Drug Delivery Applications of Core-Sheath Nanofibers Prepared by Coaxial Electrospinning: A Review

Development of magnesium hydroxide-doped nanofibrous spheres for repairing infected skin wounds

The healing of skin wounds is a continuous and coordinated process, typically accompanied by microbial colonization and growth. This may result in wound infection and subsequent delay in wound healing. Therefore, it is of particular importance to inhibit the growth of microorganisms in the wound environment. In this study, magnesium hydroxide-doped polycaprolactone (PCL/MH) nanofibrous spheres were fabricated by electrospinning and electrospray techniques to investigate their effects on infected wound healing. The prepared PCL/MH nanofibrous spheres had good porous structure and biocompatibility, providing a favorable environment for the delivery and proliferation of adipose stem cells. The incorporation of MH significantly enhanced the antimicrobial properties of the spheres, in particular, the inhibition of the growth of S. aureus and E. coli. We showed that such PCL/MH nanofibrous spheres had good antimicrobial properties and effectively promoted the regeneration of infected wound tissues, which provided a new idea for the clinical treatment of infected wounds.

Tailoring biomaterials for skin anti-aging

Skin aging is the phenomenon of degenerative changes in the structure and function of skin tissues over time and is manifested by a gradual loss of skin elasticity and firmness, an increased number of wrinkles, and hyperpigmentation. Skin anti-aging refers to a reduction in the skin aging phenomenon through medical cosmetic technologies. In recent years, new biomaterials have been continuously developed for improving the appearance of the skin through mechanical tissue filling, regulating collagen synthesis and degradation, inhibiting pigmentation, and repairing the skin barrier. This review summarizes the mechanisms associated with skin aging, describes the biomaterials that are commonly used in medical aesthetics and their possible modes of action, and discusses the application strategies of biomaterials in this area. Moreover, the synergistic effects of such biomaterials and other active ingredients, such as stem cells, exosomes, growth factors, and antioxidants, on tissue regeneration and anti-aging are evaluated. Finally, the possible challenges and development prospects of biomaterials in the field of anti-aging are discussed, and novel ideas for future innovations in this area are summarized.

Development of fast-dissolving sublingual nanofibers containing allergen and curcumin for immune response modulation in a mouse model of allergic rhinitis

Curcumin (CUR) has been considered a potential therapeutic agent for allergic reactions due to its antioxidant and anti-inflammatory activities. Nanofibers have attracted increasing attention in drug delivery. The aim of this study was to investigate the combined therapeutic effects of curcumin and allergen in nanofiber-based treatments in order to increase the effectiveness of sublingual immunotherapy (SLIT) efficacy in a mouse model of allergic rhinitis. Nanofibers containing CUR (1.25% and 2.5%) and ovalbumin 2% (OVA) as an allergen were prepared via electrospinning and characterized. BALB/c mice were sensitized with OVA to the induced allergic rhinitis model. SLIT with free and/or nanofibers was carried out. IL-4, INF-γ, and IgE serum levels were measured using ELISA. Splenocyte proliferation was evaluated by the MTT assay. Lung and nasal histological examinations and nasal lavage fluid (NALF) cell counting were carried out. Nanofibers containing 1.25% CUR and 2% OVA were chosen as the optimal formulations. SLIT treatment with the CUR and OVA nanofiber co-administration led to a significantly decreased serum IgE. Nanofiber containing 2.5 µg of CUR/mouse combined with OVA nanofiber showed a significant decrease in IL-4 and an increase in IFN-γ compared to other groups. NALF assessment showed a significant decrease in specific cell and eosinophil counts in the treated nanofiber groups. The histopathological results of NAL in the optimal formulations were near normal, with diminished cellular infiltration and inflammation. Our findings suggest that co-sublingual administration of allergen and CUR nanofibers can be considered as potential immunomodulatory agents.

Preparation and Characterization of Zein-Metformin/Gelatin Nanofibers by Coaxial Electrospinning

Metformin is a drug commonly used for the treatment of type 2 diabetes. However, it has been associated with damaging side effects when used over a long period of time. A potential solution to this problem is the implementation of a prolonged-release system for metformin, which would enhance the efficiency of the doses administered to patients. To achieve this, it is necessary to use materials compatible with humans. Electrospinning is an efficient technique that can be employed for this purpose, utilizing solvents that are safe for human use. Therefore, the objective of this study was to prepare and characterize a system for the prolonged release of metformin from zein and gelatin through coaxial electrospinning as well as to investigate its in vitro release. Metformin-loaded zein/gelatin coaxial nanofibers were prepared using the coaxial electrospinning technique and then characterized by morphological, structural, and thermal analysis. Morphologically, metformin-loaded zein/gelatin coaxial nanofibers were obtained with an average diameter of 322.6 ± 44.5 nm and a smooth surface. Fourier transform infrared spectroscopy (FTIR) analysis showed band shifts at a higher wavenumber due to drug-protein interactions by hydrogen bonding between N-H and C=O groups. Thermal gravimetric analysis (TGA) results suggested a possible interaction between materials due to an increase in the degradation temperatures of zein and gelatin when metformin was included. The transition of the crystallinity of metformin to the amorphous form was also confirmed by differential scanning calorimetry (DSC). Coaxial nanofibers exhibited an encapsulation efficiency of 66% and a profile release that showed an initial release of metformin (40%) in the first hour, followed by a gradual release until it reached equilibrium at 60 h and a cumulative release of 97% of metformin. It was concluded that using the coaxial electrospinning technique, it is possible to obtain nanofibers from polymeric solutions of zein and gelatin to encapsulate metformin, with a potential application as a prolonged-release system.

Cleaner and Sustainable Production of Core-Sheath Polymer Fibres

The amalgamation of sustainable practises throughout the fabrication process with advanced material engineering holds promise not only for eco-conscious manufacturing but also for promoting technological advancements in versatile material design and application. Moreover, technological innovation serves as a catalyst for sustainability initiatives, driving innovation and enabling the adoption of greener practises across industries. This study investigates redefining the production protocol of pressure spinning to produce core-sheath polymer fibres, deepening sustainable practises. It aims to explore innovative approaches such as modifying spinning parameters, optimising polymer solvent configurations and understanding fluid behaviour to curtail material wastage and maintain minimal energy consumption without compromising production efficiency. Utilising Polyvinylpyrrolidone (PVP) for the core and Polyethylene oxide (PEO) for the sheath, production rates of up to 64 g/h were achieved with a fibre diameter range of 3.2 ± 1.7 µm to 4.6 ± 2.0 µm. Energy consumption per mass of fibres produced showed a decreasing trend overall with increasing applied gas pressure. These findings highlight the potential for the efficient and scalable production of core-sheath fibres with applications in various advanced materials fields.

Cancer Treatment Using Nanofibers: A Review

Currently, the number of patients with cancer is expanding consistently because of a low quality of life. For this reason, the therapies used to treat cancer have received a lot of consideration from specialists. Numerous anticancer medications have been utilized to treat patients with cancer. However, the immediate utilization of anticancer medicines leads to unpleasant side effects for patients and there are many restrictions to applying these treatments. A number of polymers like cellulose, chitosan, Polyvinyl Alcohol (PVA), Polyacrylonitrile (PAN), peptides and Poly (hydroxy alkanoate) have good properties for the treatment of cancer, but the nanofibers-based target and controlled drug delivery system produced by the co-axial electrospinning technique have extraordinary properties like favorable mechanical characteristics, an excellent release profile, a high surface area, and a high sponginess and are harmless, bio-renewable, biofriendly, highly degradable, and can be produced very conveniently on an industrial scale. Thus, nanofibers produced through coaxial electrospinning can be designed to target specific cancer cells or tissues. By modifying the composition and properties of the nanofibers, researchers can control the release kinetics of the therapeutic agent and enhance its accumulation at the tumor site while minimizing systemic toxicity. The core-shell structure of coaxial electrospun nanofibers allows for a controlled and sustained release of therapeutic agents over time. This controlled release profile can improve the efficacy of cancer treatment by maintaining therapeutic drug concentrations within the tumor microenvironment for an extended period.

The urchin-like gold nanoparticles/poly(ε-caprolactone)/chitosan electrospun nanofibers for antibacterial active packaging

Inspired by the natural antimicrobial effect of the topographical features of insect wings, this study prepared urchin-like gold nanoparticles (UGNPs) and deposited them on poly(ε-caprolactone) (PCL)/chitosan (P/C) electrospun nanofiber film to strengthen antibacterial activities of this active packaging. Results showed that L-Dopa was a suitable reducing agent to prepare UGNPs, and the spine length of UGNPs increased from 21.23 to 35.83 nm as the molar ratio of L-Dopa:HAuCl4 increased from 1 to 3. As the nanofiber film was immersed in the nanoparticle solution for a longer time, the UGNP content in P/C nanofibers increased. As the spine length of UGNPs and depositing UGNP content increased, the inhibition rate against S. aureus and E. coli. of P/C nanofiber film increased. In addition, P/C nanofiber film deposited with UGNPs also exhibited good thermal stability, hydrophilicity, mechanical strength, and water vapor permeability, exhibiting its potential as an antibacterial active packaging.

Electrospun Polymeric Nanofibers: Current Trends in Synthesis, Surface Modification, and Biomedical Applications

Electrospun polymeric nanofibers are essential in various fields for various applications because of their unique properties. Their features are similar to extracellular matrices, which suggests them for applications in healthcare fields, such as antimicrobials, tissue engineering, drug delivery, wound healing, bone regeneration, and biosensors. This review focuses on the synthesis of electrospun polymeric nanofibers, their surface modification, and their biomedical applications. Nanofibers can be fabricated from both natural and synthetic polymers and their composites. Even though they mimic extracellular matrices, their surface features (physicochemical characteristics) are not always capable of fulfilling the purpose of the target application. Therefore, they need to be improved via surface modification techniques. Both needle-based and needleless electrospinning are thoroughly discussed. Various techniques and setups employed in each method are also reviewed. Furthermore, pre- and postspinning modification approaches for electrospun nanofibers, including instrument design and the modification features for targeted biomedical applications, are also extensively discussed. In this way, the remarkable potential of electrospun polymeric nanofibers can be highlighted to reveal future research directions in this dynamic field.

Electrospun Fibers Loaded with Probiotics: Fundamentals, Characterization, and Applications

Increasing demand for safe, efficient, and eco-friendly solutions for pharmaceutical and food industries has led researchers to explore new approaches to bacterial storage. Several advantages make electrospinning (ES) a promising technique for food systems, including simple manufacturing equipment, a relatively low spinning cost, a wide variety of spinnable materials, and a mild process that is easily controlled, which allows continuous fabrication of ultrafine polymeric fibers at submicron or nanoscales without high temperatures or high pressures. This review briefly describes recent advances in the development of electrospun fibers for loading probiotics (PRB) by focusing on ES technology, its efficiency for loading PRB into fibers (viability, digestive stability, growth rate, release, thermal stability, and interactions of fibers with PRB), and the application of PRB-loaded fibers as active packaging (spoilage/microbial control, antioxidant effect, shelf life). Based on the literature reviewed, the incorporation of PRB into electrospun fibers is both feasible and functional. However, several studies have been limited to proof-of-principle experiments and the use of model biological products. It is necessary to conduct further research to establish the industrial applicability of PRB-loaded fibers, particularly in the fields of food and medicine.

Application of essential oils as slow-release antimicrobial agents in food preservation: Preparation strategies, release mechanisms and application cases

Food spoilage caused by foodborne microorganisms will not only cause significant economic losses, but also the toxins produced by some microorganisms will also pose a serious threat to human health. Essential oil (EOs) has significant antimicrobial activity, but its application in the field of food preservation is limited because of its volatile, insoluble in water and sensitive to light and heat. Therefore, in order to solve these problems effectively, this paper first analyzed the antibacterial effect of EOs as an antimicrobial agent on foodborne bacteria and its mechanism. Then, the application strategies of EOs as a sustained-release antimicrobial agent in food preservation were reviewed. On this basis, the release mechanism and application cases of EOs in different antibacterial composites were analyzed. The purpose of this paper is to provide technical support and solutions for the preparation of new antibacterial packaging materials based on plant active components to ensure food safety and reduce food waste.

Hydrophilic and hydrophobic drug release from core (polyvinylpyrrolidone)-sheath (ethyl cellulose) pressure-spun fibers

A core-sheath structure is one of the methods developed to overcome the challenges often faced when using monolithic fibers for drug delivery. In this study, fibers based on polyvinylpyrrolidone (core) and ethyl cellulose (sheath) were successfully produced using a novel core-sheath pressure-spinning process. For comparison, these two polymers were also processed into as blend fibers. All samples were then investigated for their performances in releasing water-soluble ampicillin (AMP) and poorly water-soluble ibuprofen (IBU) model drugs. Scanning electron,digital and confocal microscopy confirmed that fibers with a core-sheath structure were successfully made. Fourier transform infrared spectroscopy showed the success of the pressure-spinning technique in encapsulating AMP/IBU in all fiber samples. Compared to blend fibers, the core-sheath fibers had better performance in encapsulating both water-soluble and poorly water-soluble drugs. Moreover, the core-sheath structure was able to reduce the initial burst release and provided a better sustained release profile than the blend fiber analog. In conclusion, the pressure-spinning method was capable of producing core-sheath and blend fibers that could be used for the loading of either hydrophilic or hydrophobic drugs for controlled drug delivery systems.

Pulp cellulose-based core-sheath structure based on hyperbranched grafting strategy for development of reinforced soybean adhesive

Formaldehyde adhesive is the primary source of indoor formaldehyde pollution, posing a serious threat to human health. Soybean meal (SM), as an abundant biomacromolecule and co-product of soybean oil industry, emerges as a promising alternative to formaldehyde adhesive. However, the SM adhesive exhibits inferior water resistance and unsatisfactory bonding strength. In this study, a novel core-sheath structure with an inexpensive pulp cellulose core and a hyperbranched polymer sheath is synthesized and introduced into SM to develop a robust bio-based adhesive. Specifically, aldehyde-functionalized pulp cellulose is grafted with hyperbranched polyamide, which is terminated via epoxy groups, to synthesize a core-sheath hybrid (APC@HBPA-EP). The core-sheath APC@HBPA-EP serves as both a crosslinker and an enhancer. The results show that the wet shear strength of the modified SM adhesive exhibits a remarkable 520 % increase to 0.93 MPa, and its dry shear strength reaches 2.10 MPa, meeting the established indoor use standards. The Young's modulus of the modified SM adhesive shows a significant 282 % increase to 19.27 GPa. Additionally, the modified SM adhesive exhibited superior impact toughness (7.48 KJ/m2), which increased by 24 times compared with pure SM adhesive. This study provides a versatile strategy for developing robust protein adhesives, hydrogel patch, and composite coatings.

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.

Harnessing the Potential of PLGA Nanoparticles for Enhanced Bone Regeneration

Recently, nanotechnologies have become increasingly prominent in the field of bone tissue engineering (BTE), offering substantial potential to advance the field forward. These advancements manifest in two primary ways: the localized application of nanoengineered materials to enhance bone regeneration and their use as nanovehicles for delivering bioactive compounds. Despite significant progress in the development of bone substitutes over the past few decades, it is worth noting that the quest to identify the optimal biomaterial for bone regeneration remains a subject of intense debate. Ever since its initial discovery, poly(lactic-co-glycolic acid) (PLGA) has found widespread use in BTE due to its favorable biocompatibility and customizable biodegradability. This review provides an overview of contemporary advancements in the development of bone regeneration materials using PLGA polymers. The review covers some of the properties of PLGA, with a special focus on modifications of these properties towards bone regeneration. Furthermore, we delve into the techniques for synthesizing PLGA nanoparticles (NPs), the diverse forms in which these NPs can be fabricated, and the bioactive molecules that exhibit therapeutic potential for promoting bone regeneration. Additionally, we addressed some of the current concerns regarding the safety of PLGA NPs and PLGA-based products available on the market. Finally, we briefly discussed some of the current challenges and proposed some strategies to functionally enhance the fabrication of PLGA NPs towards BTE. We envisage that the utilization of PLGA NP holds significant potential as a potent tool in advancing therapies for intractable bone diseases.

Electrospinning technologies for the delivery of Biopharmaceuticals: Current status and future trends

This review provides an in-depth exploration of electrospinning techniques employed to produce micro- or nanofibres of biopharmaceuticals using polymeric solutions or melts with high-voltage electricity. Distinct from prior reviews, the current work narrows its focus on the recent developments and advanced applications in biopharmaceutical formulations. It begins with an overview of electrospinning principles, covering both solution and melt modes. Various methods for incorporating biopharmaceuticals into electrospun fibres, such as surface adsorption, blending, emulsion, co-axial, and high-throughput electrospinning, are elaborated. The review also surveys a wide array of biopharmaceuticals formulated through electrospinning, thereby identifying both opportunities and challenges in this emerging field. Moreover, it outlines the analytical techniques for characterizing electrospun fibres and discusses the legal and regulatory requirements for their production. This work aims to offer valuable insights into the evolving realm of electrospun biopharmaceutical delivery systems.

Enhancing diabetic wound healing: advances in electrospun scaffolds from pathogenesis to therapeutic applications

Diabetic wounds are a significant subset of chronic wounds characterized by elevated levels of inflammatory cytokines, matrix metalloproteinases (MMPs), and reactive oxygen species (ROS). They are also associated with impaired angiogenesis, persistent infection, and a high likelihood of hospitalization, leading to a substantial economic burden for patients. In severe cases, amputation or even mortality may occur. Diabetic foot ulcers (DFUs) are a common complication of diabetes, with up to 25% of diabetic patients being at risk of developing foot ulcers over their lifetime, and more than 70% ultimately requiring amputation. Electrospun scaffolds exhibit a structural similarity to the extracellular matrix (ECM), promoting the adhesion, growth, and migration of fibroblasts, thereby facilitating the formation of new skin tissue at the wound site. The composition and size of electrospun scaffolds can be easily adjusted, enabling controlled drug release through fiber structure modifications. The porous nature of these scaffolds facilitates gas exchange and the absorption of wound exudate. Furthermore, the fiber surface can be readily modified to impart specific functionalities, making electrospinning nanofiber scaffolds highly promising for the treatment of diabetic wounds. This article provides a concise overview of the healing process in normal wounds and the pathological mechanisms underlying diabetic wounds, including complications such as diabetic foot ulcers. It also explores the advantages of electrospinning nanofiber scaffolds in diabetic wound treatment. Additionally, it summarizes findings from various studies on the use of different types of nanofiber scaffolds for diabetic wounds and reviews methods of drug loading onto nanofiber scaffolds. These advancements broaden the horizon for effectively treating diabetic wounds.

Electrospun fiber-based immune engineering in regenerative medicine

Immune engineering, a burgeoning field within regenerative medicine, involves a spectrum of strategies to optimize the intricate interplay between tissue regenerative biomaterials and the host tissue. These strategies are applied across different types of biomaterials and various disease models, which encompasses finely modulating the immune response at the levels of immune cells and factors, aiming to mitigate adverse effects like fibrosis and persistent inflammation that may arise at the injury site and consequently promote tissue regeneration. With the continuous progress in electrospinning technology, the immunoregulatory capabilities of electrospun fibers have gained substantial attention over the years. Electrospun fibers, with their extracellular matrix-like characteristics, high surface-area-to-volume ratio, and reliable pharmaceutical compound capacity, have emerged as key players among tissue engineering materials. This review specifically focuses on the role of electrospun fiber-based immune engineering, emphasizing their unique design strategies. Notably, electrospinning actively engages in immune engineering by modulating immune responses through four essential strategies: (i) surface modification, (ii) drug loading, (iii) physicochemical parameters, and (iv) biological grafting. This review presents a comprehensive overview of the intricate mechanisms of the immune system in injured tissues while unveiling the key strategies adopted by electrospun fibers to orchestrate immune regulation. Furthermore, the review explores the current developmental trends and limitations concerning the immunoregulatory function of electrospun fibers, aiming to drive the advancements in electrospun fiber-based immune engineering to its full potential.

Improving astaxanthin-loaded chitosan/polyvinyl alcohol/graphene oxide nanofiber membranes and their application in periodontitis

Periodontitis is a chronic inflammatory disease primarily driven by host inflammation and plaque-induced immune responses. Controlling the host inflammatory response and improving the periodontal inflammatory microenvironment are crucial to promoting periodontal tissue regeneration. In this study, the blended nanofiber membranes previously prepared by our research group were improved, and we developed multifunctional chitosan/polyvinyl alcohol/graphene oxide/astaxanthin coaxial nanofiber membranes. Scanning electron microscopy showed that the prepared nanofibers had a smooth surface and a uniform diameter distribution. The mechanical property test results showed that the coaxial nanofiber membranes exhibited higher tensile strength compared to the blended nanofiber membranes, which increased from 4.50 ± 0.32 and 3.70 ± 0.45 MPa to 7.12 ± 0.22 and 5.62 ± 0.79 MPa respectively. Drug release studies indicated that the "shell-core" structure of coaxial nanofibers significantly reduced the initial burst release of astaxanthin (ASTA), with only 13.49 % and 10.71 % release in the first 24 h, and drug release lasted for over a week. Animal experiments confirmed that the coaxial nanofiber membranes loaded with ASTA promoted periodontal bone defect repair while inhibiting periodontal inflammation. In conclusion, the prepared coaxial nanofiber membranes are a promising sustained-release drug system for treating periodontitis.

Biobran-loaded core/shell nanofibrous scaffold: a promising wound dressing candidate

This research examined the effectiveness of Biobran as a bioactive substance that could potentially improve wound healing. It also looked at how Biobran affects the properties of a nanofibrous scaffold made through coaxial electrospinning. This is the first study exploring the use of Biobran in this context and its interaction with nanofibrous scaffolds. The scaffolds were composed of poly(ε-caprolactone) (PCL) in the shell and various concentrations of Biobran blended with polyvinyl alcohol (PVA) in the core. The properties of the scaffolds were characterized by SEM, TEM, FTIR, XRD, TGA, DSC, stress-strain test, WCA, release test, MTT cytotoxicity assay, wound scratching assay, and the dye exclusion method using trypan blue. The scaffolds loaded with Biobran exhibited a more compact and smooth morphology compared with the scaffold without Biobran. The physical interaction and crystallinity of the polymers in the scaffolds were also affected by Biobran in a concentration-dependent manner. This positively influenced their tensile strength, elongation at break, thermal stability, and hydrophilicity. The porosity, water uptake capacity, and WVTR of the nanofibrous scaffolds are within the optimal ranges for wound healing. The release rate of Biobran, which revealed a biphasic release pattern, decreased with increasing Biobran concentration, resulting in controlled and sustained delivery of Biobran from the nanofiber scaffolds. The cell viability assays showed a dose-dependent effect of Biobran on WISH cells, which might be attributed to the positive effect of Biobran on the physicochemical properties of the nanofibrous scaffolds. These findings suggest that Biobran-loaded core/shell nanofiber scaffolds have a potential application in wound healing as an ideal multifunctional wound dressing.

Functional electrospun nanofibers: fabrication, properties, and applications in wound-healing process

Electrostatic spinning as a technique for producing nanoscale fibers has recently attracted increasing attention due to its simplicity, versatility, and loadability. Nanofibers prepared by electrostatic spinning have been widely studied, especially in biomedical applications, because of their high specific surface area, high porosity, easy size control, and easy surface functionalization. Wound healing is a highly complex and dynamic process that is a crucial step in the body's healing process to recover from tissue injury or other forms of damage. Single-component nanofibers are more or less limited in terms of structural properties and do not fully satisfy various needs of the materials. This review aims to provide an in-depth analysis of the literature on the use of electrostatically spun nanofibers to promote wound healing, to overview the infinite possibilities for researchers to tap into their biomedical applications through functional composite modification of nanofibers for advanced and multifunctional materials, and to propose directions and perspectives for future research.

Bilayer vascular grafts with on-demand NO and H2S release capabilities

Nitric oxide (NO) and hydrogen sulfide (H2S) gasotransmitters exhibit potential therapeutic effects in the cardiovascular system. Herein, biomimicking multilayer structures of biological blood vessels, bilayer small-diameter vascular grafts (SDVGs) with on-demand NO and H2S release capabilities, were designed and fabricated. The keratin-based H2S donor (KTC) with good biocompatibility and high stability was first synthesized and then electrospun with poly (l-lactide-co-caprolactone) (PLCL) to be used as the outer layer of grafts. The electrospun poly (ε-caprolactone) (PCL) mats were aminolyzed and further chelated with copper (II) ions to construct glutathione peroxidase (GPx)-like structural surfaces for the catalytic generation of NO, which acted as the inner layer of grafts. The on-demand release of NO and H2S selectively and synergistically promoted the proliferation and migration of human umbilical vein endothelial cells (HUVECs) while inhibiting the proliferation and migration of human umbilical artery smooth muscle cells (HUASMCs). Dual releases of NO and H2S gasotransmitters could enhance their respective production, resulting in enhanced promotion of HUVECs and inhibition of HUASMCs owing to their combined actions. In addition, the bilayer grafts were conducive to forming endothelial cell layers under flow shear stress. In rat abdominal aorta replacement models, the grafts remained patency for 6 months. These grafts were capable of facilitating rapid endothelialization and alleviating neointimal hyperplasia without obvious injury, inflammation, or thrombosis. More importantly, the grafts were expected to avoid calcification with the degradation of the grafts. Taken together, these bilayer grafts will be greatly promising candidates for SDVGs with rapid endothelialization and anti-calcification properties.

Applications of Scaffolds in Tissue Engineering: Current Utilization and Future Prospective

Current regenerative medicine tactics focus on regenerating tissue structures pathologically modified by cell transplantation in combination with supporting scaffolds and biomolecules. Natural and synthetic polymers, bioresorbable inorganic and hybrid materials, and tissue decellularized were deemed biomaterials scaffolding because of their improved structural, mechanical, and biological abilities.Various biomaterials, existing treatment methodologies and emerging technologies in the field of Three-dimensional (3D) and hydrogel processing, and the unique fabric concerns for tissue engineering. A scaffold that acts as a transient matrix for cell proliferation and extracellular matrix deposition, with subsequent expansion, is needed to restore or regenerate the tissue. Diverse technologies are combined to produce porous tissue regenerative and tailored release of bioactive substances in applications of tissue engineering. Tissue engineering scaffolds are crucial ingredients. This paper discusses an overview of the various scaffold kinds and their material features and applications. Tabulation of the manufacturing technologies for fabric engineering and equipment, encompassing the latest fundamental and standard procedures.

Overview of Tissue Engineering and Drug Delivery Applications of Reactive Electrospinning and Crosslinking Techniques of Polymeric Nanofibers with Highlights on Their Biocompatibility Testing and Regulatory Aspects

Traditional electrospinning is a promising technique for fabricating nanofibers for tissue engineering and drug delivery applications. The method is highly efficient in producing nanofibers with morphology and porosity similar to the extracellular matrix. Nonetheless, and in many instances, the process has faced several limitations, including weak mechanical strength, large diameter distributions, and scaling-up difficulties of its fabricated electrospun nanofibers. The constraints of the polymer solution's intrinsic properties are primarily responsible for these limitations. Reactive electrospinning constitutes a novel and modified electrospinning techniques developed to overcome those challenges and improve the properties of the fabricated fibers intended for various biomedical applications. This review mainly addresses reactive electrospinning techniques, a relatively new approach for making in situ or post-crosslinked nanofibers. It provides an overview of and discusses the recent literature about chemical and photoreactive electrospinning, their various techniques, their biomedical applications, and FDA regulatory aspects related to their approval and marketing. Another aspect highlighted in this review is the use of crosslinking and reactive electrospinning techniques to enhance the fabricated nanofibers' physicochemical and mechanical properties and make them more biocompatible and tailored for advanced intelligent drug delivery and tissue engineering applications.

Personalised Medicine and the Potential Role of Electrospinning for Targeted Immunotherapeutics in Head and Neck Cancer

Advanced head and neck cancer (HNC) is functionally and aesthetically destructive, and despite significant advances in therapy, overall survival is poor, financial toxicity is high, and treatment commonly exacerbates tissue damage. Although response and durability concerns remain, antibody-based immunotherapies have heralded a paradigm shift in systemic treatment. To overcome limitations associated with antibody-based immunotherapies, exploration into de novo and repurposed small molecule immunotherapies is expanding at a rapid rate. Small molecule immunotherapies also have the capacity for chelation to biodegradable, bioadherent, electrospun scaffolds. This article focuses on the novel concept of targeted, sustained release immunotherapies and their potential to improve outcomes in poorly accessible and risk for positive margin HNC cases.

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.

Tri-Layer Core-Shell Fibers from Coaxial Electrospinning for a Modified Release of Metronidazole

Polymers are the backbone of drug delivery. Electrospinning has greatly enriched the strategies that have been explored for developing novel drug delivery systems using polymers during the past two decades. In this study, four different kinds of polymers, i.e., the water-soluble polymer poly (vinyl alcohol) (PVA), the insoluble polymer poly(ε-caprolactone) (PCL), the insoluble polymer Eudragit RL100 (ERL100) and the pH-sensitive polymer Eudragit S100 (ES100) were successfully converted into types of tri-layer tri-polymer core-shell fibers through bi-fluid coaxial electrospinning. During the coaxial process, the model drug metronidazole (MTD) was loaded into the shell working fluid, which was an emulsion. The micro-formation mechanism of the tri-layer core-shell fibers from the coaxial emulsion electrospinning was proposed. Scanning electron microscope and transmission electron microscope evaluations verified the linear morphology of the resultant fibers and their obvious tri-layer multiple-chamber structures. X-ray diffraction and Fourier transform infrared spectroscopy measurements demonstrated that the drug MTD presented in the fibers in an amorphous state and was compatible with the three polymeric matrices. In vitro dissolution tests verified that the three kinds of polymer could act in a synergistic manner for a prolonged sustained-release profile of MTD in the gut. The drug controlled-release mechanisms were suggested in detail. The protocols reported here pioneer a new route for creating a tri-layer core-shell structure from both aqueous and organic solvents, and a new strategy for developing advanced drug delivery systems with sophisticated drug controlled-release profiles.

Advantages of agarose on alginate for the preparation of polysaccharide/hydroxyapatite porous bone scaffolds compatible with a proline-rich antimicrobial peptide

The optimized proline-rich antimicrobial peptide B7-005 was loaded on bone scaffolds based on polysaccharides and hydroxyapatite. Alginate was firstly chosen in order to exploit its negative charges, which allowed an efficient B7-005 loading but hindered its release, due to the strong interactions with the positive charged peptide. Hence, alginate was substituted with agarose which allowed to prepare scaffolds with similar structure, porosity, and mechanical performance than the ones prepared with alginate and hydroxyapatite. Moreover, agarose scaffolds could release B7-005 within the first 24 h of immersion in aqueous environment. The peptide did not impaired MG-63 cell adhesion and proliferation in the scaffold, and a positive cell proliferation trend was observed up to two weeks. The released B7-005 was effective against the pathogensE. coli, K. pneumoniae, andA. baumannii, but not againstS. aureusandP. aeruginosa, thus requiring further tuning of the system to improve its antimicrobial activity.

Oxymatrine Loaded Cross-Linked PVA Nanofibrous Scaffold: Design and Characterization and Anticancer Properties

This study focuses on the fabrication, characterization and anticancer properties of biocompatible and biodegradable composite nanofibers consisting of poly(vinyl alcohol) (PVA), oxymatrine (OM), and citric acid (CA) using a facile and high-yield centrifugal spinning process known as Forcespinning. The effects of varying concentrations of OM and CA on fiber diameter and molecular cross-linking are investigated. The morphological and thermo-physical properties, as well as water absorption of the developed nanofiber-based mats are characterized using microscopical analysis, energy dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, differential scanning calorimetry, and thermogravimetric analysis. In vitro anticancer studies are conducted with HCT116 colorectal cancer cells. Results show a high yield of long fibers embedded with beads. Fiber average diameters range between 462 and 528 nm depending on OM concentration. The thermal analysis results show that the fibers are stable at room temperature. The anticancer study reveals that PVA nanofiber membrane with high concentrations of OM can suppress the proliferation of HCT116 colorectal cancer cells. The study provides a comprehensive investigation of OM embedded into nanosized PVA fibers and the prospective application of these membranes as a drug delivery system.

Eflornithine Hydrochloride-Loaded Electrospun Nanofibers as a Potential Face Mask for Hirsutism Application

Hirsutism is a distressing condition that can affect women's self-esteem due to the excessive amount of hair growth in different body parts, including the face. A temporary managing option is to develop a self-care routine to remove unwanted hair through shaving or waxing. Laser or electrolysis are alternative methods, but in some cases, the use of medications, such as the topical cream Vaniqa®, can help in reducing the growth of unwanted hair. Electrospun fibers have been used in several drug delivery applications, including skin care products, owing to their biocompatibility, biodegradability, high surface area-to-volume ratio, and dry nature that can release the encapsulated drugs with maximum skin penetration. Therefore, polyvinyl pyrrolidone (PVP) fibers were fabricated in combination with hyaluronic acid to deliver the active compound of Vaniqa®, i.e., Eflornithine hydrochloride (EFH), as a face mask to inhibit excess facial hair growth. The prepared drug-loaded fibers showed a diameter of 490 ± 140 nm, with an encapsulation efficiency of 88 ± 7% and a drug loading capacity of 92 ± 7 μg/mg. The in vitro drug release of EFH-loaded fibers exhibited an initial burst release of 80% in the first 5 min, followed by a complete release after 360 min, owing to the rapid disintegration of the fibrous mat (2 s). The in vitro cytotoxicity indicated a high safety profile of EFH at all tested concentrations (500-15.625 μg/mL) after 24-h exposure to human dermal fibroblast (HFF-1) cells. Therefore, this drug-loaded nanofibrous system can be considered a potentially medicated face mask for the management of hirsutism, along with the moisturizing effect that it possesses. Topical applications of the developed system showed reduced hair growth in mice to a certain extent.

Electrosprayed Core (Cellulose Acetate)-Shell (Polyvinylpyrrolidone) Nanoparticles for Smart Acetaminophen Delivery

Smart drug delivery, through which the drug molecules are delivered according to the requests of human biological rhythms or by maximizing drug therapeutic effects, is highly desired in pharmaceutics. Many biomacromolecules have been exploited for this application in the past few decades, both in industry and laboratories. Biphasic release, with an intentional pulsatile release and a following extended release stage, represents a typical smart drug delivery approach, which aims to provide fast therapeutic action and a long time period of effective blood drug concentration to the patients. In this study, based on the use of a well-known biomacromolecule, i.e., cellulose acetate (CA), as the drug (acetaminophen, ATP)-based sustained release carrier, a modified coaxial electrospraying process was developed to fabricate a new kind of core-shell nanoparticle. The nanoparticles were able to furnish a pulsatile release of ATP due to the shell polyvinylpyrrolidone (PVP). The time cost for a release of 30% was 0.32 h, whereas the core-shell particles were able to provide a 30.84-h sustained release of the 90% loaded ATP. The scanning electron microscope and transmission electron microscope results verified in terms of their round surface morphologies and the obvious core-shell double-chamber structures. ATP presented in both the core and shell sections in an amorphous state owing to its fine compatibility with CA and PVP. The controlled release mechanisms of ATP were suggested. The disclosed biomacromolecule-based process-structure-performance relationship can shed light on how to develop new sorts of advanced nano drug delivery systems.

Preparation and Characterization of Nano-Silver-Loaded Antibacterial Membrane via Coaxial Electrospinning

The coaxial electrospinning process has been widely used in the biomedical field, and its process parameters affect product quality seriously. In this paper, the influence of key process parameters of coaxial electrostatic spinning (solution concentration, electrospinning voltage, acceptance distance and liquid supply velocity) on the preparation of a membrane with Chitosan, Polyethylene oxide and nano-silver as the core layer and Polycaprolactone as the shell layer was studied. The optimal combination of key process parameters was obtained by using an orthogonal test, scanning electron microscope, transmission electron microscope and macro-characterization diagram. The results showed that the coaxial electrospun membrane had good mechanical properties (tensile strength is about 2.945 Mpa), hydrophilicity (the water contact angle is about 72.28°) and non-cytotoxicity, which was conducive to cell adhesion and proliferation. The coaxial electrospun membrane with nano-silver has an obvious inhibitory effect on Escherichia coli and Staphylococcus aureus. In summary, the coaxial electrospun membrane that we produced is expected to be used in clinical medicine, such as vascular stent membranes and bionic blood vessels.

Lignins as Promising Renewable Biopolymers and Bioactive Compounds for High-Performance Materials

The recycling of biomass into high-value-added materials requires important developments in research and technology to create a sustainable circular economy. Lignin, as a component of biomass, is a multipurpose aromatic polymer with a significant potential to be used as a renewable bioresource in many fields in which it acts both as promising biopolymer and bioactive compound. This comprehensive review gives brief insights into the recent research and technological trends on the potential of lignin development and utilization. It is divided into ten main sections, starting with an outlook on its diversity; main properties and possibilities to be used as a raw material for fuels, aromatic chemicals, plastics, or thermoset substitutes; and new developments in the use of lignin as a bioactive compound and in nanoparticles, hydrogels, 3D-printing-based lignin biomaterials, new sustainable biomaterials, and energy production and storage. In each section are presented recent developments in the preparation of lignin-based biomaterials, especially the green approaches to obtaining nanoparticles, hydrogels, and multifunctional materials as blends and bio(nano)composites; most suitable lignin type for each category of the envisaged products; main properties of the obtained lignin-based materials, etc. Different application categories of lignin within various sectors, which could provide completely sustainable energy conversion, such as in agriculture and environment protection, food packaging, biomedicine, and cosmetics, are also described. The medical and therapeutic potential of lignin-derived materials is evidenced in applications such as antimicrobial, antiviral, and antitumor agents; carriers for drug delivery systems with controlled/targeting drug release; tissue engineering and wound healing; and coatings, natural sunscreen, and surfactants. Lignin is mainly used for fuel, and, recently, studies highlighted more sustainable bioenergy production technologies, such as the supercapacitor electrode, photocatalysts, and photovoltaics.

MXene-Embedded Electrospun Polymeric Nanofibers for Biomedical Applications: Recent Advances

Recently MXenes has gained immense attention as a new and exciting class of two-dimensional material. Due to their unique layered microstructure, the presence of various functional groups at the surface, earth abundance, and attractive electrical, optical, and thermal properties, MXenes are considered promising candidates for various applications such as energy, environmental, and biomedical. The ease of dispersibility and metallic conductivity of MXene render them promising candidates for use as fillers in polymer nanocomposites. MXene-polymer nanocomposites simultaneously benefit from the attractive properties of MXenes and the flexibility and facile processability of polymers. However, the potentiality of MXene to modify the electrospun nanofibers has been less studied. Understanding the interactions between polymeric nanofibers and MXenes is important to widen their role in biomedical applications. This review explores diverse methods of MXene synthesis, discusses our current knowledge of the various biological characteristics of MXene, and the synthesis of MXene incorporated polymeric nanofibers and their utilization in biomedical applications. The information discussed in this review serves to guide the future development and application of MXene-polymer nanofibers in biomedical fields.

Fabrication and Characterization of Polylactic Acid Electrospun Wound Dressing Modified with Polyethylene Glycol, Rosmarinic Acid and Graphite Oxide

Polylactic acid (PLA) is a biodegradable polymer made from natural sources, and its electrospinning (e-spinning) nanofiber membrane doped with antibacterial ingredients is widely used in the field of medical dressings. In this research, 9 wt% of rosmarinic acid (RosA) and 0.04 wt% of graphite oxide (GO) with synergistic antibacterial activity were introduced into the e-spinning PLA precursor solution, and the obtained PLA nanofiber membrane showed good antibacterial properties and wound healing effects. At the same time, a nonionic amphiphilic polymer, polyethylene glycol (PEG), was also introduced into this system to improve the hydrophilicity of the e-spinning membrane for wound healing application. The morphological characterization showed the RosA/GO and PEG did not affect the e-spinning of PLA. The tests of mechanical performance and wettability demonstrated that PEG and RosA/GO incorporated in PLA have migrated easily to the surface of the fiber. The e-spun PLA/PEG/RosA/GO membrane showed good antibacterial activity and promoted initial wound healing quickly, which would be a promising application in wound dressing.

Controlling Nano-to-Microscale Multilevel Architecture in Polymeric Microfibers through Polymerization-Induced Spontaneous Phase Separation

Hierarchically structured polymeric fibers, composed of structural nanoscale motifs that assemble into a microscale fiber are frequently found in natural fibers including cellulose and silk. The creation of synthetic fibers with nano-to-microscale hierarchical structures represents a promising avenue for the development of novel fabrics with distinctive physical, chemical, and mechanical characteristics. In this work, we introduce a novel approach for creating polyamine-based core-sheath microfibers with controlled hierarchical architectures. This approach involves a polymerization-induced spontaneous phase separation and subsequent chemical fixation. Through the use of various polyamines, the phase separation process can be manipulated to produce fibers with diverse porous core architectures, ranging from densely packed nanospheres to segmented "bamboo-stem" morphology. Moreover, the nitrogen-rich surface of the core enables both the chemisorption of heavy metals and the physisorption of proteins and enzymes. Our method offers a new set of tools for the production of polymeric fibers with novel hierarchical morphologies, which has a high potential for a wide range of applications such as filtering, separation, and catalysis.

Recent Advancements in Electrospun Chitin and Chitosan Nanofibers for Bone Tissue Engineering Applications

Treatment of large segmental bone loss caused by fractures, osteomyelitis, and non-union results in expenses of around USD 300,000 per case. Moreover, the worst-case scenario results in amputation in 10% to 14.5% of cases. Biomaterials, cells, and regulatory elements are employed in bone tissue engineering (BTE) to create biosynthetic bone grafts with effective functionalization that can aid in the restoration of such fractured bones, preventing amputation and alleviating expenses. Chitin (CT) and chitosan (CS) are two of the most prevalent natural biopolymers utilized in the fields of biomaterials and BTE. To offer the structural and biochemical cues for augmenting bone formation, CT and CS can be employed alone or in combination with other biomaterials in the form of nanofibers (NFs). When compared with several fabrication methods available to produce scaffolds, electrospinning is regarded as superior since it enables the development of nanostructured scaffolds utilizing biopolymers. Electrospun nanofibers (ENFs) offer unique characteristics, including morphological resemblance to the extracellular matrix, high surface-area-to-volume ratio, permeability, porosity, and stability. This review elaborates on the recent strategies employed utilizing CT and CS ENFs and their biocomposites in BTE. We also summarize their implementation in supporting and delivering an osteogenic response to treat critical bone defects and their perspectives on rejuvenation. The CT- and CS-based ENF composite biomaterials show promise as potential constructions for bone tissue creation.

Long-Acting Therapeutic Delivery Systems for the Treatment of Gliomas

Despite the emergence of cutting-edge therapeutic strategies and tremendous progress in research, a complete cure of glioma remains elusive. The heterogenous nature of tumor, immunosuppressive state and presence of blood brain barrier are few of the major obstacles in this regard. Long-acting depot formulations such as injectables and implantables are gaining attention for drug delivery to brain owing to their ease in administration and ability to elute drug locally for extended durations in a controlled manner with minimal toxicity. Hybrid matrices fabricated by incorporating nanoparticulates within such systems help to enhance pharmaceutical advantages. Utilization of long-acting depots as monotherapy or in conjunction with existing strategies rendered significant survival benefits in many preclinical studies and some clinical trials. The discovery of novel targets, immunotherapeutic strategies and alternative drug administration routes are now coupled with several long-acting systems with an ultimate aim to enhance patient survival and prevent glioma recurrences.

Structure and Performance of All-Green Electrospun PHB-Based Membrane Fibrous Biomaterials Modified with Hemin

This work addresses the challenges concerning the development of "all-green" high-performance biodegradable membrane materials based on poly-3-hydroxybutyrate (PHB) and a natural biocompatible functional additive, iron-containing porphyrin, Hemin (Hmi) via modification and surface functionalization. A new facile and versatile approach based on electrospinning (ES) is advanced when modification of the PHB membranes is performed by the addition of low concentrations of Hmi (from 1 to 5 wt.%). Structure and performance of the resultant {HB/Hmi membranes were studied by diverse physicochemical methods, including differential scanning calorimetry, X-ray analysis, scanning electron microscopy, etc. Modification of the PHB fibrous membranes with Hmi allows control over their quality, supramolecular structure, morphology, and surface wettability. As a result of this modification, air and liquid permeability of the modified electrospun materials markedly increases. The proposed approach provides preparation of high-performance all-green membranes with tailored structure and performance for diverse practical applications, including wound healing, comfort textiles, facial protective masks, tissue engineering, water and air purification, etc.

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.

Fabrication, Microstructures and Sensor Applications of Highly Ordered Electrospun Nanofibers: A Review

The review summarizes the fabrication, microstructures, and sensor applications of highly ordered electrospun nanofibers. In the traditional electrospinning process, electrospun nanofibers usually have disordered or random microstructures due to the chaotic oscillation of the electrospinning jet. Different electrospinning methods can be formed by introducing external forces, such as magnetic, electric, or mechanical forces, and ordered nanofibers can be collected. The microstructures of highly ordered nanofibers can be divided into three categories: uniaxially ordered nanofibers, biaxially ordered nanofibers and ordered scaffolds. The three microstructures are each characterized by being ordered in different dimensions. The regulation and control of the ordered microstructures can promote electrospun nanofibers' mechanical and dielectric strength, surface area and chemical properties. Highly ordered electrospun nanofibers have more comprehensive applications than disordered nanofibers do in effect transistors, gas sensors, reinforced composite materials and tissue engineering. This review also intensively summarizes the applications of highly ordered nanofibers in the sensor field, such as pressure sensors, humidity sensors, strain sensors, gas sensors, and biosensors.

Optical Properties of Electrospun Nanofiber Mats

Electrospun nanofiber mats are usually applied in fields where their high specific surface area and small pore sizes are important, such as biotechnology or filtration. Optically, they are mostly white due to scattering from the irregularly distributed, thin nanofibers. Nevertheless, their optical properties can be modified and become highly important for different applications, e.g., in sensing devices or solar cells, and sometimes for investigating their electronic or mechanical properties. This review gives an overview of typical optical properties of electrospun nanofiber mats, such as absorption and transmission, fluorescence and phosphorescence, scattering, polarized emission, dyeing and bathochromic shift as well as the correlation with dielectric constants and the extinction coefficient, showing which effects may occur and can be measured by which instruments or used for different applications.

A review on polysaccharides mediated electrospun nanofibers for diabetic wound healing: Their current status with regulatory perspective

The current treatment strategies for diabetic wound care provide only moderate degree of effectiveness; hence new and improved therapeutic techniques are in great demand. Diabetic wound healing is a complex physiological process that involves synchronisation of various biological events such as haemostasis, inflammation, and remodelling. Nanomaterials like polymeric nanofibers (NFs) offer a promising approach for the treatment of diabetic wounds and have emerged as viable options for wound management. Electrospinning is a powerful and cost-effective method to fabricate versatile NFs with a wide array of raw materials for different biological applications. The electrospun NFs have unique advantages in the development of wound dressings due to their high specific surface area and porosity. The electrospun NFs possess a unique porous structure and biological function similar to the natural extracellular matrix (ECM), and are known to accelerate wound healing. Compared to traditional dressings, the electrospun NFs are more effective in healing wounds owing to their distinct characteristics, good surface functionalisation, better biocompatibility and biodegradability. This review provides a comprehensive overview of the electrospinning procedure and its operating principle, with special emphasis on the role of electrospun NFs in the treatment of diabetic wounds. This review discusses the present techniques applied in the fabrication of NF dressings, and highlights the future prospects of electrospun NFs in medicinal applications.

Designing Lignin-Based Biomaterials as Carriers of Bioactive Molecules

There is a need to develop circular and sustainable economies by utilizing sustainable, green, and renewable resources in high-tech industrial fields especially in the pharmaceutical industry. In the last decade, many derivatives of food and agricultural waste have gained considerable attention due to their abundance, renewability, biocompatibility, environmental amiability, and remarkable biological features. Particularly, lignin, which has been used as a low-grade burning fuel in the past, recently attracted a lot of attention for biomedical applications because of its antioxidant, anti-UV, and antimicrobial properties. Moreover, lignin has abundant phenolic, aliphatic hydroxyl groups, and other chemically reactive sites, making it a desirable biomaterial for drug delivery applications. In this review, we provide an overview of designing different forms of lignin-based biomaterials, including hydrogels, cryogels, electrospun scaffolds, and three-dimensional (3D) printed structures and how they have been used for bioactive compound delivery. We highlight various design criteria and parameters that influence the properties of each type of lignin-based biomaterial and corelate them to various drug delivery applications. In addition, we provide a critical analysis, including the advantages and challenges encountered by each biomaterial fabrication strategy. Finally, we highlight the prospects and future directions associated with the application of lignin-based biomaterials in the pharmaceutical field. We expect that this review will cover the most recent and important developments in this field and serve as a steppingstone for the next generation of pharmaceutical research.

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.

Core-Shell Polyvinyl Alcohol (PVA) Base Electrospinning Microfibers for Drug Delivery

In this study, electrospun membranes were developed for controlled drug release applications. Both uniaxial Polyvinyl alcohol (PVA) and coaxial fibers with a PVA core and a poly (L-lactic acid) (PLLA) and polycaprolactone (PCL) coating were produced with different coating structures. The best conditions for the manufacture of the fibers were also studied and their morphology was analyzed as a function of the electrospinning parameters. Special attention was paid to the fiber surface morphology of the coaxial fibers, obtaining both porous and non-porous coatings. Bovine serum albumin (BSA) was used as the model protein for the drug release studies and, as expected, the uncoated fibers were determined to have the fastest release kinetics. Different release rates were obtained for the coated fibers, which makes this drug release system suitable for different applications according to the release time required.

Fabrication and characterization of anti-rosacea 3D nanofibrous customized sheet masks as a novel scaffold for repurposed use of spironolactone with pre-clinical studies

The repurposed oral use of spironolactone (SP) as an anti-rosacea drug faces many challenges that hinder its efficacy and compliance. In this study, a topically applied nanofibers (NFs) scaffold was evaluated as a promising nanocarrier that enhances SP activity and avoids the friction routine that exaggerates rosacea patients' inflamed, sensitive skin. SP-loaded poly-vinylpyrrolidone (40% PVP) nanofibers (SP-PVP NFs) were electrospun. Scanning electron microscopy showed that SP-PVP NFs have a smooth homogenous surface with a diameter of about 426.60 nm. Wettability, solid state, and mechanical properties of NFs were evaluated. Encapsulation efficiency and drug loading were 96.34% ± 1.20 and 11.89% ± 0.15, respectively. The in vitro release study showed a higher amount of SP released over pure SP with a controlled release pattern. Ex vivo results showed that the permeated amount of SP from SP-PVP NFs sheets was 4.1 times greater than that of pure SP gel. A higher percentage of SP was retained in different skin layers. Moreover, the in vivo anti-rosacea efficacy of SP-PVP NFs using croton oil challenge showed a significant reduction in erythema score compared to the pure SP. The stability and safety of NFs mats were proved, indicating that SP-PVP NFs are promising carriers of SP.

Optimal delivery of poorly soluble drugs using electrospun nanofiber technology: Challenges, state of the art, and future directions

Poor aqueous solubility of both, existing drug molecules and those which are currently in the developmental stage, have posed a great challenge to pharmaceutical scientists because they often exhibit poor dissolution behavior and subsequent poor and erratic bioavailability. This has triggered extensive research to explore nanotechnology-based technology platforms for possible rescue. Recently, nanofibers have been exploited widely for diverse biomedical applications including for drug delivery. Electrospun nanofibers are capable of preserving the homogeneously loaded therapeutic agents in amorphous state potentialy impairing devitrification. The present review aims at providing an overview of the various key factors that affect the electrospinning process and characteristics of the nanofibers while fabrication of drug loaded nanofibers for poorly soluble drug candidates. The review explores various methodological advancements in the electrospinning process and set-ups for production scale-up. The various types of electrospun nanofibers (like simple matrix, core-sheath, Janus, and inclusion complex nanofibers) that have been exploited for the delivery of poorly soluble drugs are also critically assessed. This article is categorized under: Therapeutic Approaches and Drug Discovery > Emerging Technologies.

Electrospun naringin-loaded microsphere/sucrose acetate isobutyrate system promotes macrophage polarization toward M2 and facilitates osteoporotic bone defect repair

Repairing osteoporotic bone defects is still a major clinical challenge. Recent studies have revealed that immune response is also essential in osteogenesis. The intrinsic inflammatory response of the host, especially the M1/M2 polarization status and inflammatory secretory function of macrophages, can directly affect osteogenic differentiation. Therefore, in this study, an electrospun naringin-loaded microspheres/sucrose acetate isobutyrate (Ng-m-SAIB) system was constructed to investigate its effect on the polarization of macrophage and osteoporotic bone defects. The results of both in vitro and in vivo experiments showed that Ng-m-SAIB had good biocompatibility and could promote the polarization of macrophage toward M2, thereby forming a favorable microenvironment for osteogenesis. The animal experiments also showed that Ng-m-SAIB could promote the osteogenesis of critical size defects in the skull of the osteoporotic model mouse (the senescence-accelerated mouse-strain P6). Together, these results collectively suggested that Ng-m-SAIB might be a promising biomaterial to treat osteoporotic bone defects with favorable osteo-immunomodulatory effects.

Biological Scaffolds Assembled with Magnetic Nanoparticles for Bone Tissue Engineering: A Review

Superparamagnetic iron oxide nanoparticles (SPION) are widely used in bone tissue engineering because of their unique physical and chemical properties and their excellent biocompatibility. Under the action of a magnetic field, SPIONs loaded in a biological scaffold can effectively promote osteoblast proliferation, differentiation, angiogenesis, and so on. SPIONs have very broad application prospects in bone repair, bone reconstruction, bone regeneration, and other fields. In this paper, several methods for forming biological scaffolds via the biological assembly of SPIONs are reviewed, and the specific applications of these biological scaffolds in bone tissue engineering are discussed.