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Laccases are oxidative enzymes that could be good candidates for the functionalization of biopolymers with several applications as biosensors for the determination of bioactive amine and alcohols, for bioremediation of industrial wastewater, and for greener catalysts in oxidation reactions in organic synthesis, especially used for non-phenolic compounds in combination with redox mediators in the so-called Laccase Mediator System (LMS). In this work, we describe the immobilization of Laccase from Trametes versicolor (LTv) in poly-L-lactic acid (PLLA) nanofibers and its application in LMS oxidation reactions. The PLLA-LTv catalysts were successfully produced by electrospinning of a water-in-oil emulsion with an optimized method. Different enzyme loadings (1.6, 3.2, and 5.1% w/w) were explored, and the obtained mats were thoroughly characterized. The actual amount of the enzyme in the fibers and the eventual enzyme leaching in different solvents were evaluated. Finally, the PLLA-LTv mats were successfully applied as such in the oxidation reaction of catechol, and in the LMS method with TEMPO as mediator in the oxidation of amines with the advantage of easier work-up procedures by the immobilized enzyme. However, the PLLA-LTv failed the oxidation of alcohols with respect to the free enzyme. A tentative explanation was provided.

Realizing active, light-emitting fibers made of conjugated polymers by the electrospinning method is generally challenging. Electrospinning of plasma-treated conjugated polymer solutions is here developed for the production of light-emitting microfibers and nanofibers. Active fibers from conjugated polymer solutions rapidly processed by a cold atmospheric argon plasma are electrospun in an effective way, and they show a smoother surface and bead-less morphology, as well as preserved optical properties in terms of absorption, emission, and photoluminescence quantum yield. In addition, the polarization of emitted light and more notably photon waveguiding along the length of individual fibers are remarkably enhanced by electrospinning plasma-treated solutions. These properties come from a synergetic combination of favorable intermolecular coupling in the solutions, increased order of macromolecules on the nanoscale, and resulting fiber morphology. Such findings make the coupling of the electrospinning method and cold atmospheric plasma processing on conjugated polymer solutions a highly promising and possibly general route to generate light-emitting and conductive micro- and nanostructures for organic photonics and electronics.

The regeneration of injured tendons and ligaments is challenging because the scaffolds needs proper mechanical properties and a biomimetic morphology. In particular, the morphological arrangement of scaffolds is a key point to drive the cells growth to properly regenerate the collagen extracellular matrix. Electrospinning is a promising technique to produce hierarchically structured nanofibrous scaffolds able to guide cells in the regeneration of the injured tissue. Moreover, the dynamic stretching in bioreactors of electrospun scaffolds had demonstrated to speed up cell shape modifications in vitro. The aim of the present study was to combine different imaging techniques such as high-resolution X-ray tomography (XCT), scanning electron microscopy (SEM), fluorescence microscopy and histology to investigate if hierarchically structured poly (L-lactic acid) and collagen electrospun scaffolds can induce morphological modifications in human fibroblasts, while cultured in static and dynamic conditions. After 7 days of parallel cultures, the results assessed that fibroblasts had proliferated on the external nanofibrous sheath of the static scaffolds, elongating themselves circumferentially. The dynamic cultures revealed a preferential axial orientation of fibroblasts growth on the external sheath. The aligned nanofibre bundles inside the hierarchical scaffolds instead, allowed a physiological distribution of the fibroblasts along the nanofibre direction. Inside the dynamic scaffolds, cells appeared thinner compared with the static counterpart. This study had demonstrated that hierarchically structured electrospun scaffolds can induce different fibroblasts morphological modifications during static and dynamic conditions, modifying their shape in the direction of the applied loads. LAY DESCRIPTION: To enhance the regeneration of injured tendons and ligaments cells need to growth on dedicated structures (scaffolds) with mechanical properties and a fibrous morphology similar to the natural tissue. In particular, the morphological organisation of scaffolds is fundamental in leading cells to colonise them, regenerating the collagen extracellular matrix. Electrospinning is a promising technique to produce fibres with a similar to the human collagen fibres, suitable to design complex scaffolds able to guide cells in the reconstruction of the natural tissue. Moreover, it is well established that the cyclic stretching of these scaffolds inside dedicated systems called bioreactors, can speed up cells growth and their shape modification. The aim of the present study was to investigate how hierarchically structured electrospun scaffolds, made of resorbable material such as poly(L-lactic acid) and collagen, could induce morphological changes in human fibroblasts, while cultured during static and dynamic conditions. These scaffolds were composed by an external electrospun membrane that grouped inside it a ring-shaped bundle, made of axially aligned nanofibres, resembling the morphological arrangement of tendon and ligament tissue. After 7 days of parallel cultures, the scaffolds were investigated using the following imaging techniques: (i) high-resolution X-ray tomography (XCT); (ii) scanning electron microscopy (SEM); (iii) fluorescence microscopy and (iv) histology. The results showed that fibroblasts were able to grow on the external nanofibrous sheath of the static scaffolds, by elongating themselves along their circumference. The dynamic cultures revealed instead a preferential axial orientation of fibroblasts grown on the external sheath. The aligned nanofibre bundles inside the hierarchical scaffolds allowed an axial distribution of the fibroblasts along the nanofibres direction. This study has demonstrated that the electrospun hierarchically structured scaffolds investigated can modify the fibroblasts morphology both in static and dynamic conditions, in relation with the direction of the applied loads.

Regulating stem cell adhesion and growth onto functionalized biomaterial scaffolds is an important issue in the field of tissue engineering and regenerative medicine. In this study, new electrospun scaffolds of poly(l-lactic acid) (PLLA), as bioresorbable polymer, and β-lactam compounds agonists of selected integrins, as functional components with cell adhesive properties, are designed. The new β-lactam-PLLA scaffolds contribute significantly in guiding protein translation involved in human bone marrow mesenchymal stem cells (hBM-MSC) adhesion and integrin gene expression. Scanning electron microscopy, confocal laser scanning microscopy, and Western Blot analyses reveal that GM18-PLLA shows the best results, promoting cell adhesion by significantly driving changes in focal adhesion proteins distribution (β1 integrin and vinculin) and activation (pFAK), with a notable increase of GM18-Targets subunits integrin gene expression, α4 and β1. These novel functionalized submicrometric fibrous scaffolds demonstrate, for the first time, the powerful combination of selective β-lactams agonists of integrins with biomimetic scaffolds, suggesting a designed rule that could be suitably applied to tissue repair and regeneration.

Regenerative medicine applied to skin lesions is a field in constant improvement. The use of biomaterials with integrin agonists could promote cell adhesion increasing tissue repair processes. The aim of this pilot study was to analyze the effect of an α4β1 integrin agonist on cell adhesion of equine adipose tissue (AT) and Wharton’s jelly (WJ) derived MSCs and to investigate their adhesion ability to GM18 incorporated poly L-lactic acid (PLLA) scaffolds. Adhesion assays were performed after culturing AT- and WJ-MSCs with GM18 coating or soluble GM18. Cell adhesion on GM18 containing PLLA scaffolds after 20 min co-incubation was assessed by HCS. Soluble GM18 affects the adhesion of equine AT- and WJ-MSCs, even if its effect is variable between donors. Adhesion to PLLA scaffolds containing GM18 is not significantly influenced by GM18 for AT-MSCs after 20 min or 24 h of culture and for WJ-MSCs after 20 min, but increased cell adhesion by 15% GM18 after 24 h. In conclusion, the α4β1 integrin agonist GM18 affects equine AT- and WJ-MSCs adhesion ability with a donor-related variability. These preliminary results represent a first step in the study of equine MSCs adhesion to PLLA scaffolds containing GM18, suggesting that WJ-MSCs might be more suitable than AT-MSCs. However, the results need to be confirmed by increasing the number of samples before drawing definite conclusions.

The drug discovery process is very long, costly, and challenging but essential in medical sciences. Advancements in new techniques to improve the efficacy of drug development are therefore needed. The 3D cell culture technique represents a step forward in studying human tissues and diseases, and developed in vitro 3D tissue models can be an excellent alternative to traditional 2D cell cultures and animal testing. They can replicate the physiological microenvironment of the living tissue-mimicking extracellular matrix (ECM), cell-cell/cell-ECM interactions, and the spatial cellular arrangement, thus such models are useful systems to evaluate better and comprehend drug responsiveness. The 3D bioprinting technique brings many advantages in the fabrication of 3D tissue models, such as custom-made microarchitecture, high-throughput capability, and co-culture ability. However, this technique has challenges related to cells and materials requirements as well as tissue maturation and functionality. This review introduces the leading bioprinting technologies (extrusion-based, inkjet-based and laser-assisted) and summarizes and discusses their applications to build organ models such as liver, intestine, cardiac, and tumor tissues for applications in drug discovery and drug toxicity studies. The different bioprinting approaches and 3D printed tissue constructs employed to evaluate drug dose-response and drug metabolism are critically reviewed and discussed.

Nerve growth factor (NGF) was the first-discovered member of the neurotrophin family, a class of bioactive molecules which exerts powerful biological effects on the CNS and other peripheral tissues, not only during development, but also during adulthood. While these molecules have long been regarded as potential drugs to combat acute and chronic neurodegenerative processes, as evidenced by the extensive data on their neuroprotective properties, their clinical application has been hindered by their unexpected side effects, as well as by difficulties in defining appropriate dosing and administration strategies. This paper reviews aspects related to the endogenous production of NGF in healthy and pathological conditions, along with conventional and biomaterial-assisted delivery strategies, in an attempt to clarify the impediments to the clinical application of this powerful molecule.

Vascular and traumatic injuries of the central nervous system are recognized as global health priorities. A polypharmacology approach that is able to simultaneously target several injury factors by the combination of agents having synergistic effects appears to be promising. Herein, we designed a polymeric delivery system loaded with two drugs, ibuprofen (Ibu) and thyroid hormone triiodothyronine (T3) to in vitro release the suitable amount of the anti-inflammation and the remyelination drug. As a production method, electrospinning technology was used. First, Ibu-loaded micro (diameter circa 0.95–1.20 µm) and nano (diameter circa 0.70 µm) fibers were produced using poly(l-lactide) PLLA and PLGA with different lactide/glycolide ratios (50:50, 75:25, and 85:15) to select the most suitable polymer and fiber diameter. Based on the in vitro release results and in-house knowledge, PLLA nanofibers (mean diameter = 580 ± 120 nm) loaded with both Ibu and T3 were then successfully produced by a co-axial electrospinning technique. The in vitro release studies demonstrated that the final Ibu/T3 PLLA system extended the release of both drugs for 14 days, providing the target sustained release. Finally, studies in cell cultures (RAW macrophages and neural stem cell-derived oligodendrocyte precursor cells—OPCs) demonstrated the anti-inflammatory and promyelinating efficacy of the dual drug-loaded delivery platform.

Reconstructions of ruptured tendons and ligaments currently have dissatisfactory failure rate. Failures are mainly due to the mechanical mismatch of commercial implants with respect to the host tissue. In fact, it is crucial to replicate the morphology (hierarchical in nature) and mechanical response (highly-nonlinear) of natural tendons and ligaments. The aim of this study was to develop morphologically bioinspired hierarchical Nylon 6,6 electrospun assemblies recreating the structure and performance of tendons and ligaments. First, we built different electrospun bundles to find the optimal orientation of the nanofibers. A 2nd-level hierarchical assembly was fabricated with a dedicated process that allowed tightly joining the bundles one next to the other with an electrospun sheath, so as to improve the mechanical performance. Finally, a further hierarchical 3rd-level assembly was constructed by grouping several 2nd-level assemblies. The morphology of the different structures was assessed with scanning electron microscopy and high-resolution X-ray tomography, which allowed measuring the directionality of the nanofibers in the bundles and in the sheaths. The mechanical properties of the single bundles and of the 2nd-level assemblies were measured with tensile tests. The single bundles and the hierarchical assemblies showed morphology and directionality of the nanofibers similar to the tendons and ligaments. The strength and stiffness were comparable to that of tendons and ligaments. In conclusion, this work showed an innovative electrospinning production process to build nanofibrous Nylon 6,6 hierarchical assemblies which are suitable as future implantable devices and able to mimic the multiscale morphology and the biomechanical properties of tendons and ligaments.

The selective removal of thin varnish layers from oil and egg tempera paintings is still an open challenge in the conservation field. In this paper, a new cleaning system was developed by using a gel composed of fully green components as deep eutectic solvents (DES) and agar. The gel, prepared admixing choline chloride -urea with an EtOH-H2O agar gel, exhibited good rheological properties in terms of gel stiffness, allowing easy handling and removal of the gel. The new developed cleaning gel was successfully tested for the removal of proteinaceous layers applied over both hydrophobic (linseed oil as binder) and hydrophilic (egg temperas as binder) surfaces. The procedure consists on two steps: first the choline chloride -urea agar gel was applied and let to act then an EtOH-H2O agar gel was applied for few seconds to allow the removal of the DES residues Moreover, an innovative non-destructive approach based on micro-Spatially Offset Raman Spectroscopy (micro-SORS) allowed to demonstrate how the gel impairs the diffusion of the cleaning agents in the paint layers, highlighting the good solvent retention ability of the gel.

An anomalous polystyrene gel was obtained during the copper-catalyzed “activators regenerated by electron transfer” “atom transfer radical polymerization” (ARGET ATRP) of styrene at 60–70 °C, using ascorbic acid/Na2CO3 as the reducing system and EtOAc/EtOH as the solvent mixture. The result is remarkable since no branching nor cross-linking reagents were added to the reaction mixture and their formation in situ was excluded. The anomalous PS branching, at the origin of the phenomenon, requires a generic bifunctional initiator and is mechanistically bound to termination reactions between bifunctional macroinitiators. As a matter of fact, the branching/cross-linking phenomenon loses intensity, or even disappears, under reaction conditions that cause the built-up of CuII or increase the chain polymerization rate. The temperature is also a critical variable since no branching was observed for temperatures higher than 90 °C. We believe that the route toward gelation starts with a controlled chain polymerization of styrene from the bifunctional initiator, soon integrated by a step-growth polymerization due to radical coupling of the terminal units. The progressive decrease in the number of chains and free radicals in the reaction mixture should make more and more probable the intramolecular coupling between the C−Cl ends of the remaining long and entangled chains, producing a polycatenane network. [Figure not available: see fulltext.]

In the field of artificial prostheses for damaged vessel replacement, polymeric scaffolds showing the right combination of mechanical performance, biocompatibility, and biodegradability are still demanded. In the present work, poly(butylene-co-triethylene trans-1,4-cyclohexanedicarboxylate), a biodegradable random aliphatic copolyester, has been synthesized and electrospun in form of aligned and random fibers properly designed for vascular applications. The obtained materials were analyzed through tensile and dynamic-mechanical tests, the latter performed under conditions simulating the mechanical contraction of vascular tissue. Furthermore, the in vitro biological characterization, in terms of hemocompatibility and cytocompatibility in static and dynamic conditions, was also carried out. The mechanical properties of the investigated scaffolds fit within the range of physiological properties for medium- and small-caliber blood vessels, and the aligned scaffolds displayed a strain-stiffening behavior typical of the blood vessels. Furthermore, all the produced scaffolds showed constant storage and loss moduli in the investigated timeframe (24 h), demonstrating the stability of the scaffolds under the applied conditions of mechanical deformation. The biological characterization highlighted that the mats showed high hemocompatibility and low probability of thrombus formation, finally, the cytocompatibility tests demonstrated that cyclic stretch of electrospun fibers increased endothelial cell activity and proliferation, in particular on aligned scaffolds.

Biomaterial scaffolds play crucial role to promote cell proliferation and foster the regeneration of new tissues. The progress in material science has paved the way for the generation of ingenious biomaterials. However, these biomaterials require further optimization to be effectively used in existing clinical treatments. It is crucial to develop biomaterials which mimics structure that can be actively involved in delivering signals to cells for the formation of the regenerated tissue. In this research we nanoengineered a functional scaffold to support the proliferation of myoblast cells. Poly(3-hydroxybutyrate-co-4-hydroxybutyrate) [P(3HB-co-4HB)] copolymer is chosen as scaffold material owing to its desirable mechanical and physical properties combined with good biocompatibility, thus eliciting appropriate host tissue responses. In this study P(3HB-co-4HB) copolymer was biosynthesized using Cupriavidus malaysiensis USMAA1020 transformant harboring additional PHA synthase gene, and the viability of a novel P(3HB-co-4HB) electrospun nanofiber scaffold, surface functionalized with RGD peptides, was explored. In order to immobilize RGD peptides molecules onto the P(3HB-co-4HB) nanofibers surface, an aminolysis reaction was performed. The nanoengineered scaffolds were characterized using SEM, organic elemental analysis (CHN analysis), FTIR, surface wettability and their in vitro degradation behavior was evaluated. The cell culture study using H9c2 myoblast cells was conducted to assess the in vitro cellular response of the engineered scaffold. Our results demonstrated that nano-P(3HB-co-4HB)-RGD scaffold possessed an average fiber diameter distribution between 200 and 300 nm, closely biomimicking, from a morphological point of view, the structural ECM components, thus acting as potential ECM analogs. This study indicates that the surface conjugation of biomimetic RGD peptide to the nano-P(3HB-co-4HB) fibers increased the surface wettability (15 ± 2°) and enhanced H9c2 myoblast cells attachment and proliferation. In summary, the study reveals that nano-P(3HB-co-4HB)-RGD scaffold can be considered a promising candidate to be further explored as cardiac construct for building cardiac construct.

Skeletal muscles are considered to date the best existing actuator in nature thanks to their hierarchical multiscale fibrous structure capable to enhance their strength and contractile performances. In recent years, driven by the growing of the soft robotics and tissue-engineering research field, many biomimetic soft actuators and scaffolds were designed by taking inspiration from the biological skeletal muscle. In this work we used the electrospinning technique to develop a hierarchically arranged nanofibrous structure resembling the morphology and passive biomechanical properties of skeletal muscles. To mimic the passive properties of muscle, a low-modulus polyurethane was used. Several electrospun structures (mats, bundles, and a muscle-like assembly) were produced with different internal 3D arrangements of the nanofibers. A thermal characterization through thermogravimetric and differential scanning calorimetry analysis investigated the physico-chemical properties of the material. The multiscale morphological similarities with the biological counterpart were verified by means of scanning electron microscopy investigation. The tensile tests on the different electrospun samples revealed that the muscle-like assembly presented slightly higher strength and stiffness compared to the skeletal muscle ones. Moreover, mathematical models of the mechanical behavior of the nanofibrous structures were successfully developed, allowing to better investigate the relationships between structure and mechanics of the samples. The promising results suggest the suitability of this hierarchical electrospun nanofibrous structure for applications in regenerative medicine and, if combined with active materials, in soft actuators for robotic.

Spinal cord injury (SCI) is an incurable condition, in which a cascade of cellular and molecular events triggered by inflammation and excitotoxicity impairs endogenous regeneration, namely remyelination and axonal outgrowth. We designed a treatment solution based on an implantable biomaterial (electrospun poly (l-lactic acid) [PLLA]) loaded with ibuprofen and triiodothyronine (T3) to counteract inflammation, thus improving endogenous regeneration. In vivo efficacy was tested by implanting the drug-loaded PLLA in the rat model of T8 contusion SCI. We observed the expected recovery of locomotion beginning on day 7. In PLLA-implanted rats (i.e., controls), the recovery stabilized at 21 days post-lesion (DPL), after which no further improvement was observed. On the contrary, in PLLA + ibuprofen (Ibu) + T3 (PLLA-Ibu-T3) rats a further recovery and a significant treatment effect were observed, also confirmed by the gait analysis on 49 DPL. Glutamate release at 24 h and 8 DPL was reduced in PLLA-Ibu-T3-compared to PLLA-implanted rats, such as the estimated lesion volume at 60 DPL. The myelin-and 200-neurofilament-positive area fraction was higher in PLLA-Ibu-T3-implanted rats, where the percentage of astrocytes was significantly reduced. The implant of a PLLA electrospun scaffold loaded with Ibu and T3 significantly improves the endogenous regeneration, leading to an improvement of functional locomotion outcome in the SCI.

The bacterial colonization of absorbable membranes used for guided tissue regeneration (GTR), as well as their rapid degradation that can cause their rupture, are considered the major reasons for clinical failure. To address this, composite membranes of polycaprolactone (PCL) and gelatin (Gel) loaded with zinc oxide nanoparticles (ZnO-NPs; 1, 3 and 6 wt% relative to PCL content) were fabricated by electrospinning. To fabricate homogeneous fibrillar membranes, acetic acid was used as a sole common solvent to enhance the miscibility of PCL and Gel in the electrospinning solutions. The effects of ZnO-NPs in the physico-chemical, mechanical and in vitro biological properties of composite membranes were studied. The composite membranes showed adequate mechanical properties to offer a satisfactory clinical manipulation and an excellent conformability to the defect site while their degradation rate seemed to be appropriate to allow successful regeneration of periodontal defects. The presence of ZnO-NPs in the composite membranes significantly decreased the planktonic and the biofilm growth of the Staphylococcus aureus over time. Finally, the viability of human osteoblasts and human gingival fibroblasts exposed to the composite membranes with 1 and 3 wt% of ZnO-NPs indicated that those membranes are not expected to negatively influence the ability of periodontal cells to repopulate the defect site during GTR treatments. The results here obtained suggest that composite membranes of PCL and Gel loaded with ZnO-NPs have the potential to be used as structurally stable GTR membranes with local antibacterial properties intended for enhancing clinical treatments.

Strategies that simultaneously target energy/power performance, sustainable manufacturing processes, valorization of green raw materials, and easy recycling of supercapacitors are urgently needed. Today, efforts have to be devoted not only to improve system performance but also to address the sustainability of materials and devices manufacturing and recyclability. Specifically, pullulan is herein proposed as a novel bio-degradable binder and separator for green supercapacitors. It is processed by electrospinning from aqueous solutions, therefore overcoming issues related to conventional membrane processing by organic solvents. Furthermore, combining the water-soluble, biodegradable pullulan with a hydrophobic ionic liquid electrolyte brings about a novel approach for end-of-life management of devices. The use of pullulan is demonstrated in a supercapacitor with carbon electrodes obtained from pepper-seeds waste and 1-Ethyl-3-methylimidazoliumbis(trifluoromethylsulfonyl)imide as the electrolyte. The supercapacitor delivers up to 5 kW kg−1 specific power and 27.8 Wh kg−1 specific energy at 3.2 V, that well compare with conventional electrical double-layer capacitor performance with the added value of being eco-friendly and cheap.

Inspired by Nature, one of the most ambitious challenge in soft robotics is to design actuators capable of reaching performances comparable to the skeletal muscles. Considering the perfectly balanced features of natural muscular tissue in terms of linear contraction, force‐to‐weight ratio, scalability and morphology, scientists have been working for many years on mimicking this structure. Focusing on the biomimicry, this review investigates the state‐of‐the‐art of synthetic fibrous, muscle‐inspired actuators that, aiming to enhance their mechanical performances, are hierarchically designed from the nanoscale up to the macroscale. In particular, this review focuses on those hierarchical fibrous actuators that enhance their biomimicry employing a linear contraction strategy, closely resembling the skeletal muscles actuation system. The literature analysis shows that bioinspired artificial muscles, developed up to now, only in part comply with skeletal ones. The manipulation and control of the matter at the nanoscale allows to realize ordered structures, such as nanofibers, used as elemental actuators characterized by high strains but moderate force levels. Moreover, it can be foreseen that scaling up the nanostructured materials into micro‐ and macroscale hierarchical structures, it is possible to realize linear actuators characterized by suitable levels of force and displacement.

Blends of natural and synthetic polymers have recently attracted great attention as scaffolds for tissue engineering applications due to their favorable biological and mechanical properties. Nevertheless, phase-separation of blend components is an important challenge facing the development of electrospun homogeneous fibrillar natural-synthetic polymers scaffolds; phase-separation can produce significant detrimental effects for scaffolds fabricated by electrospinning. In the present study, blends of gelatin (Gel; natural polymer) and polycaprolactone (PCL; synthetic polymer), containing 30 and 45 wt% Gel, were prepared using acetic acid as a ‘green’ sole solvent to straightforwardly produce appropriate single-step Gel-PCL solutions for electrospinning. Miscibility of Gel and PCL in the scaffolds was assessed and the morphology, chemical composition and structural and solid-state properties of the scaffolds were thoroughly investigated. Results showed that the two polymers proved miscible under the single-step solution process used and that the electrospun scaffolds presented suitable properties for potential skin tissue engineering applications. Viability, metabolic activity and protein expression of human fibroblasts cultured on the Gel-PCL scaffolds were evaluated using LIVE/DEAD (calcein/ethidium homodimer), MTT-Formazan and immunocytochemistry assays, respectively. In vitro results showed that the electrospun Gel-PCL scaffolds enhanced cell viability and proliferation in comparison to PCL scaffolds. Furthermore, scaffolds allowed fibroblasts expression of extracellular matrix proteins, tropoelastin and collagen Type I, in a similar way to positive controls. Results indicated the feasibility of the single-step solution process used herein to obtain homogeneous electrospun Gel-PCL scaffolds with Gel content ≥30 wt% and potential properties to be used as scaffolds for skin tissue engineering applications for wound healing.

The recent burst of research on smart materials is a clear evidence of the growing interest of the scientific community, industry, and society in the field. The exploitation of the great potential of stimuli-responsive materials for sensing, actuation, logic, and control applications is favored and supported by new manufacturing technologies, such as electrospinning, that allows to endow smart materials with micro- and nanostructuration, thus opening up additional and unprecedented prospects. In this wide and lively scenario, this article systematically reviews the current advances in the development of thermoactive electrospun fibers and textiles, sorting them, according to their response to the thermal stimulus. Hence, several platforms including thermoresponsive systems, shape memory polymers, thermo-optically responsive systems, phase change materials, thermoelectric materials, and pyroelectric materials, are described and critically discussed. The difference in active species and outputs of the aforementioned categories is highlighted, evidencing the transversal nature of temperature stimulus. Moreover, the potential of novel thermoactive materials are pointed out, revealing how their development could take to utmost interesting achievements.

Lithium/sulfur batteries are one of the most promising technologies for the next-generation batteries. However, this technology suffers from several problems mainly related to the instability of metallic lithium and to the polysulfides (PS) shuttle. An approach to address such issues is the design of new separators or the modification of existing commercial ones. The use of hybrid membranes is here proposed to improve the performance of Li metal anode and sulfur cathode. Composite separators are obtained by electrospinning or drop-casting a polymer solution of polyvinylidenefluoride (PVdF) containing graphene oxide (GO) on a polyolefin commercial Celgard 2300 separator. This is the first time that a thin layer of electrospun PVdF/GO composite is applied to a polyolefin separator for the use in Li metal-based batteries. We demonstrate that electrospinning is an effective method to obtain a thin polymer layer of PVdF/GO. The electrospun layer improves the wettability of the separator; it is beneficial to the growth of “soft” dendrite on Li anode and has a positive effect on the PS shuttle process. The casted layer featuring a higher GO content is also effective in increasing the separator wettability, although with a minor effect on Li interphase.

The “pulsed electron deposition” (PED) technique, in which a solid target material is ablated by a fast, high-energy electron beam, was initially developed two decades ago for the deposition of thin films of metal oxides for photovoltaics, spintronics, memories, and superconductivity, and dielectric polymer layers. Recently, PED has been proposed for use in the biomedical field for the fabrication of hard and soft coatings. The first biomedical application was the deposition of low wear zirconium oxide coatings on the bearing components in total joint replacement. Since then, several works have reported the manufacturing and characterization of coatings of hydroxyapatite, calcium phosphate substituted (CaP), biogenic CaP, bioglass, and antibacterial coatings on both hard (metallic or ceramic) and soft (plastic or elastomeric) substrates. Due to the growing interest in PED, the current maturity of the technology and the low cost compared to other commonly used physical vapor deposition techniques, the purpose of this work was to review the principles of operation, the main applications, and the future perspectives of PED technology in medicine.

The majority of the crosslinking approaches employed to confer water resistance properties to electrospun gelatin mats are based on the use of potential cytotoxic agents, turning out to be not suitable for biomedical applications. Environmentally friendly chemical strategies based on the use of non-toxic agents are, therefore, strongly demanded. In the present work, the possibility to produce crosslinked electrospun fish gelatin mats by electrospinning an aqueous solution, containing citric acid as a crosslinking agent, is reported. The effect of pH on solution rheological properties, as well as on the electrospun mat morphology, chemistry, and crosslinking degree, is assessed. The increase of solution pH from 1.8 to 3.7 allows for obtaining fibers that maintain the fibrous morphology also in the mat. Subsequent thermal treatment of the electrospun mat (80 degrees C for 30 min) turns out to increase the crosslinking degree and morphological stability of the mat. This research was funded by the Spanish Ministry of Science, Innovation and Universities (RTI2018-097100-B-C22), the Basque Government (Department of Quality and Food Industry), the Provincial Council of Gipuzkoa (Department of Economic Development, the Rural Environment and Territorial Balance) and the Italian Ministry of University and Research (MIUR).

An interpenetrating polymer network (IPN) nanocomposite hydrogel based on gum acacia, acrylamide and acrylic acid Ga-cl-poly (AAm-IPN-AA) was synthesized by a two-step aqueous polymerization followed by a one-step impregnation of silver nanoparticles. The first step comprises the preparation of a semi-interpenetrating polymer network [Ga-cl-poly (AAm)] based on AAm and Ga via free radical polymerization. The reaction was initiated by ammonium persulphate under microwave irradiation and N, N′-methylene-bis-acrylamide was used as a crosslinker during the polymerization. The maximum percentage of swelling (1256%) was exhibited by the semi-IPN. In the second step, the synthesis of IPN was carried out by the crosslinking of polyacrylic acid onto semi-IPN hydrogel. The synthesized crosslinked hydrogels were studied by FTIR, SEM and XRD techniques. Silver nanoparticles (AgNPs) (20–80 nm) were synthesized through the reduction of silver nitrate by flower extract of Koelreuteria apiculate. The synthesized hydrogels were employed as a template for the impregnation of AgNPs. The resultant nanocomposite hydrogels were characterized by XRD, FTIR, and SEM. The prepared samples were subjected to antibacterial and antifungal studies with different bacterial (Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa) and fungal strains (Aspergillus and Penicillium). Synthesized nanocomposite hydrogels have shown improved antibacterial and antifungal activities.

One of the greatest global challenges of the 21st century is facing the depletion of phosphorous reserves, widely used in fertilizers. One possibility is to recover the phosphorous discharged in the water by human activities, with the consequent additional benefit of improving water quality by limiting eutrophication. In this work, biodegradable poly( l -lactic acid) (PLLA) nonwovens produced by electrospinning are proposed as highly porous fibrous materials characterized by high surface-to-volume ratio for promoting the crystallization of struvite crystals as a means to recover both phosphorus and nitrogen from a nutrient rich solution. To this aim, PLLA fibers were intentionally loaded with a small amount of struvite crystals (3,7 wt%) by applying different preparation procedures, including sonication steps, single-nozzle and coaxial electrospinning. PLLA fibers containing struvite crystals were immersed in a synthetic solution of suitable ions to investigate the occurrence of struvite accumulation through the analysis of the soaked nonwovens with several techniques, i.e. Scanning and Transmission Electron Microscopy, Wide Angle X-Ray Diffraction, Thermogravimetric analysis and Atomic Emission Spectrometry. We demonstrated that struvite loaded in the PLLA fibers successfully acted as crystal seeds and enabled the precipitation of struvite crystals firmly attached to fiber surface. Results showed that the quality of crystal seeds dispersion in PLLA fibers as well as their location along the fiber section heavily affect struvite recovery. Prospectively, these materials can be directly used, after being in contact with wastewater and enriched with struvite, as ready-to-use fertilizers.

For regenerative medicine, the development of an optimal biomaterial system to deliver cells is crucial to precisely locate cells in the target site while preserving cell activity and function. In addition, the cell delivery construct should have the same instructive role as the extracellular microenvironment that naturally surrounds cells within a tissue. This chapter presents an overview of main concepts for the design of bioresorbable constructs for cell delivery and tissue regeneration, namely, types of polymers with recognized biocompatibility and bioresorbability, mechanical properties, structural architecture, and mass transport of the construct, as well as incorporation of biochemical and biophysical cues to provide instructive cell signaling and scaffold bioactivity. Regulatory and clinical aspects are mentioned at the end as they are important to ensure commercial success for these cutting-edge products.

Polyvinylidenedifluoride (PVdF) and polyethyleneoxide (PEO) are blended and electrospun in order to obtain membranes suitable as Li-ion battery separators. The separators are characterized, and their properties investigated and compared with those of PVdF and commercial separators. The PVdF-PEO based separators ensure increased conductivities, greater electrolyte uptake and higher porosities than commercial polyolefines, all factors that improve cell performance. They are also safer than PVdF separators thanks to lower shutdown temperature, even if their mechanical properties are not yet comparable with those of the latter.

Impedance-based sensors represent a promising tool for cell monitoring to improve current invasive biological assays. A novel research field is represented by measurements performed in dynamic conditions, monitoring cells (e.g., myocytes) for which the mechanical stimulus plays an important role for promoting maturation. In this picture, we applied printed and stretchable electronics principles, developing a system able to evaluate cells adhesion during substrate cyclic strain. Cytocompatible and stretchable sensors were ink-jet printed using carbon-based ink on crosslinked poly([Formula: see text]-caprolactone) electrospun mats. Moreover, a customized stretching device was produced, with a complete user interface to control testing condition, validated in order to correlate impedance changes with myoblasts — i.e., myocytes precursors — adhesion. Overall system sensitivity was evaluated using three different cell concentrations and DAPI imaging assay was performed to confirm myoblast adhesion. Preliminary results showed the possibility to correlate an average increase of impedance magnitude of 1[Formula: see text]k[Formula: see text] every 15,000 cells/cm2 seeded, suggesting the possibility to discriminate between different cell concentrations, with a sensitivity of 80[Formula: see text]m[Formula: see text]/(cells/cm2). In conclusion, the present system might be generalized in the development of future applications, including the differentiation process of cardiac myocytes with the aid of mechanical stimuli.

Lesions of tendons and ligaments account for over 40% of the musculoskeletal lesions. Surgical techniques and materials for repair and regeneration are currently not satisfactory. The high rate of post-operative complications and failures mainly relates to the technical difficulties in replicating the complex multiscale hierarchical structure and the mechanical properties of the native tendons and ligaments. With the aim of overcoming the limitations of non-biomimetic devices, we developed a hierarchical structure replicating the organization of tendons and ligaments. The scaffold consists of multiple bundles made of resorbable electrospun nanofibers of Poly-L-Lactic acid (PLLA) having tailored dimensions, wrapped in a sheath of nanofibers able to compact the construct. The bundles in turn consist of electrospun nanofibers with a preferential direction. High-resolution x-ray tomographic investigation at nanometer resolution confirmed that the morphology of the single bundles and of the entire scaffold replicated the hierarchical arrangement in the natural tendons and ligaments. To confirm that these structures could adequately restore tendons and ligaments, we measured the tensile stiffness, strength and toughness. The mechanical properties were in the range required to replace and repair tendons and ligaments. Furthermore, human fibroblasts were able to attach to the scaffolds and showed an increase in cell number, indicated by an increase in metabolic activity over time. Fibroblasts were preferentially aligned along the electrospun nanofibers. These encouraging in vitro results open the way for the next steps towards in vivo regeneration of tendons and ligaments.

Novel bio-based and biodegradable electrospun membranes, containing bactericidal ricinoleic acid (RA) units either by copolymerization with butylene succinate (BS) units or by blending PRA and PBS homopolymers, are characterized in their chemical, thermal, mechanical and surface properties. In the blends E. coli and S. aureus mortality rate increases with PRA amount, while the copolymer shows lower bactericidal activity compared to the blend with similar composition. XPS demonstrates that in the blends an enrichment of RA units at the fiber surface occurs during electrospinning due to phase separation, while in the copolymer RA units are homogeneously dispersed along fiber cross-section.

Innovative separators able to improve the performance and safety of Li-ion batteries are under investigation to meet the growing demand for large-size and high energy density electrochemical cells. In this work, highly porous nanofibrous Poly(vinylidene fluoride) (PVdF) separators loaded with oxide nanoparticles were produced by electrospinning. Silicon oxide and tin oxide nanoparticles were added to PVdF and membranes were characterized by SEM-EDS and TGA. The effect of nanoparticle addition on electrolyte uptake, mechanical properties and conductivity was investigated and such properties were compared to those of a commercial separator (Celgard 2400). Results showed that a small amount of additive can significantly improve the properties of PVdF electrospun membranes and that the different nanoparticles investigated in this work have different effect on membrane performances. In particular, the addition of SiO2 increases the rate of electrolyte uptake and the toughness of the electrospun membrane, while the addition of SnO2 decreases the rate of electrolyte uptake and increases the stiffness of the electrospun membrane. When loaded with nanoparticles, PVdF membranes maintain their insulating character also at high temperature. Preliminary electrochemical results on half-cell vs Li with LiFePO4 and electrospun separators showed good cycling performance, highlighting interesting features of this technology. © The Author(s) 2015. Published by ECS. This is an open access article distributed under the terms of the Creative Commons Attribution Non-Commercial No Derivatives 4.0 License (CC BY-NC-ND, http://creativecommons.org/licenses/by-nc-nd/4.0/), which permits non-commercial reuse, distribution, and reproduction in any medium, provided the original work is not changed in any way and is properly cited. For permission for commercial reuse, please email: oa@electrochem.org. [DOI: 10.1149/2.0421506jes] All rights reserved.

Bacterial cellulose has many unique properties that include its prepn. in high purity, absorption of large amts. of water, and a microfibril structure. The ability of cellulose producing bacteria to in vivo incorporate non-natural sugar units in the polymer was studied. Culturing Gluconacetobacter hansenii on glucose and corn-steep liquor (CSL) gave microbial cellulose. However, when the organism was grown on different ratios of glucose and N-acetyl glucoseamine (NAG), microfibrous polymers were obtained that had both glucose and NAG repeat units in different proportions. Studies of sugar utilization and polymer formation as a function of culture time were performed. Sequential enzymic degrdn. of the polymers using cellulases, cellobiase and chitinase liberated sugars that were analyzed by HPLC. By this method NAG contents in the copolymer up to 35 mol-% were found. Studies of the NAG/glucose copolymers by X-ray spectroscopy showed new X-ray bands and decreases in crystallinity relative to microbial cellulose.