Average Diameter Of Electrospun Nanofibers Research Articles

Facile synthesis of co-axially electrospun Co-C nanofibers and their ferromagnetic behavior

We describe a simple co-axial electrospinning approach followed by a carbonisation process to create cobalt-carbon (Co-C) nanofibers that are then thoroughly analysed using various techniques. X-ray diffraction measurements showed the creation of pure crystalline cobalt with face-centered cubic (fcc) structure, and average crystallite size was determined using the Debye–Scherrer formula. The average crystallite size has been calculated to be in the range of 10 − 15 nm. According to the Raman investigation, all Co-C nanofibers have an amorphous carbon structure with little graphitic behaviour. Field emission scanning electron microscopy was used to determine the shape and average diameter of electrospun nanofibers. The field-dependent magnetic characterisation demonstrated a satisfactory ferromagnetic behaviour with maximum saturation magnetisation values of 10, 10.2, and 11.2 emu/g for Co12.5-C sample at 300, 100, and 5 K, respectively. Compared to bulk cobalt, the produced Co-C nanofibers have a high coercivity value. With average crystallite size, the coercivity varies. Again, magnetisation versus temperature measurements have supported the existence of ferromagnetism because there is no evidence of blocking temperature or any transitional behaviour below 300 K. As a result, applications for microwave absorption, catalysis, and several magnetic recording devices can benefit from the coupling of ferromagnetic properties with carbon nanofiber materials.

Encapsulation of caffeine in sandwich structured Alyssum homolocarpum seed gum/PVA/gelatin nanofibers using electrospinning technique

In this study, multilayer sandwich nanofibers from Alyssum homolocarpum seed gum (AHSG), polyvinyl alcohol (PVA) and gelatin were created by electrospinning technique and used to encapsulate caffeine. The middle layer was prepared by electrospinning of AHSG and PVA with different mixing ratios. The average diameter of electrospun nanofibers decreased with increasing AHSG to PVA ratios. Due to their ideal morphology (smooth, uniform, and bead-free) and thinner fiber diameter, nanofibers with the volume ratio of 30:70 AHSG to PVA were chosen as the best sample for caffeine encapsulation. The second step involved spinning gelatin onto the AHSG/PVA nanofibers containing caffeine, as the outer layers. These nanofibers effectively trapped caffeine and had high thermal stability and amorphous structures. The multilayer nanofiber containing 1% caffeine had the highest encapsulation efficiency (88.2%). More than 50% of the caffeine in single-layer nanofiber was released into the saliva simulator environment in less than 60 s, but after that point the caffeine release slowed down gradually. Sandwich structured nanofibers were more resistant to caffeine release and had slower release rate. The Korsmeyer-Peppas model was chosen as the model that best describes the mechanism of caffeine release from single-layer and multi-layer nanofiber, and the release followed non-Fickian diffusion.

Determination of some quality indices of rainbow trout fillets treated with nisin-loaded polyvinylalcohol-based nanofiber and packed with polyethylene package

The combined application of nisin-loaded poly(vinyl alcohol)-based nanofibers (NP) with polyethylene (PE) packs were presented to be a new food nanotechnology application. In the electrospinning process, flow rate, distance, and voltage were defined to be 1.2 mL/h, 8 cm, and 20 kV, respectively. The zeta potential value and the average diameter of electrospun nanofibers were found as −3.38 mV and 150.88 nm, respectively. SEM images revealed that fibrous, smooth, and ultrafine nanofibers were successfully obtained. During ten days, this combination delayed Total Mesophilic Bacteria (TMB: from 5.03 to 3.52 log CFU/g) and Lactic Acid Bacteria growth (LAB: from 3.22 to 2.02 log CFU/g) in fish fillets by 31% and 38%, respectively (p < 0.05). The fish fillets coated with nisin-loaded PVA-based nanofibers had better sensory quality than the control group samples. Also, the off-odor formation in fish fillets was effectively limited and the L* (changes: 49.18 and 50.36) of the fish fillets treated with NP was defined to be more stable during the analysis period (p < 0.05).

Metronidazole-loaded polylactide stereocomplex electrospun nanofiber mats for treatment of periodontal disease

Poly(l-lactide) (PLLA)/poly(d-lactide) (PDLA) stereocomplexes nanofiber mats with a range of PLLA:PDLA ratios were fabricated by electrospinning technique, using 1,1,1,3,3,3‐hexafluoro‐2‐propanol (HFIP) as the solvent. Metronidazole (MNZ, 10% w/w) was incorporated into the nanofibers as the active compound for treatment of periodontal disease. The average diameter of electrospun nanofibers ranged from 177 to 824 nm. Differential scanning calorimetry and wide-angle x-ray diffraction confirmed stereocomplex formation in the PLLA:PDLA blends and successful incorporation of MNZ into the fibers. The fiber with the 50:50 PLLA:PDLA blend showed the highest stereocomplex formation, which decreased slightly with other blend ratios. The fiber tensile strength ranged from 3.9 to 12.9 MPa - it increased with higher stereocomplex formation. The entrapment efficiency of MNZ in the nanofiber mats was 82–99%. At least 30% of MNZ was released in the initial period followed by a sustained-release for up to 7 days. Nanofiber mats with greater stereocomplex formation exhibited higher initial burst and total release rate, and thus a greater antimicrobial activity. Most of the MNZ-loaded nanofiber mats demonstrated similar antimicrobial action against Porphyromonas gingivalis; there were comparable amounts of MNZ in the fibers. Moreover, the stereocomplex fibers showed slightly lower cytotoxicity than the fibers made from either of the single polymers. Therefore, the stereocomplex nanofiber mats were shown to be promising candidates for periodontal disease applications.

CNT Incorporated Polyacrilonitrile/Polypyrrole Nanofibers as Keratinocytes Scaffold

Polypyrrole (PPy) is an attractive scaffold material for tissue engineering with its non-toxic and electrically conductive properties. There has not been enough information about PPy usage in skin tissue engineering. The aim of this study is to investigate biocompatibility of polyacrilonitrile (PAN)/PPy nanofibrous scaffold for human keratinocytes. PAN/PPy bicomponent nanofibers were prepared by electrospinning, in various PPy concentrations and with carbon nanotube (CNT) incorporation. The average diameter of electrospun nanofibers decreased with increasing PPy concentration. Further, agglomerated CNTs caused beads and disordered parts on the surface of nanofibers. Biocompatibility of these PAN/PPy and PAN/PPy/CNT scaffolds were analyzed in vitro. Both scaffolds provided adhesion and proliferation of keratinocytes. Nanofiber diameter did not significantly influence the morphology of cells. However, with increasing number of cells, cells stayed among nanofibers and this affected their shape and size. In this study, we demonstrated that PAN/PPy and PAN/PPy/CNT scaffolds enabled the growth of keratinocytes, showing their biocompatibility.

Effect of the flame-retardant 3-hydroxyphenylphosphinyl-propanoic acid on the mechanical, thermal, and flammability properties of poly(ethylene terephthalate) nanofiber mats

The structure, thermal stability, and mechanical properties of electrospun nanofiber mats obtained from poly(ethylene terephthalate) (PET) solutions in trifluoroacetic acid/dichloromethane were evaluated. The electrospun PET nanofibers were characterized by means of attenuated total reflection Fourier transform infrared spectroscopy, scanning electron microscopy, differential scanning calorimetry, thermogravimetric analysis, limiting oxygen index, and tensile testing. PET-3-hydroxyphenylphosphinyl-propanoic acid (HPP) copolymer was used as the flame-retardant (FR) agent to improve the thermal stability and flammability of the nanofiber mats. HPP is a commercial FR for polyesters which was studied from the viewpoint of chemical reactivity and reaction mechanism. To enhance the tensile strength of the nanofiber mats, the nanofibers were collected on high-speed rotating drum. The results showed that the nanofibers were oriented, and their strength was enhanced by increasing the velocity of the collector. The average diameter of electrospun nanofibers was in the range of 110–240 nm, decreasing with the increasing drum speed. Also the mean pore size of the mats decreased significantly with increasing orientation of the nanofibers. The results showed that HPP improved the flame retardancy of PET.

Electrospun Nanofibers Based on Polyvinyl Alcohol/Chitosan and its Stability in KOH Solution

Fabrication of nanofibers based on polyvinyl alcohol and chitosan (PVA/chitosan) has been carried out by means of electrospinning with focusing on beads formation and diameter variation due to effects of weight ratio variations of PVA/chitosan. For electrospinning solution, the PVA/chitosan with artios of 10:1, 10:2 and 10:3 w/w were dissolved in 1% acetic acid. In addition, stability testing of PVA/chitosan nanofibers in an electrolyte solution was performed by soaking the nanofiber mat in KOH solution. As results, the addition of chitosan concentration increased the pH, conductivity, and viscosity of the solution. Beads were potentially generated for low chitosan concentration. Furthermore, the effect of viscosity and conductivity on diameter of electrospun nanofibers is very significant and need to be optimized. The average diameter of electrospun nanofibers were found to be 160 ± 18 nm, 120 ± 12 nm, and 148 ± 26 nm, for weight ratios of PVA and chitosan 10:1, 10:2 and 10:3, respectively. In addition, no significant change in morphology after being soaked the electrospun PVA/chitosan nanofibers in KOH 40 wt% solution for 24 hours. It indicates that the electrospun PVA/chitosan nanofibers is stable in electrolyte solution which shows a high potential for electrolyte membrane in fuel cells application.

Fabrication of PEO/chitosan/PCL/olive oil nanofibrous scaffolds for wound dressing applications

Biodegradable polyethylene oxide (PEO)/chitosan (CS)/poly(e-caprolactone) (PCL)/olive oil composite nanofibers were fabricated by electrospinning process. The prepared nanofibers were characterized using SEM and FTIR analysis. A response surface methodology based on Box-Behnken design (BBD) was used to predict the average diameter of electrospun nanofibers based on electrospinning parameters including voltage, flow rate and tip-collector distance. The optimum experimental average diameter of electrospun nanofibers was found to be 86 nm which was in good agreement with the predicted value by the BBD analysis (88 nm). In vitro release of olive oil incorporated PEO/CS/PCL/olive oil nanofibers demonstrated a rapid release of olive oil during the first 3 h which enhanced gradually afterwards. Good attachment, spreading, cell proliferation, as well as nontoxic behavior of PEO/CS/PCL/olive oil nanofibrous scaffolds on HDF fibroblast cells were proved by cytotoxicity studies. Furthermore, the high antibacterial activity of PEO/CS/PCL/olive oil composite nanofibers against Gram-negative bacteria E. coli and Gram-positive S. aureus was observed. This study suggests that the prepared PEO/CS/PCL/olive oil composite nanofibrous scaffolds could be used as an ideal patch for wound dressing applications.

Electrospinning of nylon-6,6 solutions into nanofibers: Rheology and morphology relationships

The relationship between the rheological properties of nylon-6,6 solutions and the morphology of their electrospun nanofibers was established. The viscosity of nylon-6,6 in formic acid (90%) was measured in the concentration range of 5 wt%–25 wt% using a programmable viscometer. Electrospinning of nylon-6,6 solutions was carried out under controlled parameters. The chemical structure, morphology and thermal properties of the obtained nanofibers were investigated using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and differential scanning calorimetry (DSC), respectively. Entanglement concentration (c e) was found to be 15 wt% and a power law relationship between specific viscosity and solution concentration was observed with exponents of 2.0 and 3.3 for semi-dilute unentangled (c < c e) and semi-dilute entangled (c > c e) regimes, respectively. The diameter and uniformity of the nanofibers were found to be dependent on the viscosity. Moreover, the average diameter of electrospun nanofibers was found to be dependent on zero shear rate viscosity and normalized concentration (c/c e) in a power law relationship with exponents of 0.298 and 0.816, respectively. For nylon-6,6 solutions, the entanglement concentration (c e = 15 wt%) provides the threshold viscosity required for the formation of a stable polymeric jet during electrospinning and producing uniform beadless fibers. For concentrations less than c e, beaded fibers with some irregularities are formed. DSC analysis showed an increase in crystallinity of all electrospun samples compared to original polymer. Furthermore, Based on FTIR spectroscopy, α phase is dominant in electrospun nanofibers and minor amount of β and γ phases is also available.

Preparation of Poly(vinyl alcohol)/Polyoxalate Composite Nanofibers by Electrospinning and Drug Release Profiles

This study investigated the use of a biodegradable polyoxalate blended with poly (vinyl alcohol) nanofibers to tailor properties of nanofibers and to control release of Rhodamine B from nanofibers. Nanofibers were prepared using an electrospinning technique. The morphology and average diameter of electrospun nanofibers were investigated using scanning electron microscopy. It was found that poly (vinyl alcohol) to polyoxalate ratio had a significant effect on the size of nanofibers (~175-403 nm). An in vitro release study showed that rate of Rhodamine B release increased with increasing poly (vinyl alcohol)/polyoxalate ratios yielding rate of release in the range of 0.1980.469 mg%/min. The mechanism of rhodamine B release can be explained by a two-stage process of diffusion and degradation. The results suggested that a water-insoluble polyoxalate could govern the rate of drug release. The ability to tune the release of chemicals from nanofibers has significant implications for controlled release of drugs.

Adsorption of silver ions on polypyrrole embedded electrospun nanofibrous polyethersulfone membranes

In this study we developed polypyrrole embedded electrospun nanofibrous polyethersulfone nanofibrous membranes for the removal of silver ions. Polypyrrole and polyethersulfone dissolved in N-methyl-2-pyrrolidone (NMP) were electrospun into nanofibrous membranes via an electrospinning process. The morphology of as-spun polypyrrole/polyethersulfone nanofibers was examined by scanning electron microscopy. The average diameter of electrospun nanofibers ranged from 410nm to 540nm. The adsorption capability of nanofibrous polypyrrole/polyethersulfone membranes was measured and compared with that of bulk polypyrrole. The influence of various process conditions on adsorption efficiency was also examined. The experimental results suggested that the electrospun nanofibrous membranes exhibited good silver ion uptake capabilities. The metal uptake of nanofibrous membranes increased with the initial metal ion concentrations and the pH value, while decreased with the temperature and the filtering rate of the solutions. Furthermore, the electrospun membrane could be reused after the recovery process.

Electrospun nanofibrous rhodanine/polymethylmethacrylate membranes for the removal of heavy metal ions

In this study we developed rhodanine loaded nanofibrous membranes for the removal of heavy metal ions. Rhodanine and polymethylmethacrylate dissolved in 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) were electrospun into nanofibrous membranes via an electrospinning process. The morphology of as-spun rhodanine/polymethylmethacrylate nanofibers was examined by scanning electron microscopy. The average diameter of electrospun nanofibers ranged from 840nm to 1440nm. The adsorption capability of nanofibrous rhodanine/polymethylmethacrylate membranes was measured and compared with that of bulk rhodanine. The influence of various process conditions on adsorption efficiency was also examined. The experimental results suggested that the electrospun nanofibrous membranes exhibit good Ag (I) and Pb (II) ion uptake capabilities. The metal uptake of nanofibrous membranes increased with the initial metal ion concentrations and decreased with the filtering rate of the solutions. Furthermore, the electrospun membrane could be reused after the recovery process. The empirical results in this study suggested that electrospun rhodanine/polymethylmethacrylate nanofibrous membranes can be a good candidate for the removal of heavy metal ions.

Design and evaluation of chitosan/hydroxyapatite composite nanofiber membrane for the removal of heavy metal ions from aqueous solution

The performance of chitosan/hydroxyapatite (Cs/HAp) composite nanofiber membrane prepared by electrospinning process for the removal of lead, cobalt and nickel ions from aqueous solution was investigated. The prepared nanofiber membranes were characterized by FTIR, SEM and BET analysis. A response surface methodology based on Box–Behnken Design (BBD) was used to predict the average diameter of electrospun nanofibers. In optimum conditions (voltage of 18.90kV, tip-collector distance of 15.60cm and flow rate of 0.43ml/h), the minimum experimental fiber diameter was obtained 198nm which was in good agreement with the predicted value by the BBD analysis (200.6nm). Then, the adsorption experiments were carried out to investigate the effect of different adsorption parameters, such as contact time, initial concentration and temperature in a batch system. The kinetic and equilibrium data were well described by pseudo-second-order and Langmuir models, respectively. Thermodynamic parameters were evaluated to obtain the nature of adsorption process onto the Cs/HAp composite nanofibers. The obtained results of reusability of nanofiber membrane after five sorption–desorption cycles offer promising potential in industrial activities.

Electrospun PLGA/collagen nanofibrous membrane as early-stage wound dressing

Abstract Electrospinning of polylactide–polyglycolide (PLGA)/collagen in 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) to fabricate a biomimetic nanofibrous extracellular membranes for wound dressing and tissue engineering was investigated. The morphology of as-spun PLGA/collagen nanofibers was examined by scanning electron microscopy. The average diameter of electrospun nanofibers was 250 nm (range of 150–650 nm). Degradation rate of PLGA/collagen nanofibrous membranes, cytocompatibility and cellular responses to membranes, cell and nanofibers interactions, and open wound healing in rats were studied. It was found that nanofibrous membranes made of PLGA/collagen were functionally active in responses in human fibroblasts, and were very effective as wound-healing accelerators in early-stage wound healing. The empirical results in this study indicate that electrospun PLGA/collagen nanofibers may be a good candidate as a wound dressing for skin regeneration.