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Carbon-based materials have become indispensable in the field of electrochemical applications, especially for energy storage or conversion purposes. A large diversity of materials has been proposed and investigated in the last years. In this mini-review, we present recent advances in the design of carbon-based materials for application in vanadium redox flow batteries. As main part, different modification and fabrication methods for carbon-based electrodes are described. The decoration of carbon felts and graphite felts with metals or metal compounds to enhance mostly the electrocatalysis of the negative side is illustrated with examples. Furthermore, various options of synthesizing porous C–C composites are discussed, with specific emphasis on graphene-based composites as well as nitrogen doped composites and biomass-derived carbons. Apart from that the method of electrospinning is also examined in detail, a method which not only allows the production of nanofibrous high surface area electrodes, but also allows adaptation of fiber thickness and architecture. In this review the significant strengths of each method are pointed out, but also particular weaknesses are discussed with respect to the later battery performance. Finally, an outlook is given pointing to the remaining challenges that need to be overcome in the future.

Selective modification of the morphology and intrinsic electrocatalytic activity of porous electrodes is urgently required to improve the performance of vanadium redox flow batteries (VRFBs). For this purpose, electrospinning was exploited to prepare high‐performance nanofiber‐based composites. Blends of polyacrylonitrile, polyacrylic acid, and polyaniline with carbon black were electrospun into a 3D free‐standing nanofibrous web, which was utilized as a novel electrode. By extending the recent theory of cyclic voltammetry at porous electrodes to account for interfacial double‐layer capacities, nonlinear effects of ohmic resistances, and parasitic reactions, we could quantitatively investigate non‐faradaic as well as desired and undesired faradaic current contributions. Combination of experimental and theoretical studies allowed a unique quantitative assessment of the intrinsic catalytic activity of selected electrode materials concerning the VO2+/VO2+ redox reaction.

Self-assembling peptides (SAPs) are synthetic bioinspired biomaterials that can be feasibly multi-functionalized for applications in surgery, drug delivery, optics and tissue engineering (TE). Despite their promising biocompatibility and biomimetic properties, they have never been considered real competitors of polymers and/or cross-linked extracellular matrix (ECM) natural proteins. Indeed, synthetic SAP-made hydrogels usually feature modest mechanical properties, limiting their potential applications, due to the transient non-covalent interactions involved in the self-assembling phenomenon. Cross-linked SAP-hydrogels have been recently introduced to bridge this gap, but several questions remain open. New strategies leading to stiffer gels of SAPs may allow for a full exploitation of the SAP technology in TE and beyond. We have developed and characterized a genipin cross-linking strategy significantly increasing the stiffness and resiliency of FAQ(LDLK)3, a functionalized SAP already used for nervous cell cultures. We characterized different protocols of cross-linking, analyzing their dose and time-dependent efficiency, influencing stiffness, bioabsorption time and molecular arrangements. We choose the best developed protocol to electrospin into nanofibers, for the first time, self-standing, water-stable and flexible fibrous mats and micro-channels entirely made of SAPs. This work may open the door to the development and tailoring of bioprostheses entirely made of SAPs for different TE applications.

A spinal cord injury (SCI) often causes permanent changes in strength and sensation functions below the site of the injury and affects thousands of people each year. Transplantation of stem cells is a promising approach in acute SCI as it may support spinal cord repair. However, in case of chronic SCI greater amounts of nervous tissue have to be regenerated, leaving scaffold transplantation the only feasible option for cellular engraftment and nervous bridging. The aim of regenerative medicine, specifically tissue engineering, is to create a microenvironment that mimics native extracellular matrix (ECM), capable of promoting specific cell-matrix interactions, coaxing cell behavior, and fostering host tissue regeneration. In this regard, nanostructured scaffolds are currently the most promising advanced substrates capable of supporting nervous fiber ingrowth and delivery of neurotrophic drugs. Among them, electrospinning technique and Self-Assembling Peptides (SAPs) have recently attracted lots of attention for their reproducible synthesis and high tailorability. This review highlights clinical trials and recent encouraging strategies for spinal cord repair comprising both cell therapy and nanomedicine.

Self-assembling (SAPs) and co-assembling peptides (CAPs) are driving increasing enthusiasm as synthetic but biologically inspired biomaterials amenable of easy functionalization for regenerative medicine. On the other hand, electrospinning (ES) is a versatile technique useful for tailoring the nanostructures of various biomaterials into scaffolds resembling the extracellular matrices found in organs and tissues. The synergistic merging of these two approaches is a long-awaited advance in nanomedicine that has not been deeply documented so far. In the present work, we describe the successful ES of a library of diverse SAPs and CAPs into biomimetic nanofibrous mats. Our results suggest that suitable ES solutions are characterized by high concentrations of peptides, providing backbone physical chain entanglements, and by random coil/α-helical conformations while β-sheet aggregation may be detrimental to spinnability. The resulting peptide fibers feature interconnected seamless mats with nanofibers average diameters ranging from ∼100 nm to ∼400 nm. Also, peptide chemical nature and ES set up parameters play pivotal roles in determining the conformational transitions and morphological properties of the produced nanofibers. Far from being an exhaustive description of the just-opened novel field of ES-assembled peptides, this seminal work aims at shining a light on a still missing general theory for the production of electrospun peptidic biomaterials bringing together the spatial, biochemical and biomimetic of these two techniques into unique scaffolds for tissue engineering. Statement of Significance Construction of peptide hydrogels has received considerable attention due to their potential as nanostructures amenable of easy functionalization and capable of creating microenvironments suited for culturing cells and triggering tissue regeneration. They display a superior biocompatibility unmatched by other known synthetic biomaterials so far. However, their applications are confined to body fillers because most of them do spontaneously form hydrogels, while effective tissue regeneration often requires well-defined fibrous scaffolds. In this work, we developed electrospun fibers of various peptides (cross-beta self-assembling, hierarchically assembling, functionalized, co-assembling) and we provided a deep understanding of the crucial phenomena to be taken into account when peptides fibers fabrication. These results open new venues for exploring novel regenerative applications of peptide nanofibrous scaffolds.

The demand for novel antibiotic-loaded electrospun nanofibrous structures has increased extremely in the recent years and has engaged the interests of scientists and engineers into a blend configuration of antibiotic drug and biocompatible polymers due to their unique applications in future of better therapeutic effect, reduced toxicity and sustained local antibiotic release over a period of time. One method to produce these antibiotic-loaded networks is by electrospinning process. However, it is very important to know structural characteristics and morphology of nanofibers for controlling the performance of the yields. In this paper, fabrication of electrospun nanofibers suited for antibiotic delivery system is investigated based on tetracycline hydrochloride as the antibiotic drug and poly (lactic-co-glycolic acid) as the biodegradable polymeric matrix. Furthermore, the effect of material and process parameters on morphology and release behavior of produced nonwovens is investigated. The efficacy of the medicated scaffolds using a static system for bacterial growth on agar plates was also proved.

Fabrication of core–shell nanofibers by coaxial electrospinning system suited for drug delivery applications was investigated based on tetracycline hydrochloride (TCH) as the core and poly(lactide-co-glycolide) as the shell materials. Comparison of drug release from monolithic fibers (blend electrospinning) and core–shell structures was performed to evaluate the efficacy of the core–shell morphology. The nanofibrous webs are potentially interesting for wound healing purposes since they can be maintained for an adequate length of time to gradually disinfect a local area without the need of bandage renewal. Further, our studies showed the potential of core–shell nanostructures for sustained drug release, which also suppressed the burst release effect from 62 to 44% in the first 3 hours by adding only 1 wt% TCH to the polymeric shell. POLYM. ENG. SCI., 2013. © 2013 Society of Plastics Engineers

Release profile of drug constituent encapsulated in electrospun core-shell nanofibrous mats was modeled by Peppas equation and artificial neural network. Core-shell fibers were fabricated by co-axial electrospinning process using tetracycline hydrochloride (TCH) as the core and poly(l-lactide-co-glycolide) (PLGA) or polycaprolactone (PCL) as the shell materials. The density and hydrophilicity of the shell polymers, feed rates and concentrations of core and shell phases, the contribution of TCH in core material and electrical field were the parameters fed to the perceptron network to predict Peppas constants in order to derive release pattern. This study demonstrated the viability of the prediction tool in determining drug release profile of electrospun core-shell nanofibrous scaffolds.

Such as other fields, textile industry, deal with numerous large inputs and possible outputs parameters and always feed with a complex interdependence between parameters, it is highly unlikely that an exact mathematical model will ever be developed. Furthermore, since there are many dependent and independent variables during different textile progress, it becomes difficult to conduct and to cover the entire range of the parameters. Moreover, the known and unknown variables cannot be interpolated and extrapolated in a reasonable way based on experimental observations or mill measurements due to the shortage of knowledge on the evaluation of the interaction and significance at weight contributing from each variable. For example, it is quite difficult to develop some universal practical models that can accurately predict yarn quality for different mills (Chattopadhyay & Guha, 2004). Statistical models have also shown up their limitations in use—not least their sensitivity to rogue data—and are rarely used in any branch of the textile industry as a decision-making tool. The mechanistic models proposed by various authors overtly simplify the case to make the equations manageable and pay the price with their limited accuracy. In any case, the vast volume of process parameterrelated data is hardly ever included in these models, making them unsuitable for application in an industrial scenario. By using neural networks, it seems to be possible to identify and classify different textile properties (Guruprasad & Behera, 2010). Some of the studies reported in recent years on the application of neural networks are discussed hereunder.

The extensive application in future of nano webs has attracted world tendency toward them. The identification of nano webs' characteristics can direct consumer toward their end uses. Many nano web characteristics depend on its structure. Since they are made of nano fibres and have thin structure, conventional optical techniques are not completely applicable to measure their structural properties. This paper will discuss the development of image analysis algorithms to measure and evaluate structural and morphological characteristics of nano web images including fibre properties (such as fibre orientation distribution, fibre diameter), pore properties (such as pore size and shapes) and web properties (such as web uniformity and fibre intersections). The results show that the method is capable of characterising real nano coated webs.