Papers by Keyword: Electrospinning

Abstract: From food to environmental applications, the encapsulation of bio-objects in nanofibers is widely used. In particular, for improved and sustainable performance of bioremediation, the system requires the development of cost-effective nanomaterials that containing living microorganisms for textile wastewater treatment is required. Here, bacteria-encapsulated polyethylene oxide (PEO) nanofibers (Nfs) were prepared by electrospinning. According to the Scanning Electron Microscope (SEM) images, PEO-Nfs show bead-free morphology and homogeneous distribution, while random expansions are observed in the nanofibers after bacterial encapsulation. While the number of live bacteria in the polymer before electrospinning was 10¹⁰ CFU/mL, the number of live bacteria-encapsulated after spinning was 10⁸ CFU/mL. This proves that nanofibers carry a very high number of bacteria after electrospinning which is supported by Fluorescence microscope images. Furthermore, an ATR-FTIR study confirmed the molecular interactions between PEO and bacteria in the nanofibers. The removal efficiency of PEO_bacteria-Nfs was 26.6 ± 0.3% at 5 ppm and 9 ± 0.1% at 20 ppm dye concentration. Under storage conditions of +4 °C, the bacteria-encapsulated in PEO-Nfs show cell viability for more than 60 days. In order to extend the research on bacteria-encapsulated polymer Nfs, we explored the possibility of extending the life of bacteria in electrospun Nfs by cross-linking approaches using non-toxic calcium ions. The composite Nf mats were therefore reused for up to 4 repeated cycles.

Abstract: In this study, polystyrene (PS) and recycled polyethylene terephthalate (R-PET) materials were coated by electrospun polyacrylonitrile/ polyvinyl alcohol (PAN/PVA) and PAN/ polyvinylidene fluoride (PVDF) nanofibers produced by electrospinning method to produce new polymer composite materials. Nanofibers were characterized by SEM, FT-IR and XRD confirmed the formation of PAN/PVA and PAN/PVDF electrospun nanofibers and their beadless and ordered morphology with an average diameter of 188.95±17.12 and 263.44±45.46 nm, respectively. The effect of nanofibrous coating on the tensile properties and hardness properties of the PS and R-PET composite materials obtained by plastic injection method was investigated. PS and R-PET samples were coated with PAN/PVA and PAN/PVDF nanofibers produced for 1h and 2h and these samples were compared for their mechanical properties. In terms of tensile properties, among the PS and R-PET samples, the PAN/PVDF-coated R-PET composite showed the highest tensile strength value of 22.66 MPa and the highest elongation value of 8.49%. The results showed that after nanofibrous coating on PS and R-PET elastic modulus, tensile strength, and elongation at break properties of all samples enhanced. The analysis of hardness revealed an enhancement after nanofibrous coating for R-PET samples while relatively low changes in hardness values were determined for PS composites because of the rigid nature of PS.

Abstract: Electrospinning is a cost-effective and versatile technique to fabricate continuous fibers ranging from submicron diameter to nanometer diameter. Polybutylene adipate-co-terephthalate (PBAT) has been investigated as a fibrous scaffold because of its low crystallinity, rapid biodegradability, and excellent mechanical properties, particularly for its high toughness and flexibility. However, the potential of the PBAT fibrous scaffold for medical purposes is still limited. PBAT blends with biocompatible polymers have been developed and investigated for tissue engineering applications. Herein, the preliminary research examines the processability of neat PBAT as a fibrous scaffold by varying several electrospinning processing parameters, such as solution concentration, voltage, flow rate, and tip to collector distance. The aim is to obtain continuous, smooth, and bead-free fibers. The electrospun fibers were examined using a scanning electron microscope (SEM) to determine its diameters. The optimum parameters for obtaining a continuous, bead-free PBAT fibrous scaffold were 20% w/v concentration, 19 kV voltage, 2 mL/h flow rate, and a 15 cm distance.

Abstract: In this work, electrospun membrane with excellent optical transparency has been developed and the study focuses on the optical and electromechanical properties of the membrane. Highly transparent PVDF based membrane fabricated by electrospinning exhibited appreciable piezoelectric property. Thus the study mainly focus on the multifunctional behaviour of these nanomembrane in the field of transparent sensors and energy harvesting systems. The transmittance of the fabricated membrane is measured using spectrophotometer and beta sheets content associated with the piezo activity of the membrane is measured using the Fourier Transform Infrared spectra. The surface characterization of the electrospun membrane were performed using Scanning Electron Microscope (SEM). The piezo response range of these membrane were tested using impulse loading and force voltage-based measurements. The utilization of these transparent optical membranes in the field of micro and nanoenergy harvesting systems based on piezoelectric transduction mechanism is focused.

Abstract: Aligned calcium phosphate nanorods embedded in gelatin nanofibers were fabricated to be applied as a coating material on the Ti bone implant using the conventional electrospinning method. Calcium phosphate nanorods with a strong positively charged surface were prepared by modifying with alanine (alanine/HA) to facilitate the arrangement of nanoparticles under the electric field in the electrospinning process, followed by mild hydrothermal treatment to preserve the structure of fibers. Scanning electron microscope, atomic force microscope, and transmission electron microscope measurements confirmed that the composite fibers were smooth without the presence of particles on the surface and alanine/HA was aligned within the fiber. The tensile strength of the prepared scaffolds was identical to that of the cancellous bone (2 to 12 MPa). According to MTT assay, the scaffold coated Ti showed a significant improvement on cell adhesion and biocompatibility compared to uncoated Ti.

Abstract: Water shortage has been a severe problem affecting the globe for the past decade. Therefore, appropriate and efficient technologies should be implemented to tackle the water shortage dilemma and to acquire clean water. Several desalination techniques are implemented across the world; among them is capacitive deionization (CDI). CDI is an energy-efficient and cost-effective electrochemical process employed for extracting charged ions from aqueous solutions using a pair of electrodes. Electrode materials strongly influence the CDI's desalination efficiency and conductivity. The CDI electrodes are composed of carbon materials such as activated carbon, carbon aerogel, carbon nanofibers, and porous carbon. However, in this study, carbon nanofibers that possess several advantages and properties over the existing materials have been examined to be used as CDI electrode material due to their high electrical conductivity, large surface area, dimensional stability, and low production cost. Furthermore, different conductive additives could be added to the carbon nanofibers to increase the electrical conductivity and capacitance. In particular, this paper discusses the effect of adding graphene oxide (GO) and carbon nanotubes (CNT) as additives to carbon nanofibers.

Abstract: Recently, dye sensitized solar cell (DSSC) are considered to replace the previous generation of solar cells. DSSC uses an organic dye to absorb light and convert it to electricity. One-dimensional morphological structure of photoanode that provides a straight pathway for electron transport can improve the efficiency of DSSC. TiO₂ nanofibers is one-dimensional structure of oxide semiconductor material commonly used as photoanode in DSSC. A simple method to synthesis continuous nanofiber is electrospinning method that use the influence of electrostatic forces. The nanofiber’s diameter that produced by electrospinning method depends on several parameters, one of which is the applied voltage. This study reports the synthesis of TiO₂ nanofibers with varying the applied voltages from 10 kV to 14 kV and their performance as photoanode in DSSC. TiO₂ nanofibers were electrospun directly onto a TiO₂-coated fluorine tin oxide (FTO) substrate from a mixture of titanium (IV) propoxide (TTIP), triton X-100, acetic acid, poly (vinyl) acetate (PVAc) that were dissolved in dimethyl formamide (DMF). TiO₂ nanofiber photoanodes were then immersed in ruthenium (II) dye, stacked with a counter electrode, and finally the electrolyte was injected between them. Based on the SEM results, we found that the beads disappeared with increasing applied voltage. The XRD pattern of TiO₂ nanofibers indicates the presence of the anatase phase. Based on the photocurrent-voltage characteristic, TiO₂ nanofibers produced by applied voltage of 14 kV shows the highest efficiency of 1.11% with J_SC 4.78 mA/cm², V_OC 0.74 Volt and fill factor (FF) of 31.37%.

Abstract: This research was conducted to determine the morphology, dimensions, and structure of carbon-nanofibers, using polyvinyl alcohol (PVA) as a source of polymer fibers fabricated by electrospinning technique, and given variations in carbonization temperature. Variations in temperature during the carbonization process are carried out to see changes in the structure and morphology of the carbon nanofibers formed. characterization by conducting XRD and SEM tests to determine the structure and morphology of the carbon nanofibers produced, it is seen that the amorphous carbon structure of the nanofibers produced is in the shape of random fibers and tends to be straight without beads. The results obtained from the XRD test, it appears that the structure is amorphous with two peaks that appear during the test, the two peaks are typical of amorphous carbon peaks, so that the fiber that has been formed, then with the carbonization process changes its structure to carbon nanofiber. Unique results were obtained when PVA nanofibers were characterized by SEM, namely the diameter of the fibers formed before and after the carbonization process had sizes in the range of 40 to 50 nanometers, these results were influenced by the process of initial formation of nanofibers using an electrospinning system.

Abstract: Polyvinyl alcohol (PVA) nanofibers were fabricated using the electrospinning method. The nanofibers were embedded with zinc oxide (ZnO) particles by mixing PVA liquid with the ZnO powders during the solution preparation stage. The FESEM images showed an increase in the amount of ZnO particles embedded in the PVA nanofibers as the powder content was increased. Other than that, there are no significant changes in other physical properties of the nanofibers caused by the increasing number of ZnO particle content. This means that ZnO nanopowders (with concentration in the range of 1.63 wt% - 8.14 wt%) can be effectively integrated and embedded into PVA nanofibers without negative consequences on the fibers formation and structure. This will facilitate the fabrication of ZnO embedded PVA nanofibers in some applications that may require it such as drug delivery, filtration, and biomedical application.

Abstract: The electrospinning technique is being widely used in the fabrication of micro and nanofibers, with a myriad of biomedical applications such as drug inoculation, tissue regeneration and scaffold production. In the present article, nanofibers based on polyvinyl alcohol (PVA), chitosan (C) and salicylic acid (SA) were developed experimentally. Solutions at 18% w/w of PVA and 3% w/w of C and SA were prepared using always distilled water as solvent. Solution with C and SA (labelled as CSA solution) had the same amount of both substances in it. Then, mixtures at 100/0, 98/2, 96/4, 93/7 and 90/10 in PVA/CSA weight ratio were prepared. The rheological behavior of the solutions was evaluated and they were subsequently electrospun. The samples were characterized by scanning electron microscopy, differential scanning calorimetry and Fourier transform infrared spectroscopy in attenuated total reflection mode.