Single unit functionally graded bioresorbable electrospun scaffold for scar-free full-thickness skin wound healing

Vanillin and IGF1-loaded dual-layer multifunctional wound dressing with micro-nanofibrous structure for full-thickness wound healing acceleration

Multifunctional dual-layer wound dressings hold significant promise for comprehensive full-thickness wound management by closely mimicking the native skin structure and features. Herein, we employed an innovative approach utilizing electrospinning techniques to develop a dual-layer dressing comprising a microfibrous Ecoflex®-Vanillin (Ex-Vnil) top layer (TL) and a nanofibrous Soluplus®-Insulin-like growth factor-1 (Sol-IGF1) bottom layer (BL). The tensile properties of dual-layer wound dressings were within the standard range for use in skin tissue regeneration. The TL exhibited hydrophobic properties with a contact angle value of 92.4° and significant antibacterial activity, mimicking the epidermis of the skin, thereby preventing fluid and bacterial penetration. Moreover, the dual-layer wound dressing demonstrated standard water vapour transmission rate, with 91.2 % release of IGF1 and 66.8 % release of Vnil within 5 days. Notably, the fabricated dual-layer dressing promoted cell behaviour and exhibited a significant angiogenesis effect and accelerated healing of full-thickness wound, achieving 96.4 % closure after 14 days, attributed to reduced inflammation, early blood vessel formation, and enhanced collagen density. Our findings underscore the potential of the fabricated dual-layer dressing as an innovative solution in full-thickness wound care.

In Vitro Investigation of 3D Printed Hydrogel Scaffolds with Electrospun Tidemark Component for Modeling Osteochondral Interface

Osteochondral (OC) tissue plays a crucial role due to its ability to connect bone and cartilage tissues. To address the complexity of structure and functionality at the bone-cartilage interface, relevant to the presence of the tidemark as a critical element at the bone-cartilage boundary, we fabricated graded scaffolds through sequential 3D printing. The scaffold's bottom layer was based on a gelatin/oxidized alginate mixture enriched with hydroxyapatite (HAp) to create a rougher surface and larger pores to promote osteogenesis. In contrast, the upper layer was engineered to have smaller pores and aimed to promote cartilage tissue formation and mimic the physical properties of the cartilage. An electrospun ε-polycaprolactone (PCL) membrane with micrometer-range pores was incorporated between the layers to replicate the function of tidemark-a barrier to prevent vascularization of cartilage from subchondral bone tissue. In vitro cell studies confirmed the viability of the cells on the layers of the scaffolds and the ability of PCL mesh to prevent cellular migration. The fabricated scaffolds were thoroughly characterized, and their mechanical properties were compared to native OC tissue, demonstrating suitability for OC tissue engineering and graft modeling. The distance of gradient of mineral concentration was found to be 151 µm for grafts and the native OC interface.

Functionally multifaceted alginate/curdlan/agarose-based bilayer fibro-porous dressings for addressing full-thickness diabetic wounds

Full-thickness diabetic wounds are chronic injuries characterized by bleeding, excessive exude, and prolonged inflammation. Single-layer dressings fail to address their disturbed pathophysiology. Therefore, bilayer dressings with structural and compositional differences in each layer have gained attention. We hypothesized that natural polymer (alginate, curdlan, and agarose) based bilayer dressings with inherent healing properties could effectively resolve these issues. Hence, bilayer dressings were fabricated by electrospinning curdlan/agarose/ polyvinyl alcohol blend (top layer) on an alginate/agarose/polyvinyl alcohol-based lyophilized porous (bottom) layer. Ciprofloxacin was incorporated in both layers as a potential antibacterial drug. The bilayer dressing exhibited high swelling (~1300 %), biocompatibility (>90 % with NIH 3T3 and L929 mouse fibroblasts), and hemocompatibility (hemolysis <5 %). In vitro, scratch assay revealed a faster wound closure (~ 95-100 %) than control. Inhibition zone assay revealed antibacterial activity against Staphylococcus aureus and Escherichia coli. Real-time (in vitro) gene expression experiments performed using human THP-1 macrophages exhibited a significant increase in anti-inflammatory cytokines (4.51 fold in IL-10) and a decrease in pro-inflammatory cytokines (1.42 fold in IL-6) in comparison to lipopolysaccharide. Thus, fabricated dressings with high swelling, hemostatic, immunomodulatory, and antibacterial characteristics can serve as potential multifunctional and sustainable templates for healing full-thickness diabetic wounds.

Electrospun Nanofiber Scaffolds Loaded with Metal-Based Nanoparticles for Wound Healing

Failures of wound healing have been a focus of research worldwide. With the continuous development of materials science, electrospun nanofiber scaffolds loaded with metal-based nanoparticles provide new ideas and methods for research into new tissue engineering materials due to their excellent antibacterial, anti-inflammatory, and wound healing abilities. In this review, the stages of extracellular matrix and wound healing, electrospun nanofiber scaffolds, metal-based nanoparticles, and metal-based nanoparticles supported by electrospun nanofiber scaffolds are reviewed, and their characteristics and applications are introduced. We discuss in detail the current research on wound healing of metal-based nanoparticles and electrospun nanofiber scaffolds loaded with metal-based nanoparticles, and we highlight the potential mechanisms and promising applications of these scaffolds for promoting wound healing.

Electro-conductive chitosan/graphene bio-nanocomposite scaffold for tissue engineering of the central nervous system

Degenerative central nervous system (CNS) disorders and traumatic brain injuries are common nowadays. These may induce the loss of neuronal cells and delicate connections essential for optimal CNS function. The CNS tissue has restricted regeneration ability, hindering the development of effective therapies. Developing cell and tissue instructive materials may bring up new treatment possibilities. In this study, chitosan-graphene nano platelets (GNPs) composite films were developed to regenerate brain cells. This study evaluates the effects of GNP concentration (0.5, 1 and 2 wt%) and their alignment on mechanical, electrical, surface, protein adsorption and biological properties of the regenerative scaffolds. Incorporating and aligning GNPs into chitosan matrix improved all the physical and biological properties. On reinforced scaffolds, HT22 cell morphology mimics pyramidal brain cells, which are responsible for the brain's highly branched neural network. Additionally, the reinforced scaffolds supported Mesenchymal Stem like Cells growth and were biocompatible in vivo. The alignment of GNPs in the chitosan matrix offered the appropriate physicochemical and biological properties to promote adhesion, proliferation and shape morphogenesis of hippocampal HT22 neuronal cells. Overall, this study delineates the enormous potential offered by the GNP-reinforced scaffolds for regeneration of central nervous system, especially the brain.

Nanofiber Scaffolds as Drug Delivery Systems Promoting Wound Healing

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

Advanced phosphocreatine-grafted chitosan hydrogel promote wound healing by macrophage modulation

Background: The repair of wounds usually caused by trauma or other chronic diseases remained challenging in clinics due to the potential risk of inflammation and inadequate tissue regenerative properties. Among them, the behaviour of immune cells, such as macrophages, is critical in tissue repair. Materials and methods: In this study, a water-soluble phosphocreatine-grafted methacryloyl chitosan (CSMP) was synthesized with a one-step lyophilization method, followed by the fabrication of CSMP hydrogel with a photocrosslinked method. The microstructure, water absorption and mechanical properties for the hydrogels were investigated. Then, the macrophages were co-cultured with hydrogels and the pro-inflammatory factors and polarization markers for these macrophages were detected through real-time quantitative polymerase chain reaction (RT-qPCR), Western blot (WB), and flow cytometry methods. Finally, the CSMP hydrogel was implanted in a wound defect area in mice to test its ability to promote wound healing. Results: The lyophilized CSMP hydrogel had a porous structure with pores ranging in size from 200 to 400 μm, which was larger than the CSM hydrogel's. The lyophilized CSMP hydrogel possessed a higher water absorption rate compared with the CSM hydrogel. The compressive stress and modulus of these hydrogels were increased in the initial 7 days immersion and then gradually decreased during the in vitro immersion in PBS solution up to 21 days; the CSMP hydrogel showed a higher value in these parameters versus the CSM hydrogel. The CSMP hydrogel inhibited the expression of inflammatory factors such as interleukin-1β (IL-1β), IL-6, IL-12, and tumor necrosis factor-α (TNF-α) in an in vitro study cocultured with pro-inflammatory factors in pre-treated bone marrow-derived macrophages (BMM). The mRNA sequencing results showed that the CSMP hydrogel might inhibit the macrophages' M1 type polarization through the NF-κB signaling pathway. Furthermore, when compared to the control group, the CSMP hydrogel promoted more skin area repair in the mouse wound defect area, and inflammatory factors such as IL-1β, IL-6, and TNF-α were lower in the repaired tissue for the CSMP group. Conclusion: This phosphate-grafted chitosan hydrogel showed great promise for wound healing through regulating the macrophage's phenotype via the NF-κB signaling pathway.

Evolution of nanostructured skin patches towards multifunctional wearable platforms for biomedical applications

Recent advances in the field of skin patches have promoted the development of wearable and implantable bioelectronics for long-term, continuous healthcare management and targeted therapy. However, the design of electronic skin (e-skin) patches with stretchable components is still challenging and requires an in-depth understanding of the skin-attachable substrate layer, functional biomaterials and advanced self-powered electronics. In this comprehensive review, we present the evolution of skin patches from functional nanostructured materials to multi-functional and stimuli-responsive patches towards flexible substrates and emerging biomaterials for e-skin patches, including the material selection, structure design and promising applications. Stretchable sensors and self-powered e-skin patches are also discussed, ranging from electrical stimulation for clinical procedures to continuous health monitoring and integrated systems for comprehensive healthcare management. Moreover, an integrated energy harvester with bioelectronics enables the fabrication of self-powered electronic skin patches, which can effectively solve the energy supply and overcome the drawbacks induced by bulky battery-driven devices. However, to realize the full potential offered by these advancements, several challenges must be addressed for next-generation e-skin patches. Finally, future opportunities and positive outlooks are presented on the future directions of bioelectronics. It is believed that innovative material design, structure engineering, and in-depth study of fundamental principles can foster the rapid evolution of electronic skin patches, and eventually enable self-powered close-looped bioelectronic systems to benefit mankind.