin nanofibers had more β‐sheet structures than the pure SF nanofibers. The former's breaking tenacity increased from 0.95 up to 1.60 MPa, strain at break was 7.6%, average fiber diameter was 89.2 nm, porosity was 87%, and pore diameter was 142 nm. MTT, H&E stain, and SEM results showed that the adhesion, spreading, and proliferation of human umbilic vein endothelium cells (HUVECs) and mouse fibroblasts on the SF/gelatin nanofibers scaffolds were definitely better than that on the SF nanofibers scaffolds. The scaffolds could replace the natural ECM proteins, support long‐term cell growth, form three‐dimensional networks of the nanofibrous structure, and grow in the direction of fiber orientation. Our results prove that the addition of gelatin improved the mechanical and biological properties of the pure SF nanofibers, these SF/gelatin blend nanofiber membranes are desirable for the scaffolds and may be a good candidate for blood vessel engineering scaffolds. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Thermal stability of the immobilization process of horseradish peroxidase in electrospun polymeric nanofibers

The horseradish peroxidase enzyme (type VI 250 U mg^?1) was encapsulated in polymeric nanofibers using the electrospinning technique and successfully immobilized by the exposure to glutaraldehyde (GA) vapor in order to create covalent bonds between the polyivinilalcohol (PVA) polymeric chains and the enzyme molecules. The morphology of the nanofibers was analyzed by scanning electron microscopy (SEM) showing a diameter in the range of 100–200 nm. The presence of the enzyme in the electrospun nanofibers was confirmed by infrared spectroscopy (FTIR). The optimum crosslinking time was 1 h of exposure to GA vapor. The maximum percentage of the retained protein and the enzyme activity was obtained using the lowest initial enzyme concentration. The enzyme activity of the sample was retained after four reuse cycles. Differential scanning calorimetry (DSC) was used to study the thermal stability of the samples. The thermal study of the immobilized HRP enzyme provide for the first time additional information regarding the interaction of the HRP enzyme molecules with the PVA chains of the nanofiber matrix, as well as the effect of the crosslinking time in the glass transition temperature and the heat of fusion of the samples. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 44811.     

Polyvinylpyrrolidone electrospun nanofibers doped with Eu3+: Fabrication,characterization, and application in gas sensors

Polymer nanofibers (NFs)-based optical sensors hold great potential to fabricate low-cost devices capable to monitor different volatile organic compounds (VOCs) related to healthcare and environmental conditions. For instance, ammonia detection is a subject of paramount importance, owing to the serious health problems associated to the exposition to this volatile. In this context, here, we report on the development of optical electrospun NFs composed of polyvinylpyrrolidone (PVP) doped with Europium (Eu³⁺) aiming at the detection of ammonia. The fabricated NFs were characterized by scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, fluorescence microscopy, photoluminescence, and excited state lifetime spectroscopies. The luminescence properties changes were evaluated by exposing the PVP_Eu³⁺ NFs to ammonia and other distinct interfering VOCs including toluene, tetrahydrofuran, acetone, triethylamine, acetic acid, and chloroform. The sensor exhibited a linear response to ammonia exposition in the concentration range from 0 to 50 ppm, yielding a detection limit of 4.7 ppm. Our results indicate the potential application of PVP_Eu³⁺ electrospun NFs in optical sensors for ammonia detection at room temperature based on luminescence quenching. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47775.     

Novel electrospun nanofibers incorporating polymeric prodrugs of ketoprofen: Preparation,characterization, and in vitro sustained release

A facile and efficient protocol for the preparation of nanofibers incorporating polymeric ketoprofen prodrugs and polyvinylpyrrolidone was developed. Polymeric ketoprofen prodrugs were constructed by a two‐step chemo‐enzymatic synthetic route, and nanofibers prepared by electrospinning from dimethylformamide/ethanol (1 : 1, v/v) solutions. The morphological characteristics of the fibers were influenced by the concentration of active agent in the spinning solution; average diameters varied from 196 to 370 nm. In vitro release studies indicated that the ketoprofen release rate from the electrospun fibers was significantly higher than that from the pure polymeric prodrugs. Cumulative drug release from the electrospun fibers reached 40–70% after 3 h and 75–100% after 12 h, while the pure polymeric prodrug released only 7–9% of the active agent over 12 h. Functional nanofibers incorporating polymeric prodrugs therefore comprise potentially effective drug delivery systems for sustained release. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 1570–1577, 2013     

Recent advances in mechanism,influencing parameters,and dopants of electrospun EMI shielding composites: A review

The rapid development and popularization of smart and portable electronic devices have led to increasingly related electromagnetic pollution affecting human health and equipment safety. Thus, designing high-performance electromagnetic interference (EMI) shielding materials with lightweight, flexible, and easy preparation is urgent. The intrinsic physiochemical properties of electrospun micro/nanofibers provide an attractive potential to ease and accelerate the next-generation EMI shielding materials. Here, a detailed review of the electrospun EMI shielding materials is established. First, this article outlines the shielding mechanism of EMI shielding materials obtained via electrospinning. Then, the affecting factors of electrospinning process conditions on the resulting EMI shielding micro/nanofibers are discussed. Next, diverse fillers that contribute to the EMI shielding efficiency of electrospun materials are demonstrated. Finally, the conclusion and prospects are introduced, hopefully contributing to assisting with more comprehensive and rational designs of high-performance electrospun fiber-based EMI shielding for various applications. Priority measures and future directions are suggested for the future development of electrospun EMI shielding materials.     

Self synthesize of silver nanoparticles in/on polyurethane nanofibers: Nano‐biotechnological approach

In this study, we are introducing a new class of Polyurethane (PU) nanofibers containing silver nanoparticles (NPs) by electrospinning. A simple method not depending on the addition of foreign chemicals has been used to self‐synthesize of silver NPs in/on PU nanofibers. Typically, a sol?gel consisting of AgNO₃/PU/N,N‐dimethylformamide (DMF) has been electrospun and aged for a week, so silver NPs have been created in/on PU nanofibers. Syntheses of silver NPs were carried out by exploiting the reduction ability of the DMF solvent which is the main constituent to obtain PU electrospun nanofibers in decomposition of silver nitrate precursor into silver NPs. Physiochemical characterizations confirmed well oriented nanofibers and good dispersing of pure silver NPs. Various parameters affecting utilizing of the prepared nanofibers on various nano‐biotechnological fields have been studied. For instance, the obtained nanofiber mats were checked for mechanical properties which showed the improvement of the tensile strength upon increase in silver NPs content. Moreover, the nanofibers were subjected to 10 times successive washing experiments with using solid to liquid ratio of 3 : 5000 for 25 h, UV spectroscopy analysis reveals no losses of silver NPs from the PU nanofibers. 3T3‐L1 fibroblasts were cultured in presence of the designed nanofibers. The morphological features of the cells attached on nanofibers were examined by BIO‐SEM, which showed well attachment of cells to fibrous mats. The cytotoxicity results indicated absence of toxic effect on the 3T3‐L1 cells after cell culturing. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Correlation between polymer architecture, mesoscale structure and photovoltaic performance in side-chain-modified poly(p-arylene-ethynylene)-alt-poly(p-arylene-vinylene): PCBM bulk-heterojunction solar cells

Recent investigations have shown that an anthracene containing poly(p-arylene-ethynylene)-alt-poly(p-arylene-vinylene) statistical copolymer consisting of a well defined conjugated backbone, along which linear and branched alkoxy side chains are attached in a random manner, yields, compared to its counterparts with regular side chain substitution, an improved performance in polymer [6,6]:-phenyl-C₆₁-butyric acid methyl ester (PCBM) bulk-heterojunction solar cells. The microscopic origin for the improved power conversion efficiency (η ≈ 3.8%) of the statistical copolymer - which is the best in its material class - has not been resolved. We conducted grazing incidence wide-angle x-ray scattering investigations in order to correlate the nanomorphology of the active layers to the photovoltaic performance of the device. A comparison of the results obtained for the statistical copolymer to those obtained for the corresponding regular copolymers shows that the improved performance of the former may be attributed to a combination of the following structural characteristics: 1. well, ordered stacked domains that promote backbone planarization, 2. partly face-on alignment of domains relative to the electrodes for an improved active layer-electrode charge transfer, and 3. a more isotropic domain orientation throughout the active layer that ensures that the backbone alignment direction has components perpendicular and parallel to the electrodes in order to compromise between light absorption and efficient intra-chain charge transport. The regular copolymers exhibiting inferior performance lack either sufficient stacking order or face-on alignment of the domains. None of them shows isotropic domain orientation.     

PPV/TiO2 hybrid composites prepared from PPV precursor reaction in aqueous media and their application in solar cells

In this work, poly(phenylene vinylene) (PPV) and TiO₂ nanocomposites containing different amounts of TiO₂ were prepared through PPV precursor reaction in aqueous media. The TiO₂ components were introduced into the systems by two methods, i.e. through in situ sol-gel reaction or by mixing commercially available TiO₂ nanoparticles with the PPV precursor before reaction. The composite prepared by mixing commercially available TiO₂ nanoparticles shows perfect crystal character of the anatase TiO₂, but TiO₂ particles severely agglomerate in the PPV matrix. The composite prepared by introducing TiO₂ nanoparticles through the sol-gel reaction shows uniform nanoscale dispersion of anatase TiO₂ in PPV matrix. The UV-vis and FL spectroscopic analyses confirm the formation of the TiO₂/PPV composites and reveal the enhanced PL quenching effect as the TiO₂ content increases. The PPV/TiO₂ composites can show significant photovoltaic response. Better photovoltaic performance is observed for the solar cells prepared by using the in situ sol-gel reaction method.