Electrospun chitosan/polycaprolactone-hyaluronic acid bilayered scaffold for potential wound healing applications

A 3D bioprinted gelatin/quaternized chitosan/decellularized extracellular matrix based hybrid bionic scaffold with multifunctionality for infected full-thickness skin wound healing

Skin wound repair, a highly integrated and overlapping process, is susceptible to infection, hyperoxia and excessive inflammation, which can delay wound healing or even lead to chronic wounds. In this study, a GQL/dGQue bilayered multifunctional scaffold, epidermis composed of gelatin (G), quaternized chitosan (Q) and lignin (L), and dermis composed of skin-derived decellularized extracellular matrix (d), gelatin and quercetin (Que), with bionic skin structure, was constructed by 3D bioprinting technology. The results showed that lignin effectively improved the mechanical properties (Young's modulus above 90 MPa) and regulated the appropriate degradation (about 84 % for 15 d) of the scaffold, as well as endowed it with good UV shielding properties. In addition, GQL/dGQue showed prominent antibacterial activity of 90.76 ± 4.94 % and 90.34 ± 4.14 % against E. coli and S. aureus, respectively, good free radical scavenging (87.22 ± 1.71 %) and significant anti-inflammatory properties. In vivo studies demonstrated that GQL/dGQue scaffold could effectively prevent wound infection and mitigate inflammation, thereby accelerating vascularization and regeneration of hair follicle and sebaceous gland with a remarkable wound closure of 98.29 ± 1.77 % at 21 d. Therefore, the GQL/dGQue bilayered multifunctional scaffold has a considerable potential to apply in skin tissue engineering for clinical wound repair.

Nano-fibers fabrication using biological macromolecules: Application in biosensing and biomedicine

Nanofibers, a type of nanomaterial, have been widely use in a variety of fields, both research and commercial applications. They are a material of choice in a diverse range of applications due to their characteristics and unique physicochemical properties. Nanofibers have cross-sectional dimeters varying between 1 nm and 100 nm, the nano range dimensions providing them characteristics such as high surface area-to-volume ratio, highly porous as well as interconnected networks. There are various types of materials which have been used to synthesize nanofibers both biological (namely, hyaluronic acid, chitosan, alginate, fibrin, collagen, gelatin, silk fibroin, gums, and cellulose) as well as synthetic (namely, poly(lactic acid), poly(1-caprolactone), poly(vinyl alcohol), and polyurethane) polymers which have been briefly discussed in the present review. The review also explores various fabrication techniques for producing nanofibers, such as physical/chemical/biological techniques as well as electrospinning/non-spinning techniques. Due to their distinctive physicochemical qualities, nanofibers have become intriguing one-dimensional nanomaterials with applications in a wide range of biomedical fields. In line with this, the review discusses about various applications of nanofibers, namely, wound dressing, drug delivery, implants, diagnostic devices, tissue engineering, and biosensing. Furthermore, having an insight of the distinctive characteristics of nanofibers materials which could have immense potential in various biosensing applications, this review emphasizes on application of nanofibrous materials in the field of biosensing. However, despite these advances, there remain some challenges that need to be addressed before nanofiber technology can be widely adopted for its commercial use in biomedical as well as biosensing applications.

Asymmetric natural wound dressing based on porous chitosan-alginate hydrogel/electrospun PCL-silk sericin loaded by 10-HDA for skin wound healing: In vitro and in vivo studies

An asymmetric wound dressing introduced, inspired by the skin structure made of chitosan and alginate hydrogel as the bottom layer and electrospun PCL-silk sericin (PCL-SS) as the top layer. In addition, an anti-inflammatory, bactericidal and immunomodulatory substance, 10-hydroxydecanoic acid (10-HDA), known as queen bee acid, was loaded in inner layer. The wound dressing was thoroughly characterized and confirmed to meet the criteria of a standard wound dressing through in vitro and in vivo studies. Although the mesoporous hydrogel layer shows 175 % swelling after being immersed in PBS (pH = 7.4) for 60 min and 80 % degradation after 14 days, the top layer shows 28 % swelling and 19 % degradation in the same time intervals. The hydrogel layer supports rapid wound healing, while the top layer offers protection against infection and physical threats. The dressing demonstrated antibacterial properties and enhanced cell proliferation at 1 % 10-HDA. Finally, the wound healing performance of the complete dressing was investigated in vivo using wistar rat. Clinical and histopathological assessments, along with the analysis of biophysical parameters of the skin healing, confirm that wound dressing with 10-HDA significantly accelerates wound healing compared to control groups, without any inflammatory side effects.

Metal nanoparticles incorporated chitosan-based electrospun nanofibre mats for wound dressing applications: A review

Wound healing is a dynamic physiological process essential for regenerating skin and maintaining coherence in hypodermic tissues. Chitosan-based electrospun nanofibre wound dressings show great promise for expediting the integration of skin and tissues due to their nano-topographic, biodegradable, biocompatible, and antimicrobial properties. However, their moderate bactericidal efficacy and limited mechanical strength hinder their widespread clinical application. The incorporation of specific metal nanoparticles (MNPs) and the functionalization of chitosan have brought attention to their crucial role in wound healing applications, yielding promising results by enhancing antibacterial properties, cell proliferation, cell signaling, and the mechanical robustness of the materials. Chitosan naturally mitigates the cytotoxicity of the incorporated metal nanoparticles within the nanofibers. Chitosan and modified chitosan-based electrospun mats incorporated with metal nanoparticles demonstrate substantial potential for expediting wound healing. This review offers a comprehensive overview of recent advancements in electrospun chitosan-based mats containing MNPs aimed at enhancing wound healing. It covers various aspects, including modification techniques, fabrication methods, wound closure mechanisms, MNP release profiles, histological considerations, addresses existing challenges, and outlines potential future developments.

3D printing of bacterial cellulose for potential wound healing applications: Current trends and prospects

Several advances in skin tissue engineering have been made to restore skin damage, facilitating wound healing. Bacterial cellulose (BC), a naturally occurring polymer, has gained attention as a potential material in wound healing due to its unique physical and biological properties. In recent years, with the advent of 3D bio-printing technology, new avenues have opened for fabricating customized wound dressings and scaffolds for tissue engineering purposes. The existing literature in this field mainly focuses on the ways of modifications of bacterial cellulose to make it printable. Still, the applicability of 3D printed scaffolds for wound healing needs to be explored more. This review article focuses on the current research on using 3D-printed BC for skin regeneration, including its production methods and physical and biological properties, making it a better choice than traditional dressings. Furthermore, it also highlights the limitations and future directions for using BC in wound healing and tissue engineering applications. This review provides a comprehensive and up-to-date exploration of the applications of 3D-printed BC in wound healing, drawing insights from pre-existing studies and emphasizing patient compliance, clinical outcomes, and economic viability.

Cell-free bilayer functionalized scaffold for osteochondral tissue engineering

Osteochondral tissue engineering using layered scaffolds is a promising approach for treating osteochondral defects as an alternative to microfracture procedure, autologous chondrocyte implantation, and cartilage-bone grafting. The team previously investigated the chondrogenesis of mesenchymal stem cells (MSCs) on a polycaprolactone (PCL)/acetylated hyaluronic acid scaffold. The present study first focused on fabricating a novel osteoconductive scaffold utilizing bismuth-nanohydroxyapatite/reduced graphene oxide (Bi-nHAp/rGO) nanocomposite and electrospun PCL. The osteoconductive ability of the scaffold was investigated by evaluating the alkaline phosphatase (ALP) activity and the osteogenic genes expression in the adipose-derived MSCs. The expression of Runx2, collagen I, ALP, and osteocalcin as well as the result of ALP activity indicated the osteoconductive potential of the Bi-nHA-rGO/PCL scaffold. In the next step, a bilayer scaffold containing Bi-nHAp/rGO/PCL as an osteogenic layer and acetylated hyaluronic acid/PCL as a chondrogenic layer was prepared by the electrospinning technique and transplanted into osteochondral defects of rats. The chondrogenic and osteogenic markers corresponding to the surrounding tissues of the transplanted scaffold were surveyed 60 days later by real-time polymerase chain reaction (PCR) and immunohistochemistry methods. The results showed increased chondrogenic (Sox9 and collagen II) and osteogenic (osteocalcin and ALP) gene expression and augmented secretion of collagens II and X after transplantation. The results strongly support the efficacy of this constructed cell-free bilayer scaffold to induce osteochondral defect regeneration.

Biocompatible Native Hyaluronan Nanofibers Fabricated via Aqueous PEO-Assisted Electrospinning and Heat-Quench Process

Hyaluronan (HA) is widely used in cosmetic and biomedical applications due to its excellent biocompatibility and potential to promote wound healing. Nanofibrous HA, mimicking the extracellular matrix (ECM), is considered promising for therapeutic and cosmetic applications. However, the electrospinning process of HA often necessitates cytotoxic solvents and chemical modifications, compromising its biocompatibility and advantageous properties. In this study, poly(ethylene oxide) (PEO) was added to an aqueous solution of natural HA to improve its spinnability, enabling HA to be electrospun into fibers. The HA was rendered water-insoluble by treatment with an acidic solution, and the amorphized PEO, achieved by heat-quenching, was removed through water washing. This method distinguishes it from previous reports of fibers blended with PEO or other water-soluble polymers. Consequently, the resulting HA gel fibers demonstrated suitability for mesenchymal stem cell adhesion due to the exposure of HA on the fiber surface. Additionally, HA fibers were successfully applied directly onto the skin using a hand-held electrospinning device, indicating the potential for point-of-care and home use applications.

Cross-Linking Agents in Three-Component Materials Dedicated to Biomedical Applications: A Review

In biomaterials research, using one or two components to prepare materials is common. However, there is a growing interest in developing materials composed of three components, as these can offer enhanced physicochemical properties compared to those consisting of one or two components. The introduction of a third component can significantly improve the mechanical strength, biocompatibility, and functionality of the resulting materials. Cross-linking is often employed to further enhance these properties, with chemical cross-linking agents being the most widely used method. This article provides an overview of the chemical agents utilized in the cross-linking of three-component biomaterials. The literature review focused on cases where the material was composed of three components and a chemical substance was employed as the cross-linking agent. The most commonly used cross-linking agents identified in the literature include glyoxal, glutaraldehyde, dialdehyde starch, dialdehyde chitosan, and the EDC/NHS mixture. Additionally, the review briefly discusses materials cross-linked with the MES/EDC mixture, caffeic acid, tannic acid, and genipin. Through a critical analysis of current research, this work aims to guide the development of more effective and safer biopolymeric materials tailored for biomedical applications, highlighting potential areas for further investigation and optimization.

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

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

Developing fish oil emulsion gel enriched with Lentinula edodes single cell protein and its effect on controlling the growth of Acinetobacter baumannii

In this study, the characterization of fish oil (FO) emulsion gel (EGEL) containing single cell protein (SCP) produced from Lentinula edodes (L. edodes) and its potential inhibition against Acinetobacter baumannii (A. baumannii) were investigated. Oil extracted from the fish liver was emulsified with tween 80 and water, and then gelled using gelatin with the assistance of an ultrasonic homogenizer. The characteristics and surface analysis of SCP-EGEL were examined using FTIR (Fourier-transform infrared spectroscopy) and SEM (Scanning electron microscope). The particle size distribution and zeta potential of SCP-EGEL were measured using a Malvern Zetasizer. When SCP-EGEL was applied to the surface of the medium inoculated with A. baumannii, the inhibition zone (IZ) was 8.2 mm. An expansion of the IZ was observed (10.2 mm) when SCP-EGEL was applied to a fish skin (FS) surface prepared in the shape of a 6-mm diameter disc. In the SEM images, when SCP was added to lipo gel, the gel structure appeared flattened or swollen in some areas. The appearance of SCP cells being covered with gel gave the impression that they have a secondary wall. Therefore, the resulting complex can potentially be used as an additive in animal and human nutrition, in functional food coatings to suppress A. baumannii, and in fish feed to enrich it with protein.

Electrospun Poly-ε-Caprolactone Nanofibers Incorporating Keratin Hydrolysates as Innovative Antioxidant Scaffolds

This manuscript describes the development and characterization of electrospun nanofibers incorporating bioactive hydrolysates obtained from the microbial bioconversion of feathers, a highly available agro-industrial byproduct. The electrospun nanofibers were characterized using different instrumental methods, and their antioxidant properties and toxicological potential were evaluated. Keratin hydrolysates (KHs) produced by Bacillus velezensis P45 were incorporated at 1, 2.5, and 5% (w/w) into poly-ε-caprolactone (PCL; 10 and 15%, w/v solutions) before electrospinning. The obtained nanofibers were between 296 and 363 nm in diameter, showing a string-like morphology and adequate structural continuity. Thermogravimetric analysis showed three weight loss events, with 5% of the mass lost up to 330 °C and 90% from 350 to 450 °C. Infrared spectroscopy showed typical peaks of PCL and amide bands corresponding to keratin peptides. The biological activity was preserved after electrospinning and the hemolytic activity was below 1% as expected for biocompatible materials. In addition, the antioxidant capacity released from the nanofibers was confirmed by DPPH and ABTS radical scavenging activities. The DPPH scavenging activity observed for the nanofibers was greater than 30% after 24 h of incubation, ranging from 845 to 1080 µM TEAC (Trolox equivalent antioxidant capacity). The antioxidant activity for the ABTS radical assay was 44.19, 49.61, and 56.21% (corresponding to 972.0, 1153.3, and 1228.7 µM TEAC) for nanofibers made using 15% PCL with 1, 2.5, and 5% KH, respectively. These nanostructures may represent interesting antioxidant biocompatible materials for various pharmaceutical applications, including wound dressings, topical drug delivery, cosmetics, and packaging.

A structure-functionality insight into the bioactivity of microbial polysaccharides toward biomedical applications: A review

Microbial polysaccharides (MPs) are biopolymers secreted by microorganisms such as bacteria and fungi during their metabolic processes. Compared to polysaccharides derived from plants and animals, MPs have advantages such as wide sources, high production efficiency, and less susceptibility to natural environmental influences. The most attractive feature of MPs lies in their diverse biological activities, such as antioxidative, anti-tumor, antibacterial, and immunomodulatory activities, which have demonstrated immense potential for applications in functional foods, cosmetics, and biomedicine. These bioactivities are precisely regulated by their sophisticated molecular structure. However, the mechanisms underlying this precise regulation are not yet fully understood and continue to evolve. This article presents a comprehensive review of the most representative species of MPs, including their fermentation and purification processes and their biomedical applications in recent years. In particular, this work presents an in-depth analysis into the structure-activity relationships of MPs across multiple molecular levels. Additionally, this review discusses the challenges and prospects of investigating the structure-activity relationships, providing valuable insights into the broad and high-value utilization of MPs.

Hyaluronic acid/PEO electrospun tube reduces tendon adhesion to levels comparable to native tendons - An in vitro and in vivo study

A major problem after tendon injury is adhesion formation to the surrounding tissue leading to a limited range of motion. A viable strategy to reduce adhesion extent is the use of physical barriers that limit the contact between the tendon and the adjacent tissue. The purpose of this study was to fabricate an electrospun bilayered tube of hyaluronic acid/polyethylene oxide (HA/PEO) and biodegradable DegraPol® (DP) to improve the anti-adhesive effect of the implant in a rabbit Achilles tendon full laceration model compared to a pure DP tube. Additionally, the attachment of rabbit tenocytes on pure DP and HA/PEO containing scaffolds was tested and Scanning Electron Microscopy, Fourier-transform Infrared Spectroscopy, Differential Scanning Calorimetry, Water Contact Angle measurements, and testing of mechanical properties were used to characterize the scaffolds. In vivo assessment after three weeks showed that the implant containing a second HA/PEO layer significantly reduced adhesion extent reaching levels comparable to native tendons, compared with a pure DP implant that reduced adhesion formation only by 20 %. Tenocytes were able to attach to and migrate into every scaffold, but cell number was reduced over two weeks. Implants containing HA/PEO showed better mechanical properties than pure DP tubes and with the ability to entirely reduce adhesion extent makes this implant a promising candidate for clinical application in tendon repair.

Bioassay-guided fractionation of Verbascum thapsus extract and its combination with polyvinyl alcohol in the form electrospun nanofibrous membrane for efficient wound dressing application

Verbascum thapsus (V. thpsus), family Scrophulariaceae, has considerable importance in traditional medicine worldwide because of its antioxidant and anti-inflammatory activities. V. thpsus was used in traditional medicines as a useful drug for lung disease, sore throat, wound healing, and treatment of whooping cough. The aim of this study was to extract of V. thpsus bioactive fraction using antibacterial assay guided fractionation methodology and develop a system based on electrospun nanofibrous membrane (NFM) that can be effective by releasing the extract of V. thapsus for antibacterial and wound healing applications. For this purpose, the fractionation of total extract was done using Liquid-Liquid extraction method. The selected fraction based on its anti-bacterial activity was then subjected to the silica gel column chromatography for further purification. Since electrospinning is an economical and relatively simple method to produce continuous and uniform nanofibers, and due to its high specific surface area, adjustable pore size, and flexibility, special attention has been paid to loaded the most effective fraction on PVA nanofibers for applications such as wound dressings. The obtained result showed that, the purified V. Thapsus extract has a concentration-dependent antimicrobial activity against Escherichia coli and Staphylococcus aureus. The phytochemically analyses of bioactive fraction by High-performance liquid chromatography (HPLC) proved the presence of 6 phenolic acids, 4-hydroxybenzoic acid, chlorogenic acid, caffeic acid, p-coumaric acid, ferulic acid, and flavonoid, rutin, as the major compounds. Also, physicochemical characterization of PVA-selected extract loaded electrospun nanofibrous membranes (NFM) were analyzed by scanning electron microscope (SEM), Fourier transform infrared spectrometer (FT-IR). MTT and hemolysis assays were done to affirm the biocompatibility of fabricated scaffolds. Release profile of extract loaded- NFM showed continues release of extract from mat during 90h. Moreover, the capability of these NFM in wound healing application was evaluated in-vitro and in-vivo. The cell viability test (MTT), cell adhesion images, antioxidant, antibacterial, hemolysis assays and in-vitro and in-vivo wound healing assays confirmed that fabricated NFM containing 5 % butanolic extract were the most biocompatible scaffold for wound dressing applications and accelerates the rate of wound closure. The obtained outcomes confirmed that V. thpsus/PVA NFM can be considered as promising scaffold for potential wound dressings.

An in vitro and in vivo study of electrospun polyvinyl alcohol/chitosan/sildenafil citrate mat on 3D-printed polycaprolactone membrane as a double layer wound dressing

Double-layer dermal substitutes (DS) generally provide more effective therapeutic outcomes than single-layer substitutes. The architectural design of DS incorporates an outer layer to protect against bacterial invasions and maintain wound hydration, thereby reducing the risk of infection and the frequency of dressing changes. Moreover, the outer layer is a mechanical support for the wound, preventing undue tension in the affected area. A 3D-printed polycaprolactone (PCL) membrane was utilized as the outer layer to fabricate DS wound dressing. Simultaneously, a polyvinyl alcohol/chitosan/sildenafil citrate (PVA/CS/SC) scaffold was electrospun onto the PCL membrane to facilitate cellular adhesion and proliferation. Scanning electron microscopy (SEM) analysis of the PCL filaments revealed a consistent cross-sectional surface and structure, with an average diameter of 562.72 ± 29.15 μm. SEM results also demonstrated uniform morphology and beadless structure for the PVA/CS/SC scaffold, with an average fiber diameter of 366.77 ± 1.81 nm for PVA/CS. The addition of SC led to an increase in fiber diameter while resulting in a reduction in tensile strength. However, drug release analysis indicated that the SC release from the sample can last up to 72 h. Animal experimentation confirmed that DS wound dressing positively accelerated wound closure and collagen deposition in the Wistar rat skin wound model.

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.

Electrospun nanofibers synthesized from polymers incorporated with bioactive compounds for wound healing

The development of innovative wound dressing materials is crucial for effective wound care. It's an active area of research driven by a better understanding of chronic wound pathogenesis. Addressing wound care properly is a clinical challenge, but there is a growing demand for advancements in this field. The synergy of medicinal plants and nanotechnology offers a promising approach to expedite the healing process for both acute and chronic wounds by facilitating the appropriate progression through various healing phases. Metal nanoparticles play an increasingly pivotal role in promoting efficient wound healing and preventing secondary bacterial infections. Their small size and high surface area facilitate enhanced biological interaction and penetration at the wound site. Specifically designed for topical drug delivery, these nanoparticles enable the sustained release of therapeutic molecules, such as growth factors and antibiotics. This targeted approach ensures optimal cell-to-cell interactions, proliferation, and vascularization, fostering effective and controlled wound healing. Nanoscale scaffolds have significant attention due to their attractive properties, including delivery capacity, high porosity and high surface area. They mimic the Extracellular matrix (ECM) and hence biocompatible. In response to the alarming rise of antibiotic-resistant, biohybrid nanofibrous wound dressings are gradually replacing conventional antibiotic delivery systems. This emerging class of wound dressings comprises biopolymeric nanofibers with inherent antibacterial properties, nature-derived compounds, and biofunctional agents. Nanotechnology, diminutive nanomaterials, nanoscaffolds, nanofibers, and biomaterials are harnessed for targeted drug delivery aimed at wound healing. This review article discusses the effects of nanofibrous scaffolds loaded with nanoparticles on wound healing, including biological (in vivo and in vitro) and mechanical outcomes.

Chitosan and neem gum-based polyelectrolyte complex for design of allantoin loaded biocomposite film: In-vitro, ex-vivo, and in-vivo characterization

Presently, the preference for chitosan (CS) and gum polysaccharides in biomedical applications including drug delivery and wound healing has been extensively documented. Despite this, the demerits of CS and gum polysaccharides such as poor mechanical properties, degradation rate, swelling, etc., limit their applications for designing biocomposite films for drug delivery. Therefore, the anticipated work aims to design a CS and neem gum polysaccharides (NGP) polyelectrolyte complex-based allantoin (AT)-loaded (CS/NGP-AT) biocomposite film for improved wound healing. In brief, CS, NGP, and CS/NGP-AT-based biocomposite films were prepared using the solvent-casting method, and in-vitro, ex-vivo, and in-vivo characterizations were performed to assess the performance of these biocomposite films compared to their counterparts. In this, diffractogram and thermogram analysis assured the conversion of crystalline AT into an amorphous form. The optimized CS/NGP/AT-3 formulation exhibited controlled water absorption, appropriate water uptake capacity, good water retention ability, excellent water vapor transmission rate, controlled degradation rate, enhanced mechanical properties, cell and blood biocompatibility, etc. Furthermore, it offered improved antimicrobial, anti-inflammatory, and antioxidant potential. The optimized film provided a modified release (88.3 ± 0.3 %) of AT from the film for up to 48 h. Wound healing experiments on rats and their histopathology studies confirmed a significantly higher rate of wound recovery within 14 days compared to the control and CS/NGP film, attributable to the combined effects of CS, NGP, and AT. In conclusion, the fabricated CS/NGP-based biocomposite film presents promising prospects as an excellent candidate for wound healing applications.

Inhibition performance of almond shell hydrochar-based fish oil emulsion gel on Klebsiella pneumonia inoculated fish skin and its characteristics

In this study, the inhibition potential against Klebsiella pneumoniae (K. pneumoniae) and the characterization of fish oil (FO) emulsion gel (EGE) containing almond shell hydrochar (AH) were investigated. Oily water of mullet liver was emulsified using tween 80, then gelled using gelatin and finally immobilized into hydrochar using an ultrasonic homogenizer. Characteristics and surface analysis of hydrochar-based emulsion gel (HEGE) were examined using FTIR and SEM. Stability, particle size distribution and zeta potential of HEGE were measured. In this study, a zeta potential of -18.46 indicated that HEGE was more stable than EGE (35.7 mV). The addition of hydrochar to the emulsion gel containing micro-droplets enabled the structure to become fully layered and stable. Time-dependent inactivation of K. pneumoniae exposed to HEGE and fixed in 6 mm-fish skin was evaluated for the first time in this study. While the highest log reduction and percent reduction in the bacterial count were achieved within 5 min with 0.87 CFU/cm2 and 86.60% with EGE, the lowest log reduction and percent reduction were achieved with 0.003 CFU/cm2 and 0.082% with HEGE in 30 min. In conclusion, the almond shell hydrochar-immobilized emulsion gel is a functional adsorbent that can inhibit K. pneumonia, and its stability and performance make it a unique candidate for further studies in this field.

Pectin wrapped halloysite nanotube reinforced Polycaprolactone films for potential wound healing application

The current research work focuses on preparing the polycaprolactone (PCL) based nanocomposite films embedded with surface modified Halloysite Nanotube (HNT). The avenue of the study is to unravel the applicability of polymer nanocomposites for wound healing. The flexible property of HNT was taken as the major force to accomplish the addition of biopolymer pectin onto its surface. Functionalization of HNT with pectin has certainly enhanced its binding nature with the polymer. The PCL nanocomposite films were characterized by several promising techniques such as FTIR, XRD, DSC-TGA, FESEM, TEM, AFM, and mechanical properties were too examined along. When compared to the plane PCL film, the nanocomposite films manifested favorable results in terms of mechanical and chemical properties. Additionally, biometric studies such as in-vitro swelling, enzymatic degradation, and hemolysis performed on the films gave extremely good results. The haemolytic percentage recorded for the films exhibited a steady decrease with increasing amount of nanofillers. The MTT assay showed cell proliferation and its increase as the embedded HNT is more in the matrix. Wound closure study performed on NIH3T3 cell line with 1, 3 and 5wt% of films has given a strong proof for the involvement of polymer and HNT in the healing procedure.

Bilayer regenerated cellulose/quaternized chitosan-hyaluronic acid/collagen electrospun scaffold for potential wound healing applications

In this study, a bilayer electrospun scaffold has been prepared using regenerated cellulose (RC)/quaternized chitosan (CS) as the primary layer and collagen/hyaluronic acid (HA) as the second layer. An approximate 48 mol% substituted (estimated from 1H NMR) quaternized CS was used in this study. Both layers were crosslinked with EDC/NHS, reflecting an increase in UTS (2.29 MPa for the bilayer scaffold compared to 1.82 MPa for the RC scaffold). Initial cell viability, cell adhesion and proliferation, FDA staining for live cells, and hydroxyproline release rate from cells were evaluated with L929 mouse fibroblast cells. Also, detailed in vitro studies were performed using HADF cells, which include MTT Assay, Live/Dead imaging, DAPI staining, gene expression of PDGF, VEGF-A, and COL1 in RT-PCR, and cell cycle analysis. The collagen/HA-based bilayer scaffold depicted a 9.76-fold increase of VEGF-A compared to a 2.1-fold increase for the RC scaffold, indicating angiogenesis and vascularization potential. In vitro scratch assay was performed to observe the migration of cells in simulated wounds. Antimicrobial, antioxidant, and protease inhibitory activity were further performed, and overall, the primary results highlighted the potential usage of bilayer scaffold in wound healing applications.

Surface modification strategies for improved hemocompatibility of polymeric materials: a comprehensive review

Polymeric biomaterials are a widely used class of materials due to their versatile properties. However, as with all other types of materials used for biomaterials, polymers also have to interact with blood. When blood comes into contact with any foreign body, it initiates a cascade which leads to platelet activation and blood coagulation. The implant surface also has to encounter a thromboinflammatory response which makes the implant integrity vulnerable, this leads to blood coagulation on the implant and obstructs it from performing its function. Hence, the surface plays a pivotal role in the design and application of biomaterials. In particular, the surface properties of biomaterials are responsible for biocompatibility with biological systems and hemocompatibility. This review provides a report on recent advances in the field of surface modification approaches for improved hemocompatibility. We focus on the surface properties of polysaccharides, proteins, and synthetic polymers. The blood coagulation cascade has been discussed and blood - material surface interactions have also been explained. The interactions of blood proteins and cells with polymeric material surfaces have been discussed. Moreover, the benefits as well as drawbacks of blood coagulation on the implant surface for wound healing purposes have also been studied. Surface modifications implemented by other researchers to enhance as well as prevent blood coagulation have also been analyzed.

A novel designed nanofibrous mat based on hydroxypropyl methyl cellulose incorporating mango peel extract for potential use in wound care system

Skin tissue is damaged by factors such as burns, physical injuries and diseases namely diabetes. Infection and non-healing of burn wounds and lack of angiogenesis in diabetic wounds lead to extensive injuries and death. Therefore, the design of wound dressings with antibacterial and restorative capabilities is very important. In this study, nanofibers (NFs) including polyurethane (PU) and hydroxypropyl methyl cellulose (HPMC) were prepared with different ratios and Mango peel extract (MPE) loaded into NFs by electrospinning method. The morphology, chemical structure, porosity, degradation, water vapor permeability, mechanical properties, wettability, antioxidant activity and some cell studies and evaluation of their antibacterial properties were investigated. The optimal mat (PU90/HPMC10) had a defect-free morphology with homogeneous NFs. Furthermore, it showed improved biodegradability, water vapor permeability and porosity compared to other Mats. All NFs were non-toxic with hydrophilic behavior in the cellular environment and had acceptable hemocompatibility. The PU90/HPMC10/20 % optimal scaffold had significantly higher cell viability and proliferation than other samples and also had a higher antibacterial ability against pathogenic bacteria S. aureus (17 mm) and E. coli (11 mm). All these findings confirm that the produced NF mats, especially those loaded with MPE, have a high potential to be used as an effective wound dressing.

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.

An Insight into Biodegradable Polymers and their Biomedical Applications for Wound Healing

Biodegradable polymers, encompassing both natural and synthetic polymers, have demonstrated efficacy as carriers for synthetic drugs, natural bioactive molecules, and inorganic metals. This is due to their ability to control the release of these substances. As a result, various advanced materials, such as nanoparticle- loaded hydrogels, nanofibrous scaffolds, and nanocomposites, have been developed. These materials have shown promise in enhancing processes, such as cell proliferation, vascular angiogenesis, hair growth, and wound healing management. Natural polymers, including hyaluronic acid, collagen, chitosan, gelatin, and alginate, as well as synthetic polymers like polylactic acid, polyglycolic acid, polylactic co-glycolic acid, and PCA, have significant potential for promoting wound healing. This study examines the advancements in biodegradable polymers for wound healing, specifically focusing on each polymer and its distinctive formulations. It also discusses the in vitro experiments conducted using different cell lines, as well as the in vivo studies that explore the numerous uses of these polymers in wound healing. The discussion also included the exploration of modifications or combinations of several polymers, as well as surface changes, in order to produce synergistic effects and address the limitations of individual polymers. The goal was to expedite the healing process of different chronic wounds. Due to this, there have been notable advancements in the technological use of polymeric mixes, including biodegradable polymer-based scaffolds, which have accelerated the process of wound healing.

Biomedical applications of electrospun polycaprolactone-based carbohydrate polymers: A review

Carbohydrate used in biomedical applications is influenced by numerous factors. One of the most appealing characteristic of carbohydrates is their ability to reproduce from natural resources which makes them ecologically friendly. Due to their abundance, biocompatibility, and no contamination by residual initiators, the desire for polysaccharides in medical uses is growing. Research on fiber-based materials, with a variety of medical applications including bio-functional scaffolds, continues to yield novel and intriguing findings. Almost all biopolymers of diverse structural compositions are electrospun to fulfill biomedical usage criteria, and the electrospinning technique is widely employed in biomedical technologies for both in-vivo and in-vitro therapies. Due to its biocompatibility and biodegradability, polycaprolactone (PCL) is employed in medical applications like tissue engineering and drug delivery. Although PCL nanofibers have established effects in vitro, more research is needed before their potential therapeutic application in the clinic. Here we tried to focus mainly on the carbohydrate incorporated PCL-based nanofibers production techniques, structures, morphology, and physicochemical properties along with their usage in biomedicine.

The effect of κ-carrageenan and ursolic acid on the physicochemical properties of the electrospun nanofibrous mat for biomedical application

Wound dressing materials such as nanofiber (NF) mats have gained a lot of attention in recent years owing to their wonderful effect on accelerating the healing process and protection of wounds. In this regard, three different types of NF mats were fabricated using pure polyvinylpyrrolidone (PVP), PVP/κ-carrageenan (KG), and ursolic acid (UA) in the optimal PVP/KG ratio by electrospinning method to apply them as wound dressings. The morphology, chemical structure, degradation, porosity, mechanical properties and antioxidant activity of the produced NFs were investigated. Moreover, cell studies (e.g., cell proliferation, adhesion, and migration) and their antibacterial properties were evaluated. Adding KG and UA reduced the mean diameter size of the PVP-based NFs to ∼98 nm in the optimal sample, with defect-free morphology. The PVP/KG/UA 0.25 % exhibited the highest porosity, hydrophilicity, and degradation rate and a wound closure rate of 60 %, 2.5 times higher than that of the control group. Furthermore, this sample's proliferation and antibacterial ability were significantly higher than the other groups. These findings confirmed that the produced UA-loaded NFs have excellent properties as wound dressing.

Cell electrospinning and its application in wound healing: principles, techniques and prospects

Currently, clinical strategies for the treatment of wounds are limited, especially in terms of achieving rapid wound healing. In recent years, based on the technique of electrospinning (ES), cell electrospinning (C-ES) has been developed to better repair related tissues or organs (such as skin, fat and muscle) by encapsulating living cells in a microfiber or nanofiber environment and constructing 3D living fiber scaffolds. Therefore, C-ES has promising prospects for promoting wound healing. In this article, C-ES technology and its advantages, the differences between C-ES and traditional ES, the parameters suitable for maintaining cytoactivity, and material selection and design issues are summarized. In addition, we review the application of C-ES in the fields of biomaterials and cells. Finally, the limitations and improved methods of C-ES are discussed. In conclusion, the potential advantages, limitations and prospects of C-ES application in wound healing are presented.

Bromelain- and Silver Nanoparticle-Loaded Polycaprolactone/Chitosan Nanofibrous Dressings for Skin Wound Healing

A cutaneous wound is caused by various injuries in the skin, which can be wrapped with an efficient dressing. Electrospinning is a straightforward adjustable technique that quickly and continuously generates nanofibrous wound dressings containing antibacterial and anti-inflammatory agents to promote wound healing. The present study investigated the physicochemical and biological properties of bromelain (BRO)- and silver nanoparticle (Ag NPs)-loaded gel-based electrospun polycaprolactone/chitosan (PCL/CS) nanofibrous dressings for wound-healing applications. Electron microscopy results showed that the obtained nanofibers (NFs) had a uniform and homogeneous morphology without beads with an average diameter of 176 ± 63 nm. The FTIR (Fourier transform infrared) analysis exhibited the loading of the components. Moreover, adding BRO and Ag NPs increased the tensile strength of the NFs up to 4.59 MPa. BRO and Ag NPs did not significantly affect the hydrophilicity and toxicity of the obtained wound dressing; however, the antibacterial activity against E. coli and S. aureus bacteria was significantly improved. The in vivo study showed that the wound dressing containing BRO and Ag NPs improved the wound-healing process within one week compared to other groups. Therefore, gel-based PCL/CS nanofibrous dressings containing BRO and Ag NPs could be a promising solution for healing skin wounds.

A bilayer biocompatible polycaprolactone/zinc oxide/Capparis spinosa L. ethyl acetate extract/polylactic acid nanofibrous composite scaffold for novel wound dressing applications

Capparis spinosa L. (CSL) is used in traditional medicinal purposes for wound dressing because it contains natural phenolic and flavonoid active compounds. In the current study, a bilayer of biocompatible and mechanically stable nanofiber scaffolds with polycaprolactone (PCL)/zinc oxide and Capparis spinosa L. ethyl acetate extract (CSLE)/polylactic acid (PLA) layers was successfully prepared by an electrostatic spinning technique. Microstructural observations carried out by scanning electron microscopy (SEM) have shown that the nanofibers with a smooth surface are continuous and bead-free, and that the size distribution is uniform, with an average diameter of 314.15 nm. The results of careful observation further suggested that polymers in the nanofibers have excellent compatibility with drugs. The results of Fourier transform infrared (FTIR) spectroscopy suggested that CSLE and zinc oxide nanoparticles (ZnO) were successfully loaded in the nanofiber membranes. Water contact angle measurements revealed that the bilayer nanofiber membranes exhibited satisfactory wettability (outside layer, 130°; inner layer, 72.4°). Tensile testing showed that the bilayer PCL/ZnO-CSLE/PLA nanofibers remained unbroken until reaching 10.69 MPa, which is much higher than the tensile strengths of the individual layers or the individual components. Moreover, agar disk diffusion assessment confirmed that the bilayer nanofiber membranes obviously hindered bacterial growth. Cytotoxicity studies showed that the bilayer nanofiber membranes effectively accelerated cell proliferation. The investigated PCL/ZnO-CSLE/PLA bilayer nanofibers have potential for use as membranes for wound dressing applications.

Topically Applied Biopolymer-Based Tri-Layered Hierarchically Structured Nanofibrous Scaffold with a Self-Pumping Effect for Accelerated Full-Thickness Wound Healing in a Rat Model

Wound healing has grown to be a significant problem at a global scale. The lack of multifunctionality in most wound dressing-based biopolymers prevents them from meeting all clinical requirements. Therefore, a multifunctional biopolymer-based tri-layered hierarchically nanofibrous scaffold in wound dressing can contribute to skin regeneration. In this study, a multifunctional antibacterial biopolymer-based tri-layered hierarchically nanofibrous scaffold comprising three layers was constructed. The bottom and the top layers contain hydrophilic silk fibroin (SF) and fish skin collagen (COL), respectively, for accelerated healing, interspersed with a middle layer of hydrophobic poly-3-hydroxybutyrate (PHB) containing amoxicillin (AMX) as an antibacterial drug. The advantageous physicochemical properties of the nanofibrous scaffold were estimated by SEM, FTIR, fluid uptake, contact angle, porosity, and mechanical properties. Moreover, the in vitro cytotoxicity and cell healing were assessed by MTT assay and the cell scratching method, respectively, and revealed excellent biocompatibility. The nanofibrous scaffold exhibited significant antimicrobial activity against multiple pathogenic bacteria. Furthermore, the in vivo wound healing and histological studies demonstrated complete wound healing in wounded rats on day 14, along with an increase in the expression level of the transforming growth factor-β1 (TGF-β1) and a decrease in the expression level of interleukin-6 (IL-6). The results revealed that the fabricated nanofibrous scaffold is a potent wound dressing scaffold, and significantly accelerates full-thickness wound healing in a rat model.

A Biomimetic, Bilayered Antimicrobial Collagen-Based Scaffold for Enhanced Healing of Complex Wound Conditions

Chronic, nonhealing wounds in the form of diabetic foot ulcers (DFUs) are a major complication for diabetic patients. The inability of a DFU to heal appropriately leads to an open wound with a high risk of infection. Current standards of care fail to fully address either the underlying defective wound repair mechanism or the risk of microbial infection. Thus, it is clear that novel approaches are needed. One such approach is the use of multifunctional biomaterials as platforms to direct and promote wound healing. In this study, a biomimetic, bilayered antimicrobial collagen-based scaffold was developed to deal with the etiology of DFUs. An epidermal, antimicrobial collagen/chitosan film for the prevention of wound infection was combined with a dermal collagen-glycosaminoglycan scaffold, which serves to support angiogenesis in the wound environment and ultimately accelerate wound healing. Biophysical and biological characterization identified an 1-ethyl-3-(3-(dimethylamino)propyl)carbodiimide cross-linked bilayered scaffold to have the highest structural stability with similar mechanical properties to products on the market, exhibiting a similar structure to native skin, successfully inhibiting the growth and infiltration of Staphylococcus aureus and supporting the proliferation of epidermal cells on its surface. This bilayered scaffold also demonstrated the ability to support the proliferation of key cell types involved in vascularization, namely, induced pluripotent stem cell derived endothelial cells and supporting stromal cells, with early signs of organization of these cells into vascular structures, showing great promise for the promotion of angiogenesis. Taken together, the results indicate that the bilayered scaffold is an excellent candidate for enhancement of diabetic wound healing by preventing wound infection and supporting angiogenesis.

Effects of surface patterning and topography on the cellular functions of tissue engineered scaffolds with special reference to 3D bioprinting

The extracellular matrix (ECM) of the tissue organ exhibits a topography from the nano to micrometer range, and the design of scaffolds has been inspired by the host environment. Modern bioprinting aims to replicate the host tissue environment to mimic the native physiological functions. A detailed discussion on the topographical features controlling cell attachment, proliferation, migration, differentiation, and the effect of geometrical design on the wettability and mechanical properties of the scaffold are presented in this review. Moreover, geometrical pattern-mediated stiffness and pore arrangement variations for guiding cell functions have also been discussed. This review also covers the application of designed patterns, gradients, or topographic modulation on 3D bioprinted structures in fabricating the anisotropic features. Finally, this review accounts for the tissue-specific requirements that can be adopted for topography-motivated enhancement of cellular functions during the fabrication process with a special thrust on bioprinting.

Preparation and application of chitosan-based medical electrospun nanofibers

Chitosan is a kind of polysaccharide cationic polymer, which has excellent biocompatibility, biodegradability and biological activity. In recent years, chitosan has been widely used as medical materials because of its non-toxicity, non-immunogenicity and rich sources. This paper reviews chitosan chemistry, the basic principles and influence of electrospinning technology, the blending of chitosan with polyethylene oxide, polyvinyl alcohol, polycaprolactone, polylactic acid, protein, polysaccharide and other polymer materials, the blending of chitosan with oxides, metals, carbon-based and other inorganic substances for electrospinning, the application of chitosan electrospinning nanofibers in medical field and its mechanism in clinical application. In order to provide reference for the in-depth study of electrospinning technology in the field of medical and health.

Electrospinning of Potential Medical Devices (Wound Dressings, Tissue Engineering Scaffolds, Face Masks) and Their Regulatory Approach

Electrospinning is the simplest and most widely used technology for producing ultra-thin fibers. During electrospinning, the high voltage causes a thin jet to be launched from the liquid polymer and then deposited onto the grounded collector. Depending on the type of the fluid, solution and melt electrospinning are distinguished. The morphology and physicochemical properties of the produced fibers depend on many factors, which can be categorized into three groups: process parameters, material properties, and ambient parameters. In the biomedical field, electrospun nanofibers have a wide variety of applications ranging from medication delivery systems to tissue engineering scaffolds and soft electronics. Many of these showed promising results for potential use as medical devices in the future. Medical devices are used to cure, prevent, or diagnose diseases without the presence of any active pharmaceutical ingredients. The regulation of conventional medical devices is strict and carefully controlled; however, it is not yet properly defined in the case of nanotechnology-made devices. This review is divided into two parts. The first part provides an overview on electrospinning through several examples, while the second part focuses on developments in the field of electrospun medical devices. Additionally, the relevant regulatory framework is summarized at the end of this paper.

Spray nebulization enables polycaprolactone nanofiber production in a manner suitable for generation of scaffolds or direct deposition of nanofibers onto cells

Spray nebulization is an elegant, but relatively unstudied, technique for scaffold production. Herein we fabricated mesh scaffolds of polycaprolactone (PCL) nanofibers via spray nebulization of 8% PCL in dichloromethane (DCM) using a 55.2 kPa compressed air stream and 17 ml h-1polymer solution flow rate. Using a refined protocol, we tested the hypothesis that spray nebulization would simultaneously generate nanofibers and eliminate solvent, yielding a benign environment at the point of fiber deposition that enabled the direct deposition of nanofibers onto cell monolayers. Nanofibers were collected onto a rotating plate 20 cm from the spray nozzle, but could be collected onto any static or moving surface. Scaffolds exhibited a mean nanofiber diameter of 910 ± 190 nm, ultimate tensile strength of 2.1 ± 0.3 MPa, elastic modulus of 3.3 ± 0.4 MPa, and failure strain of 62 ± 6%.In vitro, scaffolds supported growth of human keratinocyte cell epithelial-like layers, consistent with potential utility as a dermal scaffold. Fourier-transform infrared spectroscopy demonstrated that DCM had vaporized and was undetectable in scaffolds immediately following production. Exploiting the rapid elimination of DCM during fiber production, we demonstrated that nanofibers could be directly deposited on to cell monolayers, without compromising cell viability. This is the first description of spray nebulization generating nanofibers using PCL in DCM. Using this method, it is possible to rapidly produce nanofiber scaffolds, without need for high temperatures or voltages, yielding a method that could potentially be used to deposit nanofibers onto cell cultures or wound sites.

Recent advancement of nanotherapeutics in accelerating chronic wound healing process for surgical wounds and diabetic ulcers

One of the greatest challenges faced during surgical procedures is closing and healing of wounds, which are essential in the field of orthopaedics, trauma, intensive care and general surgery. One of the main causes of death has been linked to chronic wounds, especially in immunosuppressant or diabetic patients. Due to increasing chronic wound fatality along with different pathologies associated with them, the current therapeutic methods are insufficient which has established an eminent need for innovative techniques. Traditionally, wound healing was carried out using formulations and ointments containing silver combined with different biomaterial, but was found to be toxic. Hence, the advent of alternative nanomaterial-based therapeutics for effective wound healing have come into existence. In this review, we have discussed an overview of wound infections such as different wound types, the wound healing process, dressing of wounds and conventional therapies. Furthermore, we have explored various nanotechnological advances made in wound healing therapy which include the use of promising candidates such as organic, inorganic, hybrid nanoparticles/nanocomposites and synthetic/natural polymer-based nanofibers. This review further highlights nanomaterial-based applications for regeneration of tissue in wound healing and can provide a base for researchers worldwide to contribute to this advancing medical area of wound therapy.

Comparison of biopolymer scaffolds for the fabrication of skin substitutes in a porcine wound model

This study compared three acellular scaffolds as templates for the fabrication of skin substitutes. A collagen-glycosaminoglycan (C-GAG), a biodegradable polyurethane foam (PUR) and a hybrid combination (PUR/C-GAG) were investigated. Scaffolds were prepared for cell inoculation. Fibroblasts and keratinocytes were serially inoculated onto the scaffolds and co-cultured for 14 days before transplantation. Three pigs each received four full-thickness 8 cm × 8 cm surgical wounds, into which a biodegradable temporising matrix (BTM) was implanted. Surface seals were removed after integration (28 days), and three laboratory-generated skin analogues and a control split-thickness skin graft (STSG) were applied for 16 weeks. Punch biopsies confirmed engraftment and re-epithelialisation. Biophysical wound parameters were also measured and analysed. All wounds showed greater than 80% epithelialisation by day 14 post-transplantation. The control STSG displayed 44% contraction over the 16 weeks, and the test scaffolds, C-GAG 64%, Hybrid 66.7% and PUR 67.8%. Immunohistochemistry confirmed positive epidermal keratins and basement membrane components (Integrin alpha-6, collagens IV and VII). Collagen deposition and fibre organisation indicated the degree of fibrosis and scar produced for each graft. All scaffold substitutes re-epithelialised by 4 weeks. The percentage of original wound area for the Hybrid and PUR was significantly different than the STSG and C-GAG, indicating the importance of scaffold retainment within the first 3 months post-transplant. The PUR/C-GAG scaffolds reduced the polymer pore size, assisting cell retention and reducing the contraction of in vitro collagen. Further investigation is required to ensure reproducibility and scale-up feasibility.

Evaluation of poly(N-isopropylacrylamide)/tetraphenylethylene/amphotericin B-based visualized antimicrobial nanofiber wound dressing for whole skin wound healing in rats

The aim of this work is to develop a novel nanofiber wound dressing with multiple functional properties that combines suitable mechanical properties, slow and controlled drug release, antifungal activity, and visual drug monitoring to accelerate wound healing while reducing systemic circulation of the drug, achieving reduced dose and side effects, and achieving patient satisfaction and compliance. In this paper, visualized nanofiber films were prepared using electrostatic spinning technology. This nanofiber wound dressing has soft tissue-like mechanical and antifungal properties and is biocompatible. In particular, the poly(N-isopropylacrylamide) (PNIPAAm)/tetraphenylethylene (TPE)/amphotericin B (AMB) nanofiber films showed good performance in terms of antifungal activity and cytocompatibility compared with medical gauze, and significantly accelerated the wound healing process in a mouse total wound defect model with PCL+PVP+TPE+AMB+PNIPAAm. The wound healing rate of nanofibrous membrane group was 100% at 14 days. In addition, histological analysis, collagen deposition and immunohistochemistry showed, for example, fewer inflammatory cells, more fibroblasts around the damaged area, increased wound epithelial atrophy, reduced granulation tissue, connective tissue reconstruction, epithelial tissue formation, and abundant small angiogenesis in the dermis near the epidermis; a higher level of collagen deposition fraction of 49.97%; and a simultaneous reduction in HIF-1α production and upregulated the expression of CD31. In conclusion, this antifungal nanofiber film showed promising applications throughout the skin wound healing process.

Development of bioactive electrospun scaffolds suitable to support skin fibroblasts and release Lucilia sericata maggot excretion/secretion

Larval therapy has been reported to be beneficial in the treatment of chronic wounds by promoting granulation tissue formation, due to its antimicrobial properties and by degrading necrotic tissue. However, the use of live maggots is problematic for patient acceptance, and thus there is a need to develop materials which can release therapeutic biomolecules derived from maggot secretions to the wound bed. Here we describe the fabrication of a novel bioactive scaffold that can be loaded with Lucilia sericata maggot alimentary excretion/secretion fluids (L. sericata maggot E/S), and which can also provide structural stability for mammalian cell-growth and migration to support wound repair. Electrospun scaffolds were prepared from a poly(caprolactone)-poly(ethylene glycol)–block copolymer (PCL-b-PEG) blended with PCL with average fibre diameters of ~ 4 μm. The scaffolds were hydrophilic and were able to support viable fibroblasts that were able to infiltrate throughout the extent of the scaffold thickness. L. sericata maggot (E/S) was subsequently adsorbed to the surface and released over 21 days with retention of the protease activity that is responsible for supporting fibroblast migration. The incorporation of L. sericata maggot E/S on the surface of the electrospun fibres of PCL-PEG/PCL fibres is a novel approach with potential for future application to support skin wound healing within a clinical setting.

Hyaluronic Acid in Biomedical Fields: New Trends from Chemistry to Biomaterial Applications

The aim of this review is to give an updated perspective about the methods for chemical modifications of hyaluronic acid (HA) toward the development of new applications in medical devices and material engineering. After a brief introduction on chemical, structural and biological features of this important natural polysaccharide, the most important methods for chemical and physical modifications are disclosed, discussing both on the formation of new covalent bonds and the interaction with other natural polysaccharides. These strategies are of paramount importance in the production of new medical devices and materials with improved properties. In particular, the use of HA in the development of new materials by means of additive manufacturing techniques as electro fluid dynamics, i.e., electrospinning for micro to nanofibres, and three-dimensional bioprinting is also discussed.

Rheological, Surface Tension and Conductivity Insights on the Electrospinnability of Poly(lactic-co-glycolic acid)-hyaluronic Acid Solutions and Their Correlations with the Nanofiber Morphological Characteristics

In this study, solutions were prepared with fixed concentrations of hyaluronic acid (HA) but varied concentrations of poly (lactic-co-glycolic acid) (PLGA) to emphasize the effects of PLGA concentration and HA addition on solution properties and to further evaluate their electrospinning performance. The dependence of specific viscosity on PLGA concentration was studied to determine the concentration regimes and evaluate the critical concentration (C_e) for successful fiber generation. The C_e of PLGA solutions is 12.07% compared to 10.09% for PLGA-HA solutions. Blending with HA results in a lower concentration dependence and better consistency to the theoretical scaling mechanisms due to the additional topological constrains, which thus result in more chain entanglements. Solutions in semi-dilute entangled regimes show the crossover of complex moduli, verifying the stable and reliable entanglement network. Higher concentrations and HA addition both led to lower crossover frequencies and, thus, a longer relaxation time. The effects of a higher PLGA concentration and HA addition on the surface tension were not evident. However, the HA addition significantly improved the solution conductivity up to three times in the pure PLGA solutions due to its polyelectrolyte nature. Defect-free and uniform nanofibers were generated from 35% to 40% of the PLGA-HA solutions, yet fibers with bead-on-string structures were produced from all studied pure PLGA solutions. Such solution characteristics and parametric correlations can provide predictive insights on tailoring the morphological characteristics of nanofibers for specific applications.

Elastin-Hyaluronan Bioconjugate as Bioactive Component in Electrospun Scaffolds

Hyaluronic acid or hyaluronan (HA) and elastin-inspired peptides (EL) have been widely recognized as bioinspired materials useful in biomedical applications. The aim of the present work is the production of electrospun scaffolds as wound dressing materials which would benefit from synergic action of the bioactivity of elastin peptides and the regenerative properties of hyaluronic acid. Taking advantage of thiol-ene chemistry, a bioactive elastin peptide was successfully conjugated to methacrylated hyaluronic acid (MAHA) and electrospun together with poly-D,L-lactide (PDLLA). To the best of our knowledge, limited reports on peptide-conjugated hyaluronic acid were described in literature, and none of these was employed for the production of electrospun scaffolds. The conformational studies carried out by Circular Dichroism (CD) on the bioconjugated compound confirmed the preservation of secondary structure of the peptide after conjugation while Scanning Electron Microscopy (SEM) revealed the supramolecular structure of the electrospun scaffolds. Overall, the study demonstrates that the bioconjugation of hyaluronic acid with the elastin peptide improved the electrospinning processability with improved characteristics in terms of morphology of the final scaffolds.

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.

Protein and polysaccharide-based asymmetric mat with tuned bilayer configuration for enhanced wound healing efficiency

In this research we focused on the fabrication of an asymmetric bilayer membrane with core-shell/simple layer configuration providing the functions of needed hierarchically hydrophilicity and porosity, anti-infectious, tissue adhesion as well as degradation and integration with tissue, cells proliferation, and enhanced promotion of tissue regeneration. The bilayer membrane composed of collagen (Col), chitosan (CS), aloe vera (AV) and gelatin (Gel), not only simulates the features of the epidermis and dermis layer of a natural skin but also benefits from the materials necessary for the regeneration of injured skin tissue during the healing process. The results of full-thickness skin wound evaluation revealed that the fabricated asymmetric membrane could facilitate wound healing within 10 days mainly through enhancing cellular activities, enhancing collagen deposition, and promoting proliferation. Results of histopathological analysis and immunohistochemistry after 10 days of treatment, demonstrated more re-epithelialization and collagen density for the treated groups compared to the control group.

Research Progress on Emerging Polysaccharide Materials Applied in Tissue Engineering

The development and application of polysaccharide materials are popular areas of research. Emerging polysaccharide materials have been widely used in tissue engineering fields such as in skin trauma, bone defects, cartilage repair and arthritis due to their stability, good biocompatibility and reproducibility. This paper reviewed the recent progress of the application of polysaccharide materials in tissue engineering. Firstly, we introduced polysaccharide materials and their derivatives and summarized the physicochemical properties of polysaccharide materials and their application in tissue engineering after modification. Secondly, we introduced the processing methods of polysaccharide materials, including the processing of polysaccharides into amorphous hydrogels, microspheres and membranes. Then, we summarized the application of polysaccharide materials in tissue engineering. Finally, some views on the research and application of polysaccharide materials are presented. The purpose of this review was to summarize the current research progress on polysaccharide materials with special attention paid to the application of polysaccharide materials in tissue engineering.

Silver Ion Loaded Agarose-Hyaluronic Acid Hydrogel as a Potential Antibacterial Wound Dressing

Wound infection, especially chronic ones, not only increases the opportunity to generate superbacteria but also imposes significant burden, both physically and mentally, on the patients. Therefore, the development of suitable wound addressing is an important way to deal with this matter. Here in this study, we employed the good gelling property of agarose (AR) and the wound healing promotion effect of hyaluronic acid (HA) to prepare an agarose-hyaluronic acid hydrogel. The AR-HA gel was loaded with silver ion (Ag+ from AgNO3) upon gelling (AR-HA/Ag) and finally applied as a potential wound dressing for antibacterial treatment and healing promotion of wounds. Our results suggested that the AR-HA/Ag hydrogel maintained the antibacterial efficacy of Ag+ while significantly promoted the healing of human umbilical vein endothelial cells (HUVEC) due to the cell proliferation promotion effect of HA. Taken together, AR-HA/Ag might be a potential antibacterial wound dressing for future application in clinic.