Antibacterial, antioxidant and anti-inflammatory PLCL/gelatin nanofiber membranes to promote wound healing

Antibacterial and antioxidant phlorizin-loaded nanofiber film effectively promotes the healing of burn wounds

Burns usually result in damage and loss of skin forming irregular wound wounds. The lack of skin tissue protection makes the wound site highly vulnerable to bacterial infections, hindering the healing process. However, commonly used wound dressings do not readily provide complete coverage of irregular wounds compared to regular wounds. Therefore, there is an urgent need to prepare a wound dressing with high antimicrobial efficacy for the administration of drugs to irregular wounds. In this study, a chitosan (CS)/polyvinylpyrrolidone (PVP) composite nanofiber membrane (CS/PVP/Phlorizin) loaded with root bark glycosides (Phlorizin) was developed using an electrostatic spinning technique. The incorporation of phlorizin, a natural antioxidant, into the fiber membranes notably boosted their antimicrobial and antioxidant capabilities, along with demonstrating excellent hydrophilic characteristics. In vitro cellular experiments showed that CS/PVP/Phlorizin increased Hacat cell viability with the presence of better cytocompatibility. In scald wound healing experiments, Phlorizin-loaded nanofibrous membranes significantly promoted re-epithelialization and angiogenesis at the wound site, and reduced the inflammatory response at the wound site. Therefore, the above results indicate that this nanofiber membrane is expected to be an ideal dressing for burn wounds.

The mechanism of low molecular weight fucoidan-incorporated nanofiber scaffolds inhibiting oral leukoplakia via SR-A/Wnt signal axis

Oral leukoplakia (OLK) is the most common oral precancerous lesion, and 3%-17% of OLK patients progress to oral squamous cell carcinoma. OLK is susceptible to recurrence and has no effective treatment. However, conventional drugs have significant side effects and limitations. Therefore, it is important to identify drugs that target OLK. In this study, scavenger receptor A (SR-A) was found to be abnormally highly expressed in the oral mucosal epithelial cells of OLK patients, whereas molecular biology studies revealed that low molecular weight fucoidan (LMWF) promoted apoptosis of dysplastic oral keratinocytes (DOK) and inhibited the growth and migration of DOK, and the inhibitory effect of LMWF on OLK was achieved by regulating the SR-A/Wnt signaling axis and related genes. Based on the above results and the special situation of the oral environment, we constructed LMWF/poly(caprolactone-co-lactide) nanofiber membranes with different structures for the in-situ treatment of OLK using electrospinning technology. The results showed that the nanofiber membranes with a shell-core structure had the best physicochemical properties, biocompatibility, and therapeutic effect, which optimized the LMWF drug delivery and ensured the effective concentration of the drug at the target point, thus achieving precise treatment of local lesions in the oral cavity. This has potential application value in inhibiting the development of OLK.

Extracellular Matrix-Bioinspired Anisotropic Topographical Cues of Electrospun Nanofibers: A Strategy of Wound Healing through Macrophage Polarization

The skin serves as the body's outermost barrier and is the largest organ, providing protection not only to the body but also to various internal organs. Owing to continuous exposure to various external factors, it is susceptible to damage that can range from simple to severe, including serious types of wounds such as burns or chronic wounds. Macrophages play a crucial role in the entire wound-healing process and contribute significantly to skin regeneration. Initially, M1 macrophages infiltrate to phagocytose bacteria, debris, and dead cells in fresh wounds. As tissue repair is activated, M2 macrophages are promoted, reducing inflammation and facilitating restoration of the dermis and epidermis to regenerate the tissue. This suggests that extracellular matrix (ECM) promotes cell adhesion, proliferation, migrationand macrophage polarization. Among the numerous strategies, electrospinning is a versatile technique for obtaining ECM-mimicking structures with anisotropic and isotropic topologies of micro/nanofibers. Various electrospun biomaterials influence macrophage polarization based on their isotropic or anisotropic topologies. Moreover, these fibers possess a high surface-area-to-volume ratio, promoting the effective exchange of vital nutrients and oxygen, which are crucial for cell viability and tissue regeneration. Micro/nanofibers with diverse physical and chemical properties can be tailored to polarize macrophages toward skin regeneration and wound healing, depending on specific requirements. This review describes the significance of micro/nanostructures for activating macrophages and promoting wound healing.

Biological scaffold as potential platforms for stem cells: Current development and applications in wound healing

Wound repair is a complex challenge for both clinical practitioners and researchers. Conventional approaches for wound repair have several limitations. Stem cell-based therapy has emerged as a novel strategy to address this issue, exhibiting significant potential for enhancing wound healing rates, improving wound quality, and promoting skin regeneration. However, the use of stem cells in skin regeneration presents several challenges. Recently, stem cells and biomaterials have been identified as crucial components of the wound-healing process. Combination therapy involving the development of biocompatible scaffolds, accompanying cells, multiple biological factors, and structures resembling the natural extracellular matrix (ECM) has gained considerable attention. Biological scaffolds encompass a range of biomaterials that serve as platforms for seeding stem cells, providing them with an environment conducive to growth, similar to that of the ECM. These scaffolds facilitate the delivery and application of stem cells for tissue regeneration and wound healing. This article provides a comprehensive review of the current developments and applications of biological scaffolds for stem cells in wound healing, emphasizing their capacity to facilitate stem cell adhesion, proliferation, differentiation, and paracrine functions. Additionally, we identify the pivotal characteristics of the scaffolds that contribute to enhanced cellular activity.

Recent progress of electrospun nanofibers as burning dressings

Burns are a global public health problem, which brings great challenges to public health and the economy. Severe burns often lead to systemic infection, shock, multiple organ failure, and even death. With the increasing demand for the therapeutic effect of burn wounds, traditional dressings have been unable to meet people's needs due to their single function and many side effects. In this context, electrospinning shows a great prospect on the way to open up advanced wound dressings that promote wound repairing and prevent infection. With its large specific surface area, high porosity, and similar to natural extracellular matrix (ECM), electrospun nanofibers can load drugs and accelerate wound healing. It provides a promising solution for the treatment and management of burn wounds. This review article introduces the concept of burn and the types of electrospun nanofibers, then summarizes the polymers used in electrospun nanofiber dressings. Finally, the drugs (plant extracts, small molecule drugs and nanoparticles) loaded with electrospun burn dressings are summarized. Some promising aspects for developing commercial electrospun burn dressings are proposed.

Antibacterial activity of cinnamon essential oil and its main component of cinnamaldehyde and the underlying mechanism

Background: Plant essential oils have long been regarded as repositories of antimicrobial agents. In recent years, they have emerged as potential alternatives or supplements to antimicrobial drugs. Although literature reviews and previous studies have indicated that cinnamon essential oil (CIEO) and its major component, cinnamaldehyde (CID), possess potent antibacterial activities, their antibacterial mechanisms, especially the in vivo antibacterial mechanisms, remain elusive. Methods: In this study, we utilized the in vivo assessment system of Caenorhabditis elegans (C. elegans) to investigate the effects and mechanisms of high dose (100 mg/L) and low dose (10 mg/L) CIEO and CID in inhibiting Pseudomonas aeruginosa (P. aeruginosa). In addition, we also examined the in vitro antibacterial abilities of CIEO and CID against other common pathogens including P. aeruginosa and 4 other strains. Results: Our research revealed that both high (100 mg/L) and low doses (10 mg/L) of CIEO and CID treatment significantly alleviated the reduction in locomotion behavior, lifespan, and accumulation of P. aeruginosa in C. elegans infected with the bacteria. During P. aeruginosa infection, the transcriptional expression of antimicrobial peptide-related genes (lys-1 and lys-8) in C. elegans was upregulated with low-dose CIEO and CID treatment, while this trend was suppressed at high doses. Further investigation suggested that the PMK-1 mediated p38 signaling pathway may be involved in the regulation of CIEO and CID during nematode defense against P. aeruginosa infection. Furthermore, in vitro experimental results also revealed that CIEO and CID exhibit good antibacterial effects, which may be associated with their antioxidant properties. Conclusion: Our results indicated that low-dose CIEO and CID treatment could activate the p38 signaling pathway in C. elegans, thereby regulating antimicrobial peptides, and achieving antimicrobial effects. Meanwhile, high doses of CIEO and CID might directly participate in the internal antimicrobial processes of C. elegans. Our study provides research basis for the antibacterial properties of CIEO and CID both in vivo and in vitro.

Sodium alginate/polyvinyl alcohol nanofibers loaded with Shikonin for diabetic wound healing: In vivo and in vitro evaluation

Diabetic wounds are typically chronic wounds and the healing process is limited by problems such as high blood glucose levels, bacterial infections, and other issues that make wound healing difficult. Designing drug-loaded wound dressings is an effective way to promote diabetic wound healing. In this study, we developed an SA/PVA nanofiber (SPS) containing Shikonin (SK) for the treatment of diabetic wounds. The prepared nanofibers were uniform in diameter, had good hydrophilicity and high water vapor permeability, and effectively promoted gas exchange between the wound site and the outside world. The results of in vitro experiments showed that SPS was effective in antimicrobial, antioxidant, and biocompatible. In vivo tests showed that the wound healing rate of mice treated with SPS reached 85.5 %. Immunohistochemical staining results showed that SPS was involved in the diabetic wound healing process through the up-regulation of growth factors (CD31, HIF-1α) and the down-regulation of inflammatory factors (CD68). Western blotting experiments showed that SPS attenuated the inflammation through the inhibition of the IκBα/NF-κB signaling pathway. These results suggest that SPS is a promising candidate for future clinical application of chronic wound dressings.

Coaxial nanofibers encapsulated with Ampelopsis brevipedunculata extract and green synthesized AgNPs for wound repair

Silver nanoparticles (AgNPs) synthesized from Aloe vera extract exhibited a pronounced antibacterial effect, while the Ampelopsis brevipedunculata extract (ABE) showcased a high antioxidant capacity for wound healing. Spherical AgNPs with a particle size of 28.82 nm crystallized in a face-centered-cubic lattice. AgNPs/polyvinyl alcohol (PVA) and ABE/polycaprolactone (PCL) underwent electrospinning to produce coaxial and electrosprayed nanofibers, respectively. The developed coaxial nanofibers demonstrated a strain of 159%, a Young's modulus of elasticity of 7080.14 kPa, a 3.9-fold swelling ratio, a water contact angle of 38.91°, characteristic hydrophilicity, and an adequate water vapor transmission rate of 2272 g/m2/day. ABE exhibited no cytotoxicity to L929 cells and induced a twofold increase in the cell migration rate. Upon applying the developed coaxial nanofiber on an in vivo rat model with a 9 mm wound diameter, the wound rapidly and completely healed within 10 days, with a healing speed 60% greater than that of the control group. Histopathological analysis revealed that the coaxial group did not exhibit inflammation, showed complete epithelization, and featured a well-arranged deposition of collagen on the 10th day.

Biomaterials-Based Antioxidant Strategies for the Treatment of Oxidative Stress Diseases

Oxidative stress is characterized by an increase in reactive oxygen species or a decrease in antioxidants in the body. This imbalance leads to detrimental effects, including inflammation and multiple chronic diseases, ranging from impaired wound healing to highly impacting pathologies in the neural and cardiovascular systems, or the bone, amongst others. However, supplying compounds with antioxidant activity is hampered by their low bioavailability. The development of biomaterials with antioxidant capacity is poised to overcome this roadblock. Moreover, in the treatment of chronic inflammation, material-based strategies would allow the controlled and targeted release of antioxidants into the affected tissue. In this review, we revise the main causes and effects of oxidative stress, and survey antioxidant biomaterials used for the treatment of chronic wounds, neurodegenerative diseases, cardiovascular diseases (focusing on cardiac infarction, myocardial ischemia-reperfusion injury and atherosclerosis) and osteoporosis. We anticipate that these developments will lead to the emergence of new technologies for tissue engineering, control of oxidative stress and prevention of diseases associated with oxidative stress.

Sodium alginate/poly(vinyl alcohol)/taxifolin nanofiber mat promoting diabetic wound healing by modulating the inflammatory response, angiogenesis, and skin flora

Diabetes-related ulcers are still a therapeutic problem because of their susceptibility to infection, ongoing inflammation, and diminished vascularization. The design and development of novel dressings are clinically urgent for the treatment of chronic wounds due to diabetic ulcers. In this study, we made taxifolin (TAX) loaded sodium alginate (SA)/poly(vinyl alcohol) (PVA) nanofibers for the treatment of chronic wounds. The SA/PVA/TAX nanofibers that have been created are smooth and bead-free, with good thermal stability, hydrophilicity, and mechanical properties. The release profile indicated a sustained drug release, with a cumulative release rate of 64.6 ± 3.7 % at 24 h. In vitro experiments have shown that SA/PVA/TAX has good antibacterial activity, antioxidant activity, and biocompatibility. In vivo experiments have shown that SA/PVA/TAX exhibits desirable biochemical properties and is involved in the diabetic wound healing process by promoting cell proliferation (Ki67), angiogenesis (CD31, VEGFA), and alleviating inflammation (CD68). Western blotting experiments suggest that SA/PVA/TAX may promote diabetic wound healing by inhibiting the TLR4/NF-κB/NLRP3 signaling pathway and upregulating the expression of VEGFA and PDGFA. The 16S rRNA sequencing results showed that SA/PVA/TAX increased the wound surface flora's diversity and reversed the skin microbiota's structural imbalance. Therefore, SA/PVA/TAX can promote diabetic wound healing by modulating the inflammatory response, angiogenesis, and skin flora and has the potential to be an excellent wound dressing.

State-of-the-Art Review of Advanced Electrospun Nanofiber Composites for Enhanced Wound Healing

Wound healing is a complex biological process with four main phases: hemostasis, inflammation, proliferation, and remodeling. Current treatments such as cotton and gauze may delay the wound healing process which gives a demand for more innovative treatments. Nanofibers are nanoparticles that resemble the extracellular matrix of the skin and have a large specific surface area, high porosity, good mechanical properties, controllable morphology, and size. Nanofibers are generated by electrospinning method that utilizes high electric force. Electrospinning device composed of high voltage power source, syringe that contains polymer solution, needle, and collector to collect nanofibers. Many polymers can be used in nanofiber that can be from natural or from synthetic origin. As such, electrospun nanofibers are potential scaffolds for wound healing applications. This review discusses the advanced electrospun nanofiber morphologies used in wound healing that is prepared by modified electrospinning techniques.

Recent Advances in Electrospun Nanofiber-Based Strategies for Diabetic Wound Healing Application

Diabetic ulcers are the second largest complication caused by diabetes mellitus. A great number of factors, including hyperchromic inflammation, susceptible microbial infection, inferior vascularization, the large accumulation of free radicals, and other poor healing-promoting microenvironments hold back the healing process of chronic diabetic ulcer in clinics. With the increasing clinical cases of diabetic ulcers worldwide, the design and development of advanced wound dressings are urgently required to accelerate the treatment of skin wounds caused by diabetic complications. Electrospinning technology has been recognized as a simple, versatile, and cost-reasonable strategy to fabricate dressing materials composed of nanofibers, which possess excellent extracellular matrix (ECM)-mimicking morphology, structure, and biological functions. The electrospinning-based nanofibrous dressings have been widely demonstrated to promote the adhesion, migration, and proliferation of dermal fibroblasts, and further accelerate the wound healing process compared with some other dressing types like traditional cotton gauze and medical sponges, etc. Moreover, the electrospun nanofibers are commonly harvested in the structure of nonwoven-like mats, which possess small pore sizes but high porosity, resulting in great microbial barrier performance as well as excellent moisture and air permeable properties. They also serve as good carriers to load various bioactive agents and/or even living cells, which further impart the electrospinning-based dressings with predetermined biological functions and even multiple functions to significantly improve the healing outcomes of different chronic skin wounds while dramatically shortening the treatment procedure. All these outstanding characteristics have made electrospun nanofibrous dressings one of the most promising dressing candidates for the treatment of chronic diabetic ulcers. This review starts with a brief introduction to diabetic ulcer and the electrospinning process, and then provides a detailed introduction to recent advances in electrospinning-based strategies for the treatment of diabetic wounds. Importantly, the synergetic application of combining electrospinning with bioactive ingredients and/or cell therapy was highlighted. The review also discussed the advantages of hydrogel dressings by using electrospun nanofibers. At the end of the review, the challenge and prospects of electrospinning-based strategies for the treatment of diabetic wounds are discussed in depth.

Copper-Epigallocatechin Gallate Enhances Therapeutic Effects of 3D-Printed Dermal Scaffolds in Mitigating Diabetic Wound Scarring

Morbid dermal templates, microangiopathy, and abnormal inflammation are the three most critical reasons for the scarred healing and the high recurrence rate of diabetic wounds. In this present study, a combination of a methacrylated decellularized extracellular matrix (ECMMA, aka EM)-based hydrogel system loaded with copper-epigallocatechin gallate (Cu-EGCG) capsules is proposed to fabricate bio-printed dermal scaffolds for diabetic wound treatment. Copper ions act as a bioactive element for promoting angiogenesis, and EGCG can inhibit inflammation on the wound site. In addition to the above activities, EM/Cu-EGCG (E/C) dermal scaffolds can also provide optimized templates and nutrient exchange space for guiding the orderly deposition and remodeling of ECM. In vitro experiments have shown that the E/C hydrogel can promote angiogenesis and inhibit the polarization of macrophages to the M1 pro-inflammatory phenotype. In the full-thickness skin defect model of diabetic rats, the E/C dermal scaffold combined with split-thickness skin graft transplantation can alleviate pathological scarring via promoting angiogenesis and driving macrophage polarization to the anti-inflammatory M2 phenotype. These may be attributed to the scaffold-actuated expression of angiogenesis-related genes in the HIF-1α/vascular endothelial growth factor pathway and decreased expression of inflammation-related genes in the TNF-α/NF-κB/MMP9 pathway. The results of this study show that the E/C dermal scaffold could serve as a promising artificial dermal analogue for solving the problems of delayed wound healing and reulceration of diabetic wounds.

Ultra-stretchable, tissue-adhesive, shape-adaptive, self-healing, on-demand removable hydrogel dressings with multiple functions for infected wound healing in regions of high mobility

Bacterial infection in the most mobile area usually leads to delayed healing and functional restriction, which has been a long-term challenge in clinic. Developing hydrogel-based dressings with mechanical flexibly, high adhesive and anti-bacterial properties, will contribute to the healing and therapeutic effects especially for this typical skin wound. In this work, composite hydrogel named PBOF through multi-reversible bonds between polyvinyl alcohol, borax, oligomeric procyanidin and ferric ion demonstrated a 100 times ultra-stretch ability, 24 kPa of highly tissue-adhesive, rapid shape-adaptability within 2 min and self-healing feature within 40 s, was designed as the multifunctional wound dressing for the Staphylococcus aureus-infected skin wound in the mice nape model. Besides, this hydrogel dressing could be easily removed on-demand within 10 min by water. The rapid disassembly of this hydrogel is related to the formation of hydrogen bonds between polyvinyl alcohol and water. Moreover, the multifunctional properties of this hydrogel include strong anti-oxidative, anti-bacteria and hemostasis derived from oligomeric procyanidin and photothermal effect of ferric ion/polyphenol chelate. The killing ratio of the hydrogel on Staphylococcus aureus in infected skin wound reached 90.6% when exposed to 808 nm irradiation for 10 min. Simultaneously, reduced oxidative stress, suppressed inflammation, and promoted angiogenesis all together accelerated wound healing. Therefore, this well-designed multifunctional PBOF hydrogel holds great promise as skin wound dressing especially in the high mobile regions of the body. STATEMENT OF SIGNIFICANCE: An ultra-stretchable, highly tissue-adhesive, and rapidly shape-adaptive, self-healing and on-demand removable hydrogel based on multi-reversible bonds among polyvinyl alcohol, borax, oligomeric procyanidin and ferric ion is designed as dressing material for infected wound healing in the movable nape. The rapid on-demand removal of the hydrogel relates to the formation of hydrogen bonds between polyvinyl alcohol and water. This hydrogel dressing shows strong antioxidant capacity, rapid hemostasis and photothermal antibacterial ability. This is derived from oligomeric procyanidin and thephotothermal effect of ferric ion/polyphenol chelate, which eliminates bacterial infection, reduces oxidative stress, regulates inflammation, promotes angiogenesis, and finally accelerates the infected wound healing in movable part.

Gelatin as a bioactive nanodelivery system for functional food applications

Gelatin has long been used as an encapsulant agent in the pharmaceutical and biomedical industries because of its low cost, wide availability, biocompatibility, and degradability. However, the exploitation of gelatin for nanodelivery application is not fully achieved in the functional food filed. In this review article, we highlight the latest work being performed for gelatin-based nanocarriers, including polyelectrolyte complexes, nanoemulsions, nanoliposomes, nanogels, and nanofibers. Specifically, we discuss the applications and challenges of these nanocarriers for stabilization and controlled release of bioactive compounds. To achieve better efficacy, gelatin is frequently used in combination with other biomaterials such as polysaccharides. The fabrication and synergistic effects of the newly developed gelatin composite nanocarriers are also present.

Fabrication of PLCL Block Polymer with Tunable Structure and Properties for Biomedical Application

Biodegradable materials are pivotal in the biomedical field, where how to precisely control their structure and performance is critical for their translational application. In this study, poly(L-lactide-b-ε-caprolactone) block copolymers (bPLCL) with well-defined segment structure are obtained by a first synthesis of poly(ε-caprolactone) soft block, followed by ring opening polymerization of lactide to form poly(L-lactide acid)  hard block. The pre-polymerization allows for fabrication of bPLCL with the definite compositions of soft/hard segment while preserving the individual segment of their special soft or hard segment. These priorities make the bPLCL afford biodegradable polymer with better mechanical and biodegradable controllability than the random poly(L-lactide-co-ε-caprolactone) (rPLCL) synthesized via traditional one-pot polymerization. 10 mol% ε-caprolactone introduction can result in a formation of an elastic polymer with elongation at break of 286.15% ± 55.23%. Also, bPLCL preserves the unique crystalline structure of the soft and hard segments to present a more sustainable biodegradability than the rPLCL. The combinative merits make the pre-polymerization technique a promising strategy for a scalable production of PLCL materials for potential biomedical application.

Therapeutic applications of electrospun nanofibers impregnated with various biological macromolecules for effective wound healing strategy - A review

A Non-healing infected wound is an ever-growing global epidemic, with increasing burden of mortality rates and management costs. The problems of chronic wound infections and their outcomes will continue as long as their underlying causes like diabetic wounds grow and spread. Commercial wound therapies employed have limited potential that inhibits pivotal functions and tissue re-epithelialization properties resulting in wound infections. Nanomaterial based drug delivery formulations involving biological macromolecules are developing areas of interest in wound healing applications which are utilized in the re-epithelialization of skin with cost-effective preparations. Research conducted on nanofibers has shown enhanced skin establishment with improved cell proliferation and growth and delivery of bioactive organic molecules at the wound site. However, drug targeted delivery with anti-scarring properties and tissue regeneration aspects have not been updated and discussed in the case of macromolecule impregnated nanofibrous mats. Hence, this review focuses on the brief concepts of wound healing and wound management, therapeutic commercialized wound dressings currently available in the field of wound care, effective electrospun nanofibers impregnated with different biological macromolecules and advancement of nanomaterials for tissue engineering have been discussed. These new findings will pave the way for producing anti-scarring high effective wound scaffolds for drug delivery.

Electrospinning of botanicals for skin wound healing

Being the first barrier between the human body and external environments, our skin is highly vulnerable to injuries. As one of the conventional therapies, botanicals prepared in different topical formulations have been applied as medical care for centuries. With the current increase of clinical requirements, applications of botanicals are heading towards nanotechnologies, typically fused with electrospinning that forms nanofibrous membranes suitable for skin wound healing. In this review, we first introduced the main process of wound healing, and then presented botanicals integrated into electrospun matrices as either loaded drugs, or carriers, or membrane coatings. In addition, by addressing functional features of individual botanicals in the healing of injured skin, we further discussed the bioactivity of botanical electrospun membranes in relevant to the medical issues solved in the process of wound healing. As achieved by pioneer studies, due to infrequent adverse effects and the diversity in resources of natural plants, the development of electrospun products based on botanicals is gaining greater attention. However, investigations in this field have mainly focused on different methodologies used in the preparation of nanofibrous membranes containing botanicals, their translation into clinical practices remains unaddressed. Accordingly, we propose that potential clinical applications of botanical electrospun membranes require not only the further expansion and understanding of botanicals, but also an establishment of standard criteria for the evaluation of wound healing and evolutions of technologies to support the large-scale manufacturing industry.

Polysaccharide Electrospun Nanofibers for Wound Healing Applications

As a type of biological macromolecule, natural polysaccharides have been widely used in wound healing due to their low toxicity, good biocompatibility, degradability and reproducibility. Electrospinning is a versatile and simple technique for producing continuous nanoscale fibers from a variety of natural and synthetic polymers. The application of electrospun nanofibers as wound dressings has made great progress and they are considered one of the most effective wound dressings. This paper reviews the preparation of polysaccharide nanofibers by electrospinning and their application prospects in the field of wound healing. A variety of polysaccharide nanofibers, including chitosan, starch, alginate, and hyaluronic acid are introduced. The preparation strategy of polysaccharide electrospun nanofibers and their functions in promoting wound healing are summarized. In addition, the future prospects and challenges for the preparation of polysaccharide nanofibers by electrospinning are also discussed.

Hybrid-Based Wound Dressings: Combination of Synthetic and Biopolymers

Most commercialized wound dressings are polymer-based. Synthetic and natural polymers have been utilized widely for the development of wound dressings. However, the use of natural polymers is limited by their poor mechanical properties, resulting in their combination with synthetic polymers and other materials to enhance their mechanical properties. Natural polymers are mostly affordable, biocompatible, and biodegradable with promising antimicrobial activity. They have been further tailored into unique hybrid wound dressings when combined with synthetic polymers and selected biomaterials. Some important features required in an ideal wound dressing include the capability to prevent bacteria invasion, reduce odor, absorb exudates, be comfortable, facilitate easy application and removal as well as frequent changing, prevent further skin tear and irritation when applied or removed, and provide a moist environment and soothing effect, be permeable to gases, etc. The efficacy of polymers in the design of wound dressings cannot be overemphasized. This review article reports the efficacy of wound dressings prepared from a combination of synthetic and natural polymers.

Ameliorative effects of epigallocatechin-3-gallate nanoparticles on 2,4-dinitrochlorobenzene induced atopic dermatitis: A potential mechanism of inflammation-related necroptosis

Atopic dermatitis (AD) is a common autoimmune and chronic inflammatory cutaneous disease with a relapsing-remitting course. Necroptosis is a regulated necrotic cell death mediated by receptor-interacting protein 1 (RIP1), receptor-interacting protein 3 (RIP3), and mixed lineage kinase domain-like pseudokinase (MLKL), which is activated by tumor necrosis factor-α (TNF-α). However, the mechanism and the role of necroptosis have not been delineated in AD progression. (-)-Epigallocatechin-3-gallate (EGCG), the main biological activity of tea catechin, is well known for its beneficial effects in the treatment of skin diseases. Here, PEG-PLGA-EGCG nanoparticles (EGCG-NPs) were formulated to investigate the bioavailability of EGCG to rescue cellular injury following the inhibition of necroptosis after AD. 2,4-dinitrochlorobenzene (DNCB) was used to establish AD mouse models. As expected, topically applied EGCG-NPs elicited a significant amelioration of AD symptoms in skin lesions, including reductions in the ear and skin thickness, dermatitis score, and scratching behavior, which was accompanied by redox homeostasis restored early in the experiment. In addition, EGCG-NPs significantly decreased the expression of inflammatory cytokines like TNF-α, interferon-γ (IFN-γ), interleukin-4 (IL-4), interleukin-6 (IL-6), and interleukin-17A (IL-17A) in a time-dependent manner than those of in AD group. As a result, the overexpression of RIP1, RIP3, and MLKL in the entire epidermis layers was dramatically blocked by EGCG-NPs, as well as the expression ofphosphorylated p38 (p-p38), extracellular signal-regulated kinase 1 (ERK1), and extracellular signal-regulated kinase 2 (ERK2). These findings promote that EGCG-NPs formulation represents a promising drug-delivery strategy for the treatment of AD by maintaining the balance of Th1/Th2 inflammation response and targeting necroptosis.

Tuning the Drug Release from Antibacterial Polycaprolactone/Rifampicin-Based Core-Shell Electrospun Membranes: A Proof of Concept

The employment of coaxial fibers for guided tissue regeneration can be extremely advantageous since they allow the functionalization with bioactive compounds to be preserved and released with a long-term efficacy. Antibacterial coaxial membranes based on poly-ε-caprolactone (PCL) and rifampicin (Rif) were synthesized here, by analyzing the effects of loading the drug within the core or on the shell layer with respect to non-coaxial matrices. The membranes were, therefore, characterized for their surface properties in addition to analyzing drug release, antibacterial efficacy, and biocompatibility. The results showed that the lower drug surface density in coaxial fibers hinders the interaction with serum proteins, resulting in a hydrophobic behavior compared to non-coaxial mats. The air-plasma treatment increased their hydrophilicity, although it induced rifampicin degradation. Moreover, the substantially lower release of coaxial fibers influenced the antibacterial efficacy, tested against Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa. Indeed, the coaxial matrices were inhibitory and bactericidal only against S. aureus, while the higher release from non-coaxial mats rendered them active even against E. coli. The biocompatibility of the released rifampicin was assessed too on murine fibroblasts, revealing no cytotoxic effects. Hence, the presented coaxial system should be further optimized to tune the drug release according to the antibacterial effectiveness.

Eggshell membrane-mimicking multifunctional nanofiber for in-situ skin wound healing

Eggshell membrane is a naturally-occurring protective barrier layer for chickens' incubation and shows the close similarity with extracellular matrix. To fully explore and utilize its' structure and active components via a mimicking way will be of great interest for wounds healing. Herein, the well-dispersed CuS nanoparticles were prepared by using eggshell membranes as templates with strong near-infrared absorption and photothermal properties. Furthermore, the as-prepared solution was combined with polyvinyl pyrrolidone and chitosan-derived fluorescent carbon dots for the mimetic synthesis of multifunctional nanofibrous membrane by a hand-held electrospinning device, which has the merits of in-situ operation, the extracellular matrix (ECM)-like architecture, hemostatic, radical scavenging, antibacterial, as well as accelerated healing of skin injury, etc. The electrospun-nanofiber membrane with optimal addition of 100 mg/L CuS nanoparticles was confirmed to be noncytotoxic on human fibroblasts and showed strong antibacterial activities against S. aureus and E. coli under NIR irradiation (980 nm). In addition, the radical scavenging ability was also proved by DPPH experiments. The animal experiments revealed that the nanofiber membrane could accelerate the wound healing process. The work lays down a simple and environmentally-friendly approach for the fabrication and development of promising wound healing materials in skin tissue engineering applications.

Treatment of Acute Wounds With Recombinant Human-Like Collagen and Recombinant Human-Like Fibronectin in C57BL/6 Mice Individually or in Combination

Wound repair is accomplished by the interaction between the cells involved in the repair and the extracellular matrix (ECM). Collagen is the main component of ECM, which is involved in transduction of signal, transportation of growth factors and cytokines. Fibronectin (FN) is also an important ECM, which participates in the initiation of fibroblast cell (FC) and promotes adhesion, migration, proliferation and differentiation of target cells. Compared with natural protein, the recombinant protein prepared by artificial method has the advantages of poor immunogenicity, wide range of sources, low cost and high activity. In this study, we used recombinant human-like collagen (RHC) and recombinant human-like fibronectin (rhFN) to treat acute wounds in C57BL/6 mice individually or in combination, and explored their effects on wound healing. Our study confirmed that these two recombinant proteins could effectively promote the proliferation, migration and adhesion of FCs. Meanwhile, it could positively regulate the healing speed and quality of acute wounds, re-epithelialization, collagen deposition, inflammation and angiogenesis. Moreover, we proved that the combination of the two was better than the treatment alone. Consequently, it has a good prospect as a new tissue material in the field of skin repair.

State-of-the-Art Review of Electrospun Gelatin-Based Nanofiber Dressings for Wound Healing Applications

Electrospun nanofiber materials have been considered as advanced dressing candidates in the perspective of wound healing and skin regeneration, originated from their high porosity and permeability to air and moisture, effective barrier performance of external pathogens, and fantastic extracellular matrix (ECM) fibril mimicking property. Gelatin is one of the most important natural biomaterials for the design and construction of electrospun nanofiber-based dressings, due to its excellent biocompatibility and biodegradability, and great exudate-absorbing capacity. Various crosslinking approaches including physical, chemical, and biological methods have been introduced to improve the mechanical stability of electrospun gelatin-based nanofiber mats. Some innovative electrospinning strategies, including blend electrospinning, emulsion electrospinning, and coaxial electrospinning, have been explored to improve the mechanical, physicochemical, and biological properties of gelatin-based nanofiber mats. Moreover, numerous bioactive components and therapeutic agents have been utilized to impart the electrospun gelatin-based nanofiber dressing materials with multiple functions, such as antimicrobial, anti-inflammation, antioxidation, hemostatic, and vascularization, as well as other healing-promoting capacities. Noticeably, electrospun gelatin-based nanofiber mats integrated with specific functions have been fabricated to treat some hard-healing wound types containing burn and diabetic wounds. This work provides a detailed review of electrospun gelatin-based nanofiber dressing materials without or with therapeutic agents for wound healing and skin regeneration applications.