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Abstract Background Electrospinning is a novel technique for producing nanofibres (NF) having food applications. Reported methodologies have implied using non-food-grade compounds or treatments involving toxic solvents which have not been approved by current food-related regulations. Scope and approach This review has been focused on research which fulfilled requirements concerning food-grade compounds. The state of the art regarding electrospinning, its advantages, solution and process conditions and characterisation have been analysed in terms of providing suitable conditions for producing NF (i.e. a regulatory emphasis). The current state of characterisation regarding NF (especially focusing on compounds encapsulated in them). NF encapsulation efficiency regarding human digestion has been studied by in vitro release assays. Nanotechnology normativity worldwide have also been reviewed. Key findings Electrospinning applicability concerning food depends on its composition; a pertinent amount of research has involved using toxic solvents and crosslinking treatment which are not approved by the FDA. It is a novel technique in the food field (little food-related research was found) and operational conditions have encouraged its use. It has been detected that information has been missing regarding NF characterisation methodologies; this has led to the non-reproducibility, non-repeatability and misinterpretation of results. Some recommendations have thus been made. Static NF release models were found; they could provide evidence about the safety. However, dynamic release models are needed for developing clearer regulations concerning nanostructured matrices for food. Even so, many countries have developed norms or made some progress towards creating a normative framework. Finally, trends, applications and novel biopolymers were discussed. Highlights • Overview of food-grade nanofibres with a regulatory framework. • Trends and typical nanofibres characterisations are discussed. • Current state of world in food nanotechnology's normativity. • Novel uses and new biopolymers of nanofibres for food applications. [ABSTRACT FROM AUTHOR]

Fluorescent markers are critical for tracking the position and movement of molecules both in vivo and in vitro. Conventionally, synthetic dyes are non‐covalently added to polymers for fluorescent tracking, but often diffuse away. Here we demonstrate, for the first time, a facile method for the synthesis of fluorescent poly(lactic acid) nano‐/microfibres for biomedical applications using solution spin blowing. Pyrene‐end‐capped poly(l‐lactide) (PLLA) derivatives were synthesised using the ring‐opening polymerisation of l‐lactide and they were characterised using spectroscopic and thermal analyses. Submicrometre‐sized fluorescent fibres were produced from these PLLA derivatives using solution blow spinning techniques generating polymer blends and core–shell fibres. Such system could be further exploited to incorporate electrically conductive carbon allotropes via the pyrene aromaticity, producing fluorescent and electrically active fibres for in vitro monitoring and electrical stimulation. © 2018 Society of Chemical Industry We present an operationally simple method for the synthesis of pyrene‐tagged polylactides which have been fabricated into fibres using operationally simple solution blow spinning techniques. [ABSTRACT FROM AUTHOR]

In this study, limonene was encapsulated by using gelatine, Na-alginate, polyvinyl alcohol, lactalbumin or xanthan gum with the uniaxial electrospinning process. The highest encapsulation efficiency was obtained for the sample containing polyvinyl alcohol. The release kinetic studies of nanofibre encapsulated limonene were carried out at 5.5, 20, and 38.5 °C. The Peppas equation expressed the release behavior of limonene for all systems very well, indicating quasi-Fickian diffusion. The modelling data suggested that maybe more than one mechanism was involved for the release at 20 °C. The activation energy for releasing limonene from the electrospun polyvinyl alcohol-alginate encapsulation system was found to be 6.2 kJ mol–1 from the Arrhenius equation. [ABSTRACT FROM AUTHOR]

Caseins are phosphoproteins found in milk. Compared with proteins and amino acids, casein contains not only amino acid residues but also large quantities of phosphate groups, providing more active sites. In this work, uniform nanofibrous mats were obtained from various blend ratios of casein and polyvinyl alcohol (PVA) solutions by electrospinning. With above aqueous solution, when the casein/PVA mass ratios were 50/50–20/80, electrospinning of nanofibres were possible. The effect of blend ratio, viscosity and applied voltage on morphological appearance and fibre size was studied. Scanning electron microscopy showed that the addition of PVA facilitated the formation beadless nanofibres whose diameter increased with casein concentration in the range between 80 and 300 nm. Fourier transform infrared spectroscopy and X-ray diffraction studies demonstrated intermolecular hydrogen bonding and changes in crystallinity between the molecules of casein and PVA. Thermal analysis using thermo gravimetric analyzer revealed thermal degradation temperature of nanofibrous mat. BET specific surface area and pore volume of casein/PVA nanofibrous mat was measured to be 52.0541 m2/gm and 0.090 cc/gm respectively. Electrospun casein/PVA nanofibrous mat mimicked the natural biomineralization of bone, demonstrating that, it can effectively improve the bioactivity and be useful for hydroxyapatite formation. Thrombin–antithrombin complex human in vitro ELISA assay for Hemostatic activity of casein/PVA nanofibrous mat demonstrated acceleration in hemostatic activity through higher level of thrombin generation and stable blood clot. Hemostatic activity, in vitro biodegradation in proteinase enzyme and swelling characteristics shows that casein/PVA electrospun mat can have potential biomedical application in wound dressing material. [ABSTRACT FROM AUTHOR]

Breaking away from the linear structure of previously reported peptide‐based gelators, this study reports the first example of gel formation based on the use of cyclic peptides made of alternating d‐ and l‐amino acids, known to self‐assemble in solution to form long nanotubes. Herein, a library of cyclic peptides was systemically studied for their gelation properties in various solvents, uncovering key parameters driving both organogel and hydrogel formation. The hierarchical nature of the self‐assembly process in water was characterised by a combination of electron microscopy imaging and small‐angle X‐ray scattering, revealing a porous network of entangled nanofibres composed by the aggregation of several cyclic peptide nanotubes. Rheology measurements then confirmed the formation of soft hydrogels. Getting in formation: This study reports the first example of gel formation based on the use of cyclic peptides made of alternating d‐ and l‐ amino acids, which self‐assemble in solution to form long nanotubes. Herein, a library of cyclic peptides was systemically studied for their gelation properties in various solvents, uncovering key parameters driving both organogel and hydrogel formation. [ABSTRACT FROM AUTHOR]

Summary: Repair of ligaments and tendons requires scaffolds mimicking the spatial organisation of collagen in the natural tissue. Electrospinning is a promising technique to produce nanofibres of both resorbable and biostable polymers with desired structural and morphological features. The aim of this study was to perform high‐resolution x‐ray tomography (XCT) scans of bundles of Nylon6.6, pure PLLA and PLLA‐Collagen blends, where the nanofibres were meant to have a predominant direction. Characterisation was carried out via a dedicated methodology to firmly hold the specimen during the scan and a workflow to quantify the directionality of the nanofibres in the bundle. XCT scans with 0.4 and 1.0 μm voxel size were successfully collected for all bundle compositions. Better image quality was achieved for those bundles formed by thicker nanofibres (i.e. 0.59 μm for pure PLLA), whereas partial volume effect was more pronounced for thinner nanofibres (i.e. 0.26 μm for Nylon6.6). As expected, the nanofibres had a predominant orientation along the axis of the bundles (more than 20% of the nanofibres within 3° and more than 60% within 18° from the bundle axis), with a Gaussian‐like dispersion in the other directions. The directionality assessment was validated by comparison against a similar analysis performed on SEM images: the XCT analysis overestimated the amount of nanofibres very close to the bundle axis, especially for the materials with thinnest nanofibres, but adequately identified the amount of nanofibres within 12°. Lay Description: Repair of ligaments and tendons requires dedicated materials (scaffolds) mimicking the spatial organisation of the collagen (the main material composing such natural tissue). Electrospinning is a promising technique that allows production of fibres with nanometric dimension using high voltage to stretch very tiny drops of polymeric solutions. Electrospinning allows processing both polymers that can be resorbed by the host tissue, and nonresorbable ones, to obtain the desired structural and morphological features by arranging the nanofibres in bundles. The aim of this study was to perform high‐resolution x‐ray computed tomography (XCT) scans of bundles, where the nanofibres were meant to have a predominant direction. The investigation included bundles of different compositions: a biostable polymer (Nylon) and bioresorbable ones (pure Poly‐L‐lactic acid (PLLA) and PLLA‐Collagen blends). The electrospun bundles were produced using a validated method (Sensini et al 2017: https://doi.org/10.1088/1758-5090/aa6204). To this end, we developed a dedicated methodology to scan such small specimens, and a workflow to quantify the directionality of the nanofibres in the bundle. For all the compositions, XCT scans with extremely high resolution (i.e. down to 0.4 μm) were successfully collected. As expected, better images were obtained for those bundles where the nanofibres were thicker than the scanning resolution (i.e. 0.59 μm for pure PLLA). The images of the thinnest nanofibres (i.e. 0.26 μm for Nylon) were poorer because the fibre diameter was smaller than the resolution (partial volume effect). The nanofibres had a predominant orientation along the axis of the bundles (more than 60% of the nanofibres were within 18° from the bundle axis). The nanofibres had a Gaussian‐like dispersion in the other directions. As this is the first time that XCT is used to quantify the directionality of this kind of bundles, the directionality assessment was further validated by comparison against a similar analysis performed on SEM images. Overall, this study has demonstrated the usefulness and reliability of using high‐resolution x‐ray computed tomography (XCT) scans to investigate the morphology of polymeric scaffolds made of electrospun nanofibres. [ABSTRACT FROM AUTHOR]

The plastic and metal pollution accumulating in the marine environment has given many researchers motivation to investigate and provide solutions to this problem. [...]

Immobilisation of cyclodextrin glucanotransferase (CGTase) on nanofibres was demonstrated. CGTase solution (1% v/v) and PVA (8 wt%) solution were mixed followed by electrospinning (−9 kV, 3 h). CGTase/PVA nanofibres with an average diameter of 176 ± 46 nm were successfully produced. The nanofibres that consist of immobilised CGTase were crosslinked with glutaraldehyde vapour. A CGTase/PVA film made up from the same mixture and treated the same way was used as a control experiment. The immobilised CGTase on nanofibres showed superior performance with nearly a 2.5 fold higher enzyme loading and 31% higher enzyme activity in comparison with the film.

The authors report a facile approach to high‐purity carbon nanofibres (CNFs), by performing chemical vapour deposition on aluminium foils loaded with metal (nickel or cobalt) nitrates, and then peeling the as‐grown CNFs off. The growth of CNFs was catalysed by metal nanoparticles and followed bottom‐growth mechanism, and the high‐purity CNFs were achieved due to detachment of CNFs from their underlying metal nanoparticles during the peeling process. This approach may pave a new way for the controlled and scalable synthesis of high‐purity carbon materials. [ABSTRACT FROM AUTHOR]

A thermally activated shape memory polymer based on the mixture of polycaprolactone (PCL) and polydimethylsiloxane (PDMS) was fabricated into the nanofibre mesh using the electrospinning process. The added percentages of the PDMS segment in the PCL-based polymer influenced the mechanical properties. Polycaprolactone serves as a switching segment to adjust the melting temperature of the shape memory electro-spun PCL–PDMS scaffolds to our body temperature at around 37 °C. Three electro-spun PCL–PDMS copolymer nanofibre samples, including PCL6–PDMS4, PCL7–PDMS3 and PCL8–PDMS2, were characterised to study the thermal and mechanical properties along with the shape memory responses. The results from the experiment showed that the PCL switching segment ratio determines the crystallinity of the copolymer nanofibres, where a higher PCL ratio results in a higher degree of crystallinity. In contrast, the results showed that the mechanical properties of the copolymer samples decreased with the PCL composition ratio. After five thermomechanical cycles, the fabricated copolymer nanofibres exhibited excellent shape memory properties with 98% shape fixity and above 100% recovery ratio. Moreover, biological experiments were applied to evaluate the biocompatibility of the fabricated PCL–PDMS nanofibre mesh. Owing to the thermally activated shape memory performance, the electro-spun PCL–PDMS fibrous mesh has a high potential for biomedical applications such as medical shrinkable tubing and wire.

The extensive and sometimes unregulated use of synthetic chemicals, such as drugs, preservatives, and pesticides, is posing big threats to global health, the environment, and food security. This has stimulated the research of new strategies to deal with bacterial infections in animals and humans and to eradicate pests. Plant extracts, particularly essential oils, have recently emerged as valid alternatives to synthetic drugs, due to their properties which include antibacterial, antifungal, anti-inflammatory, antioxidant, and insecticidal activity. This review discusses the current research on the use of electrospinning to encapsulate essential oils into polymeric nanofibres and achieve controlled release of these bioactive compounds, while protecting them from degradation. The works here analysed demonstrate that the electrospinning process is an effective strategy to preserve the properties of essential oils and create bioactive membranes for biomedical, pharmaceutical, and food packaging applications.

In this study, sodium alginate (SA) nanofibres were obtained by electrospinning via the assistance of traditional poly(ethyl oxide) (PEO) and dimethyl sulfoxide (DMSO) with a high SA/PEO ratio of up to 94:6. However, surfactants with more or less toxicities were replaced by nontoxic and fluorescent carbon dots (CDs) to improve spinnability. Experimental details were conducted by fixing the ratio of SA/PEO to 90:10. Then, the electrospinning products of solutions with different compositions were observed with scanning electron microscopy. Properties such as conductivity, surface tension and rheology of the solutions were investigated to determine the key influencing factors. Moreover, since CDs have excellent fluorescence properties, the fluorescent properties of the nanofibre membrane that was blended with CDs were then collected. In addition, in vitro cytotoxicity assessment of the nanofibres were conducted to evaluate the toxicities and biocompatibility.

The use of surface engineering techniques to tune-up the composition of nanostructured thin-films for developing functional coatings with advanced properties is a hot topic within the scientific community. The control of the coating structure at the nanoscale level allows improving the intrinsic properties of the surface compared to bulk materials. A nanodeposition technique with increasing popularity in the field of nanotechnology is electrospinning. This technique permits the fabrication of long and continuous fibres on the micro-nano scale. The good control over fibre morphology combined with its simplicity, cost-effectiveness, easy exploitability and scalability make electrospinning a very interesting tool for technological applications. This review is focused on the use of the electrospinning technique to protect metallic surfaces against corrosion. Polymeric precursors, from natural or biodegradable to synthetic polymers and copolymers can be electrospun with an adequate control of the operational deposition parameters (applied voltage, flow rate, distance tip to collector) and the intrinsic properties of the polymeric precursor (concentration, viscosity, solvent). The electrospun fibres can be used as an efficient alternative to encapsulate corrosion inhibitors of different nature (inorganic or organic) as well as self-healing agents which can be released to reduce the corrosion rate in the metallic surfaces.

Poly(2-oxazoline) (POx) matrices in the form of non-woven fibrous mats and three-dimensional moulds were obtained by electrospinning and fused deposition modelling (FDM), respectively. To obtain these materials, poly(2-isopropyl-2-oxazoline) (PiPrOx) and gradient copolymers of 2-isopropyl- with 2-n-propyl-2-oxazoline (P(iPrOx-nPrOx)), with relatively low molar masses and low dispersity values, were processed. The conditions for the electrospinning of POx were optimised for both water and the organic solvent. Also, the FDM conditions for the fabrication of POx multi-layer moulds of cylindrical or cubical shape were optimised. The properties of the POx after electrospinning and extrusion from melt were determined. The molar mass of all (co)poly(2-oxazoline)s did not change after electrospinning. Also, FDM did not influence the molar masses of the (co)polymers; however, the long processing of the material caused degradation and an increase in molar mass dispersity. The thermal properties changed significantly after processing of POx what was monitored by increase in enthalpy of exo- and endothermic peaks in differential scanning calorimetry (DSC) curve. The influence of the processing conditions on the structure and properties of the final material were evaluated having in a mind their potential application as scaffolds.

Over the past decades, electrospinning of biopolymers down to nanoscale garnered much interest to address most of the millennia issues related to water treatment. The fabrication of these nanostructured membranes added a new dimension to the current nanotechnologies where a wide range of materials can be processed to their nanosize. Electrospinning is a simple and versatile technique to fabricate unique nanostructured membranes with fascinating properties for a wide spectrum of applications such as filtration and others. These nanostructured membranes, fabricated by electrospinning, were found to be of a paramount importance because of their advanced inherited properties such as large surface-to-volume ratio, as well as tuneable porosity, stability, and high permeability. The extensive research conducted on these materials extended the success of electrospinning not only to bio-based polymer nanofibres, but to their hybrids and their derivatives. The technique also created avenues for advanced and massive production of nanofibres. This paper reviews the recent developments in the electrospinning technique. Electrospinning of biopolymers, their blends and functionalization using metals/metal oxides, and the potential applications of electrospun nanofibrous membranes in water filtration are discussed.

This study deals with a comparison of mechanical properties of a conventional yarn and a textile from nanofibres. The conventional yarn represents the textile objects with high degree of orientation of fibres and the textile from nanofibres represents the textile objects with low degree of orientation of fibres. The theoretical section is concerned with the issue of internal structure of plied yarn and resulting differences in the orientation and straightening of fibres and in utilisation of deformation properties of fibres in comparison to the referred nano textile. The experimental section describes the manner of realisation of both static and dynamic tests of conventional yarn and strips of nanofibres. The results show differences in the mechanical properties of conventional yarn and textile strip from nanofibres under static and dynamic loading conditions. The processing technology of conventional yarn has been verified in the long term. But textiles from nanofibres are a relatively new material and mechanical properties of the detected differences point out possible problems with their behaviour during standard technological processes.

Electrospinning is remarkably a simple and versatile method for producing nanofibres. The diameter of nanofibres can vary from 10 nm to >1000 nm. In electrospinning, most of the attention is focused on producing fibres with a uniform diameter. It is very important to understand how the diameter and its distribution vary with the materials used and the processing parameters. An analysis of literature sources has shown that the distribution curves of the diameters obtained are very complex and do not resemble normal distributions, while they do more closely correspond to those of compound distributions. The goal of this article is to analyse the distributions of the nanofibre diameters and to propose a new method for the evaluation process of nanofibres and the quality of a nanofibre web. The uniformity of structure and the quality of nanofibres web must be described by average values. The peaks of modal values and the percentage quantity of them must be used for evaluation of a web structure.

Electrospun nanofibrous membranes of natural polymers, such as gelatin, are fundamental in the design of regenerative devices. Crosslinking of electrospun fibres from gelatin is required to prevent dissolution in water, to retain the original nanofibre morphology after immersion in water, and to improve the thermal and mechanical properties, although this is still challenging to accomplish in a controlled fashion. In this study, we have investigated the scalable manufacture and structural stability in aqueous environment of a UV-cured nanofibrous membrane fabricated by free surface electrospinning (FSES) of aqueous solutions containing vinylbenzylated gelatin and poly( ɛ -caprolactone) dimethacrylate (PCL-DMA). Vinylbenzylated gelatin was obtained via chemical functionalisation with photopolymerisable 4-vinylbenzyl chloride (4VBC) groups, so that the gelatin and PCL phase in electrospun fibres were integrated in a covalent UV-cured co-network at the molecular scale, rather than being simply physically mixed. Aqueous solutions of acetic acid (90 vol%) were employed at room temperature to dissolve gelatin-4VBC (G-4VBC) and PCL-DMA with two molar ratios between 4VBC and DMA functions, whilst viscosity, surface tension and electrical conductivity of resulting electrospinning solutions were characterised. Following successful FSES, electrospun nanofibrous samples were UV-cured using Irgacure I2959 as radical photo-initiator and 1-Heptanol as water-immiscible photo-initiator carrier, resulting in the formation of a water-insoluble, gelatin/PCL covalent co-network. Scanning electron microscopy (SEM), attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy, differential scanning calorimetry (DSC), tensile test, as well as liquid contact angle and swelling measurements were carried out to explore the surface morphology, chemical composition, thermal and mechanical properties, wettability and water holding capacity of the nanofibrous membranes, respectively. UV-cured nanofibrous membranes did not dissolve in water and showed enhanced thermal and mechanical properties, with respect to as-spun samples, indicating the effectiveness of the photo-crosslinking reaction. In addition, UV-cured gelatin/PCL membranes displayed increased structural stability in water with respect to PCL-free samples and were highly tolerated by G292 osteosarcoma cells. These results therefore support the use of PCL-DMA as hydrophobic, biodegradable crosslinker and provide new insight on the scalable design of water-insoluble, mechanical-competent gelatin membranes for healthcare applications. [ABSTRACT FROM AUTHOR]

Water is polluted by the effluents discharged from various industries and some of the pollutants are acids, dyes, heavy metals and nanoparticles. The polluted water bodies lead to the lack of safe drinking water. Hence an efficient method is required to remove the pollutants from the wastewater. Membrane technology is an emerging technology used for water treatment. Among the various membrane fabrication techniques, electrospinning gained popularity because of its large surface area to volume ratio and high porosity. Many polymeric nanofibre membranes have been prepared by using electrospinning technique. Electrospun nanofibre membranes have been extensively studied for the removal of hazardous pollutants from the wastewater. This review paper tells how the electrospinning works to produce nanofibres from polymeric solution, in what ways these polymeric electrospun nanofibre membranes are modified and by which mechanism the electrospun polymeric nanofibre membranes removes or degrades the pollutants from the water. [ABSTRACT FROM AUTHOR]

The combination of double layer capacitor and pseudocapacitor materials are the next generation composites for energy storage. Nitrogen enriched species like metal phthalocyanines with metal redox centres may be combined with electrical double layer capacitive carbon materials for improved charge storage. We have explored electrochemical capacitance applications of nickel phthalocyanine (NiPc) nanofibres and its composite with reduced graphene oxide (rGO) synthesized through simple chemical routes. The composite material exhibits a superior specific capacitance, 223.28 Fg −1 at 1 Ag −1 , four fold higher than the individual components and also good stability over continuous cycling for 1000 cycles. The synergistic effect of NiPc and rGO with excellent physical interface offers less charge transfer resistance and better charge storage capacity. [ABSTRACT FROM AUTHOR]

As a technique, electrospinning has been increasingly utilised for polymer nanofibre production, which has a growing list of advanced applications to which they are being applied. However, commercially scaling the process is challenging, especially when the uniformity of the nanofibres across the bulk of the material is important for the required application. At present, most commercially-scalable systems tend to rely on a drum or cylindrical-style electrode, where a multitude of electrospinning jets are formed with no specific controlled distribution or uniformity over its surface. These electrospinning systems also have the drawback of possessing a varying electrostatic field across the length of the electrode, resulting in a range of spinning conditions which result in an inconsistency in the produced nanofibres. Due to the high centrifugal stresses exerted on the polymer during electrospinning, controlling the electrostatic field is crucial for consistent nanofibre production, which forms the basis for applications such as cellular scaffolds and smart materials. In the work reported here, we utilise computational simulation to explore a range of electrode designs to achieve a large area electrospinning system with a balanced electrostatic field across its entire active surface. We demonstrate the output by producing a high-throughput of nanofibres with comparable properties to that of a traditional single spinneret system, but at a processing rate two orders of magnitude faster. [ABSTRACT FROM AUTHOR]

Poly (ɛ‐caprolactone)–chitosan–poly (vinyl alcohol) (PCL: Cs: PVA) nanofibrous blend scaffolds were known as useful materials for skin wound healing and would help the healing process about 50% faster at the final time point. From the previous studies by the authors, PCL: Cs: PVA (in 2: 1: 1.5 mass ratio) nanofibres showed high efficacy in healing on rat models. In this study, the scaffolds were examined in burn and excision wounds healing on dogs as bigger models. The scaffolds were applied on dorsum skin wounds (n = 5) then macroscopic and microscopic investigations were carried out to measure the wounds areas and to track healing rate, respectively. Macroscopic results showed good aspect healing effect of scaffolds compared with control wounds especially after 21 days post‐operating for both cutting and burn wounds. Pathological studies showed that the healing rates of the wounds covered with PCL: Cs: PVA nanofibrous scaffolds were much rapid compared to untreated wounds in control group. The immunogenicity of the scaffolds in canine model was also investigated. The findings showed that nanofibrous blend scaffolds was not immunogenic in humoural immune responses. All these results indicated that PCL: Cs: PVA nanofibrous web could be considered as promising materials for wounds healings. [ABSTRACT FROM AUTHOR]

In this study, the authors report a simple fabrication of thermoplastic polyurethane (TPU) nanofibres‐based kit for cholesterol detection. TPU is a polymer that is highly elastic, resistant to microorganisms, abrasion and compatible with blood; thus, making it a natural selection as an immobilisation matrix for cholesterol oxidase (ChOx) enzyme. The nanofibre was fabricated by electrospinning process and was characterised using scanning electron microscopy and Fourier transform‐infrared spectroscopy. ChOx was covalently immobilised on TPU nanofibre and cholesterol level/concentration was visually found using 4‐aminoantipyrine, a dye that reacts with H2 O2 produced from the oxidation of cholesterol by ChOx and changes colour from yellow to red. The efficacy of the nanofibre to act as a detecting substrate was compared with cellulose acetate (CA) membrane, a well‐documented enzyme immobilisation matrix. The optimisation of enzyme concentration and dye quantity were performed using standard ChOx spectrophotometric assay and the same was used in CA membrane and TPU nanofibre. The ChOx immobilised nanofibre showed good linear range from 2 to 10 mM with a lower detection limit of 2 mM and was highly stable compared to that of CA membrane. The enzyme immobilised nanofibre was further validated in serum samples. [ABSTRACT FROM AUTHOR]

The physical strength of the collagen fibre network in the extracellular matrix is due to the covalent crosslinks between the molecules within the fibres (intra-fibrillar crosslinks). Citric acid was investigated as an agent to introduce crosslinks within marine collagen electrospun fibres. We used collagen films to understand the ideal conditions for citric acid crosslinking. This information was used to develop an optimised method for intra-fibrillar crosslinking in electrospun marine collagen fibres, which increased the stability of these fibres in aqueous environments. The optimised method included a spinning solution containing collagen and citric acid at pH 3.5 at high concentrations (260:1 citric acid:collagen molar ratio) coupled with high temperature annealing (165 °C), which resulted in the highest intra-fibrillar crosslinking density in electrospun fibres. [ABSTRACT FROM AUTHOR]

Tendon tears are a relevant concern for today’s national health systems because of their social impact and high recurrence rate. The current gold standard for fixing tendon tears is surgical repair; however, this strategy is not able to fully re-establish tendon integrity and functionality. Tissue engineering approaches aim at promoting tissue regeneration by delivering the opportune signals to the injured site combining biomaterials, cells and biochemical cues. Electrospinning is currently one of the most versatile polymer processing techniques that allows manufacturing of nano- and micro-fibres substrates. Such fibrous morphology is deemed to be an ideal substrate to convey topographical cues to cells. Here we evaluated the potential of polycaprolactone processed by means of electrospinning technology for tendon tissue engineering. Fibrous free-of-defects substrate with random and aligned fibres were successfully fabricated. Rat tenocytes were used to assess the cytocompatibility of the substrates for application as tendon tissue engineered devices. Tenocytes were able to proliferate and adapt to the substrates topography acquiring an elongated morphology, which is the precondition for oriented collagen deposition, when seeded on aligned fibres. Real time Polymerase Chain Reaction (Rt-PCR) also revealed the overall maintenance of tenocyte phenotype over 7 days culture. To verify suitability for in vivo implantation, the level of inflammatory cytokine genes expressed by THP-1 cells cultured in presence of electrospun polycaprolactone substrates was evaluated. Inflammatory response was limited. The novel preliminary in vitro work presented herein showing tenocytes compatibility and limited inflammatory cytokines synthesis suggests that electrospun polycaprolactone may be taken into consideration as substrate for tendon healing applications. [ABSTRACT FROM AUTHOR]

Cellulose acetate (CA) is an interesting material due to its wide spectrum of utilities across different domains ranging from absorbent to membrane filters. In this study, polystyrene (PS) nanofibres, and cellulose acetate/polystyrene (CA/PS) blend nanofibres with various ratios of CA: PS from 20: 80 to 80: 20 were fabricated by using electrospinning technique. The SEM images show that the nanofibres exhibited non-uniform and random orientation with the average fibre diameter in the range of 100 to 800 nm. It was found that the incorporation of PS had a great effect on the morphology of nanofibre. At high proportion of PS, no or less beaded CA/PS nanofibres were formed. Thermal properties of the composite nanofibres were investigated by using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) techniques. The TGA results showed thermal stability of CA/PS nanofibres were higher than pristine CA. [ABSTRACT FROM AUTHOR]

The rheological properties in question are influenced by many factors, ranging from the characteristics of the given polymer or solvent to the flowing conditions. The primary focus of this study is to analyse the rheological behaviour of poly(vinyl butyral)—Mowital B 60H—(PVB) solutions dissolved in methanol and a blend of these with fumed silica nanoparticles. The preparation of the nanofibrous web and the quality of nanofibres were correlated with the rheology of the polymer solution. It was discerned that drastically intensifying shear viscosity and the elasticity of the solution exerted a negligible effect on the formation of fibres, a finding which has rarely been discussed in the literature. The morphologies and structures of the PVB/silica nanofibrous membranes were investigated by scanning electron microscopy, thermogravimetric analysis and Fourier transform infrared spectroscopy. [ABSTRACT FROM AUTHOR]

The aim of this study was to fabricate propranolol hydrochloride (Prop. HCl) (as a water-soluble drug):Eudragit® RS100 (Eud) nanobeads and nanofibres applying the electrospraying method as an economical and one-step technique. Different ratios of Prop. HCl:Eud (i.e. 1:5 and 1:10) at total solution concentrations of 10-20% W/V were investigated. The FE-SEM studies revealed that morphology and size of the samples were highly affected by the solution concentration; so that, the nanobeads (a mean diameter of 82.9 nm) were formed in low concentration and at the highest concentration of the solution, nanofibres (a mean diameter of 232.3 nm) were resulted. Besides the morphological changes, the size of processed nanoformulations was increased with an increment of the solution concentrations. X-ray diffraction results as well as DSC thermograms clearly indicated that the drug crystallinity decreased in the electrosprayed samples. Furthermore, in vitro dissolution test showed that the electrosprayed samples had relatively slower release patterns toward the pure drug and physical mixtures, where the samples with the drug:polymer ratio of 1:10 indicated a faster release rate toward 1:5 ratio; nevertheless, the concentration of the injected formulations did not remarkably impressed the release behaviours. The current study established the suitability of electrospraying method in the fabrication of the water-soluble drugs nanobeads/nanofibres; however, in vivo effectiveness of the prepared nanoformulations should be meticulously considered. [ABSTRACT FROM AUTHOR]

In recent years, carbon aerogels have attracted much attention in basic research and as potential applications in many fields. Herein, the authors report a novel approach using bamboo powder as raw material to fabricate cellulose nanofibers (CNFs)/multi‐walled carbon nanotubes (MWCNTs) carbon aerogels by a simple dipping and carbonisation process. The developed material exhibits many exciting properties including low density (0.056 g cm−3), high porosity (95%), efficient capability for separation of oily droplets from water, and high adsorption capacity for a variety of oils and organic solvents by up to 110 times its own weight. Furthermore, the CNF/MWCNT carbon aerogels (CMCA) can be recycled many times by distillation and combustion, satisfying the requirements of practical oil‐water separation. Taken together with its economical, environmentally benign manufacturing process, sustainability of the precursor and versatility of material, the CMCA developed in this study will be a promising candidate for addressing the problems arising from the spills of oily compounds. [ABSTRACT FROM AUTHOR]

The process of bone repair and regeneration requires multiple physiological cues including biochemical, electrical and mechanical - that act together to ensure functional recovery. Myriad materials have been explored as bioactive scaffolds to deliver these cues locally to the damage site, amongst these piezoelectric materials have demonstrated significant potential for tissue engineering and regeneration, especially for bone repair. Piezoelectric materials have been widely explored for power generation and harvesting, structural health monitoring, and use in biomedical devices. They have the ability to deform with physiological movements and consequently deliver electrical stimulation to cells or damaged tissue without the need of an external power source. Bone itself is piezoelectric and the charges/potentials it generates in response to mechanical activity are capable of enhancing bone growth. Piezoelectric materials are capable of stimulating the physiological electrical microenvironment, and can play a vital role to stimulate regeneration and repair. This review gives an overview of the association of piezoelectric effect with bone repair, and focuses on state-of-the-art piezoelectric materials (polymers, ceramics and their composites), the fabrication routes to produce piezoelectric scaffolds, and their application in bone repair. Important characteristics of these materials from the perspective of bone tissue engineering are highlighted. Promising upcoming strategies and new piezoelectric materials for this application are presented. Statement of significance Electrical stimulation/electrical microenvironment are known effect the process of bone regeneration by altering the cellular response and are crucial in maintaining tissue functionality. Piezoelectric materials, owing to their capability of generating charges/potentials in response to mechanical deformations, have displayed great potential for fabricating smart stimulatory scaffolds for bone tissue engineering. The growing interest of the scientific community and compelling results of the published research articles has been the motivation of this review article. This article summarizes the significant progress in the field with a focus on the fabrication aspects of piezoelectric materials. The review of both material and cellular aspects on this topic ensures that this paper appeals to both material scientists and tissue engineers. [ABSTRACT FROM AUTHOR]

A halochromic sensor of cellulose acetate nanofibres and alizarin as a fish spoilage indicator in real time is described. The colour of this on-packaging sensor changes visually with an increase in the amount of total volatile basic nitrogen (TVB-N) and a rise in the pH value of product. Rainbow trout fillets were kept at refrigerator temperature (4 °C) for 12 days. TVB-N, pH, total viable count (TVC) and colourimetric tests were performed. Results showed that the pH, the TVB-N and the TVC increased with time. No colour changes were observed within 48 h, but after the fourth day, a very light brick colour on the nanosensor was observed. This colour became darker on the sixth day, representing actual pH changes. The colour of sensor tended towards violet on the 12th day; the colourimetric result proved the expected visual colour change in the electrospun nanosensor due to alizarin usage as a halochromic dye. [ABSTRACT FROM AUTHOR]

There are several signal pathways involved in bone regeneration that can be triggered by several factors including mechanical, physical and chemical factors. Chemical growth factors are commonly used in differentiation induction to stem cells, while have side effects. In this study, inorganic poly-phosphate (poly-P) as a natural-based molecule was used to induce Wnt/β-catenin signalling in adipose-derived mesenchymal stem cells (AT-MSCs) while cultured on 2D and 3D culture systems. Common osteogenic markers were investigated to detect the influence of Wnt/β-catenin signalling induction on osteogenic differentiation of AT-MSCs and signalling genes up regulation was also evaluated by its related gene expression measurement. Results were shown that Cyclin-D1 and β-catenin gene expression was significantly increased in those cells treated by poly-P. Osteogenic differentiation of those stem cells with higher Cyclin-D1 and β-catenin gene expression was significantly higher than other groups except those stem cells cultured under osteogenic medium. According to the results, inorganic poly-P can trigger osteogenic differentiation in stem cells through Wnt/β-catenin signalling and this potential is almost close to common osteogenic growth factors and this could be used as natural-based molecules in bone regeneration, apart from concerns about the use of chemical factors. [ABSTRACT FROM AUTHOR]

The electrospinning technique was used for the nanofiber production of Alyssum lepidium mucilage with acetic acid and polyvinyl alcohol (PVA) polymer. Some parameters such as voltage, polymer concentration, tip‐to‐collector distance, and feed rate were optimised and applied for the fabrication of the nanofiber membranes of the seeds mucilage. The scanning electron microscopy images were used to find the optimised conditions for the electrospinning process. It was found that the aqueous solution of Alyssum mucilage/PVA (80:20), voltage (18 kV), polymer concentration (50%), tip‐to‐collector distance (10 cm) and feed rate (0.125 ml/h) could be successfully used to obtain uniform nanofibers with diameters as low as 139.9 nm. X‐ray diffraction and Fourier transform infrared spectrometer analysis also proved the presence of the alyssum mucilage/PVA nanofiber. In this study, the used electrospun procedure was biodegradable, inexpensive, non‐toxic, and maintainable enough to optimise the mucilage nanofiber fabrication as a new source, thereby improving the potential application of the nanofiber biomembrane in filtration and medical systems with biocompatible and biodegradable properties. [ABSTRACT FROM AUTHOR]

The production of nanofibres (NF) from fresh carrots residue was investigated with a mechanical process without using any pulping or bleaching chemicals. Refining with a PFI mill followed by mechanical fibrillation with a homogenizer was used to produce fine NF. Blanching with hot water was carried out to leach the extractives from carrot fibres prior to refining. The energy required to prepare carrot pulp is one order of magnitude lower than for wood pulp and the fibrillation of nanofibres from carrot residue is four times lower in energy than using wood pulp as feedstock. The average diameter and length of carrot NF are 18 nm and 5.1 μm, respectively. The chemical composition of the manufactured nanofibers, as measured by HPLC, was 53% glucose and 47% xylose. Translucent and strong flexible films were prepared from the carrot NF using a filtration based papermaking process. The strength and water vapor permeability of these carrot NF paper like composites are similar to those derived from wood-fibre of comparable dimensions. [ABSTRACT FROM AUTHOR]

Poly(ε-caprolactone) composite nanofibres for skin tissue engineering and regeneration applications were prepared via electrospinning of poly(ε-caprolactone) nanofibres with bioactive glass nanoparticles at bioactive glass contents of 0, 2, 4, 6 and 8 wt%. The surface properties, water absorptivities, porosities, mechanical properties and biocompatibilities of the composite electrospun nanofibres were characterised in detail. Addition of bioactive glass improved the hydrophilicity and elastic modulus of membranes. The fibre diameter of the neat poly(ε-caprolactone) nanofibres was only 700 nm, but reinforcement with 2, 4, 6 and 8 wt% bioactive glass nanofibres increased the diameter to 1000, 1100, 900 and 800 nm, respectively. The minimum elongation at break of the bioactive glass–reinforced poly(ε-caprolactone) exceeded 100%, which indicated that the composite nanofibres had good mechanical properties. The porosities of the various nanofibres containing different mass loadings of bioactive glass all exceeded 90%. The best performance in terms of cell proliferation and adhesion was found when the bioactive glass mass percent reached 6 wt%. However, higher loadings were unfavourable for cell growth. These preliminary results indicate that poly(ε-caprolactone)/bioactive glass composite nanofibres have promise for skin tissue engineering applications. [ABSTRACT FROM AUTHOR]

The isolated Gluconacetobacter sp. with accession number: KY996741 was assayed for evaluation of phytase activity. It could solubilise sodium phytate in the absence of soluble phosphate with the cells; however, the enzyme was not seen in cell free extract, to the best of their knowledge the intracellular phytase activities of Gluconacetobacter sp. was not reported previously. Also, the potential of in situ immobilisation of cells produced enzyme (/phytase producing bacteria) in bacterial cellulose was investigated and was studied by SEM and AFM. The results showed that the immobilised probiotic cells had the best activity of 1229 U/ml. The optimum temperature of the immobilised enzyme activity was at 45°C (5969 U/ml) and the immobilised phytase maintained 64% of its activities after two repeated cycles. The enzyme needs mild conditions for its activity and has a short life time and low stability and lost activities from 1229 to 500 U/ml during 30 days. However, it was showed that the addition of 1 ppm nano‐ferric oxide particles could promote the phytase activities of immobilised cell from 500 U/ml to >1500 U/ml. This immobilised phytase producing cells on bacterial cellulose can be useful as food and/feed supplement for phytin removal. [ABSTRACT FROM AUTHOR]

In this report, a novel wound dressing material has been woven by electrospinning technique and tested for its various properties. For the nanofibre mat, a mixture of polyurethane (PU) and soy protein isolate (SPI) was electrospun in conjugation with zinc oxide nanoparticles (ZnO Nps) and ciprofloxacin hydrochloride (CipHCl) to produce fibrous mats viz. PU/SPI/ZnO and PU/SPI/CipHCl. An optimum ratio (1 : 1) of PU/SPI was used as suitable polymeric ratio in order to produce homogenous nanofibres without beads having an average diameter in the range of 300–350 nm. The electrospun nanofibre‐based mats were characterised using X‐ray diffraction, Fourier transform infrared spectroscopy, ultraviolet‐visible spectroscopy, thermogravimetric analysis and scanning electron microscope. The mechanical properties of the nanofibrous mats were tested using universal testing machine. The wettability analysis was done using the contact angle measurement based on the sessile drop test. This study revealed that the electrospun PU/SPI‐based nanofibres are non‐sensitizing, non‐allergic and non‐toxic and that it can be used as a peculiar wound healing material. [ABSTRACT FROM AUTHOR]

The essential amino acid l -tryptophan is naturally present in the body, and is also available as a water soluble dietary supplement. The feasibility of preparing enriched cellulose acetate (CA)-based fibres as a vehicle for therapeutic delivery of such biomolecules was investigated. A new ternary solvent system consisting of acetone: N , N -dimethylacetamide: methanol (2:1:2) has been demonstrated to permit the solution blending of CA with the water soluble l -tryptophan. Nanofibrous webs substantially free of structural defects were continuously produced with mean fibre diameters in the range of 520–1010 nm, dependent on process parameters. Morphology and diameter of fibres were influenced by concentration of CA spinning solution, applied voltage and flow rates. The kinetic release profile of l -tryptophan from electrospun CA nanofibres was described by the pseudo-second order kinetic model. Fibres with mean diameter of 720 nm provide both the highest initial desorption rate and rate constant, which was partially attributed to the low fibre diameter and high relative surface area, but also the fact that the 720 nm fibres produced were the most bead-free, providing diffusion advantages over the fibres with lowest mean diameter (520 nm). The feasibility of combining l -tryptophan within fibres provides a promising route for manufacture of transdermal delivery devices. [ABSTRACT FROM AUTHOR]

Silver nanoparticles-attached zinc oxide (ZnO) nanorods on polyacrylonitrile/indium tin oxide (Ag-ZnO-PAN/ITO) nanofibres with three-dimensional (3D) hierarchical nanostructures were facilely prepared via electrospinning followed by hydrothermal synthesis of ZnO nanorods and silver attachment with the assistance of polydopamine (PDA) thin layer. ZnO nanorods with different dimensions and silver nanoparticles with different loadings were introduced. The morphologies and structures of the nanostructures were studied by scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD) and thermogravimetric analyzer (TGA). The effect of Ag-ZnO-PAN/ITO nanofibres with different loadings of ZnO nanorods and silver nanoparticles on their antibacterial activity against Escherichia coli and Pseudomonas aeruginosa was investigated. It is shown that the hybrid nanofibres exhibit excellent antibacterial capability. The hierarchical structure benefits the attachment of a large amount of silver nanoparticles due to its large surface area, and the deposited PDA thin layer helps improve the structure stability for long-term antibacterial application through firmly anchoring silver nanoparticles onto the surface. This work offers an effective and straightforward “all-solution” strategy to incorporate Ag-ZnO combination into nanofibrous PAN. Moreover, the hierarchical nanostructure integrates the antibacterial function of both ZnO and silver, and renders itself a promising candidate as for sportswear and equipment. [ABSTRACT FROM AUTHOR]

Continuous progress in the methods of preparation of new materials for sensing of toxic gases has attracted considerable interest due to environmental problems. In the present investigation, poly(methylmethacrylate)/polyaniline (PMMA/PANI) blend nanofibres were prepared by electrospinning and dip-coating polymerisation techniques. The semiconducting behaviour of PMMA/PANI blend was found to be highly sensitive for toxic gases like NH3 and HCl at room temperature suggesting the PMMA/PANI blends as a potential material for effective gas sensing in the environmental monitoring safety systems, chemical industry, automotive industry and medical application areas. Fourier transform infrared (FTIR) spectra clearly show the characteristic peaks indicating the presence of quinoid and benzenoid rings of PANI confirming the formation of PMMA/ PANI blend. Clusters of PANI on the uniform fibres of PMMA can be seen in the SEM images. Good thermal stability of PMMA/PANI nanofibres showed to be highly sensitive with fast response and recovery on exposure to NH3 and HCl gases. The phenomenon of increase in sensitivity with the increase in concentration of NH3 and HCl gases was found to be adsorption dominated indicating that the PMMA/PANI blend nanofibres are more sensitive to the surrounding due to their increased porosity and high aspect ratio. The sensing mechanism of PMMA/PANI blend nanofibres on account of more protonation and de-protonation due to exposing towards HCl and NH3 gases respectively is systematically explained in the present investigation. [ABSTRACT FROM AUTHOR]

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In this work, a boronic acid copolymer, poly(4-vinylphenylboronic acid- co -2-(dimethylamino)ethyl methacrylate- co - n -butyl methacrylate) (pVDB) was designed for the rapid detection of bacteria based on reversible boronate ester formation with the diol-rich saccharide moieties found on bacterial membranes. Electrospun nanofibre membranes were prepared from a blend of polyacrylonitrile (PAN) and pVDB, which was synthesized by free radical polymerization. The pVDB@PAN membranes were used as fluorescent bacterial biosensors, displaying a distinct emission at 538 nm when in contact with bacteria cells. The fluorescence intensity showed a maximum intensity after 24 h of contact with Staphyloccocus aureus or Escherichia coli , and this intensity increased proportionally with the pVDB content in the electrospun membranes. When in contact with Pseudomona putida, the membranes became non-responsive within 8 h due to the rapid formation of a bacterial biofilm. This fouling phenomena blocked the membrane surface for fluorescence readings. The pVDB@PAN bionsensor allowed for the rapid detection of the early stages of bacterial colonization well before biofilm formation, which could be advantageous for the early identification of pathogenic bacteria and prevention of their spreading. [ABSTRACT FROM AUTHOR]

A hydrophobic and oleophilic trimethyl chlorosilane/reduced graphene oxide‐coated cellulose nanofibres (TMCS/rGO/CNFs) aerogel with a three‐dimensional structure was fabricated through a facile dip‐coating process. The prepared aerogel exhibited several advantageous properties for absorption and expulsion of oils from water surfaces, such as a high specific surface area, low density (6.78 mg/cm3) and good porosity (99.12％). In addition, the TMCS/rGO/CNFs aerogel demonstrated good absorption capacities up to 39 times its own weight over a short time (1.5 min) for a broad range of oils. This research suggests that practical application of TMCS/rGO/CNFs aerogel in the cleanup of an oil spill is feasible. [ABSTRACT FROM AUTHOR]

A novel method has been proposed to prepare a Nylon/PEG/PAN composite membrane for the improvement of electrospun PAN fibre properties and filtration efficiency. Polyacrylonitrile fibre has been prepared by electrospinning technique. Different proportions of blended mixture of Nylon and PEG are prepared separately. Blended mixture of Nylon and PEG is poured over the electrospun PAN to prepare a Nylon/PEG/PAN composite membrane. The prepared Nylon/PEG/PAN composite membrane and Nylon/PEG membrane are characterized by using optical microscope, porosimeter, X-ray diffractometer and thermogravimetric analysis. Filtration efficiency of the prepared Nylon/PEG/PAN composite membrane is studied using pure water flux and oil water emulsion methods. The 50/50 proportion of Nylon and PEG has been identified for getting uniform and evenly distributed pores and also it shows around 80% of solute rejection, whereas 60/40 proportion shows little bit higher percentage due to higher proportion of Nylon. Thus, the pure water flux of 60/40 and 50/50 PAN/PEG/Nylon membranes met with the recommended pure water flux. [ABSTRACT FROM AUTHOR]

Textile materials with an electrospun nanofibrous web can be used fo ar wide range of applications, including medicine and health care. In this research, polyamide-6 and hyaluronic acid were used for the development of a nanofibrous web via electrospinning. Hyaluronic acid is one of the most interesting ingredients used in skin care. It is very important that the electrospun polyamide-6 nanofibrous structure binds nanoparticles of hyaluronic acid not covering the surface of these particles. The main goal of this work was to develop an electrospun nanofibrous polyamide-6 web with hyaluronic acid which can be used for health care and/or cosmetology A. polyamide-6 nanofibrous web with hyaluronic acid was successfully developed via electrospinning. The presence of hyaluronic acid in the nanoweb was confirmed after web treatment with hot (95%) water. Hyaluronic acid was transported from the spinning solution to the electrospun web, was not isolated from the environment by polyamide-6, and could interact with human skin. [ABSTRACT FROM AUTHOR]

Photocatalysis is considered as an environment-friendly process able to decompose organic pollutants and increasingly applied to water and air purification. Photocatalysts having the morphology of a fibrous layer are attractive candidates for practical applications due to their high structural dimensionality and improved photocatalytic performance. This paper describes the production and characterization of supported TiO nanofibre layers, produced by electrospinning process and deposited on a glass plate via solvent evaporation. The obtained structures were characterized by X-ray diffraction, scanning and transmittance electron microscopies, and ellipsometry. Depending on calcination temperature, fibres contained anatase or anatase and rutile crystal phases of TiO. The supported nanofibres formed a compact but fenestrate layer. The catalytic activity was determined by the decomposition of methylene blue and oxalic acid under UV light. The nanofibre layer proved as a competitive catalyst media based on structural properties and the degradation efficiency of several organic pollutants. Graphical abstract: [ABSTRACT FROM AUTHOR]