Regenerative medicine and drug delivery: Progress via electrospun biomaterials

UCNPs-labeled electrospun scaffolds used to monitor in vivo degradation and bone tissue regeneration

Biodegradable electrospun bone repair materials are effective means to treat bone defects. However, because the electrospun substrates are mostly organic polymer materials, there is a lack of real-time and intuitive monitoring methods for their degradation in vivo. Therefore, it is of great significance to develop in vivo traced electrospun bone repair materials for postoperative observation of their degradation. In this research, polycaprolactone/up-conversion nanoparticles/magnesium oxide (PCL/UCNPs/MgO) composite scaffolds were prepared by electrospun based on the luminescence characteristics of up-conversion nanoparticles (UCNPs) under near infrared excitation and the osteogenic ability of MgO. The in vivo and in vitro degradation results showed that with the increase of time, the electrospun scaffolds gradually degraded and its luminescence intensity decreased. The addition of UCNPs can effectively monitor the degradation of the scaffolds. In addition, the prepared electrospun scaffolds had great biocompatibility, among which PCL-1%UCNPs-1%MgO (P1U1M) electrospun scaffolds had obvious effect on promoting osteogenic differentiation of mouse embryonic osteoblasts cells (MC3T3-E1) in vitro. In conclusion, P1U1M electrospun scaffolds have the potential to induce bone regeneration at bone defect sites, and can monitor the degradation of electrospun scaffolds. It may be a potential candidate material for bone regeneration in defect area.

Electrospun drug-loaded scaffolds for nervous system repair

Nervous system injuries, encompassing peripheral nerve injury (PNI), spinal cord injury (SCI), and traumatic brain injury (TBI), present significant challenges to patients' wellbeing. Traditional treatment approaches have limitations in addressing the complexity of neural tissue regeneration and require innovative solutions. Among emerging strategies, implantable materials, particularly electrospun drug-loaded scaffolds, have gained attention for their potential to simultaneously provide structural support and controlled release of therapeutic agents. This review provides a thorough exploration of recent developments in the design and application of electrospun drug-loaded scaffolds for nervous system repair. The electrospinning process offers precise control over scaffold characteristics, including mechanical properties, biocompatibility, and topography, crucial for creating a conducive environment for neural tissue regeneration. The large surface area of the resulting fibrous networks enhances biomolecule attachment, influencing cellular behaviors such as adhesion, proliferation, and migration. Polymeric electrospun materials demonstrate versatility in accommodating a spectrum of therapeutics, from small molecules to proteins. This enables tailored interventions to accelerate neuroregeneration and mitigate inflammation at the injury site. A critical aspect of this review is the examination of the interplay between structural properties and pharmacological effects, emphasizing the importance of optimizing both aspects for enhanced therapeutic outcomes. Drawing upon the latest advancements in the field, we discuss the promising outcomes of preclinical studies using electrospun drug-loaded scaffolds for nervous system repair, as well as future perspectives and considerations for their design and implementation. This article is categorized under: Implantable Materials and Surgical Technologies > Nanomaterials and Implants Implantable Materials and Surgical Technologies > Nanotechnology in Tissue Repair and Replacement Therapeutic Approaches and Drug Discovery > Emerging Technologies.

Review: 3D cell models for organ-on-a-chip applications

Two-dimensional (2D) cultures do not fully reflect the human organs' physiology and the real effectiveness of the used therapy. Therefore, three-dimensional (3D) models are increasingly used in bioanalytical science. Organ-on-a-chip systems are used to obtain cellular in vitro models, better reflecting the human body's in vivo characteristics and allowing us to obtain more reliable results than standard preclinical models. Such 3D models can be used to understand the behavior of tissues/organs in response to selected biophysical and biochemical factors, pathological conditions (the mechanisms of their formation), drug screening, or inter-organ interactions. This review characterizes 3D models obtained in microfluidic systems. These include spheroids/aggregates, hydrogel cultures, multilayers, organoids, or cultures on biomaterials. Next, the methods of formation of different 3D cultures in Organ-on-a-chip systems are presented, and examples of such Organ-on-a-chip systems are discussed. Finally, current applications of 3D cell-on-a-chip systems and future perspectives are covered.

Biomaterials for Protein Delivery: Opportunities and Challenges to Clinical Translation

The development of biomaterials for protein delivery is an emerging field that spans materials science, bioengineering, and medicine. In this review, we highlight the immense potential of protein-delivering biomaterials as therapeutic options and discuss the multifaceted challenges inherent to the field. We address current advancements and approaches in protein delivery that leverage stimuli-responsive materials, harness advanced fabrication techniques like 3D printing, and integrate nanotechnologies for greater targeting and improved stability, efficacy, and tolerability profiles. We also discuss the demand for highly complex delivery systems to maintain structural integrity and functionality of the protein payload. Finally, we discuss barriers to clinical translation, such as biocompatibility, immunogenicity, achieving reliable controlled release, efficient and targeted delivery, stability issues, scalability of production, and navigating the regulatory landscape for such materials. Overall, this review summarizes insights from a survey of the current literature and sheds light on the interplay between innovation and the practical implementation of biomaterials for protein delivery.

Improvement of Osteogenic Differentiation of Mouse Pre-Osteoblastic MC3T3-E1 Cells on Core-Shell Polylactic Acid/Chitosan Electrospun Scaffolds for Bone Defect Repair

Electrospun hybrid scaffolds composed of synthetic and natural polymers have gained increasing interest in tissue engineering applications over the last decade. In this work, scaffolds composed of polylactic acid electrospun fibers, either treated (P-PLA) or non-treated (PLA) with air-plasma, were coated with high molecular weight chitosan to create a core-shell microfibrous structure. The effective thickness control of the chitosan layer was confirmed by gravimetric, spectroscopic (FTIR-ATR) and morphological (SEM) investigations. The chitosan coating increased the fiber diameter of the microfibrous scaffolds while the tensile mechanical tests, conducted in dry and wet environments, showed a reinforcing action of the coating layer on the scaffolds, in particular when deposited on P-PLA samples. The stability of the Chi coating on both PLA and P-PLA substrates was confirmed by gravimetric analysis, while their mineralization capacity was evaluated though scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS) after immersing the scaffolds in simulated body fluids (SBF) at 37 °C for 1 week. Sample biocompatibility was investigated through cell viability assay and SEM analysis on mouse pre-osteoblastic MC3T3-E1 cells grown on scaffolds at different times (1, 7, 14 and 21 days). Finally, Alizarin Red assay and qPCR analysis suggested that the combination of plasma treatment and chitosan coating on PLA electrospun scaffolds influences the osteoblastic differentiation of MC3T3-E1 cells, thus demonstrating the great potential of P-PLA/chitosan hybrid scaffolds for bone tissue engineering applications.

Development of antifungal fibrous ocular insert using freeze-drying technique

Candida species is one of the pathogenic fungi of the eye responsible for keratitis that frequently causes vision impairment and blindness. Effective treatment requires long-term use of antifungal drugs, which is opposed by the defensive mechanisms of the eye and inadequate corneal penetration. The objective of this study was to develop a carrier for prolonged ocular application of fluconazole (FLZ) to treat keratitis. FLZ was encapsulated into chitosan fibrous matrices (F1-F4) using different chitosan concentrations (0.02, 0.1, 0.5, and 1%w/v, respectively) by freeze-drying as a single-step technique. Studying the morphology and surface properties of the inserts revealed a porous matrix with fibrous features with a large surface area. Thermal stability and chemical compatibility were confirmed by DSC/TGA/DTA and FT-IR, respectively. Loading capacity (LC) and entrapment efficiency (EE) were determined. According to the in vitro release study, F4 (0.11 mg mg-1 LC and 87.53% EE) was selected as the optimum insert because it had the most sustained release, with 15.85% burst release followed by 75.62% release within 12 h. Ex vivo corneal permeation study revealed a 1.2-fold increase in FLZ permeation from F4 compared to FLZ aqueous solution. Also, in the in vivo pharmacokinetic study in rabbits, F4 increased the AUC0-8 of FLZ by 9.3-fold and its concentration in aqueous humor was maintained above the MIC through the experimentation time. Studies on cytotoxicity (MTT assay) provide evidence for the safety and biocompatibility of F4. Therefore, the freeze-dried FLZ-loaded chitosan fibrous insert could be a promising candidate for treating ocular keratitis.

Cnicus benedictus extract-loaded electrospun gelatin wound dressing for treating diabetic wounds: An in vitro and in vivo study

In the current study, Cnicus benedictus extract was loaded into electrospun gelatin scaffolds for diabetic wound healing applications. Scaffolds were characterized in vitro by mechanical testing, cell culture assays, electron microscopy, cell migration assay, and antibacterial assay. In vivo wound healing study was performed in a rat model of diabetic wound. In vitro studies revealed fibrous architecture of our developed dressings and their anti-inflammatory properties. In addition, Cnicus benedictus extract-loaded wound dressings prevented bacterial penetration. In vivo study showed that wound size reduction, collagen deposition, and epithelial thickness were significantly greater in Cnicus benedictus extract-loaded scaffolds than other groups. Gene expression studies showed that the produced wound dressings significantly upregulated VEGF and IGF genes expression in diabetic wounds.

Cell Electrospinning: A Mini-Review of the Critical Processing Parameters and Its Use in Biomedical Applications

Functional tissue engineering is a widely studied area of research with increasing importance in regenerative medicine, as well as in the development of in vitro models used for drug discovery and mimicking diseased tissues, among other applications. Electrospinning (ES) is one of the most widely used methods in these fields. It has attracted considerable interest because it can produce materials resembling the extracellular matrix of native tissues. The micro/nanofibers produced by this method provide a cell-friendly environment that promotes cellular activities. Cell electrospinning (C-ES) is based on the fundamental ES process and enables the encapsulation of viable cells in a micro/nanofibrous mesh. In this review, the process of C-ES and the materials used in this process are discussed. This work also discusses the applications of C-ES in tissue engineering, focusing on recent advances in this field.

Nanofibrous scaffolds for the healing of the fibrocartilaginous enthesis: advances and prospects

With the current developmental advancements in nanotechnology, nanofibrous scaffolds are being widely used. The healing of fibrocartilaginous enthesis is a slow and complex process, and while existing treatments have a certain effect on promoting their healing, these are associated with some limitations. The nanofibrous scaffold has the advantages of easy preparation, wide source of raw materials, easy adjustment, easy modification, can mimic the natural structure and morphology of the fibrocartilaginous enthesis, and has good biocompatibility, which can compensate for existing treatments and be combined with them to promote the repair of fibrocartilaginous enthesis. The nanofibrous scaffold can promote the healing of fibrocartilaginous enthesis by controlling the morphology and ensuring controlled drug release. Hence, the use of nanofibrous scaffold with stimulative response features in the musculoskeletal system has led us to imagine its potential application in fibrocartilaginous enthesis. Therefore, the healing of fibrocartilaginous enthesis based on a nanofibrous scaffold may be a novel therapeutic approach.

Electrospinning of pullulan-based orodispersible films containing sildenafil

Feasibility of electrospinning in the manufacturing of sildenafil-containing orodispersible films (ODFs) intended to enhance oxygenation and to reduce pulmonary arterial pressure in pediatric patients was evaluated. Given the targeted subjects, the simplest and safest formulation was chosen, using water as the only solvent and pullulan, a natural polymer, as the sole fiber-forming agent. A systematic characterization in terms of shear and extensional viscosity as well as surface tension of solutions containing different amounts of pullulan and sildenafil was carried out. Accordingly, electrospinning parameters enabling the continuous production, at the highest possible rate, of defect-free fibers with uniform diameter in the nanometer range were assessed. Morphology, microstructure, drug content and relevant solid state as well as ability of the resulting non-woven films to interact with aqueous fluids were evaluated. To better define the role of the fibrous nanostructure on the performance of ODFs, analogous films were produced by spin- and blade-coating and tested. Interestingly, the disintegration process of electrospun products turned out to be the fastest (i.e. occurring within few s) and compliant with Ph. Eur. and USP limits, making relevant ODFs particularly promising for increasing sildenafil bioavailability, thus lowering its dosages.

Combining Polymer and Cyclodextrin Strategy for Drug Release of Sulfadiazine from Electrospun Fibers

This study reports the fabrication of polymeric matrices through electrospinning using polymethyl methacrylate (PMMA) and poly(lactic-co-glycolic acid) (PLGA), biocompatible polymers commonly used in medical systems. These polymers were combined with an antibacterial drug, sulfadiazine sodium salt (SDS) or its supramolecular system formed with hydroxypropyl-β-cyclodextrin (HPβ/CD) at 1:1 molar ratio, aiming to assemble a transdermal drug delivery system. The formation of fibers was confirmed by scanning electron microscopy (SEM), and the fibers' surface properties were analyzed using contact angle and water vapor permeability techniques. Drug release tests and cell viability assays were performed to evaluate the potential toxicity of the material. SEM images demonstrated that the obtained fibers had nanoscale- and micrometer-scale diameters in PLGA and PMMA systems, respectively. The contact angle analyses indicated that, even in the presence of hydrophilic molecules (SDS and HPβCD), PMMA fibers exhibited hydrophobic characteristics, while PLGA fibers exhibited hydrophilic surface properties. These data were also confirmed by water vapor permeability analysis. The drug release profiles demonstrated a greater release of SDS in the PLGA system. Moreover, the presence of HPβCD improved the drug release in both polymeric systems and the cell viability in the PMMA SDS/HPβCD system. In terms of antibacterial activity, all membranes yielded positive outcomes; nevertheless, the PLGA SDS/HPβCD membrane exhibited the most remarkable results, with the lowest microbial load values. Additionally, the pseudo wound healing analysis demonstrated that the PLGA SDS/HPβCD fiber exhibited results similar to the control group. Consequently, these findings exemplify the substantial potential of the obtained materials for use in wound healing applications.

Macromolecule-based hydrogels nanoarchitectonics with mesenchymal stem cells for regenerative medicine: A review

The role of regenerative medicine in clinical therapies is becoming increasingly vital. Under specific conditions, mesenchymal stem cells (MSCs) are capable of differentiating into mesoblastema (i.e., adipocytes, chondrocytes, and osteocytes) and other embryonic lineages. Their application in regenerative medicine has attracted a great deal of interest among researchers. To maximize the potential applications of MSCs, materials science could provide natural extracellular matrices and provide an effective means to understand the various mechanisms of differentiation for the growth of MSCs. Pharmaceutical fields are represented among the research on biomaterials by macromolecule-based hydrogel nanoarchitectonics. Various biomaterials have been used to prepare hydrogels with their unique chemical and physical properties to provide a controlled microenvironment for the culture of MSCs, laying the groundwork for future practical applications in regenerative medicine. This article currently describes and summarizes the sources, characteristics, and clinical trials of MSCs. In addition, it describes the differentiation of MSCs in various macromolecule-based hydrogel nanoarchitectonics and highlights the preclinical studies of MSCs-loaded hydrogel materials in regenerative medicine conducted over the past few years. Finally, the challenges and prospects of MSC-loaded hydrogels are discussed, and the future development of macromolecule-based hydrogel nanoarchitectonics is outlined by comparing the current literature.

Nanofibers in Ocular Drug Targeting and Tissue Engineering: Their Importance, Advantages, Advances, and Future Perspectives

Nanofibers are frequently encountered in daily life as a modern material with a wide range of applications. The important advantages of production techniques, such as being easy, cost effective, and industrially applicable are important factors in the preference for nanofibers. Nanofibers, which have a broad scope of use in the field of health, are preferred both in drug delivery systems and tissue engineering. Due to the biocompatible materials used in their construction, they are also frequently preferred in ocular applications. The fact that they have a long drug release time as a drug delivery system and have been used in corneal tissue studies, which have been successfully developed in tissue engineering, stand out as important advantages of nanofibers. This review examines nanofibers, their production techniques and general information, nanofiber-based ocular drug delivery systems, and tissue engineering concepts in detail.

Electrospun transparent nanofibers as a next generation face filtration media: A review

The development of fascinating materials with functional properties has revolutionized the humankind with materials comfort, stopped the spreading of diseases, relieving the environmental pollution pressure, economized government research funds, and prolonged their serving life. The outbreak of Coronavirus Disease 2019 (COVID-19), which is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has triggered great global public health concern. Face masks are crucial tools to impede the spreading of SARS-CoV-2 from human to human. However, current face masks exhibit in a variety of colors (opaque), like blue, black, red, etc., leading to a communication barrier between the doctor and the deaf-mute patient when wearing a mask. High optical transparency filters can be utilized for both personal protection and lip-reading. Thus, shaping face air filter into a transparent appearance is an urgent need. Electrospinning technology, as a mature technology, is commonly used to form nanofiber materials utilizing high electrical voltage. With the alteration of the diameters of nanofibers, and proper material selection, it would be possible to make the transparent face mask. In this article, the research progress in the transparent face air filter is reviewed with emphasis on three parts: mechanism of the electrospinning process and light transmission, preparation of transparent face air filter, and their innovative potential. Through the assessment of classic cases, the benefits and drawbacks of various preparation strategies and products are evaluated, to provide general knowledge for the needs of different application scenarios. In the end, the development directions of transparent face masks in protective gear, particularly their novel functional applications and potential contributions in the prevention and control of the epidemic are also proposed.

Drug Delivery Systems in Regenerative Medicine: An Updated Review

Modern drug discovery methods led to evolving new agents with significant therapeutic potential. However, their properties, such as solubility and administration-related challenges, may hinder their benefits. Moreover, advances in biotechnology resulted in the development of a new generation of molecules with a short half-life that necessitates frequent administration. In this context, controlled release systems are required to enhance treatment efficacy and improve patient compliance. Innovative drug delivery systems are promising tools that protect therapeutic proteins and peptides against proteolytic degradation where controlled delivery is achievable. The present review provides an overview of different approaches used for drug delivery.

Advances in Polysaccharide- and Synthetic Polymer-Based Vitreous Substitutes

The vitreous humour is a gel-like structure that composes the majority of each eye. It functions to provide passage of light, be a viscoelastic dampener, and hold the retina in place. Vitreous liquefaction causes retinal detachment and retinal tears requiring pars plana vitrectomy for vitreous substitution. An ideal vitreous substitute should display similar mechanical, chemical, and rheological properties to the natural vitreous. Currently used vitreous substitutes such as silicone oil, perfluorocarbon liquids, and gases cannot be used long-term due to adverse effects such as poor retention time, cytotoxicity, and cataract formation. Long-term, experimental vitreous substitutes composed of natural, modified and synthetic polymers are currently being studied. This review discusses current long- and short-term vitreous substitutes and the disadvantages of these that have highlighted the need for an ideal vitreous substitute. The review subsequently focuses specifically on currently used polysaccharide- and synthetic polymer-based vitreous substitutes, which may be modified or functionalised, or employed as the derivative, and discusses experimental vitreous substitutes in these classes. The advantages and challenges associated with the use of polymeric substitutes are discussed. Innovative approaches to vitreous substitution, namely a novel foldable capsular vitreous body, are presented, as well as future perspectives related to the advancement of this field.

Encapsulation of Monodisperse Microdroplets in Nanofibers through a Microfluidic-Electrospinning Hybrid Method

Fibers with droplets encapsulated in them could build bridges between a 0D dispersed structure and a 1D continuous wire and thus provide optimal solutions requiring high surface-to-volume ratio and strong mechanical properties. However, current methods are mostly focusing on the architectures with the size of droplets smaller than that of fibers; the relatively thick barrier of fibers usually limits the rate of diffusion from inner droplets to the outer environment. Here, we report a hybrid method combining microfluidics and electrospinning to fabricate nanofibers with microdroplets encapsulated in them. Monodisperse microdroplets with controllable sizes from 36 to 95 μm are generated through microfluidic flow-focusing and split into a string of smaller droplets from 1 to 3 μm, respectively, during the electrospinning stretching. The size of encapsulated droplets could be tuned by controlling the flow rate ratio during the microfluidic process, and the shape of that could be varied by changing the viscosity of encapsulated solution. This marriage of microfluidics and electrospinning could be applied to produce a nanofiber-based moisture barrier and drug carrier, also providing efficient tools to study the under-electric-field stretching and splitting of droplets trapped in the polymer network.

Special Issue: Tissue Engineered Biomaterials and Drug Delivery Systems

Current advances in biomaterials processing and engineering for drug delivery have allowed interesting progressed in biomedical field [...].

3D-Braided Poly-ε-Caprolactone-Based Scaffolds for Ligament Tissue Engineering

The anterior cruciate ligament (ACL) is the most commonly injured intra-articular ligament of the knee. Due to its limited intrinsical healing potential and vascularization, injuries of the ACL do not heal satisfactorily, and surgical intervention is usually required. The limitations of existing reconstructive grafts and autologous transplants have prompted interest in tissue-engineered solutions. A tissue engineering scaffold for ACL reconstruction must be able to mimic the mechanical properties of the native ligament, provide sufficient porosity to promote cell growth of the neoligament tissue, and be biodegradable. This study investigates long-term biodegradable poly-ε-caprolactone (PCL)-based scaffolds for ACL replacement using the 3D hexagonal braiding technique. The scaffolds were characterized mechanically as well as morphologically. All scaffolds, regardless of their braid geometry, achieved the maximum tensile load of the native ACL. The diameter of all scaffolds was lower than that of the native ligament, making the scaffolds implantable with established surgical methods. The 3D hexagonal braiding technique offers a high degree of geometrical freedom and, thus, the possibility to develop novel scaffold architectures. Based on the findings of this study, the 3D-braided PCL-based scaffolds studied were found to be a promising construct for tissue engineering of the anterior cruciate ligament.

Electrospun Fibers: Versatile Approaches for Controlled Release Applications

Electrospinning has been one of the most attractive methods of fiber fabrication in the last century. A lot of studies have been conducted, especially in tissue engineering and drug delivery using electrospun fibers. Loading many different drugs and bioactive agents on or within these fibers potentiates the efficacy of such systems; however, there are still no commercial products with this technology available in the market. Various methods have been developed to improve the mechanical and physicochemical behavior of structures toward more controllable delivery systems in terms of time, place, or quantity of release. In this study, most frequent methods used for the fabrication of controlled release electrospun fibers have been reviewed. Although there are a lot of achievements in the fabrication of controlled release fibers, there are still many challenges to be solved to reach a qualified, reproducible system applicable in the pharmaceutical industry.

Emerging Bioactive Agent Delivery-Based Regenerative Therapies for Lower Genitourinary Tissues

Injury to lower genitourinary (GU) tissues, which may result in either infertility and/or organ dysfunctions, threatens the overall health of humans. Bioactive agent-based regenerative therapy is a promising therapeutic method. However, strategies for spatiotemporal delivery of bioactive agents with optimal stability, activity, and tunable delivery for effective sustained disease management are still in need and present challenges. In this review, we present the advancements of the pivotal components in delivery systems, including biomedical innovations, system fabrication methods, and loading strategies, which may improve the performance of delivery systems for better regenerative effects. We also review the most recent developments in the application of these technologies, and the potential for delivery-based regenerative therapies to treat lower GU injuries. Recent progress suggests that the use of advanced strategies have not only made it possible to develop better and more diverse functionalities, but also more precise, and smarter bioactive agent delivery systems for regenerative therapy. Their application in lower GU injury treatment has achieved certain effects in both patients with lower genitourinary injuries and/or in model animals. The continuous evolution of biomaterials and therapeutic agents, advances in three-dimensional printing, as well as emerging techniques all show a promising future for the treatment of lower GU-related disorders and dysfunctions.

Two-dimensional nanovermiculite and polycaprolactone electrospun fibers composite scaffolds promoting diabetic wound healing

BACKGROUND

Promoting diabetic wound healing is still a challenge, and angiogenesis is believed to be essential for diabetic wound healing. Vermiculite is a natural clay material that is very easy to obtain and exhibits excellent properties of releasing bioactive ions, buffering pH, adsorption, and heat insulation. However, there are still many unsolved difficulties in obtaining two-dimensional vermiculite and using it in the biomedical field in a suitable form.

RESULTS

In this study, we present a versatile organic-inorganic composite scaffold, which was constructed by embedding two-dimensional vermiculite nanosheets in polycaprolactone electrospun fibers, for enhancing angiogenesis through activation of the HIF-1α signaling pathway and promoting diabetic wound healing both in vitro and in vivo.

CONCLUSIONS

Together, the rational-designed polycaprolactone electrospun fibers-based composite scaffolds integrated with two-dimensional vermiculite nanosheets could significantly improve neo-vascularization, re-epithelialization, and collagen formation in the diabetic wound bed, thus promoting diabetic wound healing. This study provides a new strategy for constructing bioactive materials for highly efficient diabetic wound healing.

Functionalization of Electrospun Nanofiber for Bone Tissue Engineering

Bone-tissue engineering is an alternative treatment for bone defects with great potential in which scaffold is a critical factor to determine the effect of bone regeneration. Electrospun nanofibers are widely used as scaffolds in the biomedical field for their similarity with the structure of the extracellular matrix (ECM). Their unique characteristics are: larger surface areas, porosity and processability; these make them ideal candidates for bone-tissue engineering. This review briefly introduces bone-tissue engineering and summarizes the materials and methods for electrospining. More importantly, how to functionalize electrospun nanofibers to make them more conducive for bone regeneration is highlighted. Finally, the existing deficiencies of functionalized electrospun nanofibers for promoting osteogenesis are proposed. Such a summary can lay the foundation for the clinical practice of functionalized electrospun nanofibers.

PLA-lignin nanofibers as antioxidant biomaterials for cartilage regeneration and osteoarthritis treatment

Background

Osteoarthritis (OA) is common musculoskeletal disorders associated with overgeneration of free radicals, and it causes joint pain, inflammation, and cartilage degradation. Lignin as a natural antioxidant biopolymer has shown its great potential for biomedical applications. In this work, we developed a series of lignin-based nanofibers as antioxidative scaffolds for cartilage tissue engineering.

Results

The nanofibers were engineered by grafting poly(lactic acid) (PLA) into lignin via ring-opening polymerization and followed by electrospinning. Varying the lignin content in the system was able to adjust the physiochemical properties of the resulting nanofibers, including fiber diameters, mechanical and viscoelastic properties, and antioxidant activity. In vitro study demonstrated that the PLA-lignin nanofibers could protect bone marrow-derived mesenchymal stem/stromal cells (BMSCs) from oxidative stress and promote the chondrogenic differentiation. Moreover, the animal study showed that the lignin nanofibers could promote cartilage regeneration and repair cartilage defects within 6 weeks of implantation.

Conclusion

Our study indicated that lignin-based nanofibers could serve as an antioxidant tissue engineering scaffold and facilitate the cartilage regrowth for OA treatment.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s12951-022-01534-2.

Characterization of Electrospun Poly(ε-caprolactone) Nano/Micro Fibrous Membrane as Scaffolds in Tissue Engineering: Effects of the Type of Collector Used

Electrospinning is an electrohydrodynamic technique that transforms a polymer solution into nano/microscopic diameter fibers under the influence of a high-voltage electric field. Its use in the fabrication of nano/micro fibrous membranes as scaffolds for tissue engineering has increased rapidly in recent years due to its efficiency and reproducibility. The objective of this study is to show how the use of the same polymeric solution (polycaprolactone 9% w/v in chloroform: isopropanol 50:50) and identical electrohydrodynamic deposition parameters produces fibers with different characteristics using a flat collector platform with movements in the X and Y axes vs. a conventional rotary collector. The manufactured nano/microfibers show significant differences in most of their characteristics (morphology, roughness, hydrophilicity, and mechanical properties). Regarding the diameter and porosity of the fibers, the results were similar. Given that scaffolds must be designed to guarantee adequate survival and the proliferation and migration of a certain cell type, in this study we analyze how the variations in the characteristics of the fibers obtained are essential to defining their potential application.

Micro/Nanosystems for Magnetic Targeted Delivery of Bioagents

Targeted delivery of pharmaceuticals is promising for efficient disease treatment and reduction in adverse effects. Nano or microstructured magnetic materials with strong magnetic momentum can be noninvasively controlled via magnetic forces within living beings. These magnetic carriers open perspectives in controlling the delivery of different types of bioagents in humans, including small molecules, nucleic acids, and cells. In the present review, we describe different types of magnetic carriers that can serve as drug delivery platforms, and we show different ways to apply them to magnetic targeted delivery of bioagents. We discuss the magnetic guidance of nano/microsystems or labeled cells upon injection into the systemic circulation or in the tissue; we then highlight emergent applications in tissue engineering, and finally, we show how magnetic targeting can integrate with imaging technologies that serve to assist drug delivery.

Static and Dynamic Biomaterial Engineering for Cell Modulation

In the biological microenvironment, cells are surrounded by an extracellular matrix (ECM), with which they dynamically interact during various biological processes. Specifically, the physical and chemical properties of the ECM work cooperatively to influence the behavior and fate of cells directly and indirectly, which invokes various physiological responses in the body. Hence, efficient strategies to modulate cellular responses for a specific purpose have become important for various scientific fields such as biology, pharmacy, and medicine. Among many approaches, the utilization of biomaterials has been studied the most because they can be meticulously engineered to mimic cellular modulatory behavior. For such careful engineering, studies on physical modulation (e.g., ECM topography, stiffness, and wettability) and chemical manipulation (e.g., composition and soluble and surface biosignals) have been actively conducted. At present, the scope of research is being shifted from static (considering only the initial environment and the effects of each element) to biomimetic dynamic (including the concepts of time and gradient) modulation in both physical and chemical manipulations. This review provides an overall perspective on how the static and dynamic biomaterials are actively engineered to modulate targeted cellular responses while highlighting the importance and advance from static modulation to biomimetic dynamic modulation for biomedical applications.

Facile One-Pot Method for All Aqueous Green Formation of Biocompatible Silk Fibroin-Poly(Ethylene Oxide) Fibers for Use in Tissue Engineering

Silk fibroin (SF) fibers are highly regarded in tissue engineering because of their outstanding biocompatibility and tunable properties. A challenge remains in overcoming the trade-off between functioning and biocompatible fibers and the use of cytotoxic, environmentally harmful organic solvents in their processing and formation. The aim of this research was to produce biocompatible SF fibers without the use of cytotoxic solvents, via pressurized gyration (PG). Aqueous SF was blended with poly(ethylene oxide) (PEO) in ratios of 80:20 (labeled SF-PEO 80:20) and 90:10 (labeled SF-PEO 90:10) and spun into fibers using PG, assisted by a range of applied pressures and heat. Pure PEO (labeled PEO-Aq) and SF solubilized in hexafluoro-isopropanol (HFIP) (labeled SF-HFIP) and aqueous SF (labeled SF-Aq) were also prepared for comparison. The resulting fibers were characterized using SEM, TGA, and FTIR. Their in vitro cell behavior was analyzed using a Live/Dead assay and cell proliferation studies with the SaOS-2 human bone osteosarcoma cell line (ATCC, HTB-85) and human fetal osteoblast cells (hFob) (ATCC, CRL-11372) in 2D culture conditions. Fibers in the micrometer range were successfully produced using SF-PEO blends, SF-HFIP, and PEO-Aq. The fiber thickness ranged from 0.71 ± 0.17 μm for fibers produced using SF-PEO 90:10 with no applied pressure to 2.10 ± 0.78 μm for fibers produced using SF-PEO 80:10 with 0.3 MPa applied pressure. FTIR confirmed the presence of SF via amide I and amide II bands in the blend fibers because of a change in structural conformation. No difference was observed in thermogravimetric properties among varying pressures and no significant difference in fiber diameters for pressures. SaOS-2 cells and hFOb cell studies demonstrated higher cell densities and greater live cells on SF-PEO blends when compared to SF-HFIP. This research demonstrates a scalable and green method of producing SF-based constructs for use in bone-tissue engineering applications.

Expanding the Repertoire of Electrospinning: New and Emerging Biopolymers, Techniques, and Applications

Electrospinning has emerged as a versatile and accessible technology for fabricating polymer fibers, particularly for biological applications. Natural polymers or biopolymers (including synthetically derivatized natural polymers) represent a promising alternative to synthetic polymers, as materials for electrospinning. Many biopolymers are obtained from abundant renewable sources, are biodegradable, and possess inherent biological functions. This review surveys recent literature reporting new fibers produced from emerging biopolymers, highlighting recent developments in the use of sulfated polymers (including carrageenans and glycosaminoglycans), tannin derivatives (condensed and hydrolyzed tannins, tannic acid), modified collagen, and extracellular matrix extracts. The proposed advantages of these biopolymer-based fibers, focusing on their biomedical applications, are also discussed to highlight the use of new and emerging biopolymers (or new modifications to well-established ones) to enhance or achieve new properties for electrospun fiber materials.

Electrospun Nanofibers for Manipulating the Soft Tissue Regeneration

Soft tissue damage is a common clinical problem that affects the lives of a large number of patients all over the world. It is of great importance to develop functional...

Advanced approaches to regenerate spinal cord injury: The development of cell and tissue engineering therapy and combinational treatments

Spinal cord injury (SCI) is a central nervous system (CNS) devastate event that is commonly caused by traumatic or non-traumatic events. The reinnervation of spinal cord axons is hampered through a myriad of devices counting on the damaged myelin, inflammation, glial scar, and defective inhibitory molecules. Unfortunately, an effective treatment to completely repair SCI and improve functional recovery has not been found. In this regard, strategies such as using cells, biomaterials, biomolecules, and drugs have been reported to be effective for SCI recovery. Furthermore, recent advances in combinatorial treatments, which address various aspects of SCI pathophysiology, provide optimistic outcomes for spinal cord regeneration. According to the global importance of SCI, the goal of this article review is to provide an overview of the pathophysiology of SCI, with an emphasis on the latest modes of intervention and current advanced approaches for the treatment of SCI, in conjunction with an assessment of combinatorial approaches in preclinical and clinical trials. So, this article can give scientists and clinicians' clues to help them better understand how to construct preclinical and clinical studies that could lead to a breakthrough in spinal cord regeneration.

Melt-extrusion 3D printing of resorbable levofloxacin-loaded meshes: Emerging strategy for urogynaecological applications

Current surgical strategies for the treatment of pelvic floor dysfunctions involve the placement of a polypropylene mesh into the pelvic cavity. However, polypropylene meshes have proven to have inadequate mechanical properties and have been associated to the arising of severe complications, such as infections. Furthermore, currently employed manufacturing strategies are unable to produce compliant and customisable devices. In this work, polycaprolactone has been used to produce resorbable levofloxacin-loaded meshes in two different designs (90° and 45°) via melt-extrusion 3D printing. Drug-loaded meshes were produced using a levofloxacin concentration of 0.5% w/w. Drug loaded meshes were successfully produced with highly reproducible mechanical and physico-chemical properties. Tensile test results showed that drug-loaded 45° meshes possessed a mechanical behaviour close to that of the vaginal tissue (E ≃ 8.32 ± 1.85 MPa), even after 4 weeks of accelerated degradation. Meshes released 80% of the loaded levofloxacin in the first 3 days and were capable of producing an inhibitory effect against S. Aureus and E. coli bacterial strains with an inhibition zone equal to 12.8 ± 0.45 mm and 15.8 ± 0.45 mm respectively. Thus, the strategy adopted in this work holds great promise for the manufacturing of custom-made surgical meshes with antibacterial properties.

Hydroxyapatite grafted chitosan/laponite RD hydrogel: Evaluation of the encapsulation capacity, pH-responsivity, and controlled release behavior

In this study, a pH-responsive drug carrier was developed for the controllable release of drugs in the gastric environment. Chitosan (CS), a pH-sensitive biopolymer, and laponite RD (LAP), a nano-clay with a high drug-loading capability, were used to design the new carrier. Hydroxyapatite (HA) was grafted into CS/LAP matrix through a simple co-precipitation technique to overcome the burst release of the CS/LAP. The structural analysis and swelling tests of products demonstrated that the co-precipitation method has led to the penetration of HA nanoparticles inside the CS/LAP matrix and occupying its hollow pores. Occupation of the empty pores can lead to the entrapment of drug molecules, thereby reducing the release rate. The nanocomposite showed a high loading capacity to ofloxacin as a drug model. The effects of HA content on release behavior of nanocomposite were investigated at simulated gastric (pH 1.2) and intestine (pH 7.4) environments. The results indicated a high pH sensitivity for CS/LAP/HA. HA grafting reduced the release rate remarkably regardless of pH. The release rate of CS/LAP/HA decreased by 44-63% in pH 1.2 and 41-51% in pH 7.4 compared to CS/LAP. Kinetic studies indicated that grafting the HA in CS/LAP has changed the drug release mechanism.

Multifunctional Nanofibrous Dressing with Antimicrobial and Anti-Inflammatory Properties Prepared by Needle-Free Electrospinning

An active wound dressing should address the main goals in wound treatment, which are improved wound healing and reduced infection rates. We developed novel multifunctional nanofibrous wound dressings with three active ingredients: chloramphenicol (CAM), beta-glucan (βG) and chitosan (CHI), of which βG and CHI are active nanofiber-forming biopolymers isolated from the cell walls of Saccharomyces cerevisiae and from shrimp shells, respectively. To evaluate the effect of each active ingredient on the nanofibers' morphological features and bioactivity, nanofibers with both βG and CHI, only βG, only CHI and only copolymers, polyethylene oxide (PEO) and hydroxypropylmethylcellulose (HPMC) were fabricated. All four nanofiber formulations were also prepared with 1% CAM. The needle-free NanospiderTM technique allowed for the successful production of defect-free nanofibers containing all three active ingredients. The CAM-containing nanofibers had a burst CAM-release and a high absorption capacity. Nanofibers with all active ingredients (βG, CHI and CAM) showed a concentration-dependent anti-inflammatory activity, while maintaining the antimicrobial activity of CAM. The promising anti-inflammatory properties, together with the high absorption capacity and antimicrobial effect, make these multifunctional nanofibers promising as dressings in local treatment of infected and exuding wounds, such as burn wounds.

Milestones and current achievements in development of multifunctional bioscaffolds for medical application

Tissue engineering (TE) is a rapidly growing interdisciplinary field, which aims to restore or improve lost tissue function. Despite that TE was introduced more than 20 years ago, innovative and more sophisticated trends and technologies point to new challenges and development. Current challenges involve the demand for multifunctional bioscaffolds which can stimulate tissue regrowth by biochemical curves, biomimetic patterns, active agents and proper cell types. For those purposes especially promising are carefully chosen primary cells or stem cells due to its high proliferative and differentiation potential. This review summarized a variety of recently reported advanced bioscaffolds which present new functions by combining polymers, nanomaterials, bioactive agents and cells depending on its desired application. In particular necessity of study biomaterial-cell interactions with in vitro cell culture models, and studies using animals with in vivo systems were discuss to permit the analysis of full material biocompatibility. Although these bioscaffolds have shown a significant therapeutic effect in nervous, cardiovascular and muscle, tissue engineering, there are still many remaining unsolved challenges for scaffolds improvement.

Adipose-Derived Stem Cells Based on Electrospun Biomimetic Scaffold Mediated Endothelial Differentiation Facilitating Regeneration and Repair of Abdominal Wall Defects via HIF-1α/VEGF Pathway

Application of synthetic or biological meshes is the main therapy for the repair and reconstruction of abdominal wall defects, a common disease in surgery. Currently, no ideal materials are available, and there is an urgent need to find appropriate ones to satisfy clinical needs. Electrospun scaffolds have drawn attention in soft tissue reconstruction. In this study, we developed a novel method to fabricate a composite electrospun scaffold using a thermoresponsive hydrogel, poly (N-isopropylacrylamide)-block-poly (ethylene glycol), and a biodegradable polymer, polylactic acid (PLA). This scaffold provided not only a high surface area/volume ratio and a three-dimensional fibrous matrix but also high biocompatibility and sufficient mechanical strength, and could simulate the native extracellular matrix and accelerate cell adhesion and proliferation. Furthermore, rat adipose-derived stem cells (ADSCs) were seeded in the composite electrospun scaffold to enhance the defect repair and regeneration by directionally inducing ADSCs into endothelial cells. In addition, we found early vascularization in the process was regulated by the hypoxia inducible factor-1α (HIF-1α)/vascular endothelial growth factor (VEGF) pathway. In our study, overexpression of HIF-1α/VEGF in ADSCs using a lentivirus system promoted early vascularization in the electrospun scaffolds. Overall, we expect our composite biomimetic scaffold method will be applicable and useful in abdominal wall defect regeneration and repair in the future.

Advanced mycelium materials as potential self-growing biomedical scaffolds

Mycelia, the vegetative part of fungi, are emerging as the avant-garde generation of natural, sustainable, and biodegradable materials for a wide range of applications. They are constituted of a self-growing and interconnected fibrous network of elongated cells, and their chemical and physical properties can be adjusted depending on the conditions of growth and the substrate they are fed upon. So far, only extracts and derivatives from mycelia have been evaluated and tested for biomedical applications. In this study, the entire fibrous structures of mycelia of the edible fungi Pleurotus ostreatus and Ganoderma lucidum are presented as self-growing bio-composites that mimic the extracellular matrix of human body tissues, ideal as tissue engineering bio-scaffolds. To this purpose, the two mycelial strains are inactivated by autoclaving after growth, and their morphology, cell wall chemical composition, and hydrodynamical and mechanical features are studied. Finally, their biocompatibility and direct interaction with primary human dermal fibroblasts are investigated. The findings demonstrate the potentiality of mycelia as all-natural and low-cost bio-scaffolds, alternative to the tissue engineering systems currently in place.

Construction of chitosan scaffolds with controllable microchannel for tissue engineering and regenerative medicine

Microchannels are effective means of enabling the functional performance of tissue engineering scaffolds. Chitosan, a partial deacetylation derivative of chitin, exhibiting excellent biocompatibility, has been widely used in clinical practice. However, development of chitosan scaffolds with controllable microchannels architecture remains an engineering challenge. Here, we generated chitosan scaffolds with adjustable microchannel by combining a 3D printing microfiber templates-leaching method and a freeze-drying method. We can precisely control the arrangement, diameter and density of microchannel within chitosan scaffolds. Moreover, the integrated bilayer scaffolds with the desired structural parameters in each layer were fabricated and exhibited no delamination. The flow rate and volume of the simulated fluid can be modulated by diverse channels architecture. Additionally, the microchannel structure promoted cell survival, proliferation and distribution in vitro, and improved cell and tissue ingrowth and vascular formation in vivo. This study opens a new road for constructing chitosan scaffolds, and can further extend their application scope across tissue engineering and regenerative medicine.

MgO Nanoparticles-Incorporated PCL/Gelatin-Derived Coaxial Electrospinning Nanocellulose Membranes for Periodontal Tissue Regeneration

Electrospinning technique has attracted considerable attention in fabrication of cellulose nanofibrils or nanocellulose membranes, in which polycaprolactone (PCL) could be used as a promising precursor to prepare various cellulose nanofibril membranes for periodontal tissue regeneration. Conventional bio-membranes and cellulose films used in guided tissue regeneration (GTR) can prevent the downgrowth of epithelial cells, fibroblasts, and connective tissue in the area of tooth root but have limitations related to osteogenic and antimicrobial properties. Cellulose nanofibrils can be used as an ideal drug delivery material to encapsulate and carry some drugs. In this study, magnesium oxide (MgO) nanoparticles-incorporated PCL/gelatin core-shell nanocellulose periodontal membranes were fabricated using coaxial electrospinning technique, which was termed as Coaxial-MgO. The membranes using single-nozzle electrospinning technique, namely Blending-MgO and Blending-Blank, were used as control. The morphology and physicochemical property of these nanocellulose membranes were characterized by scanning electron microscopy (SEM), energy-dispersive spectrum of X-ray (EDS), transmission electron microscopy (TEM), contact angle, and thermogravimetric analysis (TGA). The results showed that the incorporation of MgO nanoparticles barely affected the morphology and mechanical property of nanocellulose membranes. Coaxial-MgO with core-shell fiber structure had better hydrophilic property and sustainable release of magnesium ion (Mg²⁺). CCK-8 cell proliferation and EdU staining demonstrated that Coaxial-MgO membranes showed better human periodontal ligament stem cells (hPDLSCs) proliferation rates compared with the other group due to its gelatin shell with great biocompatibility and hydrophilicity. SEM and immunofluorescence assay results illustrated that the Coaxial-MgO scaffold significantly enhanced hPDLSCs adhesion. In vitro osteogenic and antibacterial properties showed that Coaxial-MgO membrane enhanced alkaline phosphatase (ALP) activity, formation of mineralized nodules, osteogenic-related genes [ALP, collagen type 1 (COL1), runt-related transcription factor 2 (Runx2)], and high antibacterial properties toward Escherichia coli (E. coli) and Actinobacillus actinomycetemcomitans (A. a) when compared with controls. Our findings suggested that MgO nanoparticles-incorporated coaxial electrospinning PCL-derived nanocellulose periodontal membranes might have great prospects for periodontal tissue regeneration.

Cardiac Regeneration: the Heart of the Issue

Purpose of Review

The regenerative capacity of the heart is insufficient to compensate for the pathological loss of cardiomyocytes during a large injury, such as a myocardial infarction. Therapeutic options for patients after cardiac infarction are limited: treatment with drugs that only treat the symptoms or extraordinary measures, such as heart transplantation. Cell therapies offer a promising strategy for cardiac regeneration. In this brief review, the major issues in these areas are discussed, and possible directions for future research are indicated.

Recent Findings

Cardiac regeneration can be obtained by at least two strategies: the first is direct to generate an ex vivo functional myocardial tissue that replaces damaged tissue; the second approach aims to stimulate endogenous mechanisms of cardiac repair. However, current cell therapies are still hampered by poor translation into actual clinical applications.

Summary

In this scenario, recent advancements in cell biology and biomaterial-based technologies can play a key role to design effective therapeutic approaches.

Bioactive anti-oxidative polycaprolactone/gelatin electrospun nanofibers containing selenium nanoparticles/vitamin E for wound dressing applications

In this study, polycaprolactone/gelatin (PCL/GEL) electrospun nanofibers containing biogenic selenium nanoparticles (Se NPs) and Se NPs/vitamin E (VE) with average diameters of 397.8 nm and 279.5 nm, respectively (as determined by SEM inspection) were prepared and their effect on wound healing was evaluated using in-vivo studies. The energy dispersive X-ray (EDX) mapping, TEM micrograph, and FTIR spectra of the prepared nanofibers strongly demonstrated well entrapment of Se NPs and VE into scaffolds. An amount of 57% Se NPs and 43% VE were gradually released from PCL/GEL/Se NPs/VE scaffold after 4 days immersion in PBS solution (pH 7.4). The both PCL/GEL/Se NPs and PCL/GEL/Se NPs/VE scaffolds supported 3T3 cell proliferation and attachment as confirmed by MTT assay and SEM imaging. Complete re-epithelialization, low level of edema and inflammatory cells in coordination with high level of oriented collagens demonstrated the wound healing activity of PCL/GEL/Se NPs/VE. Besides, significant antioxidant efficacy of PCL/GEL/Se NPs and PCL/GEL/Se NPs/VE scaffolds was demonstrated according to GSH and MDA assays. To sum up, the prepared PCL/GEL/Se NPs/VE scaffold in the present study represented suitable healing effect on animal model which candidate it for further studies.

Next-generation surgical meshes for drug delivery and tissue engineering applications: materials, design and emerging manufacturing technologies

Abstract

Surgical meshes have been employed in the management of a variety of pathological conditions including hernia, pelvic floor dysfunctions, periodontal guided bone regeneration, wound healing and more recently for breast plastic surgery after mastectomy. These common pathologies affect a wide portion of the worldwide population; therefore, an effective and enhanced treatment is crucial to ameliorate patients’ living conditions both from medical and aesthetic points of view. At present, non-absorbable synthetic polymers are the most widely used class of biomaterials for the manufacturing of mesh implants for hernia, pelvic floor dysfunctions and guided bone regeneration, with polypropylene and poly tetrafluoroethylene being the most common. Biological prostheses, such as surgical grafts, have been employed mainly for breast plastic surgery and wound healing applications. Despite the advantages of mesh implants to the treatment of these conditions, there are still many drawbacks, mainly related to the arising of a huge number of post-operative complications, among which infections are the most common. Developing a mesh that could appropriately integrate with the native tissue, promote its healing and constructive remodelling, is the key aim of ongoing research in the area of surgical mesh implants. To this end, the adoption of new biomaterials including absorbable and natural polymers, the use of drugs and advanced manufacturing technologies, such as 3D printing and electrospinning, are under investigation to address the previously mentioned challenges and improve the outcomes of future clinical practice. The aim of this work is to review the key advantages and disadvantages related to the use of surgical meshes, the main issues characterizing each clinical procedure and the future directions in terms of both novel manufacturing technologies and latest regulatory considerations.

Graphic abstract

Detecting and targeting neurodegenerative disorders using electrospun nanofibrous matrices: current status and applications

Neurodegeneration is defined as the progressive atrophy and loss of function of neurons; it is present in neurodegenerative disorders such as Multiple Sclerosis, Alzheimer's, Huntington's, and Parkinson's diseases. The detection of such disorders is performed by various imaging modalities while their therapeutic management is quite challenging. Besides, the pathogenesis of neurodegenerative disorders is still under ongoing research due to complex and multi-factorial mechanisms. Currently, targeting the specific proteins responsible for neurodegeneration is of great interest to many researchers. Furthermore, nanotechnology-based approaches for targeting the affected neurons became an emerging field of interest. Nanostructures of various forms have been developed aiming to act as therapeutics for neurodegeneration, in which electrospun nanofibers seem to play an important role as biomedical products for both detection and management of the diseases. Electrospinning is an intriguing method able to produce nanofibers with a wide range of sizes and morphological characteristics. Such nanofibrous matrices can be delivered through different administration routes to target various diseases. In this review, the most recent advancements in electrospun nanofibrous systems that target or detect multiple neurodegenerative diseases have been enlightened and an introduction to the general aspects of neurodegenerative diseases and the electrospinning process has been made. Finally, future perspectives of neurodegeneration targeting were also discussed.

Generation of Core-Sheath Polymer Nanofibers by Pressurised Gyration

The ability to generate core-sheath bicomponent polymer nanofibers in a single-step with scale-up possibilities is demonstrated using pressurised gyration manufacturing. This is the first time that nanofiber containing more than one polymer having a core-sheath configuration has been generated in this way. Water-soluble polymers polyethylene oxide (PEO) and polyvinyl pyrrolidone (PVP) are used as the core and sheath layers, respectively. Core-sheath nanofibers with a diameter in the range of 331 to 998 nm were spun using 15 wt % PEO and 15 wt % PVP polymer solutions. The forming parameters, working pressure and rotating speed, had a significant influence on the size, size distribution and the surface morphology of the nanofibers generated. Overall, fibre size decreased with increasing working pressure and rotating speed. The fibre size was normally distributed in all cases, with 0.2 MPa working pressure in particular showing narrower distribution. The fibre size distributions for 0.1 and 0.3 MPa working pressure were broader and a mean fibre size of 331 nm was obtained in the latter case. The fibre size was evenly distributed and narrower for rotating speeds of 2000 and 4000 RPMs. The distribution was broader for rotating speed of 6000 RPM with a mean value obtained at 430 nm. Continuous, smooth and bead-free fibre morphologies were obtained in each case. The fibre cross-section analysis using a focused ion beam machine showed a solid core surrounded by a sheath layer. Our findings demonstrate that the pressurised gyration could be used to produce core-sheath polymer nanofibers reliably and cost-effectively with scale-up possibilities (~4 kg h-1).