Tip To Collector Distance Research Articles

Surface and Morphological Investigation of Synthesized Nanostructured Ridges from Electrospun Polyvinyl Alcohol-Albumin Blend—A Taguchi Design of Experiment Approach

We report the synthesis of presumably a “nanoridge” from the electrospinning of a hydrophilic polymer–protein blend. The material exhibits vertical elevation from the substrate, distinct from the morphologies seen in electrospinning. It is hypothesized that the formation of the nanostructured ridges is due to the migration of the charged protein to the apex through a highly polarized electric field in electrospinning conditions. In this study, we assessed the polyvinyl alcohol–egg albumin (PVA–EA) system in a solvent comprising of water, formic and acetic acid, together with the tip-to-collector distance (TCD) and solution flowrate. To quantify the factor effects in the surface properties of the material, a Taguchi design of experiment was used. The ridge heights observed ranged from 84.8–639.9 nm, and the material height is predominantly affected by the PVA–EA ratio and solution flow rate. The root mean square roughness was influenced by the TCD and flow rate, which has values ranging from 11.37–57.56 nm. In evaluating the sharpness of the ridge, we used the radius of curvature, where the TCD highly affects the apex sharpness. The work offers not just a likely new class of morphology, but a new perspective on the surface characterization of an electrospun material which could affect the performance of such a use in biological and physical systems.

Development and Characterization of Electrospun Nanostructures Using Polyethylene Oxide: Potential Means for Incorporation of Bioactive Compounds

The development of processes for stabilization of the properties of bioactive compounds has been studied in recent years, and the use of nanotechnology is among the most discussed routes. The present work addressed the assembly of nanostructures using polyethylene oxide (PEO), the production of core-shell nanofibers (NFs) with bioactive compounds, and the evaluation of their microscopic and physical characteristics. Aqueous solutions of PEO were electrospun by varying different process and solution parameters (PEO and NaCl concentrations, feeding rate, the tip-to-collector distance (TCD), and applied voltage) in order to optimize production of nanostructures. The best condition obtained was evaluated to form core-shell NFs composed by jussara pulp as a source of anthocyanins. To assess the production of NFs with PEO and jussara pulp, feed solutions were prepared in acetate buffer (pH 4.5) with 6% PEO and 10% lyophilized jussara pulp, at a feeding rate of 150 μL·h−1 and TCD of 15 cm using an applied voltage of 10 kV to form core-shell NFs. The results revealed the formation of core-shell NFs with a diameter of 126.5 ± 50.0 nm. The outcomes achieved represent a crucial step in the application of anthocyanins in food systems as pigments, establishing a basis for further research on the incorporation of nanomaterials into foodstuff.

Edible gelatin-based nanofibres loaded with oil encapsulating high-oleic palm oil emulsions

Gelatin-based nanofibres (NF) incorporating a high-oleic palm oil (HOPO) nanoemulsion or macroemulsion were electrospun. An I-optimal response surface design was used for studying the effect of gelatin mass fraction, tip-collector distance and emulsion type (factors) on fibre diameter (Df). The NF had a Df ranging from 136.9 to 240.8 nm and no beads; synergic effects between factors were observed as significant over Df. Furthermore, topography, roughness, oil distribution, peroxide value (PV), antioxidant activity (AOX), thermal stability and crystallinity of two optimised NF were analysed; smooth and slightly rugose NF were observed by atomic force microscopy (AFM) and heterogeneously distributed oil by confocal laser scanning microscopy (CLSM). Microfluidisation and electrospinning had low PV, high encapsulation efficiency (>94 %) and high AA values, i.e., efficient encapsulation processes. NF thermal stability was affected by emulsion type; a more amorphous structure tended to give higher droplet size inside fibres. Despite Df was not affected by emulsion droplet size, NF’s physico-chemical properties showed changes.

Optimization of the electrospinning process variables for gelatin/silver nanoparticles/bioactive glass nanocomposites for bone tissue engineering

AbstractThe current research focuses on the findings of an investigation on optimizing of an electrospun antibacterial gelatin nanocomposite membrane for bone tissue engineering applications. For this reason, soluble starch coated silver nanoparticles (Ag‐NPs) and bioactive glass particles (BG) were incorporated in to gelatin (Gt) to fabricate Gt/Ag‐NPs/BG nanocomposite membranes. Employing Box‐Behnken design, second‐order models have been successfully obtained to evaluate the statistical significance of individual and interaction effects of applied voltage, tip‐to‐collector distance (TCD), and flow rate on fiber diameter. There was a reasonable agreement between the regression R2 value (0.9542), R2 predicted value (0.8768), and the R2 adjusted value (0.9286) across the entire factor space with identical observations for the experimental and model values. Under optimum conditions (applied voltage of 26 kV, TCD of 180 mm, and flow rate of 0.5 mL/h), the nanocomposite membrane with similar fiber size of bone tissue extracellular matrix can be fabricated with the predicted value of 557 nm obtained by the proposed model. The optimized nanofiber membrane was fabricated under these conditions and average fiber diameter of this membrane was found as 472 ± 94 nm. The characterization studies of this nanofiber suggest that obtained nanocomposite is a potential candidate for bone tissue engineering applications.

Electrospinning of Poly(vinyl alcohol)-Graphene oxide aligned fibers

Abstract Electrospinning is a well know technology for the production of nano and micro fibers. Graphene has been used in different fields due to its unique stability. Reduced graphene oxide (rGO) is prepared from the reduction of graphene oxide. In this work, we electrospun of Polyvinyl Alcohol (PVA) solutions with rGO to combine the different physical properties of the materials, on a rotating collector to verify the influence of the solutions and rotation on the morphology of the fibers. The optimization of the process highlighted the influence of the flow rate and tip-collector distance in relation to the rotation speed used.

Hydrolysed Gelatin-Derived, Solvent-Free, Electrospun Nanofibres for Edible Applications: Physical, Chemical and Thermal Behaviour

Electrospinning is a novel technique which has been used recently in the food field. Electrospun nanofibres (NF) have often been produced from non-edible compounds. Biopolymer solutions were developed from gelatin hydrolysed by bromelain in slightly acid medium (pH 4.5). The effects of gelatin concentration, bromelain activity and tip-collector distance on NF morphology and diameter (Df) were studied. Defect-free NF were produced (no beads or droplets), having a 109.5 to 229.3 nm Df. A Box-Behnken design was optimised for studying acetic acid’s effect on gelatin NF thermal behaviour and residual solvent concentration. Gelatin ionisation by acetic acid improved the solutions’ electrospinnability. NF denaturing temperature (Td) was 98.4 °C and gelatin powder Td 102.3 °C. These values were associated with smaller amorphous structure in NF than in gelatin powder. Total acetic acid became evaporated during electrospinning; solvent-free NF were thus produced in line with international food regulations.

Development of Coaxial Air-blown Electrospinning Process for Manufacturing Non-woven Nanofiber. II. Intelligent Modeling

This study describes the development of an electro-coaxial air-blown spinning system, using a sheath-core type nozzle and an intelligent model for predicting the morphological changes induced by varying four process parameters. We prepared 65 samples with different parametric conditions and analyzed their characteristics. We could confirm that the mean fiber diameter decreased with increase in the air flow rate and voltage, and increased with an increase in the solution concentration. A too short tip-to-collector distance (TCD) resulted in flat and thick fiber deposition, and no changes in fiber diameter were observed beyond a specific TCD value. Based on experimentally measured morphological data, we could establish an intelligent prediction model with four inputs (air flow rate, solution concentration, applied voltage, and TCD) and one output (mean fiber diameter). The simple linear regression analysis model and multiple linear regression analysis model were found to yield mean squared error (MSE) values too high to be used as predictive models. The neural network training model and fuzzy logic model were confirmed to have low MSE values. Among the three prediction models, the neural network training model was confirmed to have the smallest error between the experimental and predicted values. The results of the analysis of the BET specific surface area confirmed the same tendencies as those shown by the image analysis results, which allowed us to conclude that electrospinning using a coaxial air-blown nozzle can enhance the performance of nonwoven nanofibers.

Development of Coaxial Air-blown Electrospinning Process for Manufacturing Non-woven Nanofiber. I. Morphology Changes in Non-woven Nanofiber

This study led to the development of an electro-coaxial air blown spinning system, which involves using a sheath-core nozzle for electrospinning, and the authors examined how the morphology of the fabricated nanofiber changed according to four process parameters. When the morphology changes of the nanofiber were analyzed using different process parameters, the increase in air flow rate was accompanied by the decrease in fiber diameter owing to shear force. On the other hand, as the concentration of the solution increased, the diameter of the nanofiber increased owing to the force of attraction between polymer chains. In addition, the diameter of the nanofiber decreased at a higher voltage owing to increasing orientation and the whipping phenomenon. Finally, when the tip to collector distance (TCD) was too close, it was difficult to obtain a perfect fiber, and the fiber produced in such a scenario was excessively thick and flat. However, when the TCD exceeded a certain value, no change in diameter of the nanofiber was observed. An intelligent prediction model needs to be developed to apply the results of this study to real processes.

Optimal Electrospun TiO2 Nanofiber Photocatalytic Performance via Synergistic Morphology and Particle Crystallinity with Anatase/Rutile Phase Tuning

TiO2 nanofiber photocatalysts offer a highly efficient and stable method of dye degradation through photogenerated radicals. Through electrospinning, the synthesis of the nanofibers with high surface area (i.e., low fiber diameter) and particle crystallinity (e.g., crystallite size and crystal phases) is highly desired to yield the best degradation performance. In this study, it is demonstrated that a synergistic combination of low fiber diameter, high crystallite size, and mixed anatase/rutile ratio is obtained to yield an optimal methylene blue degradation rate constant of 0.04100 min−1. The optimization is conducted with the aid of response surface analysis of electrospinning parameters (flow rate, applied voltage, and tip‐to‐collector distance (TCD)) toward the obtained fiber diameter response. The nanofiber diameter is observed to be from 177.3 to 310.4 nm across the studied range of parameters. The change in nanofiber diameter exhibits linear relationship with the applied voltage while quadratic relationships are observed for both solution flow rate and TCD. Through selective comparison, the lowering of fiber diameter has an adverse effect on the crystallinity and phase transformation (anatase‐rutile) of TiO2 particles. This relationship is shown to have a significant effect on the photocatalytic performance of the TiO2 nanofibers.

Synthesis and characterization of electrospun PVA/Zn2+ metal composite nanofibers for lipase immobilization with effective thermal, pH stabilities and reusability

Polyvinyl alcohol (PVA)/Zn2+ electrospun nanofibers that were a kind of polymer/ionic metal composite was successfully embedded in the hybrid fibers for the first time in the literature, due to chemical interactions between PVA and Zn2+. Also, the nanofibers were used as carriers for the first time in enzyme immobilization. The nanofibers were optimized and synthesized by electrospinning technique according to the operational parameters like as PVA concentration (%), Zn2+ concentration (%), voltage (kV), needle tip-collector distance (cm) and injection speed (ml/h). The morphology and structure of the nanofibers were characterized by SEM, XRD, ATR-FTIR and TGA. Lipase was immobilized on the nanofibers by adsorption and crosslinking methods. According to immobilization results, nanofiber enhanced enzyme stability properties like as thermal stability, pH stability and reusability. Lipase immobilized nanofiber protected 90% of its activity after 14 reuses.

Synthesis of ZnO/In2O3 composite nanofibers by co-electrospinning: A comprehensive parametric investigating the process

ZnO/In2O3 composite nanofibers were fabricated by electrospinning method and effects of process parameters on the distribution and mean diameter of synthesized NFs were investigated. Electrospinning process followed by post calcination was performed at two different temperatures to optimize the synthesis condition of ZnO and In2O3 NFs. Thermal Analysis was done on electrospun fibrocomposites to find calcination temperatures. Electrospinning parameters (Tip to Collector Distance (TCD), feeding rate, and applied voltage), which led to a uniform distribution and thinnest NFs, were used for synthesizing ZnO/In2O3 composite in the co-electrospinning process. Structural, morphological, and chemical studies were also carried out on the NFs. TCD increment led to the improvement of diameter distribution and homogeneity of synthesized NFs. Low voltages (below 20 kV) resulted in thinner fibers without appearing any remarkable beads defect and the optimum feeding rate was found to be 1 ml/h. For further application of NFs in gas sensors, well distributed thinnest fibers were obtained.

Optimizing electrospinning parameters for piezoelectric PVDF nanofiber membranes

In this study, nanofiber membranes were fabricated using electrospinning to induce piezoelectric properties. Optimization of the piezoelectric properties was achieved using the Taguchi design method to systematically vary the electrospinning parameters (acetone fraction, tip-to-collector distance (TCD), flow rate, and voltage setting). The optimized settings for piezoelectric properties were a solvent ratio of 60 v% DMF/40 v% acetone, a TCD of 16 cm, a flow rate of 0.8 mL/h, and a voltage setting of 14 kV. Additionally, the effect of three solvents (dimethylformamide, N-methylpyrrolidone, and dimethyl sulfoxide) on fiber formation and piezoelectric properties was compared; dimethylformamide (DMF) created the smallest fiber diameter and highest piezoelectric properties. During filtration of a synthetic solution mimicking biofouling, severe fouling was observed for both the commercial flat-sheet PVDF microfiltration membranes and unactivated electrospun membranes, although fouling occurred at different times for the electrospun membranes fabricated with different solvents. Little to no flux decline or increase in TMP was observed for the piezoelectrically activated nanofiber membranes. Total suspended solids removal of anaerobic digester mixed liquor for the electrospun membranes were comparable to the commercial PVDF microfiltration membrane. The results demonstrate that piezoelectrically activated nanofiber membranes have the potential to mitigate fouling in water treatment applications, particularly for systems with high levels of biofouling that require suspended solids separation (i.e., membrane bioreactors).

Effect of organic solvents in morphology and mechanical properties of electrospun polyvinylpyrrolidone fibers

In this work, the electrospinning technique was used to obtain fibers for mechanical characterization. polyvinylpyrrolidone (PVP) was combined with organic solvents (ethanol and dimethylformamide (DMF)) to generate solutions, looking for the appropriate parameters to obtain fibers with the best morphology and the best mechanical properties. Starting from previous investigations to find the adequate percentages of solvent and PVP, several solutions were made, varying the different parameters like voltage, flow, tip collector distance. Seeking to obtain acceptable samples, the diameter was measured in a scanning electron microscope (SEM). The elastic modulus was measured for the fibers with the best aspect. Mechanical properties were measured in an atomic force microscope (AFM) with the Hertz contact method and the data were approximated to its mathematical model. The solutions that resulted in the best morphological properties were: ethanol - 8% PVP, DMF – 14% PVP, 70% ethanol - 30% DMF - 8% PVP, with diameters in the micrometer range of 1.6, 1.22 and 1.35 respectively, and elastic modulus of 40.08 MPa, 8.8 MPa and 32.78 MPa correspondingly. An analysis of all the parameters influencing the process was performed and an analysis of the influence of the solvents, based on the data of the elastic moduli was carried out.

FABRICATION OF CURCUMIN LOADED NANO POLYCAPROLACTONE/CHITOSAN NONWOVEN FABRIC VIA ELECTROSPINNING TECHNIQUE

Cucurmin loaded poly e–caprolactone/chitosan (PCL/CTS) nanoscale nonwoven fabric was successfully fabricated using electrospinning, a facial and efficient method. The surface tensions of PCL/CTS blend solutions in various ratios were measured to evaluate the influence of PCL/CTS ratio on fibers formation. The effects of process parameter such as the applied voltage, tip–collector distance and the solution flow rate on the fiber generation and morphology of final fiber were optimized. Nanofibers morphology and structure were characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM), respectively. The prepared fibers had a smooth surface and fine morphology. The diameter of fibers ranges from 200 nm to 400 nm. The release kinetics of curcumin loaded samples were also analyzed via in vitro technique. Results demonstrated that the polycaprolactone/chitosan–based nanofibers encapsulate curcumin is a potential material for wound healing acceleration.

Preparation of PVA/TiO2 Composites Nanofibers by using Electrospinning Method for Photocatalytic Degradation

PVA/TiO2 composites nanofibers have been prepared by using electrospinning method. Electrospinning was performed at a voltage of 15 kV, with a tip-collector distance of 14 cm. The PVA/TiO2 composites nanofibers were characterized by FTIR, SEM, and EDAX. The results showed that PVA/TiO2 composites nanofibers were successfully formed. SEM observation showed that the nanofibers has several hundred nanometers with a smooth surface and have TiO2 nanoparticle distributed in the nanofibers. FTIR result shows a functional group of PVA and EDAX result demonstrates the presence of TiO2 in the nanofibers. The photocatalytic activity of PVA/TiO2 composites nanofibers were investigated for the degradation of methylene blue under UV light. The PVA/TiO2 composite nanofibers suspending in the dye solution have dye removal of 70% dye was degraded in 5 h. As a comparison, the TiO2 powder that has dye removal of 95% dye was degraded in 5 h. Photocatalytic activity of PVA/TiO2 nanofiber was lower than TiO2 powder, but PVA/TiO2 nanofiber was more efficient than TiO2 powder regarding process treatments photocatalytic.

Parametric study of nanofiber fabrication by biocompatible polymers

This paper introduces a parametric study of nanofiber fabrication. Poly-Caprolactone(PCL) and Chloroform are basic material for nanofiber fabrication with electrospinning method. The device for electrospinning was composed of a syringe pump, syringe, high voltage generator and 32gauge plastic nozzle. PCL concentration, applied voltage, solution flow rate and the tip to collector distance (TCD) were parameters in electrospinning method. As a result of electrospinning experiment, it was found that as TCD and applied voltage increased, the diameter of fibres was decreased. In feed rate experiment, the size of fibres decreased when feed rate decreased. The optimized PCL concentration was found at 6w/v% for the minimum of fibres.

The sustained delivery of temozolomide from electrospun PCL-Diol-b-PU/gold nanocompsite nanofibers to treat glioblastoma tumors

In the present study, the PCL-Diol-b-PU/Au nanocompsite nanofibers were fabricated via electrospinning process during two different stages to load an anticancer temozolomide (TMZ) drug into the nanofibers. The first stage was the incorporation of Au nanoparticles into the nanofibers and the second stage was coating the gold nanoparticles on the surface of PCL-Diol-b-PU/Au composite nanofibers. The prepared nanofibrous formulations were characterized using FTIR, SEM and TEM analysis. Box-Behnken-design was used to investigate the influence of electrospinning parameters including solution concentration, applied voltage to tip-collector distance ratio and collector speed on the morphology and fiber diameter of PCL-Diol-b-PU/Au nanofibers. Drug loading efficiency, in vitro release profiles of TMZ from PCL-Diol-b-PU/Au and gold-coated PCL-Diol-b-PU/Au composite nanofibers as well as in vitro antitumor efficacy against U-87 MG human glioblastoma cells were carried out. The TMZ release data were well described using Korsmayer-Peppas kinetic model in which results indicated Fickian diffusion of TMZ from nanofibers. The obtained results revealed the higher efficiency of PCL-Diol-b-PU/Au@TMZ nanofibrous implants for treatment of glioblastoma tumors.

Effect of electrospinning parameters on the air filtration performance using electrospun polyamide-6 nanofibers

Due to their high filtration efficiency and low basis weight nanofibrous filters are suitable for filtration applications. The objective of this study was to investigate the effect of electrospinning parameters including polymer solution concentration (10-15 wt.%), applied voltage (15-25 kV) and tip-collector distance (7.5-12.5 cm) on the filtration efficiency of polyamide (PA) nanofibers. The morphology of the PA nanofibers was characterized using scanning electron microscope (SEM) analysis. The SEM image results indicated that the average fiber diameter of PA nanofibers was 220 nm at PA solution concentration of 12.5 wt.%, applied voltage of 20 kV, tip-collector distance of 10 cm, flow rate of 0.5 mL h-1, temperature of 25 ?C and humidity of 40%. The obtained results showed that the highest quality factor and efficiency of 7.02?10-2 Pa-1 and 96% were optimal parameters for nanofibrous filters during 30 and 240 min of electrospinning time, respectively. The presented study showed that the morphology optimization of nanofibers is an effective method for improvement of filtration performance.

Efficacy of piezoelectric electrospun nanofiber membrane for water treatment

In this work, a piezoelectric electrospun nanofiber membrane (pENM) was prepared to confirm its antifouling ability through the vibrational inducement of fluid instability. For the optimization of the pENM properties, the synthetic conditions (solvent ratio, tip-to-collector distance (TCD), and heat treatment time) were adjusted. The optimized properties were observed at a 5/5 acetone/N-methyl-2-pyrrolidone (NMP) solvent ratio, a TCD of 20cm, and a heat treatment time of 0.5h. The optimized pENM exhibited three times higher water permeability (5573LMH/bar) and rejection performance (99.87%) for particulates than a commercial microfiltration (MF) membrane. The flux decline was reduced by 15% in the presence of a piezoelectric effect when compared to the flux decline in the absence of a piezoelectric effect. This result shows that the pENM has potential for water-treatment applications.

Preparation and Characterization of SnO<sub>2</sub> Nanofibers via Electrospinning

Tin oxide (SnO2) nanofibers are successfully prepared by electrospinning homogeneous viscous solutions of tin acetate in polyvinylpyrrolidone (PVP). The electrospinning is carried out by applying a DC voltage to the tip of a syringe and maintaining the tip to collector distance (TCD), i.e. at DC electric field of 1.25 kV•cm–1. The electrospun nanofibers are calcined between 550℃ and 650℃ for 4 h. Both spun and heat treated nanofibers are characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infra red spectroscopy (FTIR) etc. XRD analysis of calcined nanofibers confirms the formation of pure tin oxide. TEM study showed that fibers have a polycrystalline structure with multiple nano-grains.