Comparative Analysis of Fiber Alignment Methods in Electrospinning

Enhancing Calcium Phosphate Cements: A review of Bacterial Cellulose (BC) and other Biopolymer Reinforcements for Biomedical Applications

Calcium phosphate cements (CPCs) are renowned for their biocompatibility and osteoconductivity, making them ideal for bone tissue engineering. However, their brittleness and low tensile strength limit their use in load-bearing applications. Bacterial cellulose (BC) has emerged as a promising reinforcement material due to its high tensile strength, biocompatibility, and biodegradability. The incorporation of 2 wt% BC into CPCs increased compressive strength from 5 MPa to 12 MPa, representing a 2.4-fold enhancement, while also improving toughness and promoting cellular interactions through its nanofibrillar structure. Additionally, hybrid composites combining BC with collagen, chitosan, or polycaprolactone (PCL) exhibit synergistic effects, further enhancing mechanical properties and biodegradability. These advancements highlight the potential of BC-reinforced CPCs for clinical applications in bone repair and regeneration. Despite these improvements, limited research addresses tensile and flexural properties, which are critical for load-bearing applications, as well as the effects of BC on injectability and setting time for minimally invasive procedures. Emerging innovations, such as electroactive BC-reinforced CPCs for stimulating bone healing, hold significant potential but remain underexplored. Future research should focus on optimising mechanical properties, validating clinical performance, and developing hybrid formulations to expand their use in load-bearing bone repairs.

Recent advances in structural and functional design of electrospun nanofibers for wound healing

The global prevalence of acute and chronic wounds has surged, escalating healthcare burdens and necessitating advanced therapeutic strategies for effective wound management. Electrospun nanofibers have emerged as promising biomimetic platforms for tissue engineering and drug delivery, due to their structural resemblance to the native extracellular matrix (ECM), high porosity, and tunable surface-to-volume ratio. Recent advances in structural design have expanded their applications from conventional two-dimensional (2D) wound dressings to multifunctional three-dimensional (3D) architectures, enabling enhanced mechanical adaptability, bioactive molecule loading, and spatiotemporal control over wound microenvironments. These innovations leverage nanofibers' customizable topography and composition to recapitulate critical ECM cues, thereby fostering cell proliferation, angiogenesis, and immunomodulation during tissue regeneration. This review systematically evaluates cutting-edge strategies focusing on optimizing 2D arrangements and the structural design of multilayered and functionally patterned 3D electrospun nanofibers in wound healing applications. We further present the advantages and limitations of various nanofiber structures, along with the key challenges and future directions for advancing electrospun nanofibers specifically designed for enhanced wound healing.

An emulsion electrospun nanofibrous scaffold loaded with glial cell line-derived neurotrophic factor for nerve regeneration

Introduction

Damage to peripheral nerves is common in major trauma cases, and current options for surgical repair are often not sufficient to promote satisfactory recovery of sensory and motor function. In this study we describe the development of a biomaterial scaffold with aligned nanofibrous topography and encapsulated neurotrophic factor, designed to direct and enhance axonal regeneration and so effectuate faster return of function.

Methods

Glial cell line-derived neurotrophic factor (GDNF) was loaded into aligned polycaprolactone (PCL) nanofibres using emulsion electrospinning, and the biomaterial was characterised alongside random and aligned PCL scaffolds without growth factor.

Results and discussion

This fabrication route produced fine and uniform nanofibres with sustained release of GDNF over at least four weeks, and the aligned topography was able to orientate the growth of Schwann cells. Finally, the GDNF-loaded aligned nanofibrous scaffold significantly enhanced and directed the outgrowth of primary rat neurons cultured on its surface, demonstrating its promise as a pro-regenerative biomaterial for the surgical repair of nerve injury.

Multifunctional Sensitive Positive Friction Layer of TPU/MXene/STO Composited Film for Triboelectric Nanogenerator

Triboelectric nanogenerators (TENGs) are ideal candidates for flexible wearable electronics due to their simple structure, high output voltage, and sensitivity. However, the output of the flexible TENG for wearable electronics still needs further improvement. This study fabricated a positive triboelectric layer with fillers to improve the output equipped with a dense, irregular surface structure by using electrospinning. The effect of the composite filler consisting of conductive MXene nanosheets and ferroelectric strontium titanate nanoparticles was investigated by adjusting their ratio. Compared to pure thermoplastic polyurethane (TPU), the voltage and current of the TMS-based (TPU/MXene/STO) TENG increased by 7 and 34 times. Furthermore, the fabricated TENG has been successfully applied in flexible sensing. It can detect the curvature of different object grips and various breathing conditions, making it promising for intelligent sensing and health monitoring applications. This study successfully developed a low-cost, high-performance, and highly sensitive TENG, which shows significant potential in smart wearable devices.

Cellular Spatial Sensing Determines Cell Mechanotransduction Activity on the Aligned Nanofibers

The geometric properties of extracellular matrix (ECM) fibers play a crucial role in regulating cellular behaviors and functions. Although extensive research has examined the effects of fiber alignment, conflicting results have often arisen, leaving the precise mechanisms by which electrospun fiber alignment affects cellular behavior still unclear. This study investigates how the arrangement of polycaprolactone (PCL) electrospun fiber substrates affects cellular mechanosensing by modulating cell positioning. Larger cells, whose width on a coverslip exceeds 5 times the width of the aligned fiber gaps (≈8 µm in this study) and that span multiple aligned fibers, demonstrate enhanced spreading and mechanotransduction. Conversely, smaller cells, whose width is less than or equal to 2.5 times the width of the aligned fiber gaps and are confined within fiber interstices, exhibit limited mechanotransductive signaling. These findings are further supported by manipulating cell size and, more importantly, have led to the fabrication of semi-aligned fiber networks that enhance both cell spreading and mechanotransduction. This research emphasizes the importance of optimizing fiber architecture to improve cellular interactions, offering valuable insights for the design of biomimetic scaffolds in tissue regeneration.

Electrospun anisotropic fiber reinforced composites for artificial heart valves

Anisotropic composite valves that approximate natural heart valves are essential for the successful construction of tissue-engineered heart valves. In this work, anisotropic nylon (polyamides, PA) fiber membranes were prepared via electrospinning and further composited with thermoplastic polyurethane (TPU) by the impregnation method to obtain anisotropic PA/TPU composite valves. Young's modulus of the PA/TPU composite valves in the axial and radial directions along the fibers was 85.07 ± 4.22 MPa and 28.72 ± 1.16 MPa, respectively. The anisotropic PA/TPU composite valve exhibited excellent anisotropy, and its anisotropy ratio was 3.03, which was close to that of natural valves. Besides, the anisotropic PA/TPU composite valve exhibits high transparency (∼87%). The in vitro experiments revealed that anisotropic PA/TPU composite valves have better resistance to calcification and good blood compatibility compared with anisotropic nylon fiber membranes. Moreover, the hydrophilicity presented by the anisotropic PA/TPU composite valve reduced the adhesion of calcified particles. The good anticoagulant properties exhibited by the anisotropic PA/TPU composite valve effectively reduced the formation of thrombus after implantation. Cellular experiments and subcutaneous implantation experiments in rats showed that anisotropic PA/TPU composite valves exhibit cellular nontoxicity and good biocompatibility, contributing to cellular differentiation and growth. This preparation method has great potential in preparing anisotropic composite valves.

Fabrication of 3D Hemispherical PCL-Based Scaffolds Through Far-Field Electrospinning Method for Their Potential Use as Contact Lenses

Maintaining precise control over fiber alignment during the electrospinning process is a significant challenge in material science. Various techniques have been explored to enhance fiber alignment, including the use of rotating collectors, patterned electrodes, and magnetic fields. However, these methods are typically complex, expensive, and involve multiple procedural steps, which can hinder their practical application in industrial settings. In this work, polycaprolactone (PCL) was used to electrospun scaffolds characterized by meshed, aligned, and grid fiber structures. A cost-effective approach for fabricating grid fibers, offering enhanced control over the scaffold, and potentially beneficial for medical applications was developed in this study. Using previously fabricated aligned fibers served as a foundation for developing ocular contact lenses incorporating the newly designed grid and meshed fibers. A comparative proof-of-concept study was conducted, utilizing three distinct fiber orientations to evaluate the efficacy and potential use in ocular drug delivery of each fiber type within the scaffolds. The morphology, light transmittance, mechanical properties, and wettability of the contact lenses were systematically assessed. The PCL-based ocular contact lenses, specifically tailored to conform to the anatomical shape of the eye, demonstrated a significant extension in Rhodamine B residence time, achieving an increase of up to two hours compared to conventional eye drops on the porcine cornea. Among the fiber types analyzed, grid fibers emerged as the most promising, followed by aligned fibers, both exhibiting superior Rhodamine B retention compared to meshed fibers. In conclusion, the innovative advancements in fiber alignment techniques and the use of PCL in the fabrication of ocular contact lenses underscore the potential for enhanced medical applications.

Physical properties of zinc, silver, or cerium ion doped borate glass incorporated PCL/gelatin electrospun fibers and their interaction with NG108-15 neural cells

In this study, 1393-B3 based borate bioactive glasses (BGs) undoped and doped with 1 wt% zinc (ZnBG), cerium (CeBG), or silver (AgBG) were prepared and were incorporated into gelatin/PCL (GEL/PCL) electrospun fibers for neural tissue engineering applications. Particle sizes of the prepared BGs were 3.1, 10.6, 14.6, and 3.7 µm for undoped BG, ZnBG, AgBG, and CeBG, respectively. Aligned electrospun fibers were prepared with 5 wt% of BG particles to produce 5BG/PCL/GEL, 5ZnBG/PCL/GEL, 5AgBG/PCL/GEL and 5CeBG/PCL/GEL fibers. Random 5CeBG/PCL/GEL fibers were also prepared for comparison. A rise in fiber diameter was measured for BG-incorporated fibers compared to PCL/GEL fibers. Mechanical tests on the fibers indicated ultimate tensile strength values of 1-3.5 MPa, the range of mechanical properties of neural tissue. Cell culture studies were carried out with the NG108-15 cell line. Cell alignment was observed on the electrospun fibers on day 2. On days 1 and 2, the optical density was higher for ZnBG/PCL/GEL, CeBG/PCL/GEL, and AgBG/PCL/GEL than for BG/PCL/GEL fibers. On day 4, undoped BG-containing nanofibers had higher optical density compared to those containing doped BGs. This result could be due to a slower release rate of boron from the pure BG/PCL/GEL fiber mat. Overall, within the studied range, all fiber mats were found to be suitable for neural tissue engineering in terms of neural cell compatibility and mechanical properties. In the future, a wider range of ion doping must be considered to fully comprehend the potential of such ion-releasing fibers for neural regeneration.

Gelatin nanofibers coated with hyaluronic acid as a mesenchymal stromal cell scaffold for corneal regeneration

Electrospun gelatin nanofibers coated with hyaluronic acid (GelNF-HA) were synthesized as a scaffold for delivering human corneal mesenchymal stromal cells (C-MSCs) directly to deep corneal injuries. Aligned GelNFs were produced by electrospinning, crosslinked using vapor of glutaraldehyde, coated with HA, and crosslinked with EDC/NHS. The GelNF-HA was characterized by SEM, mechanical, and optical properties. It was then investigated as a substrate for C-MSC proliferation and migration in vitro and in a rabbit cornea culture model. The expression of α-smooth muscle actin (α-SMA) was determined in the ex vivo model. SEM showed that the GelNF-HA scaffold was composed of aligned GelNFs with 75 % of the fibers oriented against the same angle. It exhibited a Young's modulus of 1.66 ± 0.59 MPa and approximately 93 % transmittance of visible light. The GelNF-HA membranes supported C-MSC proliferation in vitro. In a scratch migration assay, it facilitated complete wound closure after 48 h in culture. C-MSC-laden GelNF-HA scaffolds supported corneal wound healing in an ex vivo model as well, expressing a lower percentage of stromal α-SMA compared to both the no-treatment keratectomy-only and C-MSC groups (p < 0.05). The C-MSC-supportive GelNF-HA scaffolds hold therapeutic potential for stromal regeneration in the treatment of deep corneal defects.

Titanium dioxide nanoparticles: a promising candidate for wound healing applications

Effective wound management and treatment are crucial in clinical practice, yet existing strategies often fall short in fully addressing the complexities of skin wound healing. Recent advancements in tissue engineering have introduced innovative approaches, particularly through the use of nanobiomaterials, to enhance the healing process. In this context, titanium dioxide nanoparticles (TiO2 NPs) have garnered attention due to their excellent biological properties, including antioxidant, anti-inflammatory, and antimicrobial properties. Furthermore, these nanoparticles can be modified to enhance their therapeutic benefits. Scaffolds and dressings containing TiO2 NPs have demonstrated promising outcomes in accelerating wound healing and enhancing tissue regeneration. This review paper covers the wound healing process, the biological properties of TiO2 NPs that make them suitable for promoting wound healing, methods for synthesizing TiO2 NPs, the use of scaffolds and dressings containing TiO2 NPs in wound healing, the application of modified TiO2 NPs in wound healing, and the potential toxicity of TiO2 NPs.

Electrospun fiber patches for inflammatory skin diseases - Correlating in vitro drug release with ex vivo permeation

In this proof-of-concept study, we aimed to develop an anti-inflammatory patch that in contrast to the semi-solid standard therapy is dry and non-greasy, and only needs to be changed once a day due to continuous release of the active ingredient over 24 h. While fiber materials for the treatment of inflammatory skin diseases have been reported in the literature, the majority of studies focuses solely on material characterization including in vitro release studies; however, there is a lack of ex vivo permeation studies as well as comparison with standard therapy. However, such experiments are crucial to deduct the potential efficacy of the drug delivery system, as skin absorption of the drug may be the rate-limiting step and not the drug release. Therefore, we set out to investigate different types of electrospun fiber systems based on polycaprolactone, a polymer with a well-established safety profile widely used for fabricating electrospun patches. The electrospun fiber patches were loaded with the anti-inflammatory drug hydrocortisone and characterized not only for their drug release properties, but for the first time also for their skin permeation and retention as well as their cytocompatibility and anti-inflammatory properties on human skin. While in the release studies, the layer-by-layer fiber system proved to be best suited for an application time of 24 h, this was not reflected in the permeation studies, where all fiber systems showed a similar skin permeation and retention of the drug. In our study set-up, a comparison with standard cream formulations revealed that electrospun fibers offer an advantage in terms of the permeated amount of hydrocortisone. Overall, this study supports the importance of conducting comparisons with standard therapies and, additionally, confirms that electrospun fibers are a promising dosage form for the controlled release of anti-inflammatory drugs for the treatment of inflammatory skin diseases.

Expandable Microspheres Transform 2D Electrospun Mats Into 3D Composite Scaffolds

Electrospun nanofibers have proven versatile across numerous fields, including environmental, energy, and biomedical applications. Typically, however, electrospun nanofiber materials are fabricated as two-dimensional sheets, membranes, or mats. In this study, a straightforward and adaptable foaming method is presented to create three-dimensional microsphere-nanofiber composite structures. This approach involves incorporating expandable microspheres within the nanofiber mats during electrospinning, followed by thermal treatment to achieve the 3D morphology. The expansion ratio and compressive strength increase with higher concentrations of expandable microspheres. In addition, the compressive strength of the 3D composite structures significantly surpasses that of 3D nanofiber scaffolds expanded with subcritical CO2 fluids. This approach presents a promising pathway for fabricating 3D microsphere-nanofiber composite scaffolds with broad potential applications.

Recent trends on polycaprolactone as sustainable polymer-based drug delivery system in the treatment of cancer: Biomedical applications and nanomedicine

The unique properties-such as biocompatibility, biodegradability, bio-absorbability, low cost, easy fabrication, and high versatility-have made polycaprolactone (PCL) the center of attraction for researchers. The derived introduction in this manuscript gives a pretty detailed overview of PCL, so you can first brush up on it. Discussion on the various PCL-based derivatives involves, but is not limited to, poly(ε-caprolactone-co-lactide) (PCL-co-LA), PCL-g-PEG, PCL-g-PMMA, PCL-g-chitosan, PCL-b-PEO, and PCL-g-PU specific properties and their probable applications in biomedicine. This paper has considered examining the differences in the diverse disease subtypes and the therapeutic value of using PCL. Advanced strategies for PCL in delivery systems are also considered. In addition, this review discusses recently patented products to provide a snapshot of recent updates in this field. Furthermore, the text probes into recent advances in PCL-based DDS, for example, nanoparticles, liposomes, hydrogels, and microparticles, while giving special attention to comparing the esters in the delivery of bioactive compounds such as anticancer drugs. Finally, we review future perspectives on using PCL in biomedical applications and the hurdles of PCL-based drug delivery, including fine-tuning mechanical strength/degradation rate, biocompatibility, and long-term effects in living systems.

Magnetic control of soft microrobots near step-out frequency: Characterization and analysis

Magnetically actuated soft microrobots hold promise for biomedical applications that necessitate precise control and adaptability in complex environments. These microrobots can be accurately steered below their step-out frequencies where they exhibit synchronized motion with external magnetic fields. However, the step-out frequencies of soft microrobots have not been investigated yet, as opposed to their rigid counterparts. In this work, we develop an analytic model from the magneto-elastohydrodynamics to establish the relationship between the step-out frequency of soft sperm-like microrobots and their magnetic properties, geometry, wave patterns, and the viscosity of the surrounding medium. We fabricate soft sperm-like microrobots using electrospinning and assess their swimming abilities in mediums with varying viscosities under an oscillating magnetic field. We observe slight variations in wave patterns of the sperm-like microrobots as the actuation frequency changes. Our theoretical model, which analyzes these wave patterns observed without exceeding the step-out threshold, quantitatively agrees with the experimentally measured step-out frequencies. By accurately predicting the step-out frequency, the proposed model lays a foundation for achieving precise control over individual soft microrobots and enabling selective control within a swarm when executing biomedical tasks.

ROS Scavenging and Osteogenic Differentiation Potential of L-Methionine-Substituted Poly(Organophosphazene) Electrospun Fibers

This study investigated the application of poly[bis (ethylmethionato) phosphazene] (PαAPz-M) electrospun fibers in tissue engineering, focusing on their reactive oxygen species (ROS) scavenging capabilities and material-directed cell behavior, including the influence of their degradation products on cell viability and differentiation, and the scaffold topography's influence on cell alignment. The ROS scavenging ability of PαAPz-M was assessed by DPPH assay, and then PαAPz-M's protection against exogenous ROS was studied. The results showed enhanced cell viability on PαAPz-M fiber mats under oxidative stress conditions. This study also investigated the effects of the degradation products of PαAPz-M on cell viability and osteogenic differentiation. It was observed that the late-stage degradation product, phosphoric acid, can significantly influence the osteogenic differentiation of MSCs. In contrast, methionine, which is the early-stage degradation product, showed a minimal influence. Additionally, the study fabricated fiber mats that can lead to enhanced cell alignment while maintaining high porosity. Collectively, this study expanded the applications of PαAPz-M fiber mat protection against oxidative stress and guiding osteogenic differentiation and cell alignment.

Advanced applications in enzyme-induced electrospun nanofibers

Electrospun nanofibers, renowned for their high specific surface area, robust mechanical properties, and versatile chemical functionalities, offer a promising platform for enzyme immobilization. Over the past decade, significant strides have been made in developing enzyme-induced electrospun nanofibers (EIEN). This review systematically summarizes the advanced applications of EIEN which are fabricated using both non-specific immobilization methods including interfacial adsorption (direct adsorption, cross-linking, and covalent binding) and encapsulation, and specific immobilization techniques (coordination and affinity immobilization). Future research should prioritize optimizing immobilization techniques to achieve a balance between enzyme activity, stability, and cost-effectiveness, thereby facilitating the industrialization of EIEN. We elucidate the rationale behind various immobilization methods and their applications, such as wastewater treatment, biosensors, and biomedicine. We aim to provide guidelines for developing suitable EIEN immobilization techniques tailored to specific future applications.

The Effects of Biomimetic Surface Topography on Vascular Cells: Implications for Vascular Conduits

Cardiovascular diseases (CVDs) are the leading cause of mortality worldwide and represent a pressing clinical need. Vascular occlusions are the predominant cause of CVD and necessitate surgical interventions such as bypass graft surgery to replace the damaged or obstructed blood vessel with a synthetic conduit. Synthetic small-diameter vascular grafts (sSDVGs) are desired to bypass blood vessels with an inner diameter <6 mm yet have limited use due to unacceptable patency rates. The incorporation of biophysical cues such as topography onto the sSDVG biointerface can be used to mimic the cellular microenvironment and improve outcomes. In this review, the utility of surface topography in sSDVG design is discussed. First, the primary challenges that sSDVGs face and the rationale for utilizing biomimetic topography are introduced. The current literature surrounding the effects of topographical cues on vascular cell behavior in vitro is reviewed, providing insight into which features are optimal for application in sSDVGs. The results of studies that have utilized topographically-enhanced sSDVGs in vivo are evaluated. Current challenges and barriers to clinical translation are discussed. Based on the wealth of evidence detailed here, substrate topography offers enormous potential to improve the outcome of sSDVGs and provide therapeutic solutions for CVDs.

Tailoring silk fibroin fibrous architecture by a high-yield electrospinning method for fast wound healing possibilities

In this study, a novel array electrospinning collector was devised to generate two distinct regenerated silk fibroin (SF) fibrous membranes: ordered and disordered. Leveraging electrostatic forces during the electrospinning process allowed precise control over the orientation of SF fiber, resulting in the creation of membranes comprising both aligned and randomly arranged fiber layers. This innovative approach resulted in the development of large-area membranes featuring exceptional stability due to their alternating patterned structure, achievable through expansion using the collector, and improving the aligned fiber membrane mechanical properties. The study delved into exploring the potential of these membranes in augmenting wound healing efficiency. Conducting in vitro toxicity assays with adipose tissue-derived mesenchymal stem cells (AD-MSCs) and normal human dermal fibroblasts (NHDFs) confirmed the biocompatibility of the SF membranes. We use dual perspectives on exploring the effects of different conditioned mediums produced by cells and structural cues of materials on NHDFs migration. The nanofibers providing the microenvironment can directly guide NHDFs migration and also affect the AD-MSCs and NHDFs paracrine effects, which can improve the chemotaxis of NHDFs migration. The ordered membrane, in particular, exhibited pronounced effectiveness in guiding directional cell migration. This research underscores the revelation that customizable microenvironments facilitated by SF membranes optimize the paracrine products of mesenchymal stem cells and offer valuable physical cues, presenting novel prospects for enhancing wound healing efficiency.

Innovative Substrate Design with Basement Membrane Components for Enhanced Endothelial Cell Function and Endothelization

Enhancing endothelial cell growth on small-diameter vascular grafts produced from decellularized tissues or synthetic substrates is pivotal for preventing thrombosis. While optimized decellularization protocols can preserve the structure and many components of the extracellular matrix (ECM), the process can still lead to the loss of crucial basement membrane proteins, such as laminin, collagen IV, and perlecan, which are pivotal for endothelial cell adherence and functional growth. This loss can result in poor endothelialization and endothelial cell activation causing thrombosis and intimal hyperplasia. To address this, the basement membrane's ECM is emulated on fiber substrates, providing a more physiological environment for endothelial cells. Thus, fibroblasts are cultured on fiber substrates to produce an ECM membrane substrate (EMMS) with basement membrane proteins. The EMMS then underwent antigen removal (AR) treatment to eliminate antigens from the membrane while preserving essential proteins and producing an AR-treated membrane substrate (AMS). Subsequently, human endothelial cells cultured on the AMS exhibited superior proliferation, nitric oxide production, and increased expression of endothelial markers of quiescence/homeostasis, along with autophagy and antithrombotic factors, compared to those on the decellularized aortic tissue. This strategy showed the potential of pre-endowing fiber substrates with a basement membrane to enable better endothelization.

Impact of morphological features and chemical composition of tendon biomimetic scaffolds on immune recognition via Toll-like receptors

Tendinopathies are a major worldwide clinical problem. The development of tendon biomimetic scaffolds is considered a promising, therapeutic approach. However, to be clinically effective, scaffolds should avoid immunological recognition. It has been well described that scaffolds composed of aligned fibers lead to a better tenocyte differentiation, vitality, proliferation and motility. However, little has been studied regarding the impact of fiber spatial distribution on the recognition by immune cells. Additionally, it has been suggested that higher hydrophilicity would reduce their immune recognition. Herein, polycaprolactone (PCL)-hyaluronic acid (HA)-based electrospun scaffolds were generated with different fiber diameters (in the nano- and micro-scales) and orientations as well as different grades of wettability and the impact of these properties on immunological recognition has been assessed, by means of Toll-like receptor (TLR) reporter cells. Our results showed that TLR 2/1 and TLR 2/6 were not triggered by the scaffolds. In addition, the TLR 4 signalling pathway seems to be triggered to a greater extent by higher PCL and HA concentrations, but the alignment of the fibers prevents the triggering of this receptor. Taken together, TLR reporter cells were shown to be a useful and effective tool to study the potential of scaffolds to induce immune responses and the results obtained can be used to inform the design of fibrous scaffolds for tendon repair.

In vitro development of a muscle-tendon junction construct using decellularised extracellular matrix: Effect of cyclic tensile loading

The muscle tendon junction (MTJ) plays a crucial role in transmitting the force generated by muscles to the tendon and then to the bone. Injuries such as tears and strains frequently happen at the MTJ, where the regenerative process is limited due to poor vascularization and the complex structure of the tissue. Current solutions for a complete tear at the MTJ have not been successful and therefore, the development of a tissue-engineered MTJ may provide a more effective treatment. In this study, decellularised extracellular matrix (DECM) derived from sheep MTJ was used to provide a scaffold for the MTJ with the relevant mechanical properties and differentiation cues such as the relase of growth factors. Human mesenchymal stem cells (MSCs) were seeded on DECM and 10 % cyclic strain was applied using a bioreactor. MSCs cultured on DECM showed significantly higher gene and protein expression of MTJ markers such as collagen 22, paxillin and talin, than MSCs in 2D culture. Although collagen 22 protein expression was higher in the cells with strain than without strain, reduced gene expression of other MTJ markers was observed when the strain was applied. DECM combined with 10 % strain enhanced myogenic differentiation, while tenogenic differentiation was reduced when compared to static cultures of MSCs on DECM. For the first time, these results showed that DECM derived from the MTJ can induce MTJ marker gene and protein expression by MSCs, however, the effect of strain on the MTJ development in DECM culture needs further investigation.

Assessing the impact of extracellular matrix fiber orientation on breast cancer cellular metabolism

The extracellular matrix (ECM) is a dynamic and complex microenvironment that modulates cell behavior and cell fate. Changes in ECM composition and architecture have been correlated with development, differentiation, and disease progression in various pathologies, including breast cancer [1]. Studies have shown that aligned fibers drive a pro-metastatic microenvironment, promoting the transformation of mammary epithelial cells into invasive ductal carcinoma via the epithelial-to-mesenchymal transition (EMT) [2]. The impact of ECM orientation on breast cancer metabolism, however, is largely unknown. Here, we employ two non-invasive imaging techniques, fluorescence-lifetime imaging microscopy (FLIM) and intensity-based multiphoton microscopy, to assess the metabolic states of cancer cells cultured on ECM-mimicking nanofibers in a random and aligned orientation. By tracking the changes in the intrinsic fluorescence of nicotinamide adenine dinucleotide and flavin adenine dinucleotide, as well as expression levels of metastatic markers, we reveal how ECM fiber orientation alters cancer metabolism and EMT progression. Our study indicates that aligned cellular microenvironments play a key role in promoting metastatic phenotypes of breast cancer as evidenced by a more glycolytic metabolic signature on nanofiber scaffolds of aligned orientation compared to scaffolds of random orientation. This finding is particularly relevant for subsets of breast cancer marked by high levels of collagen remodeling (e.g. pregnancy associated breast cancer), and may serve as a platform for predicting clinical outcomes within these subsets [3-6].

Development of a Tri-Layered Vascular Construct and In Vitro Evaluation of Endothelization

Advances in the development of vascular substitutes for small-sized arteries are ongoing because the present grafts do not entirely meet the requirements of native equivalents and are suboptimal in clinical performance. This study aims to develop a tri-layered vascular construct mimicking natural tissue using polyester blends and to investigate its endothelization through in vitro studies as a potential small-caliber vascular graft. The innermost layer is obtained by dip coating as a tubular porous film with a lumen diameter of 3 mm and a pore size of ≤8 µm. Circumferentially aligned electrospun fiber (diameter 100-800 nm) with a deviation angle of 15° are deposited over the porous film forming the intermediate layer. The random electrospun fibers (diameter 100-1100 nm) deviating at different angles are wrapped as the outermost layer. The mechanical properties of the tri-layered vascular construct are determined to be 44.80 ± 14.80 MPa for Young's modulus and 4.25 ± 0.75 MPa for ultimate tensile strength. MTS and cell behavior studies show that the isolated human umbilical cord vein endothelial cells proliferate and line the lumen of the vascular substitute. The vascular construct developed, with its biomimetic architecture, mechanical features, size, and endothelization, can be tested with in vivo studies.

Hydrogel-polyurethane fiber composites with enhanced microarchitectural control for heart valve replacement

Polymeric heart valves offer the potential to overcome the limited durability of tissue based bioprosthetic valves and the need for anticoagulant therapy of mechanical valve replacement options. However, developing a single-phase material with requisite biological properties and target mechanical properties remains a challenge. In this study, a composite heart valve material was developed where an electrospun mesh provides tunable mechanical properties and a hydrogel coating confers an antifouling surface for thromboresistance. Key biological responses were evaluated in comparison to glutaraldehyde-fixed pericardium. Platelet and bacterial attachment were reduced by 38% and 98%, respectively, as compared to pericardium that demonstrated the antifouling nature of the hydrogel coating. There was also a notable reduction (59%) in the calcification of the composite material as compared to pericardium. A custom 3D-printed hydrogel coating setup was developed to make valve composites for device-level hemodynamic testing. Regurgitation fraction (9.6 ± 1.8%) and effective orifice area (1.52 ± 0.34 cm2 ) met ISO 5840-2:2021 requirements. Additionally, the mean pressure gradient was comparable to current clinical bioprosthetic heart valves demonstrating preliminary efficacy. Although the hemodynamic properties are promising, it is anticipated that the random microarchitecture will result in suboptimal strain fields and peak stresses that may accelerate leaflet fatigue and degeneration. Previous computational work has demonstrated that bioinspired fiber microarchitectures can improve strain homogeneity of valve materials toward improving durability. To this end, we developed advanced electrospinning methodologies to achieve polyurethane fiber microarchitectures that mimic or exceed the physiological ranges of alignment, tortuosity, and curvilinearity present in the native valve. Control of fiber alignment from a random fiber orientation at a normalized orientation index (NOI) 14.2 ± 6.9% to highly aligned fibers at a NOI of 85.1 ± 1.4%. was achieved through increasing mandrel rotational velocity. Fiber tortuosity and curvilinearity in the range of native valve features were introduced through a post-spinning annealing process and fiber collection on a conical mandrel geometry, respectively. Overall, these studies demonstrate the potential of hydrogel-polyurethane fiber composite as a heart valve material. Future studies will utilize the developed advanced electrospinning methodologies in combination with model-directed fabrication toward optimizing durability as a function of fiber microarchitecture.

Electrospinning of biomimetic materials with fibrinogen for effective early-stage wound healing

Electrospun biomimetic materials based on polyester of natural origin poly-3-hudroxybutyrate (PHB) modified with hemin (Hmi) and fibrinogen (Fbg) represent a great interest and are potentially applicable in various fields. Here, we describe formulation of the new fibrous PHB-Fbg and PHB-Hmi-Fbg materials with complex structure for biomedical application. The average diameter of the fibers was 3.5 μm and 1.8 μm respectively. Hmi presence increased porosity from 80 % to 94 %, significantly reduced the number of defects, ensured the formation of a larger number of open pores, and improved mechanical properties. Hmi presence significantly improved the molding properties of the material. Hmi facilitated effective Fbg adsorption on the of the PHB wound-healing material, ensuring uniform localization of the protein on the surface of the fibers. Next, we evaluated cytocompatibility, cell behavior, and open wound healing in mice. The results demonstrated that PHB-Fbg and PHB-Hmi-Fbg electrospun materials had pronounced properties and may be promising for early-stage wound healing - the PHB-Hmi-Fbg sample accelerated wound closure by 35 % on the 3rd day, and PHB-Hmi showed 45 % more effective wound closure on the 15th day.

Optimization of Electrospun Bilayer Vascular Grafts through Assessment of the Mechanical Properties of Monolayers

Small-diameter vascular grafts must be obtained with the most appropriate materials and design selection to harmoniously display a variety of features, including adequate tensile strength, compliance, burst strength, biocompatibility, and biodegradability against challenging physiological and hemodynamic conditions. In this study, monolayer vascular grafts with randomly distributed or radially oriented fibers are produced using neat, blended, and copolymer forms of polycaprolactone (PCL) and poly(lactic acid) (PLA) via the electrospinning technique. The blending ratio is varied by increasing 10 in the range of 50-100%. Bilayer graft designs are realized by determining the layers with a random fiber distribution for the inner layer and radial fiber orientation for the outer layer. SEM analysis, wall thickness and fiber diameter measurements, tensile strength, elongation, burst strength, and compliance tests are done for both mono- and bilayer scaffolds. The findings revealed that the scaffolds made of neat PCL show more flexibility than the neat PLA samples, which possess higher tensile strength values than neat PCL scaffolds. Also, in blended samples, the tensile strength values do not show a significant improvement, whereas the elongation values are enhanced in tubular samples, depending on the blending ratio. Also, neat poly(l-lactide-co-caprolactone) (PLCL) samples have both higher elongation and strength values than neat and blended scaffolds, with some exceptions. The blended specimens comprising a combination of PCL and PLA, with blending ratios of 80/20 and 70/30, exhibited the most elevated burst pressures. Conversely, the PLCL scaffolds demonstrated superior compliance levels. These findings suggest that the blending approach and fiber orientation offer enhanced burst strength, while copolymer utilization in PLCL scaffolds without fiber alignment enhances their compliance properties. Thus, it is evident that using a copolymer instead of blending PCL and PLA and combining the PLCL layer with PCL and PLA monolayers in bilayer vascular graft design is promising in terms of mechanical and biological properties.

Micropatterned Nanofiber Scaffolds of Salmon Gelatin, Chitosan, and Poly(vinyl alcohol) for Muscle Tissue Engineering

The development of scaffolds that mimic the aligned fibrous texture of the extracellular matrix has become an important requirement in muscle tissue engineering. Electrospinning is a widely used technique to fabricate biomimetic scaffolds. Therefore, a biopolymer blend composed of salmon gelatin (SG), chitosan (Ch), and poly(vinyl alcohol) (PVA) was developed by electrospinning onto a micropatterned (MP) collector, resulting in a biomimetic scaffold for seeding muscle cells. Rheology and surface tension studies were performed to determine the optimum solution concentration and viscosity for electrospinning. The scaffold microstructure was analyzed using SEM to determine the nanofiber's diameter and orientation. Blends of SG/Ch/PVA exhibited better electrospinnability and handling properties than pure PVA. The resulting scaffolds consist of a porous surface (∼46%), composed of a random fiber distribution, for a flat collector and scaffolds with regions of aligned nanofibers for the MP collector. The nanofiber diameters are 141 ± 2 and 151 ± 2 nm for the flat and MP collector, respectively. In vitro studies showed that myoblasts cultured on scaffold SG/Ch/PVA presented a high rate of cell growth. Furthermore, the aligned nanofibers on the SG/Ch/PVA scaffold provide a suitable platform for myoblast alignment.

Fabrication of Customizable and Reproducible 3D Chondrocyte-Laden Nanofibrous Architectures: Effect of Specific Fiber Alignments and Porosities on Chondrocyte Response under Cyclic Compression

Electrospinning has been widely employed to fabricate complex extracellular matrix-like microenvironments for tissue engineering due to its ability to replicate structurally biomimetic micro- and nanotopographic cues. Nevertheless, these nanofibrous structures are typically either confined to bidimensional systems or confined to three-dimensional ones that are unable to provide controlled multiscale patterns. Thus, an electrospinning modality was used in this work to fabricate chondrocyte-laden nanofibrous scaffolds with highly customizable three-dimensional (3D) architectures in an automated manner, with the ultimate goal of recreating a suitable 3D scaffold for articular cartilage tissue engineering. Three distinct architectures were designed and fabricated by combining multiple nanofibrous and chondrocyte-laden hydrogel layers and tested in vitro in a compression bioreactor system. Results demonstrated that it was possible to precisely control the placement and alignment of electrospun polycaprolactone and gelatin nanofibers, generating three unique architectures with distinctive macroscale porosity, water absorption capacity, and mechanical properties. The architecture organized in a lattice-like fashion was highly porous with substantial pore interconnectivity, resulting in a high-water absorption capacity but a poor compression modulus and relatively weaker energy dissipation capacity. The donut-like 3D geometry was the densest, with lower swelling, but the highest compression modulus and improved energy dissipation ability. The third architecture combined a lattice and donut-like fibrous arrangement, exhibiting intermediary behavior in terms of porosity, water absorption, compression modulus, and energy dissipation capacity. The properties of the donut-like 3D architecture demonstrated great potential for articular cartilage tissue engineering, as it mimicked key topographic, chemical, and mechanical characteristics of chondrocytes' surrounding environment. In fact, the combination of these architectural features with a dynamically compressive mechanical stimulus triggered the best in vitro results in terms of viability and biosynthetic production.

Electrospun Poly(carbonate-urea-urethane)s Nonwovens with Shape-Memory Properties as a Potential Biomaterial

Poly(carbonate-urea-urethane) (PCUU)-based scaffolds exhibit various desirable properties for tissue engineering applications. This study thus aimed to investigate the suitability of PCUU as polymers for the manufacturing of nonwoven mats by electrospinning, able to closely mimic the fibrous structure of the extracellular matrix. PCUU nonwovens of fiber diameters ranging from 0.28 ± 0.07 to 0.82 ± 0.12 μm were obtained with an average surface porosity of around 50-60%. Depending on the collector type and solution concentration, a broad range of tensile strengths (in the range of 0.3-9.6 MPa), elongation at break (90-290%), and Young's modulus (5.7-26.7 MPa) at room temperature of the nonwovens could be obtained. Furthermore, samples collected on the plate collector showed a shape-memory effect with a shape-recovery ratio (Rr) of around 99% and a shape-fixity ratio (Rf) of around 96%. Biological evaluation validated the inertness, stability, and lack of cytotoxicity of PCUU nonwovens obtained on the plate collector. The ability of mesenchymal stem cells (MSCs) and endothelial cells (HUVECs) to attach, elongate, and grow on the surface of the nonwovens suggests that the manufactured nonwovens are suitable scaffolds for tissue engineering applications.

Optimization and evaluation of oxygen-plasma-modified, aligned, poly (Є-caprolactone) and silk fibroin nanofibrous scaffold for corneal stromal regeneration

The shortage of human donor corneas for transplantation necessitates the exploration of tissue engineering approaches to develop corneal substitutes. However, these substitutes must possess the necessary strength, transparency, and ability to regulate cell behaviour before they can be used in patients. In this study, we investigated the effectiveness of an oxygen plasma surface-modified poly-ε-caprolactone (PCL) combined with silk fibroin (SF) nanofibrous scaffold for corneal stromal regeneration. To fabricate the electrospun scaffolds, PCL and SF blends were used on a rotating mandrel. The optimization of the blend aimed to replicate the structural and functional properties of the human cornea, focusing on nanofibre alignment, mechanical characteristics, and in vitro cytocompatibility with human corneal stromal keratocytes. Surface modification of the scaffold resulted in improved transparency and enhanced cell interaction. Based on the evaluation, a composite nanofibrous scaffold with a 1:1 blend of PCL and SF was selected for a more comprehensive analysis. The biological response of keratocytes to the scaffold was assessed through cellular adhesion, proliferation, cytoskeletal organization, gene expression, and immunocytochemical staining. The scaffold facilitated the adhesion of corneal stromal cells, supporting cell proliferation, maintaining normal cytoskeletal organization, and promoting increased expression of genes associated with healthy corneal stromal keratocytes. These findings highlight the potential of a surface-modified PCL/SF blend (1:1) as a promising scaffolding material for corneal stromal regeneration. The developed scaffold not only demonstrated favourable biological interactions with corneal stromal cells but also exhibited characteristics aligned with the requirements for successful corneal tissue engineering. Further research and refinement of these constructs could lead to significant advancements in addressing the shortage of corneas for transplantation, ultimately improving the treatment outcomes for patients in need.

Recent Progress in Fabrication of Electrospun Nanofiber Membranes for Developing Physiological In Vitro Organ/Tissue Models

Nanofiber membranes (NFMs), which have an extracellular matrix-mimicking structure and unique physical properties, have garnered great attention as biomimetic materials for developing physiologically relevant in vitro organ/tissue models. Recent progress in NFM fabrication techniques immensely contributes to the development of NFM-based cell culture platforms for constructing physiological organ/tissue models. However, despite the significance of the NFM fabrication technique, an in-depth discussion of the fabrication technique and its future aspect is insufficient. This review provides an overview of the current state-of-the-art of NFM fabrication techniques from electrospinning techniques to postprocessing techniques for the fabrication of various types of NFM-based cell culture platforms. Moreover, the advantages of the NFM-based culture platforms in the construction of organ/tissue models are discussed especially for tissue barrier models, spheroids/organoids, and biomimetic organ/tissue constructs. Finally, the review concludes with perspectives on challenges and future directions for fabrication and utilization of NFMs.

Development of Adjustable High- to Low-Adhesive Superhydrophobicity Using Aligned Electrospun Fibers

Superhydrophobic surfaces based on electrospun fibrous structures exhibit advantages of additive manufacturing and enable the passage of gases. Compared to randomly deposited fibers, directionally aligned fibers improve the control of surface wetting by a specified fiber orientation and predictable liquid-fiber contact interface. In this article, we create superhydrophobicity with adjustable adhesion based on the understanding of droplet wetting behavior on directionally aligned fibers. Directionally aligned polystyrene fibers with different diameters and interfiber distances (l) are produced using electrospinning with a rotating fin collector. The wetting behavior of droplets on the surfaces dressed by aligned fibers is characterized, and a thermodynamic model of wetting behavior is established to guide the experimental studies. As a result, high-adhesive superhydrophobicity is achieved on weak hydrophobic substrate surfaces dressed by aligned polystyrene fibers with a diameter of 1.8 μm and l between 5 and 130 μm. Water droplets (2 μL) exhibit a maximum contact angle of 156° and adhere to the fiber-dressed surfaces by tilting upside down. Low-adhesive superhydrophobicity is achieved by introducing an additional layer of aligned fibers to increase the transition energy barrier. On the dual-layer structure with an upper-layer l of 9 μm, droplets show a contact angle of 155° and can readily roll off the surface. Moreover, increasing the upper-layer l to 15 μm reserves the surface to high-adhesive superhydrophobicity.

Structural Control of Nanofibers According to Electrospinning Process Conditions and Their Applications

Nanofibers have gained much attention because of the large surface area they can provide. Thus, many fabrication methods that produce nanofiber materials have been proposed. Electrospinning is a spinning technique that can use an electric field to continuously and uniformly generate polymer and composite nanofibers. The structure of the electrospinning system can be modified, thus making changes to the structure, and also the alignment of nanofibers. Moreover, the nanofibers can also be treated, modifying the nanofiber structure. This paper thoroughly reviews the efforts to change the configuration of the electrospinning system and the effects of these configurations on the nanofibers. Excellent works in different fields of application that use electrospun nanofibers are also introduced. The studied materials functioned effectively in their application, thereby proving the potential for the future development of electrospinning nanofiber materials.

Development of a hyaluronic acid-collagen bioink for shear-induced fibers and cells alignment

Human tissues are characterized by complex composition and cellular and extracellular matrix (ECM) organization at microscopic level. In most of human tissues, cells and ECM show an anisotropic arrangement, which confers them specific properties.In vitro, the ability to closely mimic this complexity is limited. However, in the last years, extrusion bioprinting showed a certain potential for aligning cells and biomolecules, due to the application of shear stress during the bio-fabrication process. In this work, we propose a strategy to combine collagen (col) with tyramine-modified hyaluronic acid (THA) to obtain a printable col-THA bioink for extrusion bioprinting, solely-based on natural-derived components. Collagen fibers formation within the hybrid hydrogel, as well as collagen distribution and spatial organization before and after printing, were studied. For the validation of the biological outcome, fibroblasts were selected as cellular model and embedded in the col-THA matrix. Cell metabolic activity and cell viability, as well as cell distribution and alignment, were studied in the bioink before and after bioprinting. Results demonstrated successful collagen fibers formation within the bioink, as well as collagen anisotropic alignment along the printing direction. Furthermore, results revealed suitable biological properties, with a slightly reduced metabolic activity at day 1, fully recovered within the first 3 d post-cell embedding. Finally, results showed fibroblasts elongation and alignment along the bioprinting direction. Altogether, results validated the potential to obtain collagen-based bioprinted constructs, with both cellular and ECM anisotropy, without detrimental effects of the fabrication process on the biological outcome. This bioink can be potentially used for a wide range of applications in tissue engineering and regenerative medicine in which anisotropy is required.

Processing and characterization of aligned electrospun gelatin/polycaprolactone nanofiber mats incorporating borate glass (13-93B3) microparticles

Aligned biodegradable fibers incorporating bioactive glass particles are being highly investigated for tissue engineering applications. In this study, 5, 7 and 10 wt% melt-derived 1393B3 borate glass (BG) microparticles (average size: 3.15 µm) were incorporated in 83 wt% polycaprolactone (PCL) and 17 wt% gelatin (GEL) (83PCL/17GEL) solutions to produce aligned electrospun composite nanofiber mats. Addition of 5 wt% BG particles significantly increased the alignment of the nanofibers. However, further incorporation of BG particles led to reduced degree of alignment, likely due to an increase of viscosity. Mechanical tests indicated a tensile modulus and tensile strength of approximately 51 MPa and 3.4 MPa, respectively, for 5 wt% addition of 1393B3 BG microparticles, values considered suitable for soft tissue engineering applications. However, with the increasing amount of 1393B3 BG, the nanofiber mats became brittle. Contact angle was reduced after the addition of 5 wt% of 1393B3 BG particles from∼45° to∼39°. Cell culture studies with normal human dermal fibroblast (NHDF) cells indicated that 5 wt% 1393B3 BG incorporated nanofiber mats were cytocompatible whereas higher doping with 1393B3 BGs reduced biocompatibility. Overall, 5 wt% 1393B3 BG doped PCL/GEL nanofiber mats were aligned with high biocompatibility exhibiting desirable mechanical properties for soft tissue engineering, which indicates their potential for applications requiring aligned nanofibers, such as peripheral neural regeneration.

Nanofiber mats functionalized with Mentha piperita essential oil stabilized in a chitosan-based emulsion designed via an electrospinning technique

A nanostructured device based on poly(vinyl alcohol) (PVA) loaded with a cross-linked chitosan (CH) emulsion, soy lecithin, and peppermint essential oil (Mentha piperita) was designed for topical applications using an electrospinning instrument coupled to a rotary drum collector. Different suspensions were obtained by varying the PVA to emulsion ratio (PVA:Em) 87.5:12.5, 82:18, and 75:25, using a PVA solution as a control. ATR-FTIR spectra confirmed the interactions among the components of the system. Scanning electron microscopy (SEM) of the mats evinced that the aligned fiber diameter decreased with higher proportions of emulsion while dynamic mechanical analysis (DMA) revealed a decrease in the storage modulus. The entrapment of the functionalized emulsions not only improved the elongation of the matrices but also provided them with greater structural integrity compared to the single PVA matrix. The most favorable formulation in terms of mechanical properties was found to be the 82:18 ratio. After 1 h of close contact between the 82:18 matrix and a porcine skin explant, the latter was examined by confocal microscopy, which revealed the localization of the essential oil mainly on the surface of the stratum corneum (SC).However, after 7 h of contact, the distribution of the peppermint EO throughout the viable epidermis was observed, which was further supported by ATR-FTIR studies. Tailored electrospun matrices would have potential applications as devices for topical or transdermal treatments due to their vehiculization role that allows the diffusion of peppermint essential oil as a skin penetration enhancer.

Nanofiber-based Stretchable Electrodes for Oriented Culture and Mechanotransduction Monitoring of Smooth Muscle Cells

Vascular smooth muscle cells (SMCs) are circumferentially oriented perpendicular to the blood vessel and maintain the contractile phenotype in physiological conditions. They can sense the mechanical forces of blood vessels expanding and contracting and convert them into biochemical signals to regulate vascular homeostasis. However, the real-time monitoring of mechanically evoked biochemical response while maintaining SMC oriented growth remains an important challenge. Herein, we developed a stretchable electrochemical sensor by electrospinning aligned and elastic polyurethane (PU) nanofibers on the surface of PDMS film and further modification of conductive polymer PEDOT:PSS-LiTFSI-CoPc (PPLC) on the nanofibers (denoted as PPLC/PU/PDMS). The aligned nanofibers on the electrode surface could guide the oriented growth of SMCs and maintain the contractile phenotype, and the modification of PPLC endowed the electrode with good electrochemical sensing performance and stability under mechanical deformation. By culturing cells on the electrode surface, the oriented growth of SMCs and real-time monitoring of stretch-induced H2O2 release were achieved. On this basis, the changes of H2O2 level released by SMCs under the pathology (hypertension) and intervention of natural product resveratrol were quantitatively monitored, which will be helpful to further understand the occurrence and development of vascular-related diseases and the mechanisms of pharmaceutical intervention.

The cytisine-enriched poly(3-hydroxybutyrate) fibers for sustained-release dosage form

The polymeric cytisine-enriched fibers based on poly(3-hydroxybutyrate) were obtained using electrospinning method. The biocompatibility study, advanced thermal analysis and release of cytisine from the poly(3-hydroxybutyrate) fibers were carried out. The nanofibers' morphology was evaluated by scanning electron microscopy. The formation and description of phases during the thermal processes of fibers by the advanced thermal analysis were examined. The new quantitative thermal analysis of polymeric fibers with cytisine phases based on vibrational, solid and liquid heat capacities was presented. The apparent heat capacity of fibers was measured using the standard differential scanning calorimetry. The quantitative analysis allowed for the study of the glass transition and melting/crystallization process. The mobile amorphous fraction, degree of crystallinity and rigid amorphous fraction were determined depending on the thermal history of semicrystalline polymeric fibers. Furthermore, the cytisine dissolution behaviour was studied. It was observed that the kinetic of the release from polymeric nanofiber is delayed than for the marketed product. The immunosafety of the tested polymeric nanofibers with cytisine was confirmed by the Food and Drug Agency Guidance as well as the European Medicines Agency. The polymeric matrix with cytisine seems to be a promising candidate for the prolonged release formulation.

Bio-Based Polymeric Membranes: Development and Environmental Applications

Nowadays, membrane technology is an efficient process for separating compounds with minimal structural abrasion; however, the manufacture of membranes still has several drawbacks to being profitable and competitive commercially under an environmentally friendly approach. In this sense, this review focuses on bio-based polymeric membranes as an alternative to solve the environmental concern caused by the use of polymeric materials of fossil origin. The fabrication of bio-based polymeric membranes is explained through a general description of elements such as the selection of bio-based polymers, the preparation methods, the usefulness of additives, the search for green solvents, and the characterization of the membranes. The advantages and disadvantages of bio-based polymeric membranes are discussed, and the application of bio-based membranes to recover organic and inorganic contaminants is also discussed.

Role of silk nanocrystal (SNC)-ZnO as an antibacterial nucleating nanohybrid for a patterned mimic poly(lactic acid) based nanofabric

This new investigation deals with the synthesis of an organic-inorganic nanohybrid using SNC with magnificent flower bud-shaped ZnO, termed SNC-ZnO by precipitation method. The nanohybrid (with concentrations 1 wt%, 3 wt%, and 5 wt%) was in situ incorporated into the PLA matrix to prepare the electrospun solution. The functionalized PLA composite nanofibres produced by electrospinning with SNC-ZnO nanohybrid were systematically studied using different structural and morphological analyses to meet the challenging processing requirements. The FESEM analysis gives an average diameter of nanofibres 246 ± 10.2 nm where nanohybrid tends to adhere on the surface of the PLA nanofabric increasing hydrophobicity up to water contact angle 135.3 ± 0.25 °C with 5 wt% nanohybrid incorporation. The nanofabric has significant antibacterial activity against E.Coli and S.Aureus bacteria. Further, an extensive study has been made on thermally stipulated processes using DSC on non-isothermal crystallization kinetics using different models: Avrami, Ozawa, Mo, and Tobin. The results revealed sites for heterogeneous nucleation and improvement in crystallinity, t_1/2, and nucleation effects due to the incorporation of crystalline nanohybrid in PLA nanofibres. Further, the Avrami plot has confirmed both primary and secondary crystallization processes thereby considering its potential to utilize functionalized PLA nanofabric for applications in protective textile.

A Compact Piezo-Inertia Actuator Utilizing the Double-Rocker Flexure Hinge Mechanism

With a simple structure and control method, the piezo-inertia actuator is a preferred embodiment in the field of microprecision industry. However, most of the previously reported actuators are unable to achieve a high speed, high resolution, and low deviation between positive and reverse velocities at the same time. To achieve a high speed, high resolution, and low deviation, in this paper we present a compact piezo-inertia actuator with a double rocker-type flexure hinge mechanism. The structure and operating principle are discussed in detail. To study the load capacity, voltage characteristics, and frequency characteristics of the actuator, we made a prototype and conducted a series of experiment. The results indicate good linearity in both positive and negative output displacements. The maximum positive and negative velocities are about 10.63 mm/s and 10.12 mm/s, respectively, and the corresponding speed deviation is 4.9%. The positive and negative positioning resolutions are 42.5 nm and 52.5 nm, respectively. In addition, the maximum output force is 220 g. These results show that the designed actuator has a minor speed deviation and good output characteristics.

Recent Advances in Tissue-Engineered Cardiac Scaffolds-The Progress and Gap in Mimicking Native Myocardium Mechanical Behaviors

Heart failure is the leading cause of death in the US and worldwide. Despite modern therapy, challenges remain to rescue the damaged organ that contains cells with a very low proliferation rate after birth. Developments in tissue engineering and regeneration offer new tools to investigate the pathology of cardiac diseases and develop therapeutic strategies for heart failure patients. Tissue -engineered cardiac scaffolds should be designed to provide structural, biochemical, mechanical, and/or electrical properties similar to native myocardium tissues. This review primarily focuses on the mechanical behaviors of cardiac scaffolds and their significance in cardiac research. Specifically, we summarize the recent development of synthetic (including hydrogel) scaffolds that have achieved various types of mechanical behavior-nonlinear elasticity, anisotropy, and viscoelasticity-all of which are characteristic of the myocardium and heart valves. For each type of mechanical behavior, we review the current fabrication methods to enable the biomimetic mechanical behavior, the advantages and limitations of the existing scaffolds, and how the mechanical environment affects biological responses and/or treatment outcomes for cardiac diseases. Lastly, we discuss the remaining challenges in this field and suggestions for future directions to improve our understanding of mechanical control over cardiac function and inspire better regenerative therapies for myocardial restoration.

Water-stable, biocompatible, and highly luminescent perovskite nanocrystals-embedded fiber-based paper for anti-counterfeiting applications

In this study, we present a promising and facile approach toward the fabrication of non-toxic, water-stable, and eco-friendly luminescent fiber paper composed of polycaprolactone (PCL) polymer and CsPbBr₃@SiO₂ core-shell perovskite nanocrystals. PCL-perovskite fiber paper was fabricated using a conventional electrospinning process. Transmission electron microscopy (TEM) clearly revealed incorporation of CsPbBr₃@SiO₂ nanocrystals in the fibers, while scanning electron microscopy (SEM) demonstrated that incorporation of CsPbBr₃@SiO₂ nanocrystals did not affect the surface and diameter of the PCL-perovskite fibers. In addition, thermogravimetric analysis (TGA) and contact angle measurements have demonstrated that the PCL-perovskite fibers exhibit excellent thermal and water stability. The fabricated PCL-perovskite fiber paper exhibited a bright green emission centered at 520 nm upon excitation by ultra-violet (UV) light (374 nm). We have demonstrated that fluorescent PCL-perovskite fiber paper is a promising candidate for anti-counterfeiting applications because various patterns can be printed on the paper, which only become visible after exposure to UV light at 365 nm. Cell proliferation tests revealed that the PCL-perovskite fibers are cytocompatibility. Consequently, they may be suitable for biocompatible anti-counterfeiting. The present study reveals that PCL-perovskite fibers may pave way toward next generation biomedical probe and anti-counterfeiting applications.

Electrospun Nanofibers for Dura Mater Regeneration: A Mini Review on Current Progress

Dural defects are a common problem in neurosurgical procedures and should be repaired to avoid complications such as cerebrospinal fluid leakage, brain swelling, epilepsy, intracranial infection, and so on. Various types of dural substitutes have been prepared and used for the treatment of dural defects. In recent years, electrospun nanofibers have been applied for various biomedical applications, including dural regeneration, due to their interesting properties such as a large surface area to volume ratio, porosity, superior mechanical properties, ease of surface modification, and, most importantly, similarity with the extracellular matrix (ECM). Despite continuous efforts, the development of suitable dura mater substrates has had limited success. This review summarizes the investigation and development of electrospun nanofibers with particular emphasis on dura mater regeneration. The objective of this mini-review article is to give readers a quick overview of the recent advances in electrospinning for dura mater repair.

Designing an Innovative Electrospinning Strategy to Generate PHBV Nanofiber Scaffolds with a Radially Oriented Fibrous Pattern

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.

Gelatin/calcium chloride electrospun nanofibers for rapid hemostasis

Blood coagulation is the body's main defense to bleeding caused by trauma and is divided into endogenous and exogenous pathways. Calcium ions play a very important role in the process of blood coagulation, as the ions activate the many enzymes that are required for coagulation. In this paper, gelatin hemostatic membranes containing calcium ions were prepared by electrospinning. The fibers were characterized with scanning electron microscopy, Fourier transform infrared spectroscopy, and X-ray diffraction. The biocompatibility and coagulation processes using the calcium ion-containing gelatin fibrous membranes were evaluated in vitro with dynamic whole-blood coagulation tests, hemolysis tests, coagulation time tests, and platelet adhesion tests. It was demonstrated that the calcium ion-containing gelatin membranes had lower hemolysis rates and shorter clotting times than commercially available hemostatic sponges and hemostatic gauzes. In vivo hemostasis experiments were also conducted on the tail vein and liver of mice. Animal experiments demonstrated that the incorporation of calcium ions into the electrospun gelatin membranes promoted platelet aggregation, ensured adhesion of the electrospun membrane to the wound and reduced the bleeding volume and hemostasis time. The composite calcium ion-gelatin electrospun membranes exhibited good in vivo and in vitro hemostatic abilities and accelerated blood clotting by stimulating the coagulation pathway to promote platelet aggregation at the wounds and the formation of mature blood clots for a new approach for acute trauma treatment.

Dual-Phasic, Well-Aligned, and Strong Flexible Hydrophobic Ceramic Membranes for Efficient Thermal Insulation in Extreme Conditions

The inherent brittleness and hydrophilicity of ceramics pose a great challenge to designing a reliable structure that can resist mechanical loads and moisture in extreme conditions with high temperature and high humidity. Here, we report a two-phase hydrophobic silica-zirconia composite ceramic nanofiber membrane (H-ZSNFM) with exceptional mechanical robustness and high-temperature hydrophobic resistance. For the dual-phasic nanofibers, the amorphous silica blocked the connection of zirconia nanocrystals, and the lattice distortion was observed due to Si in the ZrO2 lattice. H-ZSNFM has strong strength (5-8.4 MPa), high hydrophobic temperature resistance (450 °C), high porosity (89%), low density (40 mg/cm3), low thermal conductivity (30 mW/m·K), and excellent thermal radiation reflectivity (90%). By simulating the actual high-temperature and high-humidity environment, 10-mm-thick H-ZSNFMs can reduce the heat source from 1365 to 380 °C and maintain complete hydrophobicity even in a water vapor environment of 350 °C. This means that it has superior insulation and waterproof performance even in a high-temperature water environment. For firefighting clothing, H-ZSNFM displayed waterproof and insulation layers, which have excellent thermal protection performance and achieve incompatibility between water and fire, providing valuable time for fire rescue and a safety line of defense for emergency personnel. This design strategy with mechanical robust and hydrophobic temperature resistance applies to the development of many other types of high-performance thermal insulation materials and presents a competitive material system for thermal protection in extreme conditions.

Fabrication of Glutaraldehyde Vapor Treated PVA/SA/GO/ZnO Electrospun Nanofibers with High Liquid Absorbability for Antimicrobial of Staphylococcus aureus

In this study, we aim to develop organic-inorganic hybrid nanofibers containing high moisture retention and good mechanical performance as an antimicrobial dressing platform. The main theme of this work focuses on several technical tasks including (a) the electrospinning process (ESP) to produce organic polyvinyl alcohol/sodium alginate (PVA/SA) nanofibers with an excellent diameter uniformity and fibrous orientation, (b) the fabrication of inorganic nanoparticles (NPs) as graphene oxide (GO) and ZnO NPs to be added to PVA/SA nanofibers for enhancement of the mechanical properties and an antibacterial function to Staphylococcus aureus (S. aureus), and then (c) the crosslinking process for PVA/SA/GO/ZnO hybrid nanofibers in glutaraldehyde (GA) vapor atmosphere to improve the hydrophilicity and moisture absorption of specimens. Our results clearly indicate that the uniformity nanofiber with 7 wt% PVA and 2 wt% SA condition demonstrates 199 ± 22 nm in diameter using an electrospinning precursor solution of 355 cP in viscosity by the ESP process. Moreover, the mechanical strength of nanofibers was enhanced by 17% after the handling of a 0.5 wt% GO nanoparticles addition. Significantly, the morphology and size of ZnO NPs can be affected by NaOH concentration, where 1 M NaOH was used in the synthesis of 23 nm ZnO NPs corresponding to effective inhibition of S. aureus strains. The PVA/SA/GO/ZnO mixture successfully performed an antibacterial ability with an 8 mm inhibition zone in S. aureus strains. Furthermore, the GA vapor as a crosslinking agent acting on PVA/SA/GO/ZnO nanofiber provided both swelling behavior and structural stability performance. The swelling ratio increased up to 1.406%, and the mechanical strength was 1.87 MPa after 48 h of GA vapor treatment. Finally, we successfully synthesized the hybrid nanofibers of GA-treated PVA/SA/GO/ZnO accompanied with high moisturizing, biocompatibility, and great mechanical properties, which will be a novel multi-functional candidate for wound dressing composites for patients receiving surgical operations and first aid treatments.

Biomanufacturing of biomimetic three-dimensional nanofibrous multicellular constructs for tissue regeneration

Biomanufacturing of functional tissue analogues is of great importance in regenerative medicine. However, this is still highly challenging due to extreme difficulties in recreating/recapitulating complicated anatomies of body tissues that have both well-defined three-dimensional (3D) multicellular organizations and bioactive nanofibrous extracellular matrix (ECM). In the current investigation, a biomanufacturing approach via concurrent emulsion electrospinning and coaxial cell electrospraying was developed, which could fabricate 3D nanofibrous multicellular constructs that resemble both the multicellular organizations and bioactive nanofibrous microenvironments of body tissues. In the proof-of-concept study, endothelial cells (ECs) and smooth muscle cells (SMCs) were placed in respective layers of multilayer-structured constructs. The two different construct layers consisted of nanofibers providing different topographies (randomly oriented nanofibers or aligned nanofibers) and contained different growth factors (vascular endothelial growth factor or platelet-derived growth factor). The ECs and SMCs in the different construct layers showed high cell densities (> 4 ×10⁵ cells/cm² after 4-day incubation) and high cell viabilities (> 95%). Owing to the contact guidance/stimulation by different fibrous topographies and sequential release of different growth factors, ECs and SMCs exhibited distinct morphologies (uniformly stretched plaque-shaped or directionally elongated) and displayed enhanced proliferative activities. Our biomanufacturing approach is shown to be effective and efficient in reconstituting/replicating cell-ECM organizations as well as their interactions similar to those in body tissues such as blood vessels, indicating the great promise to produce a range of tissue analogues with biomimetic structures and functions for modeling or regenerating body tissues.