Electrospinning Conditions Research Articles

Electrospun Nanofibers Embedded with Copper Oxide Nanoparticles to Improve Antiviral Function.

Many studies on anti-bacterial/antiviral surfaces have been conducted to prevent epidemic spread worldwide. Several nanoparticles such as those composed of silver and copper are known to have antiviral properties. In this study, we developed copper oxide (CuO) nanoparticle-incorporated nanofibers to inactivate or remove viruses. The CuO nanoparticle-incorporated nanofiber was fabricated with a hydrophobic polymer-polyvinylpyrrolidone (PVP)-using electrospinning, and CuO nanoparticles were exposed from the PVP polymer surface by etching the nanofiber with oxygen plasma. The fabrication conditions of electrospinning and oxygen plasma etching were investigated by scanning electron microscopy (SEM), and field emission transmission electron microscopy (FETEM)/ energy dispersive spectrometry (EDS). H1N1 virus was utilized as the target sample and quantified by RT-qPCR. The antiviral efficacy of CuO nanoparticle-incorporated nanofibers was compared against bare CuO nanoparticles. Overall, 70% of the viruses were inactivated after CuO nanoparticle-incorporated nanofibers were incubated with 10² pfu/mL of H1N1 virus solution for 4 h. This indicates that the developed CuO nanoparticle-incorporated nanofibers have noticeable antiviral efficacy. As the developed CuO nanoparticle-incorporated nanofibers exerted promising antiviral effects against H1N1 virus, it is expected to benefit global health by preventing epidemic spread.

Polycaprolactone/Polyethylene Glycol Blended with Dipsacus asper Wall Extract Nanofibers Promote Osteogenic Differentiation of Periodontal Ligament Stem Cells

Dipsacus asper wall (DA) is an ancient Chinese medicinal material that has long been used to maintain the health of human bones. The present study aimed to evaluate the osteogenic differentiation of periodontal ligament stem cells (PDLSCs) of Dipsacus asper wall extracts (DAE). Microwave-assisted alcohol extraction of 100 mesh DA powder under optimal conditions can obtain 58.66% (w/w) yield of the crude extract. PDLSCs have excellent differentiation potential. PDLSCs treated with DA extract (DAE) underwent osteogenesis, exhibiting a higher expression of the Col-1, ALP, Runx2, and OCN genes, and had a 1.4-fold increase in mineralization, demonstrating the potential of DAE to promote osteogenic differentiation. After the addition of PI3K inhibitor LY294002, the expression of osteogenic genes was significantly inhibited, confirming that PI3K is an important pathway for DAE to induce osteogenesis. Mix DAE with polycaprolactone/polyethylene glycol (PCL/PEO) to obtain nanofibers with a diameter of 488 nm under optimal electrospinning conditions. The physical property analysis of nanofibers with and without DAE includes FTIR, mechanical strength, biodegradability, swelling ratio and porosity, and cell compatibility. When cells induced by nanofibers with or without DAE, the mineralization of PDLSCs cultured on PCL/PEO/DAE was 2.6-fold higher than that of PCL/PEO. The results of the study confirm that both DAE and PCL/PEO nanofibers have the effect of promoting osteogenic differentiation. In order to obtain the best induction effect, the optimal amount of DAE can be discussed in future research.

Novel Poly(ester urethane urea)/Polydioxanone Blends: Electrospun Fibrous Meshes and Films.

In this work, we report the electrospinning and mechano-morphological characterizations of scaffolds based on blends of a novel poly(ester urethane urea) (PHH) and poly(dioxanone) (PDO). At the optimized electrospinning conditions, PHH, PDO and blend PHH/PDO in Hexafluroisopropanol (HFIP) solution yielded bead-free non-woven random nanofibers with high porosity and diameter in the range of hundreds of nanometers. The structural, morphological, and biomechanical properties were investigated using Differential Scanning Calorimetry, Scanning Electron Microscopy, Atomic Force Microscopy, and tensile tests. The blended scaffold showed an elastic modulus (~5 MPa) with a combination of the ultimate tensile strength (2 ± 0.5 MPa), and maximum elongation (150% ± 44%) in hydrated conditions, which are comparable to the materials currently being used for soft tissue applications such as skin, native arteries, and cardiac muscles applications. This demonstrates the feasibility of an electrospun PHH/PDO blend for cardiac patches or vascular graft applications that mimic the nanoscale structure and mechanical properties of native tissue.

Electrospinning of cellulose carboxylic esters synthesized under homogeneous conditions: Effects of the ester degree of substitution and acyl group chain length on the morphology of the fabricated mats

The increased awareness about environmental issues has resulted in developing novel materials and sustainable solutions to reduce the dependence on fossil-based products. Herein, cellulose from sisal was derivatized into carboxylic esters (acetate, Ac; butyrate, Bu; and hexanoate, Hx); the produced materials were “shaped” into mats composed of nano- and ultrathin fibers. Our objective was to assess the effects of cellulose ester degree of substitution (DS), low- and high DS, ca. 0.2 and 2.6; the length of the acyl group and the electrospinning flow rate, 45.5 and 65.5 μL/min on the morphology of the fibrous material obtained therefrom. Cellulose was converted into its carboxylic esters under homogeneous conditions using LiCl/N,N-dimethylacetamide solvent, and acid anhydrides as acylating agents. The obtained cellulose- acetate, Cel-Ac, butyrate, Cel-Bu, and hexanoate, Cel-Hx were dissolved in trifluoracetic acid. The solutions of esters were subjected to electrospinning, under positive voltage of 25 kV, and needle-collector distance of 4 cm. Scanning Electron Microscopy of the electrospun mats showed the formation of ultrathin- (100 nm > diameter < 1000 nm) and nanofibers (diameter ≤ 100 nm). No fibers were formed from Cel-Ac of low DS. Lower ester solution flow rate favored the formation of nanofibers from Cel-Ac (DS = 2.7), Cel-Bu (DS = 0.2 and 2.6), and Cel-Hx (DS = 0.2), and ultrathin fibers without beads from Cel-Hx (DS = 2.8). Using a flow rate of 65.5 μL/min favored the formation of ultrathin fibers without beads from Cel-Ac (DS = 2.7), Cel-Bu (DS = 0.2 and 2.6), and Cel-Hx (DS = 0.2, and 2.8). That is, the morphology of the fibers formed can be “fine-tuned” by a judicious choice of the length of the acyl group and the conditions of electrospinning. To the best of our knowledge, this is the first study that the effects of these variables on the morphology of the electrospun fibers were studied. The electrospun mats have potential applications in wastewater treatment, filters for air purification, and tissue engineering scaffolds, to be confirmed by future investigations.

Effects of solution concentration on the synthesis of polyvinylidene fluoride (PVDF) electrospun nanofibers

Recent advances in nanotechnology have witnessed tremendous progress concerning nanofiber synthesis and practical applications. Electrospinning is a simple, versatile, and cost-effective technology that relies on electrostatic repulsions between surface charges to continuously fabricate various scalable assemblies from a wide range of raw materials (polymers, ceramics, nanoparticles, carbon nanomaterials, gels, etc.) with diameters down to macro-nano scale. Nanofibers prepared by electrospinning possess remarkable large and specific surface area to volume ratio, interconnected and tunable structures, diverse morphologies, physio-chemical and mechanical properties. In this paper, Polyvinylidene fluoride (PVDF) nanofibers with different concentrations and under constant electrospinning conditions have been prepared and characterized. The increase of the PVDF polymeric concentration improved the morphological structure of the PVDF nanofibers due to the enhanced molecular chain entanglement which allows the stretching and elongation of the fibers during the electrospinning process. At higher PVDF concentration, the fiber diameters become thinner and beadless nanofiber mats are obtained. Finally, the potential practical applications of electrospun PVDF nanofibers are addressed in this paper.

Effects of preparation parameters on the properties of the crosslinked pectin nanofiber mats

Pectin nanofiber mats prepared with periodate oxidation–electrospinning–adipic acid dihydrazide crosslinking strategy are promising for biomedical applications. In this study, we systematically examined the effects of electrospinning and crosslinking conditions on the properties of pectin nanofiber mats. The properties of mats were tunable in the range of 200–400 nm fiber size, 11–21% ADH residue content, 13–28 times absorbency, 13°–21° contact angle, 2 weeks or longer degradation time, 1.5–2.2 MPa tensile strength, 40–70% elongation, and 0.25–0.27 g/(cm2·24 h) permeability. Increasing polymer concentration, adipic acid dihydrazide amount, time or temperature could increase fiber size and its tensile strength, and decrease the absorbency, hydrophilicity, degradation rate, and elongation. These results indicate that controlling the process parameters can effectively regulate the properties of pectin nanofiber mats and meet the requirements of various biomedical applications.

Effect of electrospinning conditions on β-phase and surface charge potential of PVDF fibers

Electrospun polyvinylidene fluoride (PVDF) fibers, can act as electrets in filtration applications. Relevant to this is the extent at which electrospinning conditions affect the beta-phase content of PVDF fibers. The beta-phase content is a strong factor in measured charge potentials on PVDF fiber mats. PVDF fiber mats were electrospun from three different polymer solution concentrations (10, 14 and 18 wt%) to fabricate mats of three average fiber diameters (328, 780, 1167 nm) respectively and of five different basis weights (10, 20, 30, 40, and 50 g/m2). Furthermore, fiber mat samples were electrospun at varying conditions of applied voltage (21, 24, 27 and 30 kV), solution flow rates (2, 5 and 8 ml/h), needle-tip to collector distances (12, 15, 18, 22 cm) and collector drum rotation speeds (5, 45, 100 rpm) while holding constant the 10 wt% solution concentration and 20 g/m2 mat basis weight. SEM images and FTIR spectra were analyzed to estimate the average fiber diameter and amount of beta-phase content. The apparent surface charge potential was measured using a custom-made Faraday Bucket. The solution compositions, flow rates, and needle-tip distance had moderate effects on fiber diameters and on the beta-phase content. The measured surface potential was found to be directly proportional to beta-phase content. The rotation rate of the drum collector had negligible effect on fiber diameter but did affect the beta-phase and surface potential. The measured surface charge potential was directly proportional to the basis weight and inversely proportional to the fiber diameter.

Ecofriendly development of electrospun antibacterial membranes loaded with silver nanoparticles

Functional polymeric membranes with antibacterial properties have gained significant importance in many applications. Silver NPs offer advantage over other materials for their effective antibacterial properties and being safer for humans at low concentrations. The synthesis of silver NPs may not always be environmental friendly and their incorporation in the polymer membranes is usually a multistep process. In this study, PVDF/PVP/AgNPs electrospun membranes were developed in a single step process where silver NPs were synthesized using reducing and stabilizing properties of PVP. The UV-vis spectroscopy confirmed the synthesis of silver NPs in PVP solution by sharp absorption peak at 398 nm. The membranes were loaded with various concentrations of silver NPs (1, 1.5, 2 and 2.5 wt%). The scanning electron microscopy of the developed membranes showed nano fibers of uniform diameter at optimized electrospinning conditions. FTIR spectroscopy also confirmed the successful development of polymeric composite (PVDF/PVP/AgNPs) membranes. The composite membranes demonstrated effective antibacterial properties against Staphylococcus aureus in disk diffusion test. The size of the inhibition halo increased with the concentration of the silver NPs in electrospun membranes. The findings of this study will be helpful in the simple and environmentally friendly development of antibacterial membranes for applications such as air and water filtration.

Production of Styrene-[Ethylene-(Ethylene-Propylene)]-Styrene Block Copolymer (SEEPS) Microfibers by Electrospinning

Thermoplastic elastomer-based fibers have many advantages including lightness, flexibility, resilience. Styrene-[ethylene-(ethylene-propylene)]-styrene (SEEPS) is a styrenic block copolymer based thermoplastic elastomer and it can be used for many applications with many functions as a matrix, compatibilizer, modifier or adhesive. It has good resistance to oxidizing agents, weathering, aging, and it can be used under various conditions. In this study, SEEPS block copolymer fibers were electrospun. This study is the first study about the electrospinning of SEEPS block copolymer in the literature. Various spinning solutions were used, and process was optimized by changing the electrospinning conditions. Fiber morphology was analyzed by an optical microscope and fiber diameter distribution histograms were drawn. In order to understand the effects of polymer concentration on electrospinning, viscosity of the spinning solutions was measured. Although electrospinning conditions were found to be critical in terms of spinnability, solution concentration and viscosity were the most significant factors for obtaining flexible SEEPS based fibrous nonwoven mats.

Fabrication and Characterization of Electrospun Poly(acrylonitrile-co-Methyl Acrylate)/Lignin Nanofibers: Effects of Lignin Type and Total Polymer Concentration.

Lignin macromolecules are potential precursor materials for producing electrospun nanofibers for composite applications. However, little is known about the effect of lignin type and blend ratios with synthetic polymers. This study analyzed blends of poly(acrylonitrile-co-methyl acrylate) (PAN-MA) with two types of commercially available lignin, low sulfonate (LSL) and alkali, kraft lignin (AL), in DMF solvent. The electrospinning and polymer blend solution conditions were optimized to produce thermally stable, smooth lignin-based nanofibers with total polymer content of up to 20 wt % in solution and a 50/50 blend weight ratio. Microscopy studies revealed that AL blends possess good solubility, miscibility, and dispersibility compared to LSL blends. Despite the lignin content or type, rheological studies demonstrated that PAN-MA concentration in solution dictated the blend’s viscosity. Smooth electrospun nanofibers were fabricated using AL depending upon the total polymer content and blend ratio. AL’s addition to PAN-MA did not affect the glass transition or degradation temperatures of the nanofibers compared to neat PAN-MA. We confirmed the presence of each lignin type within PAN-MA nanofibers through infrared spectroscopy. PAN-MA/AL nanofibers possessed similar morphological and thermal properties as PAN-MA; thus, these lignin-based nanofibers can replace PAN in future applications, including production of carbon fibers and supercapacitors.

Polycaprolactone/chitosan core/shell nanofibrous mat fabricated by electrospinning process as carrier for rosuvastatin drug

In this study, for the first time, core/shell nanofibrous mats of polycaprolactone (PCL) and chitosan (CS) as a carrier for the rosuvastatin (RSV) drug were fabricated. To do this, the electrospinning technique using a two-fluid stainless steel coaxial spinneret consisted of two concentrically arranged needles was used. The CS layer as a shell contained 5% (w/w) of the RSV drug. The fabricated nanofibrous mats were characterized by different techniques, including scanning electron microscopy (SEM), atomic force microscopy (AFM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), tensile testing, and hydrophilicity measurements. Then, the fabricated core/shell nanofibrous mats containing the RSV drug as a drug delivery system (DDS) were used to evaluate the in vitro drug release behavior in a typical phosphate-buffered saline (PBS) solution at different pH values (i.e., 4, 6, and 7.4) for 48 h. Moreover, the corresponding drug release mechanism was investigated. To study the cytotoxicity, the viability of the human fibroblast cells exposed to the fabricated DDS was examined. The results showed that under optimum electrospinning conditions, the average diameter of the PCL core was about 120 nm, and the thickness of the CS shell was about 60 nm. Also, the presence of all the components was confirmed in the structure of the fabricated DDS. Moreover, the addition of the RSV drug had no significant effect on the mechanical properties of the PCL/CS core/shell nanofibrous mats. Due to the pH-responsive feature of the CS shell, the RSV drug release from the fabricated DDS showed a reasonable environmental response as the pH value of the PBS solution decreased, the degree of drug release correspondingly increased. It was also found that the prolonged release of the RSV drug from the fabricated DDS followed the Korsmeyer–Peppas kinetic model with the Fickian diffusion mechanism at all the pH conditions. The CS layer enhanced the cytotoxicity and hydrophilicity of the fabricated DDS and led to the controllable drug release behavior, which would provide a beneficial approach for drug delivery technology.

A Comparative Study on the Dissolution of Argema mimosae Silk Fibroin and Fabrication of Films and Nanofibers.

Limited studies have been done on silk fibroins of wild silkworm species owing to their relative insolubility in many solvents. In this study, the solubility of Argema mimosae wild silk fibroin in different salts (LiBr, LiCl, Ca(NO3)2, and CaCl2) dissolved in formic acid under varying temperatures was investigated. The dissolution conditions under which the solubility was optimum were optimized using a central composite design approach. The optimum range for solvation of the fibroin were visualized using contour plots. The influence of temperature and salt concentration were found to significantly influence the solvation of the fibroin. Following the successful dissolution of the fibroin, the regenerated silk fibroin solutions were cast to obtain water insoluble films which were used in investigating optimum electrospinning conditions. Average nanofiber diameters in the 110–141 nm range were obtained under optimum electrospinning conditions. The silk forms were characterized using the FTIR, TGA, XRD, and SEM to understand their properties. The investigations revealed that formic acid—salt solvents were effective in the solvation of the wild silk fibroin. Some of the dissolution conditions induced mild effects on the silk fibroin while others were harsh. Furthermore, processing to nanofibers resulted in the degradation of the β-sheets producing nanofibers rich in α-helices. However, post-treatment using methanol and water vapor were effective in restoring β-sheet crystallinity.

Electroconductive nylon-6/multi-walled carbon nanotube nanocomposite for sodium sensing applications

Developing smart fabric materials that can withstand stress, strain, and bending is a key factor to successful integration into smart clothing. The aims of this study were (1) development and characterization of multiwall carbon nanotube (MWCNT)- based electroconductive materials for sensing applications, (2) optimization of experimental fabrication parameters to sensor response, (3) optimization of experimental fabrication parameters for mechanical properties. Nylon-6/MWCNT nanocomposites have enhanced mechanical and electrical properties which make them an ideal candidate for integration into smart clothing. Nylon-6/MWCNT nanocomposites were fabricated by functionalizing an electrospun Nylon-6 scaffold for selective sodium detection. Selective sodium detection is realized using a calixarene functionalization of the MWCNT and the MWCNT is only responsible for increased charge transfer of the nanocomposite. Initially, three factors were considered for optimization of nylon-6/MWCNT nanocomposite fabrication: nanotube type, nanotube concentration, and the weight percent of nylon in the electrospinning solution. The sensing nanocomposite materials were characterized for the electrical and mechanical properties. The sensitivity of the sensor to changing sodium ion concentration (µA/mM) was optimized for 20wt% nylon-6 nanofiber base functionalized in a solution of 0.5 mg/mL of CNT. The optimized sensor has a nanotube length less than 0.2 µm and fiber diameter ranging between 0.25–0.32 µm. The target-controlled coat weight is 20 GSM (g/m2) for electrospun nylon nanofibers. Secondly, the impact of electrospinning conditions, particularly flow rate, on sensor response was considered. Sensor materials produced at an electrospinning flow rate of 1.0 mL/min had an enhanced stress at break, compared to neat nylon-6, without sacrificing elasticity. Additionally, sensors produced at electrospinning flow rates of 1.0 mL/h maintain their sensor response for approximately 20 stretches with no statistical difference between sensor response of the stretched and unstretched sensors.

Efficient Removal of Lead and Copper from Aqueous Solutions by Using Modified Polyacrylonitrile Nanofiber Membranes

The performance of the prepared polyacrylonitrile (PAN) nanofiber membrane by electrospinning process for the removal of lead and copper ions from aqueous solutions was investigated. The optimum electrospinning conditions were obtained to be 14 wt% concentration, 20 kV voltages, 120 mm tips to collector distance and 0.8 ml h−1 flow rate. Chemical functionalities were grafted by a two steps grafting process which involves hydrolysis and chemical modification with ethyleneglycol (EG), ethylenediamine (EDA), diethylenetriamine (DTA). The prepared nanofibers were characterized by Attenuated total reflectance-Fourier transform infrared (ATR-FTIR), Scanning Electron Microscope (SEM), Atomic Force Microscopy (AFM), UV-Visible Spectrophotometer and Energy Dispersive X-ray Spectroscopy (EDS or EDX) analysis. The adsorption capacity of Cu2+ and Pb2+ ions on modified PAN nanofiber mats were evaluated by atomic absorption spectroscopy (AAS). Adsorption isotherms were used to find the model of the adsorption behavior and to calculate the removal percentage. The results show that modified nanofibers with ethylenediamine have the maximum adsorption capacity about of 22.954 mmol/gr and 12.367 mmol/gr for Cu2+ and Pb2+ ions, respectively. Therefore, these modified nanofibers open up delighted opportunities for the efficient removal of Pb2+ and Cu2+ from aqueous solutions.

Electrospun porous bilayer nano-fibrous fish collagen/PCL bio-composite scaffolds with covalently cross-linked chitooligosaccharides for full-thickness wound-healing applications

The development of tissue-engineered biodegradable artificial tissue substitutes with extracellular matrix-mimicking properties that govern the interaction between the material and biological environment is of great interest in wound-healing applications. In the present study, novel bilayer nanofibrous scaffolds composed of fish collagen (FC) and poly(ε-caprolactone) (PCL) were fabricated using electrospinning, with the covalent attachment of chitooligosaccharides (COS) via carbodiimide chemistry. The architecture and fiber diameter of the non-cross-linked nanofibrous scaffolds remained consistent irrespective of the polymer ratio under different electrospinning conditions, but the fiber diameter changed after cross-linking in association with the FC content. Fourier-transform infrared spectroscopy analysis indicated that the blend of biomaterials was homogenous, with an increase in COS levels with increasing FC content in the nanofibrous scaffolds. Based on cytocompatibility analysis (i.e., the cellular response to the nanofibrous scaffolds and their interaction), the nanofibrous scaffolds with high FC content were functionally active in response to normal human dermal fibroblast‑neonatal (NHDF-neo) and HaCaT keratinocyte cells, leading to the generation of a very effective tissue-engineered implant for full-thickness wound-healing applications. In addition to these empirical results, an assessment of the hydrophilicity, swelling, and mechanical integrity of the proposed COS-containing FC-rich FC/PCL (FCP) nanofibrous scaffolds confirmed that they have significant potential for use as tissue-engineered skin implants for rapid skin regeneration.

Electrospun Gelatin Fiber Mats Mixed With C.carandas Extract and its Enhanced Stability and Bioactivity.

Crude C.carandas fruits ethanol extract (CCE) constituents important bioactive compounds such as phenolics, flavonoids, and vitamin C. Its biological activities include anti-inflammatory, antioxidant, antibacterial, etc. The present work was carried out to study the optimal conditions for fabricating electrospun gelatin fiber mats (GFM) loaded with CCE (CCE-GFM) and to evaluate the release capacity and stability of these bioactive compounds loaded into GFM. The optimal conditions for electrospinning GFM were the electrospinning 30% (w/v) gelatin solution prepared in 25% (v/v) ethanol solution containing 30% (v/v) acetic acid, under the fixed electrostatic field strength of 20kV and at a distance between noodle tip and ground of 15cm. The feed rate of an electrospinning solution was 1.5mL/h. The electrospun gelatin fibers were smooth and continuous under the optimized electrospinning conditions, with an average diameter of 235.69±10.45nm. Additionally, at the loading of 15% (w/w) CCE in GFM, CCE-GFM exhibited the highest DPPH radical scavenging activity with 88.22±2.62% and the highest tyrosinase inhibitory activity with 38.17±1.86%. Compared with free CCE, CCE-GFM was more thermally stable upon the heating and cooling cycle testing. CCE-GFM had the percent reductions in total contents of phenolics, flavonoids and vitamin C togethering with the percent reductions of DPPH scavenging and anti-tyrosinase activities slower than pure CCE had. Furthermore, the drug release efficiency from CCE-GFM of 15% (w/w) CCE loading that was tested using modified Franz diffusion cell in an acetate buffer solution of pH 5.5 was 30%. CCE-GFM has shown the potential to utilize a facial mask sheet containing CCE valuable in high antioxidant activity for cosmetic applications.

Electrospun PGS/PCL, PLLA/PCL, PLGA/PCL and pure PCL scaffolds for retinal progenitor cell cultivation

Recent advances in cell transplantation technologies have shown that polymeric fibrous tissue-engineered scaffolds provide a suitable physical environment, including the structural support, for cell delivery and effectively mimic the transplanted cells’ extracellular matrix. Our study investigates the structure, composition and properties of three most commonly used polyester-based biopolymer materials blended with poly(ε-caprolactone) (PCL) at 2:1 (wt.%) ratio, namely, poly(glycerol sebacate) (PGS)/PCL, polylactic-co-glycolic acid (PLGA)/PCL, poly-l-lactide (PLLA)/PCL and pure PCL as carrier vehicles for retinal progenitor cell (RPC) attachment and RPC proliferation. The physicochemical properties of PGS/PCL, PLLA/PCL, PLGA/PCL and pure PCL fibrous scaffolds, fabricated under the identical electrospinning conditions, were analysed employing scanning electron microscopy, contact angle analysis, Raman spectroscopy, electrical and ionic conductivity measurements, and supplemented by an in-vitro RPC adhesion and proliferation studies. Our findings have shown that PGS/PCL scaffolds promote RPC attachment and RPC proliferation more favourably compared to other polymeric blends and pure PCL, owing to a combination of advantageous surface and bulk properties, overall demonstrating a potential for PGS/PCL blend to become a suitable vehicle for RPC delivery in a possible future clinical therapy for the treatment of retinal degenerative disorders.

Electrospun Nanofibers for Applications in Energy Harvesting and Generation

Nanofibers have long been exploited as a versatile, attractive material compared to their bulk counterparts due to their exceptionally high specific surface area and aspect ratio, highly porous structure, and wide range of materials that can be used for synthesis. Such unique properties helped exhibit their potential in a variety of applications in areas of energy, healthcare, and environment. Applications in energy are widely studied especially because of the global need for a source of energy and method of energy production that is alternative to the combustion of fossil fuels, as it presents many environmental drawbacks, which ultimately lead to adverse health effects on humans. To bypass the use of fossil fuels, renewable sources such as wind, hydro, geothermal, and solar energy have been introduced; devices that take advantage of alternative sources of energy such as nanogenerators, fuel cells, and thermoelectric generators have been developed.In this work, hybrid nanofibers were fabricated with precise control of the working parameters to fine tune their properties for various applications, including piezoelectrics and enzymatic fuel cell electrodes. Pure polyacrylonitrile (PAN) nanofibers were first electrospun based on a series of design of experiments to minimize both the diameter and beading. By correlating the solution, electrospinning, and environmental conditions to the resulting solution and nanofiber properties, it was found that not only physical properties such as electrical conductivity but also electrochemical properties of the nanofibers could be controlled. Physical and electrochemical properties of porous carbonaceous nanofibers derived from PAN, zinc acetate and multi-walled carbon nanotubes were studied with SEM, 4-point probe measurement, CV, LSV, and EIS. Based on the electroanalytical methods, the best nanofiber mats were chosen and used as electrodes to immobilize multienzyme cascade systems, a concept of which was demonstrated with a glucose oxidase-BglA bienzymatic system on a customized DNA scaffold as the anodic biocatalyst.

High recovery, point‐of‐collection plasma separation from blood using electrospun polyacrylonitrile membranes

AbstractMicrovolume blood collection technologies are of intense interest in healthcare. Whereas dried blood spots collect all the blood components, the majority of clinical tests are performed on the noncellular, plasma component of blood. Thus, there is a critical need for a robust plasma‐collecting device, which can stabilize biomarkers of interest for clinical analysis. A dried plasma spot, which consists of a separation membrane for removing red blood cells (RBC) while avoiding cell lysis and an absorbing layer for collecting and stabilizing plasma biomarkers after separation may provide such a solution. We report a novel use of electrospun polyacrylonitrile membranes to achieve a very promising separation of RBCs with near‐zero retention of human albumin protein (MW: 66.5 kDa). Physicochemical qualities of the separation membranes can be further optimized through doping and refinement of electrospinning conditions. The membranes may have future potential in microvolume sample collecting applications.

Multilayered electrospinning strategy for increasing the bioaccessibility of lycopene in gelatin-based sub-micron fiber structures

The main drawback of gelatin nano- and sub-micron fibers for delivery of lipophilic compounds such as lycopene is its quick dissolving in the oral phase. Herein, electrospinning is used to design a multilayer sandwich structure to enhance the bioaccessibility of lycopene in the target site, small intestine. For this purpose, the gelatin layers loaded with 0.05 and 0.075% (w/w) lycopene were sandwiched between the two layers of the hydrophobic electrospun proteins of zein. The rheological, physicochemical and bioaccessibility properties of the designed solutions and spun samples were comprehensively studied. The most favorable conditions for electrospinning of each layer were selected and judged by the morphological, fiber diameter distributions, production efficiency and particularly higher protection of lycopene. The encapsulation efficiencies of lycopene for the sandwich samples were measured between 83.97 and 90.51% which is in a highly acceptable level. The FTIR and DSC analyses confirmed the presence of lycopene, suggested its chemical or physicochemical interactions with protein. The improvement in the thermal resistance of encapsulated lycopene was also confirmed by DSC experiment. The release behavior of lycopene was evaluated by Kopcha, Peppas-Sahlin and Korsmeyer-Peppas models in the simulated digestive environments whereby a Fickian diffusion assisted with matrix erosion was observed. The fast and higher release of lycopene in the small intestine phase was also seen, so that the highest bioaccessibility reached to the 16.44% for the multilayered sample loaded with 0.075% (w/w) lycopene. These findings show a promising approach for designing safe delivery systems based on electrospun fibers with higher bioaccessibility for lipophilic compounds.