A Review: Electrospinning of Biopolymer Nanofibers and their Applications

Fabrication of elastomeric silk fibers

Methods to generate fibers from hydrogels, with control over mechanical properties, fiber diameter, and crystallinity, while retaining cytocompatibility and degradability, would expand options for biomaterials. Here, we exploited features of silk fibroin protein for the formation of tunable silk hydrogel fibers. The biological, chemical, and morphological features inherent to silk were combined with elastomeric properties gained through enzymatic crosslinking of the protein. Postprocessing via methanol and autoclaving provided tunable control of fiber features. Mechanical, optical, and chemical analyses demonstrated control of fiber properties by exploiting the physical cross-links, and generating double network hydrogels consisting of chemical and physical cross-links. Structure and chemical analyses revealed crystallinity from 30 to 50%, modulus from 0.5 to 4 MPa, and ultimate strength 1-5 MPa depending on the processing method. Fabrication and postprocessing combined provided fibers with extensibility from 100 to 400% ultimate strain. Fibers strained to 100% exhibited fourth order birefringence, revealing macroscopic orientation driven by chain mobility. The physical cross-links were influenced in part by the drying rate of fabricated materials, where bound water, packing density, and microstructural homogeneity influenced cross-linking efficiency. The ability to generate robust and versatile hydrogel microfibers is desirable for bottom-up assembly of biological tissues and for broader biomaterial applications.

Modulating Immunological Responses of Electrospun Fibers for Tissue Engineering

The promise of tissue engineering is to improve or restore functions of impaired tissues or organs. However, one of the biggest challenges to its translation to clinical applications is the lack of tissue integration and functionality. The plethora of cellular and molecular events occurring following scaffold implantation is a major bottleneck. Recent studies confirmed that inflammation is a crucial component influencing tissue regeneration. Immuno-modulation or immune-engineering has been proposed as a potential solution to overcome this key challenge in regenerative medicine. In this review, strategies to modify scaffold physicochemical properties through the use of the electrospinning technique to modulate host response and improve scaffold integration will be discussed. Electrospinning, being highly versatile allows the fabrication of ECM-mimicking scaffolds and also offers the possibility to control scaffold properties for instance, tailoring of fiber properties, chemical conjugation or physical adsorption of non-immunogenic materials on the scaffold surface, encapsulating cells or anti-inflammatory molecules within the scaffold. Such electrospun scaffold-based immune-engineering strategies can significantly improve the resulting outcomes of tissue engineering scaffolds.

A novel approach for fabricating highly tunable and fluffy bioinspired 3D poly(vinyl alcohol) (PVA) fiber scaffolds

The excellent biocompatibility, biodegradability and chemo-thermal stability of poly(vinyl alcohol) (PVA) have been harnessed in diverse practical applications. These properties have motivated the fabrication of high performance PVA based nanofibers with adequate control over the micro and nano-architectures and surface chemical interactions. However, the high water solubility and hydrophilicity of the PVA polymer limits the application of the electrospun PVA nanofibers in aqueous environments owing to instantaneous dissolution. In this work, we report a novel yet facile concept for fabricating extremely light, fluffy, insoluble and stable three dimensional (3D) PVA fibrous scaffolds with/without coating for multifunctional purposes. While the solubility, morphology, fiber density and mechanical properties of nanofibers could be tuned by optimizing the cross-linking conditions, the surface chemical reactivity could be readily enhanced by coating with a polydopamine (pDA) bioinspired polymer without compromising the stability and innate properties of the native PVA fiber. The 3D pDA-PVA scaffolds exhibited super dye adsorption and constructive synergistic cell-material interactions by promoting healthy adhesion and viability of the human mesenchymal stem cells (hMSCs) within 3D micro-niches. We foresee the application of tunable PVA 3D as a highly adsorbent material and a scaffold material for tissue regeneration and drug delivery with close consideration of realistic in vivo parameters.

Complex Coacervation: Chemically Stable Fibers Electrospun from Aqueous Polyelectrolyte Solutions

In this study, we provide the first demonstration that aqueous complex coacervates can be electrospun into chemically robust polyelectrolyte complex (PEC) fiber mats. PECs form due to electrostatic complexation between oppositely charged polymers. Here, we exploit the ability of salt to plasticize PECs, thus enabling the electrospinning of solid fibers. Electrospinning solutions were composed of a pair of strong polyelectrolytes, poly(4-styrenesulfonic acid, sodium salt) and poly(diallyldimethylammonium chloride) using potassium bromide as the plasticizing salt. We systematically investigated the effect of salt concentration and electrospinning apparatus parameters on fiber formation. Electrospun PEC fiber mats were stable over a wide range of pH values, ionic strength conditions, and many organic solvents. This study demonstrates that the electrospinning of aqueous complex coacervates can generate chemically robust, free-standing PEC fiber mats while circumventing the reliance on organic solvents, the challenge of working with entangled polyelectrolytes in solution, and the need to chemically cross-link the as-spun fibers. These PEC fiber mats hold potential in applications where environmentally benign fiber mats are imperative, such as tissue engineering scaffolds and water purification technologies.

Flexible and Highly Biocompatible Nanofiber-Based Electrodes for Neural Surface Interfacing

Polyimide (PI)-based electrodes have been widely used as flexible biosensors in implantable device applications for recording biological signals. However, the long-term quality of neural signals obtained from PI-based nerve electrodes tends to decrease due to nerve damage by neural tissue compression, mechanical mismatch, and insufficient fluid exchange between the neural tissue and electrodes. Here, we resolve these problems with a developed PI nanofiber (NF)-based nerve electrode for stable neural signal recording, which can be fabricated via electrospinning and inkjet printing. We demonstrate an NF-based nerve electrode that can be simply fabricated and easily applied due to its high permeability, flexibility, and biocompatibility. Furthermore, the electrode can record stable neural signals for extended periods of time, resulting in decreased mechanical mismatch, neural compression, and contact area. NF-based electrodes with highly flexible and body-fluid-permeable properties could enable future neural interfacing applications.

A nanofibrous electrospun patch to maintain human mesenchymal cell stemness

Mesenchymal stem cells (MSCs) have been extensively investigated in regenerative medicine because of their crucial role in tissue healing. For these properties, they are widely tested in clinical trials, usually injected in cell suspension or in combination with tridimensional scaffolds. However, scaffolds can largely affect the fates of MSCs, inducing a progressive loss of functionality overtime. The ideal scaffold must delay MSCs differentiation until paracrine signals from the host induce their change. Herein, we proposed a nanostructured electrospun gelatin patch as an appropriate environment where human MSCs (hMSCs) can adhere, proliferate, and maintain their stemness. This patch exhibited characteristics of a non-linear elastic material and withstood degradation up to 4 weeks. As compared to culture and expansion in 2D, hMSCs on the patch showed a similar degree of proliferation and better maintained their progenitor properties, as assessed by their superior differentiation capacity towards typical mesenchymal lineages (i.e. osteogenic and chondrogenic). Furthermore, immunohistochemical analysis and longitudinal non-invasive imaging of inflammatory response revealed no sign of foreign body reaction for 3 weeks. In summary, our results demonstrated that our biocompatible patch favored the maintenance of undifferentiated hMSCs for up to 21 days and is an ideal candidate for tridimensional delivery of hMSCs. The present work reports a nanostructured patch gelatin-based able to maintain in vitro hMSCs stemness features. Moreover, hMSCs were able to differentiate toward osteo- and chondrogenic lineages once induces by differentiative media, confirming the ability of this patch to support stem cells for a potential in vivo application. These attractive properties together with the low inflammatory response in vivo make this patch a promising platform in regenerative medicine.

In vitro proliferation and differentiation of human bone marrow mesenchymal stem cells into osteoblasts on nanocomposite scaffolds based on bioactive glass (64SiO2-31CaO-5P2O5)-poly-l-lactic acid nanofibers fabricated by electrospinning method

Electrospinning method was employed for fabrication of SiO₂-CaO-P₂O₅ bioactive glass (BG) nanofibers, poly-l-lactic acid (PLLA) nanofibers and nanocomposite scaffolds fabricated from as-prepared nanofibers. Characterization of the prepared nanofibers and scaffolds by XRD, FTIR, and SEM techniques revealed the formation of nanofibers with mean diameter of about 500nm and fully fibrous scaffolds with porous structure and interconnected pores. The growth, viability and proliferation of cultured human bone marrow mesenchymal stem cells in the fabricated nanofibers and bioactive glass-poly-l-lactic acid (BG-PLLA) nanocomposite scaffolds were studied using various biological assays including MTT, ALP activity, calcium deposit content, Alizarin red staining, and RT-PCR test. Based on the obtained results, incorporation of BG nanofibers in the nanocomposite scaffolds causes the better biological behavior of the scaffolds. In addition, three-dimensional and fibrous-porous structure of the scaffolds further contributes to their improved cell behavior compared to the components.

Polysaccharide Fabrication Platforms and Biocompatibility Assessment as Candidate Wound Dressing Materials

Wound dressings are critical for wound care because they provide a physical barrier between the injury site and outside environment, preventing further damage or infection. Wound dressings also manage and even encourage the wound healing process for proper recovery. Polysaccharide biopolymers are slowly becoming popular as modern wound dressings materials because they are naturally derived, highly abundant, inexpensive, absorbent, non-toxic and non-immunogenic. Polysaccharide biopolymers have also been processed into biomimetic platforms that offer a bioactive component in wound dressings that aid the healing process. This review primarily focuses on the fabrication and biocompatibility assessment of polysaccharide materials. Specifically, fabrication platforms such as electrospun fibers and hydrogels, their fabrication considerations and popular polysaccharides such as chitosan, alginate, and hyaluronic acid among emerging options such as arabinoxylan are discussed. A survey of biocompatibility and bioactive molecule release studies, leveraging polysaccharide's naturally derived properties, is highlighted in the text, while challenges and future directions for wound dressing development using emerging fabrication techniques such as 3D bioprinting are outlined in the conclusion. This paper aims to encourage further investigation and open up new, disruptive avenues for polysaccharides in wound dressing material development.

"Practical" Electrospinning of Biopolymers in Ionic Liquids

To address the need to scale up technologies for electrospinning of biopolymers from ionic liquids to practical volumes, a setup for the multi-needle electrospinning of chitin using the ionic liquid 1-ethyl-3-methylimidazolium acetate, [C₂ mim]-[OAc], was designed, built, and demonstrated. Materials with controllable and high surface area were prepared at the nanoscale using ionic-liquid solutions of high-molecular-weight chitin extracted with the same ionic liquid directly from shrimp shells.

Design of biomimetic cellular scaffolds for co-culture system and their application

The extracellular matrix of most natural tissues comprises various types of cells, including fibroblasts, stem cells, and endothelial cells, which communicate with each other directly or indirectly to regulate matrix production and cell functionality. To engineer multicellular interactions in vitro, co-culture systems have achieved tremendous success achieving a more realistic microenvironment of in vivo metabolism than monoculture system in the past several decades. Recently, the fields of tissue engineering and regenerative medicine have primarily focused on three-dimensional co-culture systems using cellular scaffolds, because of their physical and biological relevance to the extracellular matrix of actual tissues. This review discusses several materials and methods to create co-culture systems, including hydrogels, electrospun fibers, microfluidic devices, and patterning for biomimetic co-culture system and their applications for specific tissue regeneration. Consequently, we believe that culture systems with appropriate physical and biochemical properties should be developed, and direct or indirect cell-cell interactions in the remodeled tissue must be considered to obtain an optimal tissue-specific microenvironment.

Swollen liquid crystals (SLCs): a versatile template for the synthesis of nano structured materials

Swollen liquid crystals (SLCs) are the class of lyotropic liquid crystals (LLCs) that are usually formed by a quaternary mixture of aqueous phase, oil phase, surfactant and cosurfactant.

Synthesis and characterization of PLGA/collagen composite scaffolds as skin substitute produced by electrospinning through two different approaches

Skin damage can occur for many reasons, including burns and injuries, which in extreme cases can even lead to death. Different methods such as electrospinning are used to produce scaffolds used in skin tissue engineering. Natural and synthetic polymers were used in this method. It was observed that the use of both natural and synthetic polymers gives better results for cell culturing rather than using of each material solely. In this study, scaffolds of poly(lactic-co-glycolic acid) and collagen were prepared using coating and common solvent methods. The characteristics of samples were evaluated through scanning electron microscopy, porosimetry, mechanical testing, degradation behavior, and in vitro assays. The mechanical and biocompatibility test results of the scaffold prepared by coating method were better than the other one. However, the degradation rate of the common solvent was nearly five times more than coating sample that leads to cytotoxicity in contact with the skin cells.

Design and criteria of electrospun fibrous scaffolds for the treatment of spinal cord injury

The complex pathophysiology of spinal cord injury may explain the current lack of an effective therapeutic approach for the regeneration of damaged neuronal cells and the recovery of motor functions. Many efforts have been performed to design and develop suitable scaffolds for spinal cord regeneration, keeping in mind that the reconstruction of a pro-regenerative environment is the key challenge for an effective neurogenesis. The aim of this review is to outline the main features of an ideal scaffold, based on biomaterials, produced by the electrospinning technique and intended for the spinal cord regeneration. An overview of the polymers more investigated in the production of neural fibrous scaffolds is also provided.

Electrospun nanofibres in agriculture and the food industry: a review

The interesting characteristics of electrospun nanofibres, such as high surface-to-volume ratio, nanoporosity, and high safety, make them suitable candidates for use in a variety of applications. In the recent decade, electrospun nanofibres have been applied to different potential fields such as filtration, wound dressing, drug delivery, etc. and a significant number of review papers have been published in these fields. However, the use of electrospun nanofibres in agriculture is comparatively novel and is still in its infancy. In this paper, the specific applications of electrospun nanofibres in agriculture and food science, including plant protection using pheromone-loaded nanofibres, plant protection using encapsulation of biocontrol agents, preparation of protective clothes for farm workers, encapsulation of agrochemical materials, deoxyribonucleic acid extraction in agricultural research studies, pre-concentration and measurement of pesticides in crops and environmental samples, preparation of nanobiosensors for pesticide detection, encapsulation of food materials, fabrication of food packaging materials, and filtration of beverage products are reviewed and discussed. This paper may help researchers develop the use of electrospun nanofibres in agriculture and food science to address some serious problems such as the intensive use of pesticides. © 2016 Society of Chemical Industry.

The influence of melt mixing on the stability of cellulose acetate and its carbon nanotube composites

Cellulose derivatives, such as cellulose acetate (CA), are commonly used due to their ease of processing. These polymers present interesting mechanical properties and biodegradability, but low thermal stability under melt processing conditions. Composites of carbon nanotubes (CNTs) and cellulose derivatives are expected to present enhanced properties, depending on the effect of nanotubes on polymer structure and thermal properties. This work aims to investigate the influence of melt mixing on the stability of CA and its CNT composites. Composites with 0 wt%, 0.1 wt% and 0.5 wt% CNTs, as received and functionalized with pyrrolidine groups, were prepared using a batch mixer and an extruder. Chain scission of CA occurred during processing, but the effect was considerably reduced in the presence of CNTs. The incorporation of small amounts of CNTs (with or without functionalization) decreased polymer degradation by thermomechanical effects induced during polymer processing.

Incorporation of Rutin in Electrospun Pullulan/PVA Nanofibers for Novel UV-Resistant Properties

This study aimed to investigate the incorporation of rutin into electrospun pullulan and poly(vinyl alcohol) (PVA) nanofibers to obtain ultraviolet (UV)-resistant properties. The effect of weight ratios between pullulan and PVA, and the addition of rutin on the nanofibers’ morphology and diameters were studied and characterized by scanning electron microscopy (SEM). Fourier transform infrared (FTIR) analysis was utilized to investigate the interaction between pullulan and PVA, as well as with rutin. The results showed that the inclusion of PVA results in the increase in the fiber’s diameter. The addition of rutin had no obvious effect on the fibers’ average diameters when the content of rutin was less than 7.41%. FTIR results indicated that a hydrogen bond formed between pullulan and PVA, also between these polymers and rutin. Moreover, the addition of rutin could enhance the mechanical properties due to its stiff structure and could decrease the transmittance of UVA and UVB to be fewer than 5%; meanwhile, the value of ultraviolet protection factor (UPF) reached more than 40 and 50 when the content of rutin was 4.46% and 5.67%, respectively. Therefore, the electrospun pullulan/PVA/rutin nanofibrous mats showed excellent UV resistance and have potential applications in anti-ultraviolet packaging and dressing materials.

Electrospun fibers based on Arabic, karaya and kondagogu gums

Nanofibers of natural tree polysaccharides based on three gums namely Arabic (GA), karaya (GK) and kondagogu (KG) have been prepared for the first time using electrospinning. Electrospinning solutions were prepared by mixing gum solutions of GA, GK & KG with eco-friendly polymers such as polyvinyl alcohol (PVA) or polyethylene oxide (PEO). The present study focuses on the effect of electrospinning blended solutions of GA, GK or KG with PVA or PEO, additives which influence system parameters and process parameters. This has important effects on the electrospinning process and the resulting fibers whose morphology and physicochemical properties were evaluated. The mass ratios of 70:30 to 90:10 for PVA: GA, PVA: GK and PVA: KG were observed to establish an optimum blend solution ratio in order to fabricate uniform beadless nanofibers with an average diameter of 240±50, 220±40 and 210±30nm, respectively. Various structural and physicochemical properties of the electrospun fibers were investigated. Furthermore, the comparisons of various functionalities of the untreated and plasma treated electrospun fibers were assessed. The methane plasma treated nanofibers were shown to be of extremely specific surface area, improved water contact angle, high surface porosity and roughness and superior hydrophobic properties compared to untreated fibers.

Fabrication and characterization of vitamin B5 loaded poly (l-lactide-co-caprolactone)/silk fiber aligned electrospun nanofibers for schwann cell proliferation

Bioengineering strategies for peripheral nerve regeneration have been focusing on the development of alternative treatments for nerve repair. In present study we have blended the Vitamin B5 (50mg) with 8% P(LLA-CL) and P(LLA-CL)/SF solutions and produced aligned electrospun nanofiber mashes and characterized the material for its physiochemical and mechanical characteristics. The vitamin loaded composites nanofibers showed tensile strength of 8.73±1.38 and 8.4±1.37 in P(LLA-CL)/Vt and P(LLA-CL)/SF/Vt nanofibers mashes, respectively. By the addition of vitamin B5 the P(LLA-CL) nanofibers become hydrophilic and the contact angle decreased from 96° to 0° in 6min of duration. The effect of vitamin B5 on Schwann cells proliferation and viability were analyzed by using MTT assay and the number of cells cultured on vitamin loaded nanofiber mashes was significantly higher than the without vitamin loaded nanofiber samples after 5th day (p<0.05) whereas, P (LLA-CL)/SF/Vt exhibit the consistently highest cell numbers after 7th days culture as compare to P (LLA-CL)/Vt. The in vitro vitamin release behavior was observed in PBS solution and released vitamin was calculated by revers phase HPLC method. The sustain release behavior of vitamin B5 were noted higher in P(LLA-CL)/Vt (80%) nanofibers as compared to P (LLA-CL)/SF/Vt (62%) nanofibers after 24h. The present work provided a basis for further studies of this novel aligned nanofibrous material in nerve tissue repair or regeneration.

Electrospun PCL/Gelatin composite fibrous scaffolds: mechanical properties and cellular responses

Electrospinning of hybrid polymer has gained widespread interest by taking advantages of the biological property of the natural polymer and the mechanical property of the synthetic polymer. However, the effect of the blend ratio on the above two properties has been less reported despite the importance to balance these two properties in various tissue engineering applications. To this aim, we investigated the electrospun PCL/Gelatin composite fibrous scaffolds with different blend ratios of 4:1, 2:1, 1:1, 1:2, 1:4, respectively. The morphology of the electrospun samples was observed by SEM and the result showed that the fiber diameter distribution became more uniform with the increase of the gelatin content. The mechanical testing results indicated that the 2:1 PCL/Gelatin sample had both the highest tensile strength of 3.7 MPa and the highest elongation rate of about 90%. Surprisingly, the 2:1 PCL/Gelatin sample also showed the best mesenchymal stem cell responses in terms of attachment, spreading, and cytoskeleton organization. Such correlation might be partly due to the fact that the enhanced mechanical property, an integral part of the physical microenvironment, likely played an important role in regulating the cellular functions. Overall, our results indicated that the PCL/Gelatin sample with the blend ratio of 2:1 was a superior candidate for scaffolds for tissue engineering applications.

Antimicrobial Nanomaterials Derived from Natural Products-A Review

Modern medicine has relied heavily on the availability of effective antibiotics to manage infections and enable invasive surgery. With the emergence of antibiotic-resistant bacteria, novel approaches are necessary to prevent the formation of biofilms on sensitive surfaces such as medical implants. Advances in nanotechnology have resulted in novel materials and the ability to create novel surface topographies. This review article provides an overview of advances in the fabrication of antimicrobial nanomaterials that are derived from biological polymers or that rely on the incorporation of natural compounds with antimicrobial activity in nanofibers made from synthetic materials. The availability of these novel materials will contribute to ensuring that the current level of medical care can be maintained as more bacteria are expected to develop resistance against existing antibiotics.

Electrospun Fibers for Spinal Cord Injury Research and Regeneration

Electrospinning is the process by which a scaffold containing micrometer and nanometer diameter fibers are drawn from a polymer solution or melt using a large voltage gradient between a polymer emitting source and a grounded collector. Ramakrishna and colleagues first investigated electrospun fibers for neural applications in 2004. After this initial study, electrospun fibers are increasingly investigated for neural tissue engineering applications. Electrospun fibers robustly support axonal regeneration within in vivo rodent models of spinal cord injury. These findings suggest the possibility of their eventual use within patients. Indeed, both spinal cord and peripheral nervous system regeneration research over the last several years shows that physical guidance cues induce recovery of limb, respiration, or bladder control in rodent models. Electrospun fibers may be an alternative to the peripheral nerve graft (PNG), because PNG autografts injure the patient and are limited in supply, and allografts risk host rejection. In addition, electrospun fibers can be engineered easily to confront new therapeutic challenges. Fibers can be modified to release therapies locally or can be physically modified to direct neural stem cell differentiation. This review summarizes the major findings and trends in the last decade of research, with a particular focus on spinal cord injury. This review also demonstrates how electrospun fibers can be used to study the central nervous system in vitro.

Recent trends in electrospinning of polymer nanofibers and their applications in ultra thin layer chromatography

Fabrication of polymer derived electrospun nanofibers by electrospinning as chromatographic sorbent bed for ultra-thin layer chromatography (UTLC) is a very demanding topic in analytical chemistry. This review presents an overview of recent development in the fabrication of polymer derived electrospun nanofibers and their applications to design UTLC plates as stationary phases for on-plate identification and separation of analytes from their mixture solutions. It has been reported that electrospun fiber based stationary phases in UTLC have enhanced separation efficiency to provide separation of analyte mixture in a shorter development time than those of traditional particle-based TLC stationary phases. In addition, electrospun UTLC is cost effective and can be modified for obtaining different surface selectivities by changing the polymer materials to electrospun devices. Electrospun UTLC plates are not available commercially till date and efforts are being rendered for their commercialization. The morphology and diameter of electrospun nanofibers are highly dependent on several parameters such as type of polymer, polymer molecular weight, solvent, viscosity, conductivity, surface tension, applied voltage, collector distance and flow rate of the polymer solution during electrospinning process. Among the aforementioned parameters, solution viscosity is an important parameter which is mainly influenced by polymer concentration. This review provides evidence for the fabrication of UTLC plates containing electrospun polymer nanofibers. Furthermore, the future prospects related to electrospinning and its application in obtaining of different types of electrospun nanofibers are discussed. The present communication is aimed to review the work which appeared during 2009-2014 on the application of polymer derived electrospun nanofibers in ultra thin layer chromatography.

In situ deposition of a personalized nanofibrous dressing via a handy electrospinning device for skin wound care

Current strategies for wound care provide limited relief to millions of patients who suffer from burns, chronic skin ulcers or surgical-related wounds. The goal of this work is to develop an in situ deposition of a personalized nanofibrous dressing via a handy electrospinning (e-spinning) device and evaluate its properties related to skin wound care. MCM-41 type mesoporous silica nanoparticles decorated with silver nanoparticles (Ag-MSNs) were prepared by a facile and environmentally friendly approach, which possessed long-term antibacterial activity and low cytotoxicity. Poly-ε-caprolactone (PCL) incorporated with Ag-MSNs was successfully electrospun (e-spun) into nanofibrous membranes. These in situ e-spun nanofibrous membranes allowed the continuous release of Ag ions and showed broad-spectrum antimicrobial activity against two common types of pathogens, Staphylococcus aureus and Escherichia coli. In addition, the in vivo studies revealed that these antibacterial nanofibrous membranes could reduce the inflammatory response and accelerate wound healing in Wistar rats. The above results strongly demonstrate that such patient-specific dressings could be broadly applied in emergency medical transport, hospitals, clinics and at the patients' home in the near future.

General Deposition of Metal-Organic Frameworks on Highly Adaptive Organic-Inorganic Hybrid Electrospun Fibrous Substrates

Electrospun nanofibrous mats are ideal substrates for metal-organic frameworks (MOFs) crystal deposition because of their specific structural parameters and chemical tenability. In this work, we utilized organic-inorganic hybrid electrospun fibrous mats as support material to study the deposition of various MOF particles. HKUST-1 and MIL-53(Al) were produced through solvothermal method, while ZIF-8 and MIL-88B(Fe) were prepared using microwave-induced heating method. The synthesis procedure for both methods were simple and effective because the hybrid nanofibrous mats showed considerable affinity to MOF particles and could be used without additional modifications. The obtained MOF composites exhibited effective incorporation between MOF particles and the porous substrates. MIL-53(Al) composite was applied as fibrous sorbent and showed enhanced adsorption capacity and removal rate, as well as easier operation, compared with thepowdered sample. Moreover, MIL-53(Al) composite was easier to be regenerated compared with powder form.

Needleless electrospinning for scaled-up production of ultrafine chitosan hybrid nanofibers used for air filtration

This filter media showed better performance than commercial HEPA for nanoparticles filtration.

Polyacrylonitrile (PAN)/crown ether composite nanofibers for the selective adsorption of cations

Electrospun PAN/crown ether nanofibers have potential for selective recovery of specific ions from mixtures with ions.

Recent advances in electrospun metal-oxide nanofiber based interfaces for electrochemical biosensing

Synthesis of various electrospun metal-oxide nanofibers and their application towards electrochemical enzymatic and enzyme-free biosensor platforms has been critically discussed.

In situ precision electrospinning as an effective delivery technique for cyanoacrylate medical glue with high efficiency and low toxicity

The side effects or toxicity of cyanoacrylate used in vivo have been argued since its first application in wound closure. We propose an airflow-assisted in situ precision electrospinning apparatus as an applicator and make a detailed comparison with traditional spraying via in vitro and in vivo experiments. This novel method can not only improve operational performance and safety by precisely depositing cyanoacrylate fibers onto a wound, but significantly reduce the dosage of cyanoacrylate by almost 80%. A white blood cell count, liver function test and histological analysis prove that the in situ precision electrospinning applicator produces a better postoperative outcome, e.g., minor hepatocyte injury, moderate inflammation and the significant ability for liver regeneration. This in situ precision electrospinning method may thus dramatically broaden both civilian and military applications of cyanoacrylates.

Genipin-Crosslinked Chitosan Gels and Scaffolds for Tissue Engineering and Regeneration of Cartilage and Bone

The present review article intends to direct attention to the technological advances made since 2009 in the area of genipin-crosslinked chitosan (GEN-chitosan) hydrogels. After a concise introduction on the well recognized characteristics of medical grade chitosan and food grade genipin, the properties of GEN-chitosan obtained with a safe, spontaneous and irreversible chemical reaction, and the quality assessment of the gels are reviewed. The antibacterial activity of GEN-chitosan has been well assessed in the treatment of gastric infections supported by Helicobacter pylori. Therapies based on chitosan alginate crosslinked with genipin include stem cell transplantation, and development of contraction free biomaterials suitable for cartilage engineering. Collagen, gelatin and other proteins have been associated to said hydrogels in view of the regeneration of the cartilage. Viability and proliferation of fibroblasts were impressively enhanced upon addition of poly-l-lysine. The modulation of the osteocytes has been achieved in various ways by applying advanced technologies such as 3D-plotting and electrospinning of biomimetic scaffolds, with optional addition of nano hydroxyapatite to the formulations. A wealth of biotechnological advances and know-how has permitted reaching outstanding results in crucial areas such as cranio-facial surgery, orthopedics and dentistry. It is mandatory to use scaffolds fully characterized in terms of porosity, pore size, swelling, wettability, compressive strength, and degree of acetylation, if the osteogenic differentiation of human mesenchymal stem cells is sought: in fact, the novel characteristics imparted by GEN-chitosan must be simultaneously of physico-chemical and cytological nature. Owing to their high standard, the scientific publications dated 2010-2015 have met the expectations of an interdisciplinary audience.

Electrospun Aligned Fibrous Arrays and Twisted Ropes: Fabrication, Mechanical and Electrical Properties, and Application in Strain Sensors

Electrospinning (e-spinning) is a versatile technique to fabricate ultrathin fibers from a rich variety of functional materials. In this paper, a modified e-spinning setup with two-frame collector is proposed for the fabrication of highly aligned arrays of polystyrene (PS) and polyvinylidene fluoride (PVDF) nanofibers, as well as PVDF/carbon nanotube (PVDF/CNT) composite fibers. Especially, it is capable of producing fibrous arrays with excellent orientation over a large area (more than 14 cm × 12 cm). The as-spun fibers are suspended and can be easily transferred to other rigid or flexible substrates. Based on the aligned fibrous arrays, twisted long ropes are also prepared. Compared with the aligned arrays, twisted PVDF/CNT fiber ropes show enhanced mechanical and electrical properties and have potential application in microscale strain sensors.