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High strength and ductility are highly desired in fiber‐reinforced composites, yet achieving both simultaneously remains elusive. A hierarchical architecture is developed utilizing high aspect ratio chemically transformable thermoplastic nanofibers that form covalent bonding with the matrix to toughen the fiber‐matrix interphase. The nanoscale fibers are electrospun on the micrometer‐scale reinforcing carbon fiber, creating a physically intertwined, randomly oriented scaffold. Unlike conventional covalent bonding of matrix molecules with reinforcing fibers, here, the nanofiber scaffold is utilized ‒ interacting non‐covalently with core fiber but bridging covalently with polymer matrix ‒ to create a high volume fraction of immobilized matrix or interphase around core reinforcing elements. This mechanism enables efficient fiber‐matrix stress transfer and enhances composite toughness. Molecular dynamics simulation reveals enhancement of the fiber‐matrix adhesion facilitated by nanofiber‐aided hierarchical bonding with the matrix. The elastic modulus contours of interphase regions obtained from atomic force microscopy clearly indicate the formation of stiffer interphase. These nanoengineered composites exhibit a ≈60% and ≈100% improved in‐plane shear strength and toughness, respectively. This approach opens a new avenue for manufacturing toughened high‐performance composites. [ABSTRACT FROM AUTHOR]

Abstract High strength and ductility are highly desired in fiber‐reinforced composites, yet achieving both simultaneously remains elusive. A hierarchical architecture is developed utilizing high aspect ratio chemically transformable thermoplastic nanofibers that form covalent bonding with the matrix to toughen the fiber‐matrix interphase. The nanoscale fibers are electrospun on the micrometer‐scale reinforcing carbon fiber, creating a physically intertwined, randomly oriented scaffold. Unlike conventional covalent bonding of matrix molecules with reinforcing fibers, here, the nanofiber scaffold is utilized ‒ interacting non‐covalently with core fiber but bridging covalently with polymer matrix ‒ to create a high volume fraction of immobilized matrix or interphase around core reinforcing elements. This mechanism enables efficient fiber‐matrix stress transfer and enhances composite toughness. Molecular dynamics simulation reveals enhancement of the fiber‐matrix adhesion facilitated by nanofiber‐aided hierarchical bonding with the matrix. The elastic modulus contours of interphase regions obtained from atomic force microscopy clearly indicate the formation of stiffer interphase. These nanoengineered composites exhibit a ≈60% and ≈100% improved in‐plane shear strength and toughness, respectively. This approach opens a new avenue for manufacturing toughened high‐performance composites.

BACKGROUND: Cartilage decellularized extracellular matrix (dECM) is an ideal biomaterial for the preparation of cartilage tissue engineering scaffolds, which can be used to repair cartilage defects. OBJECTIVE: To use polyvinyl alcohol (PVA) as the loading material of dECM and poly3-hydroxybutyrate 4-hydroxybutyrate (P34HB) as the frame material to prepare P34HB-PVA-dECM composite nanofiber scaffolds by two-needle electrospinning, and preliminarily explore the bioactivity of the scaffolds in vitro. METHODS: The cellular components in the cartilage tissue were removed by a combination of enzyme, chemical, and ultrasonic concussion cleaning methods to prepare cartilage dECM. P34HB, P34HB-PVA, and P34HB-PVA-dECM scaffolds were prepared by two-neezle electrospinning. The fiber morphology, composition, hydrophilicity, and mechanical properties of the scaffolds were characterized. Human bone marrow mesenchymal stem cells were co-cultured with the three kinds of scaffolds. The viability of cells on scaffolds was evaluated by the Live/Dead staining. The adhesion morphology of the cells on the scaffolds was observed by scanning electron microscopy. The proliferation performance of the cells on the scaffolds was detected by the alamar blue kit. The chondrogenic differentiation of human bone marrow stem cells on the scaffolds was evaluated by type II collagen immunofluorescence. RESULTS AND CONCLUSION: (1) Scanning electron microscopy results showed that the scaffold fibers in each group were randomly distributed and the interconnections between the fibers showed a porous structure. The fiber diameter of P34HB-PVA-dECM scaffolds was the smallest. The P34HB-PVA-dECM scaffolds had the smallest water contact angle (P < 0.05) and the highest water absorption rate compared with the P34HB and P34HB-PVA scaffolds (P < 0.05). The elastic modulus of the P34HB-PVA-dECM scaffolds was higher than that of the P34HB and P34HB-PVA scaffolds (P < 0.05). (2) Live/Dead staining showed that most cells survived well on the three groups of scaffolds. The scanning electron microscope observation showed that the bone marrow mesenchymal stem cells on P34HB-PVA-dECM scaffolds extended pseudopod more fully and fused better with the scaffolds. Alamar blue staining exhibited that the proliferation rate of bone marrow mesenchymal stem cells on the P34HB-PVA-dECM scaffolds was faster than that on the P34HB and P34HB-PVA scaffolds (P < 0.05). The immunofluorescence staining results showed that more type II collagen produced after chondrogenic induction on the P34HB-PVA-dECM scaffolds was more than that on the P34HB and P34HB-PVA scaffolds (P < 0.05). (3) To sum up, the P34HB-PVA-dECM composite nanofiber scaffolds have smaller fiber structure, more optimized hydrophilicity and mechanical properties, which is more favorable for the adhesion, proliferation, and differentiation into chondrocytes of bone marrow mesenchymal stem cells. [ABSTRACT FROM AUTHOR]

Pulp-Dentin regeneration is a key aspect of maintain tooth vitality and enabling good oral-systemic health. This study aimed to investigate a nanofibrous scaffold loaded with a small molecule i.e. Tideglusib to promote odontogenic differentiation. Tideglusib (GSK-3β inhibitor) interaction with GSK-3β was determined using molecular docking and stabilization of β-catenin was examined by confocal microscopy. 3D nanofibrous scaffolds were fabricated through electrospinning and their physicochemical characterizations were performed. Scaffolds were seeded with mesenchymal stem cells or pre-odontoblast cells to determine the cells proliferation and odontogenic differentiation. Our results showed that Tideglusib (TG) binds with GSK-3β at Cys199 residue. Stabilization and nuclear translocation of β-catenin was increased in the odontoblast cells treated with TG. SEM analysis revealed that nanofibers exhibited controlled architectural features that effectively mimicked the natural ECM. UV-Vis spectroscopy demonstrated that TG was incorporated successfully and released in a controlled manner. Both kinds of biomimetic nanofibrous matrices (PCLF-TG100, PCLF-TG1000) significantly stimulated cells proliferation. Furthermore, these scaffolds significantly induced dentinogenic markers (ALP, and DSPP) expression and biomineralization. In contrast to current pulp capping material driving dentin repair, the sophisticated, polymeric scaffold systems with soluble and insoluble spatiotemporal cues described here can direct stem cell differentiation and dentin regeneration. Hence, bioactive small molecule-incorporated nanofibrous scaffold suggests an innovative clinical tool for dentin tissue engineering. Graphical Abstract [ABSTRACT FROM AUTHOR]

Nanofiber scaffolds have emerged as a revolutionary drug delivery platform for promoting wound healing, due to their unique properties, including high surface area, interconnected porosity, excellent breathability, and moisture absorption, as well as their spatial structure which mimics the extracellular matrix. However, the use of nanofibers to achieve controlled drug loading and release still presents many challenges, with ongoing research still exploring how to load drugs onto nanofiber scaffolds without loss of activity and how to control their release in a specific spatiotemporal manner. This comprehensive study systematically reviews the applications and recent advances related to drug-laden nanofiber scaffolds for skin-wound management. First, we introduce commonly used methods for nanofiber preparation, including electrostatic spinning, sol–gel, molecular self-assembly, thermally induced phase separation, and 3D-printing techniques. Next, we summarize the polymers used in the preparation of nanofibers and drug delivery methods utilizing nanofiber scaffolds. We then review the application of drug-loaded nanofiber scaffolds for wound healing, considering the different stages of wound healing in which the drug acts. Finally, we briefly describe stimulus-responsive drug delivery schemes for nanofiber scaffolds, as well as other exciting drug delivery systems. [ABSTRACT FROM AUTHOR]

Electrospun fibers, with proven ability to promote tissue regeneration, are widely being explored for rotator cuff repairing. However, without post treatment, the microstructure of the electrospun scaffold is vastly different from that of natural extracellular matrix (ECM). Moreover, during mechanical loading, the nanofibers slip that hampers the proliferation and differentiation of migrating stem cells. Here, electrospun nanofiber scaffolds, with crimped nanofibers and welded joints to biomimic the intricate natural microstructure of tendon-to-bone insertion, were prepared using poly(ester-urethane)urea and gelatin via electrospinning and double crosslinking by a multi-bonding network densification strategy. The crimped nanofiber scaffold (CNS) features bionic tensile stress and induces chondrogenic differentiation, laying credible basis for in vivo experimentation. After repairing a rabbit massive rotator cuff tear using a CNS for 3 months, the continuous translational tendon-to-bone interface was fully regenerated, and fatty infiltration was simultaneously inhibited. Instead of micro-CT, μCT was employed to visualize the integrity and intricateness of the three-dimensional microstructure of the CNS-induced-healed tendon-to-bone interface at an ultra-high resolution of less than 1 μm. This study sheds light on the correlation between nanofiber post treatment and massive rotator cuff repair and provides a general strategy for crimped nanofiber preparation and tendon-to-bone interface imaging characterization.

Electrospinning has contributed substantially to the construction of nanofibrous scaffolds for potential tissue engineering and regenerative medicine applications. However, conventional electrospinning only has the ability to generate and collect nanofiber scaffolds with a randomly oriented fibrous pattern, which lack the necessary cell alignment guidance function. In this study, a novel electrospinning fiber-collecting device was designed and developed by setting a series of small pin-ring-structured collectors on a large plain plate. Specifically, we demonstrated that the pin-ring-structured collectors, which were constructed by inserting a metal pin into the center of a metal ring, could collect the as-electrospun nanofibers with radially oriented structures in an innovative manner. We first investigated the suitable polymeric concentration for electrospinning poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), and the optimum electrospinning concentration of PHBV was found to be 12% (w/v) PHBV dissolved in hexafluoroisopropyl alcohol (HFIP). Then, 12% (w/v) PHBV solution was electrospun into radially oriented nanofiber scaffolds using our novel electrospinning strategy, and their various performances were further compared with conventionally randomly oriented nanofiber scaffolds that were also produced from 12% (w/v) PHBV solution. The results showed that the radially oriented PHBV nanofiber scaffolds exhibited obviously enhanced mechanical properties and decreased hydrophobicity compared with the randomly oriented PHBV nanofiber scaffold controls. Importantly, the biological properties of radially oriented PHBV nanofiber scaffolds were also demonstrated to be enhanced, compared with randomly oriented PHBV nanofiber scaffolds, by effectively inducing cell alignment and significantly promoting cell proliferation. In sum, the present study indicates that our as-prepared nanofiber scaffolds with a radially oriented pattern are of great interest for advanced applications, such as wound dressings and tissue-engineered scaffolds. [ABSTRACT FROM AUTHOR]

Synthetic peptides are promising structural and functional components of bioactive and tissue-engineering scaffolds. Here, we demonstrate the design of self-assembling nanofiber scaffolds based on peptide amphiphile (PA) molecules containing multi-functional histidine residues with trace metal (TM) coordination ability. The self-assembly of PAs and characteristics of PA nanofiber scaffolds along with their interaction with Zn, Cu, and Mn essential microelements were studied. The effects of TM-activated PA scaffolds on mammalian cell behavior, reactive oxygen species (ROS), and glutathione levels were shown. The study reveals the ability of these scaffolds to modulate adhesion, proliferation, and morphological differentiation of neuronal PC-12 cells, suggesting a particular role of Mn(II) in cell-matrix interaction and neuritogenesis. The results provide a proof-of-concept for the development of histidine-functionalized peptide nanofiber scaffolds activated with ROS- and cell-modulating TMs to induce regenerative responses. [ABSTRACT FROM AUTHOR]

Electrospun nonwovens have great potential for biomedical applications. They can be used, for example, to mimic the structure of the extracellular matrix of biological tissue. In this work, it is demonstrated that the surface properties of nanofiber nonwovens made of biocompatible and very slowly biodegrading polyamide can be modified by UV picosecond laser processing. Basically, the nanofiber structure is only slightly changed by the corresponding laser process. Significant laser‐induced material change occurs only along narrow lines determined by the scanning process. The newly formed surface structures resemble a bulk surface. It is shown that the growth of mammalian chondrocyte cells (SW1353) is initially more effective on the laser‐processed surface. Cell growth occurs preferably along the laser‐generated lines. After several days of cell growth, an extended layer of cells is formed over the laser‐modified and unmodified surface sections. Thus, laser‐based surface modification provides another tool to affect cell proliferation on polyamide nanofiber nonwovens. [ABSTRACT FROM AUTHOR]

Nanofiber scaffolds have emerged as a revolutionary drug delivery platform for promoting wound healing, due to their unique properties, including high surface area, interconnected porosity, excellent breathability, and moisture absorption, as well as their spatial structure which mimics the extracellular matrix. However, the use of nanofibers to achieve controlled drug loading and release still presents many challenges, with ongoing research still exploring how to load drugs onto nanofiber scaffolds without loss of activity and how to control their release in a specific spatiotemporal manner. This comprehensive study systematically reviews the applications and recent advances related to drug-laden nanofiber scaffolds for skin-wound management. First, we introduce commonly used methods for nanofiber preparation, including electrostatic spinning, sol–gel, molecular self-assembly, thermally induced phase separation, and 3D-printing techniques. Next, we summarize the polymers used in the preparation of nanofibers and drug delivery methods utilizing nanofiber scaffolds. We then review the application of drug-loaded nanofiber scaffolds for wound healing, considering the different stages of wound healing in which the drug acts. Finally, we briefly describe stimulus-responsive drug delivery schemes for nanofiber scaffolds, as well as other exciting drug delivery systems.

Synthetic peptides are promising structural and functional components of bioactive and tissue-engineering scaffolds. Here, we demonstrate the design of self-assembling nanofiber scaffolds based on peptide amphiphile (PA) molecules containing multi-functional histidine residues with trace metal (TM) coordination ability. The self-assembly of PAs and characteristics of PA nanofiber scaffolds along with their interaction with Zn, Cu, and Mn essential microelements were studied. The effects of TM-activated PA scaffolds on mammalian cell behavior, reactive oxygen species (ROS), and glutathione levels were shown. The study reveals the ability of these scaffolds to modulate adhesion, proliferation, and morphological differentiation of neuronal PC-12 cells, suggesting a particular role of Mn(II) in cell-matrix interaction and neuritogenesis. The results provide a proof-of-concept for the development of histidine-functionalized peptide nanofiber scaffolds activated with ROS- and cell-modulating TMs to induce regenerative responses.

In this study, soybean protein nanoparticles (SPN) modified poly(hydroxybutyrate) (PHB) electrospun nanofiber scaffold is fabricated by a facile two-step method combination of PHB electrospinning and SPN evaporation-induced self-assembly. The surface characteristics, structure and properties are investigated by SEM, EDS, XPS, FTIR, XRD, DMA, WCA, tensile test and water uptake capacity measurements. To characterize biodegradability and cytocompatibility, biodegradation tests are performed in simulated body fluid with and without lysozyme and cell cultures are carried out using NIH3T3 mouse fibroblast cells by in vitro studies. The as-obtained SPN-modified PHB nanofiber scaffold presents better cytocompatibility and is more suitable for biomedical applications. [ABSTRACT FROM AUTHOR]

Electrospinning has contributed substantially to the construction of nanofibrous scaffolds for potential tissue engineering and regenerative medicine applications. However, conventional electrospinning only has the ability to generate and collect nanofiber scaffolds with a randomly oriented fibrous pattern, which lack the necessary cell alignment guidance function. In this study, a novel electrospinning fiber-collecting device was designed and developed by setting a series of small pin-ring-structured collectors on a large plain plate. Specifically, we demonstrated that the pin-ring-structured collectors, which were constructed by inserting a metal pin into the center of a metal ring, could collect the as-electrospun nanofibers with radially oriented structures in an innovative manner. We first investigated the suitable polymeric concentration for electrospinning poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), and the optimum electrospinning concentration of PHBV was found to be 12% (w/v) PHBV dissolved in hexafluoroisopropyl alcohol (HFIP). Then, 12% (w/v) PHBV solution was electrospun into radially oriented nanofiber scaffolds using our novel electrospinning strategy, and their various performances were further compared with conventionally randomly oriented nanofiber scaffolds that were also produced from 12% (w/v) PHBV solution. The results showed that the radially oriented PHBV nanofiber scaffolds exhibited obviously enhanced mechanical properties and decreased hydrophobicity compared with the randomly oriented PHBV nanofiber scaffold controls. Importantly, the biological properties of radially oriented PHBV nanofiber scaffolds were also demonstrated to be enhanced, compared with randomly oriented PHBV nanofiber scaffolds, by effectively inducing cell alignment and significantly promoting cell proliferation. In sum, the present study indicates that our as-prepared nanofiber scaffolds with a radially oriented pattern are of great interest for advanced applications, such as wound dressings and tissue-engineered scaffolds.

The paper describes the synthesis of hydroxyapatite (HAp) and strontium-substituted hydroxyapatite (SrHAp) from sand lobster shells by a hydrothermal method. The HAp and SrHAp were incorporated into the polyvinyl alcohol (PVA) nanofiber scaffold through the eletrospinning method. The scaffolds were incorporated with 5wt% of hydroxyapatite (HAp), 5wt%, 10wt%, and 15% of SrHAp. The physicochemical, mechanical, and in vitro biological properties of the scaffold were evaluated. The incorporation of HAp or SrHAp was evidenced by the diffraction patterns and the phosphate functional groups related to HAp. The morphological results showed the decrement of fiber diameter in line with the increased SrHAp concentration. A tensile test was conducted to investigate the mechanical properties of the scaffolds, and the results showed that the scaffolds perform poorly at a higher SrHAp concentration because of exceeding agglomeration levels. The PVA/SrHAp15 performed the best antibacterial activity against E. coli and S. aureus with an inhibition zone of (15.2 ± 0.2) and (14.5 ± 0.8), respectively. The apatite formation was more abundant in PVA/SrHAp10 after immersion in a simulated body fluid (SBF). Cell viability results showed that the scaffold enabled the osteoblast cells to grow and proliferate. The biocompatibility of HAp and SrHAp resulted in the enhancement of cell adhesion. Based on all tests, the PVA/SrHAp 10 scaffold shows a strong candidate for further in vivo studies., (© 2024 IOP Publishing Ltd. All rights, including for text and data mining, AI training, and similar technologies, are reserved.)

Polyvinyl alcohol (PVA), as an important polymeric material, has various applications in industry and medicine. The present study investigated these nanofibers' mechanical properties, including modulus of elasticity (MOE), the adhesion between them and the atomic force microscope probe. The study used an electrospinning system to synthesize PVA nanofibers with different concentrations as well as aligned and random scaffold assemblies. The effect of different concentrations and nanofiber scaffold assemblies on the MOE and adhesion was investigated for the extension and retraction strokes in JPK SPM. The results showed that increasing the PVA concentration increased the MOE but decreased adhesion. Considering the random format of PVA nanofiber scaffolds, the increasing MOE rate and decreasing adhesion rate due to increasing PVA concentration are, respectively, 0.097 Mpa (PVA Concentration %) - 1 and 1.868 Nn (PVA Concentration %) - 1 for extension stroke and for retraction stroke are 0.255 Mpa (PVA Concentration %) - 1 and 4.75 Nn (PVA Concentration %) - 1 . Moreover, using the aligned nanofiber format reduced the MOE, and the adhesion was greater for the retraction strokes than extension strokes, while the situation was reversed for the MOE. Finally, in nanofibers with random format scaffolds, increasing the PVA concentration increased the diameter of the nanofibers. The increasing rate of average nanofiber diameters by increasing PVA concentration is 89.424 nm (PVA Concentration %) - 1 for random and aligned scaffolds. [ABSTRACT FROM AUTHOR]

Mechanical loading influences on the chondrocyte and may promote articular cartilage repair in vivo. That is thought to play a key role in the differentiation of MSCs and in tissue healing and repair. We aimed to evaluate the effect of mechanical Loading of walking on articular cartilage repair. So the stem cells were isolated from the infrapatellar adipose tissue and were seeded on PCL. Then cell-scaffold constructs were sputter-coated with gold and observed by scanning electron microscopy to determine the adhesion of ASCs on the scaffold. ASCs-PCL constructs were transplanted into defects in sheep knees then ASCs on the scaffold was induced by the mechanical loading in vivo. Repaired tissue was evaluated with Q(RT-PCR), immunofluorescence staining, toluidine blue staining and Masson's trichrome staining, the results revealed the largest areas of type II collagen staining, Sox9 expression, aggrecan and presence of chondrocytes in repaired cartilage in experimental groups. Also, the results of this study suggest that mechanical loading of walking could be used to induce ASCs to repair articular cartilage in vivo. [ABSTRACT FROM AUTHOR]

Critical-sized segmental long bone defects represent a challenging clinical dilemma in the management of battlefield and trauma-related injuries. The residual bone marrow cavity of damaged long bones contains many bone marrow mesenchymal stem cells (BMSCs), which provide a substantial source of cells for bone repair. Thus, a three-dimensional (3D) vertically aligned nanofiber scaffold (VAS) is developed with long channels and large pore size. The pore of VAS toward the bone marrow cavity after transplantation, enables the scaffolds to recruit BMSCs from the bone marrow cavity to the defect area. In vivo, it is found that VAS can significantly shorten gap distance and promote new bone formation compared to the control and collagen groups after 4 and 8 weeks of implantation. The single-cell sequencing results discovered that the 3D nanotopography of VAS can promote BMSCs differentiation to chondrocytes and osteoblasts, and up-regulate related gene expression, resulting in enhancing the activities of bone regeneration, endochondral ossification, bone trabecula formation, bone mineralization, maturation, and remodeling. The Alcian blue and bone morphogenetic protein 2 (BMP-2) immunohistochemical staining verified significant cartilage formation and bone formation in the VAS group, corresponding to the single-cell sequencing results. The study can inspire the design of next-generation scaffolds for effective long-bone regeneration is expected by the authors., (© 2024 Wiley‐VCH GmbH.)

Nanofiber scaffolds provide numerous advantages over common carriers engineered for microorganisms. The most important advantage is an increased speed of primary surface colonization (up to four times faster), which shortens the time required for the areal biofilm formation and optimum performance of attached microorganisms (higher efficiency of biological activity of up to twice as fast). Image analysis predicts early formation of biofilm even in beginning stages; analysis of biofilm reveals the different structures of bacterial colonies on both scaffolds (higher porosity, size, and number of bacterial colonies on nanofiber's surface). The image analysis correlates well with determinations of dry matter (linear correlation of 0.96) and proteins (linear correlation of 0.89). [ABSTRACT FROM AUTHOR]

Implants or cell carriers made of biopolymers or biodegradable polymers are well suited for the regeneration of defects in various tissues. They act as an adhesion surface for autologous cells and provide sufficient stability. Electrospun nonwovens have a favourable surface to volume ratio and mimic the structure of the fiber proteins of the extracellular matrix in tissues. Their high porosity ensures a sufficient supply of nutrients to the cells while maintaining high mechanical strength. In addition, drug-release functionality can be installed in biodegradable nonwovens, which can support the regeneration. Particularly promising are flakes made of electrospun nonwovens which, in an appropriate suspension, can be injected into defective areas. For the production of such flakes, laser cutting or surface structuring can be applied. Typically, ablation by ultrashort laser pulses reduces the heat-affected zones significantly in microprocessing of many polymers. In this work, the quality of processing of electrospun gelatine and poly-lactide (PLA) nonwovens was investigated for UV-solidstate lasers with pulse durations in the nano- and picosecond range. We observed comparable ablation quality of electrospun gelatine nonwovens with UV nanosecond and with UV picosecond ablation. A similar behaviour was found for electrospun PLA nonwovens. Higher pulse energy was necessary for nanosecond ablation with the same focal spot diameter. [ABSTRACT FROM AUTHOR]

Full-thickness skin defect is one of the main clinical problems, which cannot be repaired spontaneously. The aim of this study was to evaluate the feasibility of combining nanofibers with ADM as a bilayer scaffold for treatment of full-thickness skin wounds in a single-step procedure. The nanofibrous polycaprolactone/fibrinogen scaffolds were fabricated by electrospinning. Subsequently, mesenchymal stem cells were isolated from rat adipose tissues and characterized by flow cytometry. Cell adhesion, proliferation, and the epidermal differentiation potential of adipose-derived stem cells (ADSCs) on nanofibrous scaffolds were investigated by scanning electron microscopy (SEM), alamarBlue, and real-time PCR, respectively. In animal studies, full-thickness excisional wounds were created on the back of rats and treated with following groups: ADM, ADM-ADSCs, nanofiber, nanofiber-ADSCs, bilayer, and bilayer-ADSCs. In all groups, wounds were harvested on days 14 and 21 after treatment to evaluate re-epithelialization, blood vessel density, and collagen content. The results indicated that ADSCs seeded on ADM, nanofiber, and bilayer scaffolds can promote re-epithelialization, angiogenesis, and collagen remodeling in comparison with cell-free scaffolds. In conclusion, nanofiber-ADSCs showed the best results for re-epithelialization (according to histological scoring), average blood vessel density (92.7 ± 6.8), and collagen density (87.4 ± 4.9%) when compared to the control and other experimental groups. [ABSTRACT FROM AUTHOR]

In this study, a system of dexamethasone sodium phosphate (DEXP)-loaded chitosan nanoparticles embedded in poly-e-caprolacton (PCL) and gelatin electrospun nanofiber scaffold was introduced with potential therapeutic application for treatment of the nervous system. Besides anti-inflammatory properties, DEXP act through its glucocorticoid receptors, which are involved in the inhibition of astrocyte proliferation and microglial activation. Bovine serum albumin (BSA) was used to improve the encapsulation efficiency of DEXP within chitosan nanoparticles and to overcome its initial burst release. BSA incorporation within the chitosan nanoparticles increased the encapsulation efficiency of DEXP from 30% to 77%. The comparison between DEXP release profile from PCL/gelatin scaffold with and without chitosan nanoparticles revealed that the system of DEXP-BSA-loaded chitosan nanoparticles embedded in electrospun PCL nanofiber scaffold provided a more controlled release pattern of the loaded drug. The scaffolds properties in terms of structure, hydrophilicity, cell compatibility, mechanical property, and biodegradability were further investigated, which might show its potential application for the repair of spinal cord injury. [ABSTRACT FROM AUTHOR]

• PGCC enhances wound healing using piezoelectric and photothermal functionalities. • PGCC with CaO 2 treats chronic hypoxia by converting ROS into molecular O 2. • The wound dressing exhibited ∼ 10 % (E. coli) and ∼ 13 % (S. aureus) survival rates. • US and NIR radiation synergistically enhance wound recovery by ∼ 1.5 folds in vivo. The process of wound healing is often obstructed by the prevalence of bacterial infection at the wound site. Hence, innovative strategies to alleviate infection is extremely necessary to realize effective wound recovery in a timely manner. Here, we report a self-activated composite dressing consisting of piezoelectric and photothermal functional layers for combating wound infection and provide the desired treatment. The synergistic dressing is functionalized with piezoelectric Poly-L-lactic acid (PLLA) which under the effect of ultrasound irradiation controllably generates reactive oxygen species (ROS) for antibacterial activity, thus facilitating the dressing to inhibit the growth of bacteria at the wound bed. Further, the dressing is modified with calcium peroxide (CaO 2) which can effectively convert the generated ROS into molecular oxygen (O 2) in presence of catalase enzyme for treating chronic hypoxia in the infected wounds. The sustained generation of O 2 by the wound dressing augmented the cell proliferation, migration and tissue regeneration aiding in wound healing. By combining the inherent photothermal activity of reduced graphene oxide (rGO), the synergistic dressing under NIR irradiation enhanced the wound recovery by upregulating the heat shock protein 90 (Hsp90) secretion owing to the heat generation on the wounds. The results obtained demonstrate that the self-triggered multifunctional wound dressing is a promising candidate for clinical treatment of infected wounds with a user-friendly interface. [ABSTRACT FROM AUTHOR]

Electrospun nanofiber scaffolds of different polymers are used in tissue engineering to mimic the extracellular matrices with favourable conditions for cell growth and proliferation. Structures such as cavities, holes and cuts in the scaffolds can be used to optimize cell growth. We investigated the influence of different laser sources used for direct laser writing on the cutting and structuring quality of electrospun polyamide nonwovens. Ablation thresholds and rates were determined. Because of different approaches in cell colonization with scaffolds, the investigations were carried out on dry, wet and immersed nonwovens. The results show that femto- and picosecond lasers are very well suited for processing of dry nonwovens. Processing with green wavelengths is more effective and leads to similar minimum feature sizes than in the ultraviolet range. Ablation rates up to 8000 μm³/pulse were obtained which are about a factor of 100 higher than those for polyamide bulk material. Nanosecond UV lasers produced structures of reduced quality. Excimer lasers at 193 nm offer a possible alternative for large-area structures when operated at low fluences. Processing of wet and immersed nanofibers is possible with smaller processing speed and with a slightly degraded quality. [ABSTRACT FROM AUTHOR]

A straightforward, fast, and versatile technique is developed to fabricate nanofibrous scaffold with excellent hydrophilicity, mechanical properties, and biocompatibility for tissue engineering. The thermoplastic polyurethane (TPU) nanofiber is fabricated by utilizing electrospinning, and then its surface is modified through simply immersing it into cellulose nanofibrils (CNF) dispersion and subjecting to ultrasonication. The results show that the CNF particles are successfully absorbed on the surface of TPU nanofiber. By introducing CNF particles on the surface of TPU nanofiber, the hydrophilicity, mechanical properties of fabricated CNF-absorbed TPU scaffold are significantly increased. Additionally, the adhesion and proliferation of human umbilical vein endothelial cells cultured on CNF-absorbed TPU scaffold are prominently enhanced in comparison with those of cultured on TPU scaffold. These findings suggest that the ultrasound-assisted technique opens up a new way to simply and effectively modify the surface of various scaffolds and the modified scaffold could be shown a great potential in tissue engineering. [ABSTRACT FROM AUTHOR]

Biphasic materials, comprised of an ordered arrangement of two different material phases within a material, have the potential for a wide variety of applications including filtration, protective clothing and tissue engineering. This study reports for the first time, a process for engineering biphasic Janus-type polymeric nanofiber (BJPNF) networks via the centrifugal jet spinning technique. BJPNF alignment and fiber diameter was dependent on fabrication rotational speed as well as solution composition. The biphasic character of these BJPNFs, which was controlled via the rotational speed of fabrication, was confirmed at the individual nanofiber scale using energy dispersive X-ray spectroscopy, and at the bulk, macro-scale using attenuated total reflectance-Fourier transform infrared spectroscopy. Biphasic character was also demonstrated at the functional level via differing affinities on either side of the BJPNF for cell attachment. Our work thus presents a method for fabricating BJPNF scaffold networks where there might be a need for different properties on either side of a material. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 2455-2464, 2017. [ABSTRACT FROM AUTHOR]

Recent trends in tissue engineering have focused on the development of electrically conductive composite scaffolds (i.e. with carbon nanotubes) and on increasing the cell interaction of electrospun synthetic polymers by means of incorporation of biological molecules (i.e. via functionalition with polydopamine). In this study the electrospinning process was first optimized for the processing of poly(ε-caprolactone) and the use of formic acid allowed mats of 100–200 nm nanofibers with (0.5% of CNT) or without CNT to be created. Then, the PCL nanofibers were successfully coated by a polydopamine layer of approximately 15 nm thick, confirmed by XPS analysis and SEM images. This coating did not add mechanical strength and decreased the Young’s modulus of the mats from 25.5 MPa to 13.6 MPa at 21 °C. Consequently, the PCL-PDA coated scaffolds showed higher deformation values when the equilibrium was reached (13.7%) during the fatigue tests (at 37 °C in aqueous medium, 0.5 MPa of stress) under conditions that simulate the heart beats (1 Hz), experiments in which both PCL and the modified mats (with PDA or CNT) exhibited a fatigue life of more than 10 6 cycles. However, at a cyclic stress of 1.5 MPa the PDA treated mats underwent fatigue failures by plastic deformation while those of non-modified PCL failed after partial tearing (only 40% of them exceeded 10 3 cycles). The incorporation of CNTs within the PCL fibers was confirmed by TEM and improved the fatigue performance by means of preventing the fraying of the fibers (80% of the specimens reached at least 10 3 cycles). Both the PDA layer and the presence of embedded stiff carbon nanotubes, hindered fiber orientation in the tensile tests and their elongation at break were lower than those of PCL scaffolds. [ABSTRACT FROM AUTHOR]

Considering the important factor of bioactive nanohydoxyapatite (nHA) to enhance osteoconductivity or bone-bonding capacity, nHA was incorporated into an electrospun polycaprolactone (PCL) membrane using electrospinning techniques. The viscosity of the PCL and nHA/PCL with different concentrations of nHA was measured and the morphology of the electrospun membranes was compared using a field emission scanning electron microscopy. The water contact angle of the nanofiber determined the wettability of the membranes of different concentrations. The surface roughness of the electrospun nanofibers fabricated from pure PCL and nHA/PCL was determined and compared using atomic force microscopy. Attenuated total reflectance Fourier transform infrared spectroscopy was used to study the chemical bonding of the composite electrospun nanofibers. Beadless nanofibers were achieved after the incorporation of nHA with a diameter of 200-700 nm. Results showed that the fiber diameter and the surface roughness of electrospun nanofibers were significantly increased after the incorporation of nHA. In contrast, the water contact angle (132° ± 3.5°) was reduced for PCL membrane after addition of 10% (w/w) nHA (112° ± 3.0°). Ultimate tensile strengths of PCL membrane and 10% (w/w) nHA/PCL membrane were 25.02 ± 2.3 and 18.5 ± 4.4 MPa. A model drug tetracycline hydrochloride was successfully loaded in the membrane and the membrane demonstrated good antibacterial effects against the growth of bacteria by showing inhibition zone for E. coli (2.53 ± 0.06 cm) and B. cereus (2.87 ± 0.06 cm). [ABSTRACT FROM AUTHOR]

The capacity of gelatin/chitosan/bioactive glass nanopowders (GEL/CS/BGNPs) scaffolds was investigated for increasing human endometrial stem cells (hEnSCs) differentiation into the endothelial cells in the presence of angiogenic factors. GEL/CS nanofibrous scaffold with different contents of BGNPs were fabricated and assessed. Expression of endothelial markers (CD31, vascular endothelial cadherin (VE-cadherin), and KDR) in differentiated cells was evaluated. Results showed the diameter of nanofiber increases with decreasing the BG content in GEL/CS scaffolds. Moreover,in vitrostudy indicated that the GEL/CS/BGNPs scaffold with 1.5% BGNPs content provided a suitable three-dimensional structure for endothelial cells differentiation. Thus, the GEL/CS/BGNPs scaffold can be recommended for blood vessels repair. [ABSTRACT FROM AUTHOR]

Bone fractures are often companied with poor bone healing and high rates of infection. Early recruitment of mesenchymal stem cells (MSCs) is critical for initiating efficient bone repair, and mild thermal stimulation can accelerate the recovery of chronic diseases. Here, a bioinspired, staged photothermal effect-reinforced multifunctional scaffold was fabricated for bone repair. Uniaxially aligned electrospun polycaprolactone nanofibers were doped with black phosphorus nanosheets (BP NSs) to endow the scaffold with excellent near-infrared (NIR) responsive capability. Apt19S was then decorated on the surface of the scaffold to selectively recruit MSCs toward the injured site. Afterward, microparticles of phase change materials loaded with antibacterial drugs were also deposited on the surface of the scaffold, which could undergo a solid-to-liquid phase transition above 39 °C, triggering the release of payload to eliminate bacteria and prevent infection. Under NIR irradiation, photothermal-mediated up-regulation of heat shock proteins and accelerated biodegradation of BP NSs could promote the osteogenic differentiation of MSCs and biomineralization. Overall, this strategy shows the ability of bacteria elimination, MSCs recruitment, and bone regeneration promotion with the assistance of photothermal effect in vitro and in vivo , which emphasizes the design of a bioinspired scaffold and its potential for a mild photothermal effect in bone tissue engineering.

Extracellular matrix (ECM) structure and biochemistry provide cell-instructive cues that promote and regulate tissue growth, function, and repair. From a structural perspective, the ECM is a scaffold that guides the self-assembly of cells into distinct functional tissues. The ECM promotes the interaction between individual cells and between different cell types, and increases the strength and resilience of the tissue in mechanically dynamic environments. From a biochemical perspective, factors regulating cell–ECM adhesion have been described and diverse aspects of cell–ECM interactions in health and disease continue to be clarified. Natural ECMs therefore provide excellent design rules for tissue engineering scaffolds. The design of regenerative three-dimensional (3D) engineered scaffolds is informed by the target ECM structure, chemistry, and mechanics, to encourage cell infiltration and tissue genesis. This can be achieved using nanofibrous scaffolds composed of polymers that simultaneously recapitulate 3D ECM architecture, high-fidelity nanoscale topography, and bio-activity. Their high porosity, structural anisotropy, and bio-activity present unique advantages for engineering 3D anisotropic tissues. Here, we use the heart as a case study and examine the potential of ECM-inspired nanofibrous scaffolds for cardiac tissue engineering. We asked: Do we know enough to build a heart ? To answer this question, we tabulated structural and functional properties of myocardial and valvular tissues for use as design criteria, reviewed nanofiber manufacturing platforms and assessed their capabilities to produce scaffolds that meet our design criteria. Our knowledge of the anatomy and physiology of the heart, as well as our ability to create synthetic ECM scaffolds have advanced to the point that valve replacement with nanofibrous scaffolds may be achieved in the short term, while myocardial repair requires further study in vitro and in vivo. [ABSTRACT FROM AUTHOR]