Synthetic polymeric biomaterials for wound healing: a review

Polyurethane-Nanolignin Composite Foam Coated with Propolis as a Platform for Wound Dressing: Synthesis and Characterization

This piece of research explores porous nanocomposite polyurethane (PU) foam synthesis, containing nanolignin (NL), coated with natural antimicrobial propolis for wound dressing. PU foam was synthesized using polyethylene glycol, glycerol, NL, and 1, 6-diisocyanato-hexane (NCO/OH ratio: 1.2) and water as blowing agent. The resultant foam was immersed in ethanolic extract of propolis (EEP). PU, NL-PU, and PU-NL/EEP foams were characterized from mechanical, morphological, and chemical perspectives. NL Incorporation into PU increased mechanical strength, while EEP coating showed lower strength than PU-NL/EEP. Morphological investigations confirmed an open-celled structure with a pore diameter of 150-200 μm, a density of nearly 0.2 g/cm3,, and porosity greater than 85%, which led to significantly high water absorption (267% for PU-NL/EEP). The hydrophilic nature of foams, measured by the contact angle, proved to be increased by NL addition and EEP coating. PU and PU-NL did not show important antibacterial features, while EEP coating resulted in a significant antibacterial efficiency. All foams revealed high biocompatibility toward L929 fibroblasts, with the highest cell viability and cell attachment for PU-NL/EEP. In vivo wound healing using Wistar rats' full-thickness skin wound model confirmed that PU-NL/EEP exhibited an essentially higher wound healing efficacy compared with other foams. Hence, PU-NL/EEP foam could be a promising wound dressing candidate.

Photocrosslinking silver nanoparticles-aloe vera-silk fibroin composite hydrogel for treatment of full-thickness cutaneous wounds

Damage to the skin causes physiological and functional issues. The most effective treatment approach is the use of wound dressings. Silk fibroin (SF) is a promising candidate biomaterial for regulating wound healing; however, its antibacterial properties and biological activity must be further improved. In this study, a photocrosslinking hydrogel was developed to treat full-thickness cutaneous wounds. The composite hydrogel (Ag–AV–SF hydrogel) was prepared by introducing the silver nanoparticles (AgNPs) and aloe vera (AV) as the modifiers. In vitro study exhibited great antibacterial ability, biocompatibility and cell-proliferation and -migration-promoting capacities. It also showed the pH-response releasing properties which release more AgNPs in a simulated chronic infection environment. The healing effect evaluation in vivo showed the healing-promoting ability of the Ag–AV–SF hydrogel was stronger than the single-modifiers groups, and the healing rate of it reached 97.02% on Day 21, higher than the commercial wound dressing, silver sulfadiazine (SS) cream on sale. Additionally, the histological and protein expression results showed that the Ag–AV–SF hydrogel has a greater effect on the pro-healing regenerative phenotype with M2 macrophages at the early stage, reconstructing the blood vessels networks and inhibiting the formation of scars. In summary, the Ag–AV–SF hydrogel developed in this study had good physical properties, overwhelming antibacterial properties, satisfactory biocompatibility and significantly promoting effect on cell proliferation, migration and wound healing. Overall, our results suggest that the Ag–AV–SF hydrogel we developed has great potential for improving the wound healing in clinical treatment.

A Critical Review on Polymeric Biomaterials for Biomedical Applications

Natural and synthetic polymers have been explored for many years in the field of tissue engineering and regeneration. Researchers have developed many new strategies to design successful advanced polymeric biomaterials. In this review, we summarized the recent notable advancements in the preparation of smart polymeric biomaterials with self-healing and shape memory properties. We also discussed novel approaches used to develop different forms of polymeric biomaterials such as films, hydrogels and 3D printable biomaterials. In each part, the applications of the biomaterials in soft and hard tissue engineering with their in vitro and in vivo effects are underlined. The future direction of the polymeric biomaterials that could pave a path towards successful clinical implications is also underlined in this review.

Healing Effects of Human Amniotic Membrane and Burned Wool on the Second-degree Burn in Rats

Background:

This study aimed to compare sheep burnt wool and human amniotic membrane (AM) on second-degree burn wound healing in rats.

Materials and Methods:

Seventy-two adult male rats of Sprague Dawley underwent general anesthesia, and a deep second-degree burn was created on their skin by a hot iron plate. Afterward, human AM, silver sulfadiazine ointment (SSD), and sheep burned wool were used on wound area for burn treatment. On days 7, 14, and 21 of the experiment, the rats were sacrificed, and histopathological assessments were done.

Results:

Human AM, in comparison with other groups, significantly (P<0.05) showed better improvement in all pathologic variables. Burned wool showed significant improvement compared to the control group on day 7 in the angiogenesis, on day 14 in granulation tissue formation and epithelial formation, and on day 21 in new epithelial formation (P<0.05). Burned wool compared with SSD ointment in granulation tissue formation improved significantly (P<0.05) on days 7 and 14. Also, SSD ointment in comparison with the control group significantly improved (P<0.05) granulation tissue formation and macrophage on day 7.

Conclusion:

Human AM has a significant effect on the treatment of second-degree burn. Burned wool has a better effect on wound healing than SSD ointment and negative control group without treatment in terms of granulation tissue and epithelium formation.

Development of Spanish Broom and Flax Dressings with Glycyrrhetinic Acid-Loaded Films for Wound Healing: Characterization and Evaluation of Biological Properties

The selection of an appropriate dressing for each type of wound is a very important procedure for a faster and more accurate healing process. So, the aim of this study was to develop innovative Spanish Broom and flax wound dressings, as alternatives to cotton used as control, with polymeric films containing glycyrrhetinic acid (GA) to promote wound-exudate absorption and the healing process. The different wound dressings were prepared by a solvent casting method, and characterized in terms of drug loading, water uptake, and in vitro release. Moreover, biological studies were performed to evaluate their biocompatibility and wound-healing efficacy. Comparing the developed wound dressings, Spanish Broom dressings with GA-loaded sodium hyaluronate film had the best functional properties, in terms of hydration ability and GA release. Moreover, they showed a good biocompatibility, determining a moderate induction of cell proliferation and no cytotoxicity. In addition, the wound-healing test revealed that the Spanish Broom dressings promoted cell migration, further facilitating the closure of the wound.

Preparation and characterization of a novel polysialic acid/gelatin composite hydrogels cross-linked by tannic acid to improve wound healing after cesarean section dressing

The infections and delayed wound healing after cesarean delivery is one of the most complicated issues in surgical medicinal field. In the present investigation, designed novel polysialic acid loaded gelatin (PSA-Gel) composite hydrogels cross-linked by tannic acid (TA) has been developed and used as a facile wound dressing to improve cesarean wound healing ability with prevent bactericidal infections. The cross-linking effect was predominant when the TA content was lower, resulting in the formation of a cross-linked network. An effective TA cross-linking effect on the PSA-Gel hydrogel matrix was achieved when the amount of TA was around 15 wt %. The morphology of as-fabricated hydrogels was characterized using scanning electron microscopy (SEM) with an average pore sizes of PSA-Gel, PSA-Gel-TA-5%, PSA-Gel-TA-10%, and PSA-Gel-TA-15% hydrogels were 95.4 ± 12.6 μm, 120.4 ± 8.2 μm, 165.3 ± 21.6 μm, and 270.2 ± 32.5 μm, respectively. The effects of hydrogels on the swelling ratio, in vitro degradation, and mechanical properties were systemically evaluated. The TA cross-linked PSA-Gel hydrogels display strong antimicrobial behavior against gram-positive (Staphylococcus aureus) gram-negative (Escherichia coli) bacteria strains. Moreover, PSA-Gel-TA hydrogels also displayed favorable cytotoxicity toward L929 fibroblast cell lines. Finally, the therapeutic and wound healing potential of the PSA-Gel-TA hydrogels has been studied in vivo using the excision wound model in rats. The results indicate that the PSA-Gel-TA hydrogels have a greater and significant effect on wound closure and increased the wound healing rate compared with native PSA-Gel hydrogels and untreated control group at 94%, 73% and 65% on day 21. The findings suggest that PSA-Gel-TA hydrogels are promising dressing materials for the treatment of wound healing.

In vitro biocompatibility and wound healing properties of latex proteins dressing

The chronification of ulcers or sores may result in a dramatic outcome such as amputation. Currently, the search for plant based treatments of various diseases/disorders, including complicated ones, is getting the attention of researchers worldwide. The soluble latex protein fraction (CpLP) obtained from Calotropis procera (Apocynaceae) was previously demonstrated to accelerate wound healing by topical application or when incorporated in a polyvinyl alcohol biomembrane (BioMemCpLP). Here, in vitro assays were performed to investigate and characterize the biocompatibility and bioactivity of latex proteins dressing. Macrophages (RAW 264.7), fibroblasts (L929) and keratinocytes (HaCaT) cell lines were used to evaluate the effect of CpLP. These cell lines were exposed to concentrations of CpLP comparable to those found in BioMemCpLP during 24-72 h. The cytotoxicity, proliferation, release of wound healing mediators (TGF-β, VEGF, IL-10, IL-6, IL-1β, TNF-α and NO) and migration of cells (E-cadherin and β-catenin) incubated with CpLP was assessed and the cell adhesion to BioMemCpLP as well. The results showed that CpLP has no cytotoxic effects. It induced a suitable balance between pro- and anti-inflammatory mediators, enhanced proliferation and re-epithelialization in all cell lines, but the intensity of each effect was different at various doses in all cell strains. The BioMemCpLP stimulated cell adhesion to PVA substrate. The CpLP-PVA based biomembrane can be a good option for healing of different wounds.

Skin wounds, the healing process, and hydrogel-based wound dressings: a short review

Skin wounds are damage to the epithelial layer and the integrity of living tissue. The healing mechanism is dynamic and complex, and often treatments with wound dressings help in tissue regeneration, reducing the risk of infections. Polymeric hydrogels become good candidates for wet curing process. These materials prevent dehydration of the tissue and avoid discomfort to the patient when changing the dressing. In this short review, we demonstrate the importance of the healing process, the types of skin wounds, and the hydrogels that are potentially attractive as wound dressings.

Chitosan/Hyaluronic acid/Alginate and an assorted polymers loaded with honey, plant, and marine compounds for progressive wound healing-Know-how

Biomaterials are being extensively used in regenerative medicine including tissue engineering applications, as these enhance tissue development, repair, and help in the process of angiogenesis. Wound healing is a crucial biological process of regeneration of ruptured tissue after getting injury to the skin and other soft tissue in humans and animals. Besides, the accumulation of microbial biofilms around the wound surface can increase the risk and physically obstruct the wound healing activity, and may even lead to amputation. Hence, in both acute and chronic wounds, prominent biomaterials are required for wound healing along with antimicrobial agents. This review comprehensively addresses the antimicrobial and wound healing effects of chitosan, chitin, cellulose acetate, hyaluronic acid, pullulan, bacterial cellulose, fibrin, alginate, etc. based wound dressing biomaterials fabricated with natural resources such as honey, plant bioactive compounds, and marine-based polymers. Due to their excellent biocompatibility and biodegradability, bioactive compounds derived from honey, plants, and marine resources are commonly used in biomedical and tissue engineering applications. Different types of polymer-based biomaterials including hydrogel, film, scaffold, nanofiber, and sponge dressings fabricated with bioactive agents including honey, curcumin, tannin, quercetin, andrographolide, gelatin, carrageenan, etc., can exhibit significant wound healing process in, diabetic wounds, diabetic ulcers, and burns, and help in cartilage repair along with good biocompatibility and antimicrobial effects. Among the reviewed biomaterials, carbohydrate polymers such as chitosan-based biomaterials are prominent and widely used for wound healing applications followed by hyaluronic acid and alginate-based biomaterials loaded with honey, plant, and marine compounds. This review first provides an overview of the vast natural resources used to formulate different biomaterials for the treatment of antimicrobial, acute, and chronic wound healing processes.

Improvement of the Wound-Healing Process by Curcumin-Loaded Chitosan/Collagen Blend Electrospun Nanofibers: In Vitro and In Vivo Studies

Chronic wounds have become a major health problem worldwide. Curcumin (Cur), with strong anti-inflammatory and anti-infective properties, is introduced as a unique molecule for wound dressing applications. In the present study, Cur-loaded chitosan/poly(ethylene oxide)/collagen (Cho/PEO/Col) nanofibers were developed for wound dressing applications by the blend-electrospinning process. Structural, mechanical, and biological properties of nanofibers were evaluated using SEM, FTIR, tensile testing, in vitro release study, Alamar blue cytotoxicity assay, and in vivo study in a rat model. According to the results, Cur was successfully released up to 3 days without any significant cytotoxicity of the above hybrid to human dermal fibroblasts. In vivo studies on full-thickness wounds in the rat model indicated significant improvement in the mean wound area closure by applying Cur-loaded Cho/PEO/Col nanofibers. The electrospun Cho/PEO/Col nanofibers loaded with Cur could be considered as a promising type of wound dressing in the wound-healing process.

Nanomaterials in Skin Regeneration and Rejuvenation

Skin is the external part of the human body; thus, it is exposed to outer stimuli leading to injuries and damage, due to being the tissue mostly affected by wounds and aging that compromise its protective function. The recent extension of the average lifespan raises the interest in products capable of counteracting skin related health conditions. However, the skin barrier is not easy to permeate and could be influenced by different factors. In the last decades an innovative pharmacotherapeutic approach has been possible thanks to the advent of nanomedicine. Nanodevices can represent an appropriate formulation to enhance the passive penetration, modulate drug solubility and increase the thermodynamic activity of drugs. Here, we summarize the recent nanotechnological approaches to maintain and replace skin homeostasis, with particular attention to nanomaterials applications on wound healing, regeneration and rejuvenation of skin tissue. The different nanomaterials as nanofibers, hydrogels, nanosuspensions, and nanoparticles are described and in particular we highlight their main chemical features that are useful in drug delivery and tissue regeneration.

Hyaluronan as a Prominent Biomolecule with Numerous Applications in Medicine

Hyaluronan (HA) is a natural glycosaminoglycan present in many tissues of all vertebrates. HA has various biological functions, which are dependent on its molar mass. High-molar-mass HA has anti-angiogenic, immunosuppressive and anti-inflammatory properties, while low-molar-mass HA has opposite effects. HA has also antioxidative properties, however on the other hand it can be readily degraded by reactive oxygen species. For many years it has been used in treatment of osteoarthritis, cosmetics and in ophthalmology. In the last years there has been a growing interest of HA to also be applied in other fields of medicine such as skin wound healing, tissue engineering, dentistry and gene delivery. In this review we summarize information on modes of HA administration, properties and effects of HA in various fields of medicine including recent progress in the investigation of HA.

Polymer-Based Scaffolds Loaded with Aloe vera Extract for the Treatment of Wounds

The treatment of wounds is one challenging biomedical field due to delayed wound healing common in chronic wounds. Several factors delay wound healing, including microbial infections, malnutrition, underlying physiological conditions, etc. Most of the currently used wound dressing materials suffer from poor antimicrobial properties, poor biodegradability and biocompatibility, and weak mechanical performance. Plant extracts, such as Aloe vera, have attracted significant attention in wound management because of their interesting biological properties. Aloe vera is composed of essential constituents beneficial for the wound healing process, such as amino acids, vitamins C and E, and zinc. Aloe vera influences numerous factors that are involved in wound healing and stimulates accelerated healing. This review reports the therapeutic outcomes of aloe vera extract-loaded polymer-based scaffolds in wound management.

6-deoxy-aminocellulose derivatives embedded soft gelatin methacryloyl (GelMA) hydrogels for improved wound healing applications: In vitro and in vivo studies

Hydrogels were prepared by mixing protein and carbohydrate-based biopolymers to increase the mechanical properties and efficient cell adhesion and proliferation for wound healing applications. Microcrystalline cellulose (MCC) and its 6-deoxy-aminocellulose derivatives (6-deoxy-6-hydrazide Cellulose (Cell-Hyd), 6-deoxy-6-diethylamide Cellulose (Cell-DEA), and 6-deoxy-6-diethyltriamide Cellulose (Cell-DETA)) were embedded in methacrylated gelatin (GelMA). GelMA and 6-deoxy-aminocellulose derivatives were synthesized and characterized by spectroscopic techniques. MCC and cellulose derivatives embedded GelMA gels were characterized by FTIR, SEM and Tensile mechanical testing. SEM images revealed that, porosity of the amine MCC incorporated GelMA was decreased compared to GelMA and MCC incorporated GelMA. Tensile strain of GelMA 61.30% at break was increased to 64.3% in case of GelMA/Cell-HYD. In vitro cytocompatibility and cell proliferation using NIH-3T3 cell lines showed cell density trend on scaffold as GelMA/Cell-DETA>GelMA/Cell-Hyd > GelMA. Scratch assay for wound healing revealed that GelMA/Cell-DETA showed complete wound closure, while GelMA/Cell-Hyd and GelMA exhibited 85.7%, and 66.1% wound healing, respectively in 8 h. In vivo tests on rats revealed that GelMA/Cell-DETA exhibited 98% wound closure on day 9, whereas GelMA/Cell-Hyd exhibited 97.7% and GelMA 66.1% wound healing on day 14. Our findings revealed that GelMA embedded amine MCC derivatives hydrogels can be applied for achieving accelerated wound healing.

Biopolymer and Synthetic Polymer-Based Nanocomposites in Wound Dressing Applications: A Review

Biopolymers are materials obtained from a natural origin, such as plants, animals, microorganisms, or other living beings; they are flexible, elastic, or fibrous materials. Polysaccharides and proteins are some of the natural polymers that are widely used in wound dressing applications. In this review paper, we will provide an overview of biopolymers and synthetic polymer-based nanocomposites, which have promising applications in the biomedical research field, such as wound dressings, wound healing, tissue engineering, drug delivery, and medical implants. Since these polymers have intrinsic biocompatibility, low immunogenicity, non-toxicity, and biodegradable properties, they can be used for various clinical applications. The significant advancements in materials research, drug development, nanotechnology, and biotechnology have laid the foundation for changing the biopolymeric structural and functional properties. The properties of biopolymer and synthetic polymers were modified by blending them with nanoparticles, so that these materials can be used as a wound dressing application. Recent wound care issues, such as tissue repairs, scarless healing, and lost tissue integrity, can be treated with blended polymers. Currently, researchers are focusing on metal/metal oxide nanomaterials such as zinc oxide (ZnO), cerium oxide (CeO₂), silver (Ag), titanium oxide (TiO₂), iron oxide (Fe₂O₃), and other materials (graphene and carbon nanotubes (CNT)). These materials have good antimicrobial properties, as well as action as antibacterial agents. Due to the highly antimicrobial properties of the metal/metal oxide materials, they can be used for wound dressing applications.

Classification and Production of Polymeric Foams among the Systems for Wound Treatment

This work represents an overview on types of wounds according to their definition, classification and dressing treatments. Natural and synthetic polymeric wound dressings types have been analyzed, providing a historical overview, from ancient to modern times. Currently, there is a wide choice of materials for the treatment of wounds, such as hydrocolloids, polyurethane and alginate patches, wafers, hydrogels and semi-permeable film dressings. These systems are often loaded with drugs such as antibiotics for the simultaneous delivery of drugs to prevent or cure infections caused by the exposition of blood vessel to open air. Among the presented techniques, a focus on foams has been provided, describing the most diffused branded products and their chemical, physical, biological and mechanical properties. Conventional and high-pressure methods for the production of foams for wound dressing are also analyzed in this work, with a proposed comparison in terms of process steps, efficiency and removal of solvent residue. Case studies, in vivo tests and models have been reported to identify the real applications of the produced foams.

Design and fabrication of electrospunMorinda citrifolia-based nanofibrous scaffold as skin wound dressing material:in vitroandin silicoanalysis

Wound healing is an urgent problem that impacts quality of life, and the need for biomaterials suitable for the treatment of skin wound healing disease is increasing annually. Innovative biomaterials and treatments for skin abrasions are being relentlessly researched and established in order to improve treatment efficacy. Here, we describe a novel electrospun polymeric nanofibrous scaffold enriched with pharmaceutical bioactive materials extracted fromMorinda citrifolia(MC), which demonstrated efficient skin wound healing therapy due to its excellent human skin keratinocyte proliferation and adhesion inin vitroanalysis. Surface morphological analysis was used to reveal the nano-architectural structure of the electrospun scaffolds. The fabricated nanofibers displayed good antibacterial efficacy by creating an inhibitory zone for the pathogenic microbes studied. MC supported active healing due to the presence of pharmaceuticals associated with wound healing, as revealed by the results of gas chromatography-mass spectrometry and the prediction of activity spectra for substances (PASS) analysis. Since MC is a multi-potential therapeutic herbal plant, it was found that the linoleic acid, olelic acid, and diethyl phthalate present in the extract supported the wound healing proteins glycogen-synthase-kinase-3-β-protein and Protein Data Bank-1Q5K with binding energies of -4.6, -5.2, and -5.9 kcal mol^-1, as established by the results ofin silicoanalysis. Thus, by being hydrophilic in nature, targeting wound proteins, increasing the proliferation and adhesion of keratinocytes and combating pathogens, the nanofibrous scaffolds endowed with MC extract proved to be an effective therapeutic material for skin wound dressing applications.

'Smart' wound dressings for advanced wound care: a review

Hard-to-heal wounds are a common side-effect of diabetes, obesity, pressure ulcers and age-related vascular diseases, the incidences of which are growing worldwide. The increasing financial burden of hard-to-heal wounds on global health services has provoked technological research into improving wound diagnostics and therapeutics via 'smart' dressings, within which elements such as microelectronic sensors, microprocessors and wireless communication radios are embedded. This review highlights the progress being made by research groups worldwide in producing 'smart' wound device prototypes. Significant advances have been made, for example, flexible substrates have replaced rigid circuit boards, sensors have been printed on commercial wound dressing materials and wireless communication has been demonstrated. Challenges remain, however, in the areas of power supply, disposability, low-profile components, multiparametric sensing and seamless device integration in commercial wound dressings.

Self-Assembly and Mechanical Properties of Engineered Protein Based Multifunctional Nanofiber for Accelerated Wound Healing

The present work reports a new route for preparing tunable multifunctional biomaterials through the combination of synthetic biology and material chemistry. Genetically encoded catechol moiety is evolved in a nanofiber mat with defined surface and secondary reactive functional chemistry, which promotes self-assembly and wet adhesion property of the protein. The catechol moiety is further exploited for the controlled release of boric acid that provides a congenial cellular microenvironment for accelerated wound healing. The presence of 3,4-dihydroxyphenylalanine in the nanofiber mat act as a stimulus to trigger cell proliferation, migration, and vascularization to accelerate wound healing. Electron paramagnetic resonance, NMR, FTIR, and circular dichroism spectroscopy confirm the structural integrity, antioxidant property, and controlled release of boric acid. Fluorescent and scanning electron microscopy reveals the 3D architecture of nanofiber mat, which favors fibroblast growth, endothelial cell attachment, and tube formation, which are the desirable properties of a wound-healing material. Animal studies in the murine wound healing model assert that the multifunctional biomaterial significantly improve re-epithelialization and accelerate wound closure.

Synthetic, Natural, and Semisynthetic Polymer Carriers for Controlled Nitric Oxide Release in Dermal Applications: A Review

Nitric oxide (NO•) is a free radical gas, produced in the human body to regulate physiological processes, such as inflammatory and immune responses. It is required for skin health; therefore, a lack of NO• is known to cause or worsen skin conditions related to three biomedical applications- infection treatment, injury healing, and blood circulation. Therefore, research on its topical release has been increasing for the last two decades. The storage and delivery of nitric oxide in physiological conditions to compensate for its deficiency is achieved through pharmacological compounds called NO-donors. These are further incorporated into scaffolds to enhance therapeutic treatment. A wide range of polymeric scaffolds has been developed and tested for this purpose. Hence, this review aims to give a detailed overview of the natural, synthetic, and semisynthetic polymeric matrices that have been evaluated for antimicrobial, wound healing, and circulatory dermal applications. These matrices have already set a solid foundation in nitric oxide release and their future perspective is headed toward an enhanced controlled release by novel functionalized semisynthetic polymer carriers and co-delivery synergetic platforms. Finally, further clinical tests on patients with the targeted condition will hopefully enable the eventual commercialization of these systems.

A double-network polysaccharide-based composite hydrogel for skin wound healing

Effective wound dressings are of great significance in preventing infections and promoting wound healing. However, most existing hydrogel dressings have an inadequacy in either mechanical performance, biological activities, or versatilities. Here we presented a double-network cross-linked polysaccharide-based hydrogel composed of collagen peptide-functionalized carboxymethyl chitosan (CS) and oxidized methacrylate sodium alginate (SA). The hydrogel possessed interconnected porous morphologies, suitable swelling ratios, excellent mechanical properties, and favorable biocompatibility. Meanwhile, the in vivo studies using a mouse full-thickness skin defect model showed that the double-network CS/SA hydrogel significantly accelerated wound healing by regulating the inflammatory process, promoting collagen deposition, and improving vascularization. Therefore, the functionalized double-network hydrogel should be a potential candidate as wound dressings.

Evaluation of Keratin/Bacterial Cellulose Based Scaffolds as Potential Burned Wound Dressing

The study presents the preparation and characterization of new scaffolds based on bacterial cellulose and keratin hydrogel which were seeded with adipose stem cells. The bacterial cellulose was obtained by developing an Acetobacter xylinum culture and was visualized using SEM (scanning electron microscopy) and elementally determined through EDAX (dispersive X-ray analysis) tests. Keratin species (β–keratose and γ-keratose) was extracted by hydrolytic degradation from non-dyed human hair. SEM, EDAX and conductometric titration tests were performed for physical–chemical and morphological evaluation. Cytocompatibility tests performed in vitro confirmed the material non-toxic effect on cells. The scaffolds, with and without stem cells, were grafted on the burned wounds on the rabbit’s dorsal region and the grafts were monitored for 21 days after the application on the wounds. The clinical monitoring of the grafts and the histopathological examination demonstrated the regenerative potential of the bacterial cellulose–keratin scaffolds, under the test conditions.

Antibiotic-Loaded Psyllium Husk Hemicellulose and Gelatin-Based Polymeric Films for Wound Dressing Application

Wound infections are one of the major reasons for the delay in the healing of chronic wounds and can be overcome by developing effective wound dressings capable of absorbing exudate, providing local antibiotic release, and improving patient comfort. Arabinoxylan (AX) is a major hemicellulose present in psyllium seed husk (PSH) and exhibits promising characteristics for developing film dressings. Herein, AX-gelatin (GL) films were prepared by blending AX, gelatin (GL), glycerol, and gentamicin (antibiotic). Initially, the optimal quantities of AX, GL, and glycerol for preparing transparent, bubble-free, smooth, and foldable AX-GL films were found. Physiochemical, thermal, morphological, drug release, and antibacterial characteristics of the AX-GL films were evaluated to investigate their suitability as wound dressings. The findings suggested that the mechanical, water vapor transmission, morphological, and expansion characteristics of the optimized AX-GL films were within the required range for wound dressing. The results of Fourier-transform infrared (FTIR) analyses suggested chemical compatibility among the ingredients of the films. In in vitro drug release and antibacterial activity experiments, gentamicin (GM)-loaded AX-GL films released approximately 89% of the GM in 24 h and exhibited better antibacterial activity than standard GM solution. These results suggest that AX-GL films could serve as a promising dressing to protect against wound infections.

Polyphenols: A Promising Avenue in Therapeutic Solutions for Wound Care

In chronic wounds, the regeneration process is compromised, which brings complexity to the therapeutic approaches that need to be adopted, while representing an enormous loss in the patients’ quality of life with consequent economical costs. Chronic wounds are highly prone to infection, which can ultimately lead to septicemia and morbidity. Classic therapies are increasing antibiotic resistance, which is becoming a critical problem beyond complex wounds. Therefore, it is essential to study new antimicrobial polymeric systems and compounds that can be effective alternatives to reduce infection, even at lower concentrations. The biological potential of polyphenols allows them to be an efficient alternative to commercial antibiotics, responding to the need to find new options for chronic wound care. Nonetheless, phenolic compounds may have some drawbacks when targeting wound applications, such as low stability and consequent decreased biological performance at the wound site. To overcome these limitations, polymeric-based systems have been developed as carriers of polyphenols for wound healing, improving its stability, controlling the release kinetics, and therefore increasing the performance and effectiveness. This review aims to highlight possible smart and bio-based wound dressings, providing an overview of the biological potential of polyphenolic agents as natural antimicrobial agents and strategies to stabilize and deliver them in the treatment of complex wounds. Polymer-based particulate systems are highlighted here due to their impact as carriers to increase polyphenols bioavailability at the wound site in different types of formulations.

Nanomaterials Versus The Microbial Compounds With Wound Healing Property

Age and diabetes related slow-healing or chronic wounds may result in morbidity and mortality through persistent biofilms infections and prolonged inflammatory phase. Nano-materials [metal/metal oxide NPs (39%), lipid vehicles (21%), polymer NPs (19%), ceramic nanoparticles (NPs) (14%), and carbon nanomaterials (NMs) (7%)] can be introduced as a possible next-generation therapy because of either their intrinsic wound healing activity or via carrying bioactive compounds including, antibiotics, antioxidants, growth factor or stem cell. The nanomaterials have been shown to implicate in all four stages of wound healing including hemostasis (polymer NPs, ceramic NPs, nanoceria-6.1%), inflammation (liposome/vesicles/solid lipid NPs/polymer NPs/ceramic NPs/silver NPs/gold NPs/nanoceria/fullerenes/carbon-based NPs-32.7%), proliferation (vesicles/liposome/solid lipid NPs/gold NPs/silver NPs/iron oxide NPs/ceramic NPs/copper NPs/self-assembling elastin-like NPs/nanoceria/micelle/dendrimers/polymer NPs-57.1%), remodeling (iron oxide NPs/nanoceria-4.1%). Natural compounds from alkaloids, flavonoids, retinoids, volatile oil, terpenes, carotenoids, or polyphenolic compounds with proven antioxidant, anti-inflammatory, immunomodulatory, or antimicrobial characteristics are also well known for their potential to accelerate the wound healing process. In the current paper, we survey the potential and properties of nanomaterials and microbial compounds in improving the process of wound and scar healing. Finally, we review the potential biocompounds for incorporation to nano-material in perspective to designate more effective or multivalent wound healing natural or nano-based drugs.

Polymer-based biomaterials for chronic wound management: Promises and challenges

Chronic non-healing wounds tender a great challenge to patients, physicians, and wound care professionals. In view of the increasing prevalence of chronic wounds due to ischemia, diabetic foot, venous, and pressure ulcers, their appropriate management requires significant attention. Along with the basic techniques of medical and surgical treatments; an ideal dressing is essential for a speedy recovery and rapid healing of such wounds. Mechanistic understanding of chronic wound pathology will not only help towards future directions for an ideal dressing model but also to resonant advance research related to specific dressings for various wound types. This review provides key insights into causes, pathophysiology, and critical issues pertaining to chronic wounds and their management. It also summarizes the challenges faced for chronic wound treatment and specified factors responsible for delayed healing. Moreover, this review delivers a detailed discussion on available polymeric materials (alginate, chitosan, hyaluronic acid, collagen, polyurethane, cellulose, dextran, gelatin, silk, and polyaniline), their functional characteristics, and usage as chronic wound healing agents for polymeric wound dressing development. Incorporation and comparison of the research studies for their thermal behavior, structural analysis, and microscopic studies by Fourier transform infrared spectroscopy, thermogravimetric analysis and scanning electron microscopy, respectively and swelling studies of different polymeric materials are discussed. Additionally, studies of anatomy cum physiology of wound healing, pathophysiology, tissue engineering and advance healing management approaches makes the content of this review a significant tool for future studies on chronic wounds healing by polymeric wound dressings. In this review, polymeric wound dressings have been explained in terms of their structures, function, chemistry, and key characteristics. These features are directly linked to the polymeric systems' potential in the management of chronic wounds. These polymeric systems have gained promising success in solving real word global health problems. More recently, innovative approaches to fabricate the polymer dressings have been introduced, but their commercial, sustainable, and high-scale production largely remains unexplored. This review also summarizes the promises of polymeric wound dressings and provides a future perspective on how the clinical and commercial landscape could potentially be propelled by utilizing polymers in wound care management.

Development of Bacterial Cellulose Biocomposites Combined with Starch and Collagen and Evaluation of Their Properties

One of the major benefits of biomedicine is the use of biocomposites as wound dressings to help improve the treatment of injuries. Therefore, the main objective of this study was to develop and characterize biocomposites based on bacterial cellulose (BC) with different concentrations of collagen and starch and characterize their thermal, morphological, mechanical, physical, and barrier properties. In total, nine samples were produced with fixed amounts of glycerol and BC and variations in the amount of collagen and starch. The water activity (0.400–0.480), water solubility (12.94–69.7%), moisture (10.75–20.60%), thickness (0.04–0.11 mm), water vapor permeability (5.59–14.06 × 10⁻⁸ g·mm/m²·h·Pa), grammage (8.91–39.58 g·cm⁻²), opacity (8.37–36.67 Abs 600 nm·mm⁻¹), elongation (4.81–169.54%), and tensile strength (0.99–16.32 MPa) were evaluated and defined. In addition, scanning electron microscopy showed that adding biopolymers in the cellulose matrix made the surface compact, which also influenced the visual appearance. Thus, the performance of the biocomposites was directly influenced by their composition. The performance of the different samples obtained resulted in them having different potentials for application considering the injury type. This provides a solution for the ineffectiveness of traditional dressings, which is one of the great problems of the biomedical sector.

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

Abstract

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

Graphic abstract

In vivo wound healing efficiency of curcumin-incorporated pectin-chitosan biodegradable films

Curcumin incorporated pectin/chitosan thin films application as a potential wound dressing material with good mechanical, barrier and antibacterial properties.

Advances in gelatin-based hydrogels for wound management

The normal wound healing process and the foreign body reaction to wound management materials.

Hydrogel Dressings for Chronic Wound Healing in Diabetes: Beyond Hydration

Chronic wounds caused by diabetes are a significant medical challenge. Complications from non-healing can result in dire consequences for patients and cost the healthcare system billions of dollars annually. Non-healing in wounds for diabetic patient's results from a combination of factors which impair clearing of injured tissue, proliferation of healthy cell populations and increase risk of infection. Wound dressings continue to form the basis for the treatment of chronic wounds. Traditionally, these focused solely on hydration of the wound site and mitigating infection risk. Hydrogel systems are ready made to meet these basic requirements due to their intrinsic hydration properties and ability to deliver active ingredients. Flexibility in materials and methods of release allowed these systems to remain targets of research into the 21st century. Improved understanding of the wound environment and healing cascades has led to the development of more advanced systems which incorporate endogenous growth factors and living cells. Despite their promise, clinical efficacy of these systems has remained a challenge. Further, the regulatory pathways for approval add a layer of complexity to translate pre-clinical work into marketed products. In this review, we discuss systems currently in clinical use, pre-clinical directions and regulatory challenges for hydrogels in the treatment of diabetic chronic wounds.

Oromucosal precursors of in loco hydrogels for wound-dressing and drug delivery in oral mucositis: Retain, resist, and release

Oromucosal films and tablets were developed as multifunctional biomaterials for the treatment of oral mucositis. These are intended to function as a hybrid, performing as a controlled drug delivery system and as a wound-dressing device. The dosage forms are precursors for in loco hydrogels that are activated by the saliva. An anti-inflammatory and anesthetic activity is attained from budesonide tripartite polymeric nanoparticles and lidocaine, while the polymeric network allows the protection and cicatrization of the wound. Different biomaterials and blends were investigated, focusing on the capacity to retain and resist on-site, as well as achieve a long-lasting controlled release. As the limiting factor, the choice was made according to the films' results. A polymer mix of Methocel™ K100M and Carbopol® (974P, EDT 2020, or Ultrez 10) blends were used. Overall, regrading critical factors, Carbopol® increased films' elasticity and flexibility, mucoadhesion, and the strength of the hydrogels, while higher concentrations led to thicker, more opaque, and lower strain resistance products. Whereas 974P and Ultrez 10 performed similarly, EDT 2020 led to uniformity problems and weaker films, hydrogels and bioadhesion. The optimized products were enhanced with sodium hyaluronate and drug-loaded for further characterization. Concerning the dosage form, the films' hydrogels were more resilient, while the tablets had higher mucoadhesiveness and longer swelling. Although through different networks and mechanisms, both dosage forms and grades revealed similar release profiles. A Case II time-evolving stereoselectivity for the 22R and 22S budesonide epimers was found, and Fickian-diffusion for lidocaine. Ultimately, the developed formulations show great potential to be used in OM management. Both of the selected grades at 0.6% displayed excellent performance, while Ultrez 10 can be preferable for the films' production due to its lower viscosity before neutralization and higher after activation. Where the tablets are easier to produce and offer better adhesion, the films are more customizable post-production and have higher rheological performance for wound-dressing.

Silk fibroin and silk-based biomaterial derivatives for ideal wound dressings

Silk fibroin (SF) is derived from Bombyx mori silkworm cocoons and has been used in textiles and as a suture material for decades. More recently, SF has been used for various new biomedical applications, including as a wound dressing, owing to its excellent biological and mechanical properties. Specifically, the mechanical stiffness, versatility, biocompatibility, biodegradability, water vapour permeability and slight bactericidal properties make SF an excellent candidate biomaterial for wound dressing applications. The effectiveness of SF as a wound dressing has been tested and well-documented in vitro as well as in-vivo, as described here. Dressings based on SF are currently used for treating a wide variety of chronic and acute (e.g. burn) wounds. SF and its derivatives prepared as biomaterials are available as sponges, hydrogels, nanofibrous matrices, scaffolds, micro/nanoparticles, and films. The present review discusses the potential role of SF in wound dressing and its modulation for wound dressing applications. The comparison of SF based dressings with other natural polymers understands the readers, the scope and limitation of the subject in-depth.

Recent trends on wound management: New therapeutic choices based on polymeric carriers

Wound healing is an unmet therapeutic challenge among medical society since wound assessment and management is a complex procedure including several factors playing major role in healing process. Wounds can mainly be categorized as acute or chronic. It is well referred that the acute wound displays normal wound physiology while healing, in most cases, is seemed to progress through the normal phases of wound healing. On the other hand, a chronic wound is physiologically impaired. The main problem in wound management is that the majority of wounds are colonized with microbes, whereas this does not mean that all wounds will be infected. In this review, we address the problems that clinicians face to manage while treat acute and chronic wounds. Moreover, we demonstrate the pathophysiology, etiology, prognosis and microbiology of wounds. We further introduce the state of art in pharmaceutical technology field as part of wound management aiming to assist health professionals to overcome the current implications on wound assessment. In addition, authors review researches which included the use of gels and dermal films as wound healing agents. It can be said that natural and synthetic drugs or carriers provide promising solutions in order to meet the wound management standards. However, are the current strategies as desirable as medical society wish?

Advanced SA/PVA-based hydrogel matrices with prolonged release of Aloe vera as promising wound dressings

This work focuses on the influence of different amounts (5, 10, 15, 20 and 25%, v/v) of solution of Aloe vera on the chemical structure and properties of sodium alginate/poly(vinyl alcohol) hydrogel films. The polymeric matrix was prepared following the chemical cross-linking method using poly(ethylene glycol) diacrylate (PEGDA, Mn = 700 g/mol) as a cross-linking agent. First, the gel fractions of the modified hydrogels were determined and their swelling behavior in distilled water and phosphate-buffered saline (PBS) was tested. Subsequently, the following properties of the modified hydrogel materials were studied: structural (FT-IR spectra analysis), morphological (SEM analysis) and mechanical (tensile strength, elongation at break and hardness). Moreover, a thermal analysis (TG/DTG and DSC) confirmed that the SA/PVA hydrogels containing Aloe vera exhibited slightly higher thermal stability than the unmodified hydrogels, which allows concluding that a rigid and thermally stable three-dimensional structure had been obtained. Additionally, the release profile of polysaccharides from the hydrogel matrix was evaluated in PBS at 37 °C. The results show that the active substance was released in a prolonged manner, gradually, even for a week. It was found that the presence of Aloe vera inside the cross-linked polymeric network improved the active substance delivery properties of the hydrogel films. When greater amounts of Aloe vera were applied, the hydrogel had an irregular surface structure, as revealed by SEM images. The chemical structure was confirmed on the basis of an FT-IR spectral analysis. Concluding, SA/PVA/Aloe vera matrices are promising compounds and deserve further studies towards application in interactive wound dressings. Additionally, the cytotoxicity of the materials was studied and the results indicated good adhesion properties and no toxicity. In vitro experiments performed on normal human dermal fibroblasts proved excellent cell attachment on the Aloe vera hydrogel discs, which promoted cells spreading and proliferation.

A Facile Synthesis of Self-Catalytic Hydrogel Films and Their Application as a Wound Dressing Material Coupled with Natural Active Compounds

A simple and economical method for polyvinyl alcohol/polyvinylpyrrolidone/citric acid (PVA/PVP/CA) hydrogel preparation using microwave-assisted irradiation was presented. The synthesized hydrogels embedded with berberine or chlorogenic acid were investigated as a wound dressing agent. This study showed that the optimum condition for the hydrogel synthesis based on gel fraction and a degree of swelling values was 6:6:3% (w/v) of PVA/PVP/CA under 600 W at 120 °C for 3 min of microwave irradiation. Herbal active compounds, berberine and chlorogenic acid, were loaded onto the hydrogel (4% (w/v)), and both were able to inhibit the growth of Staphylococcus aureus. Additionally, the anti-inflammatory study revealed that 700 μg/mL berberine and 2500 μg/mL chlorogenic acid could inhibit protein degradation equivalent to a 200 μg/mL aspirin solution. The drug release study demonstrated that both compounds showed a more sustained release into PBS than water. The mechanism for the three-dimensional network formation based on esterification and the hydrogen-bonding interaction was also proposed. The ionic liquid-like structure of PVP-CA possibly played an important role in the cross-linking process. In addition, sodium bicarbonate applied to the synthesized hydrogel also had a significant effect in enhancing gel formation. The proposed approach showed a potential of the loaded hydrogels to protect wounds from infection and enhance the healing process.

Chitin-Based Double-Network Hydrogel as Potential Superficial Soft-Tissue-Repairing Materials

Chitin is a biopolymer, which has been proven to be a biomedical material candidate, yet the weak mechanical properties seriously limit their potentials. In this work, a chitin-based double-network (DN) hydrogel has been designed as a potential superficial repairing material. The hydrogel was synthesized through a double-network (DN) strategy composing hybrid regenerated chitin nanofiber (RCN)-poly (ethylene glycol diglycidyl ether) (PEGDE) as the first network and polyacrylamide (PAAm) as the second network. The hybrid RCN-PEGDE/PAAm DN hydrogel was strong and tough, possessing Young's modulus (elasticity) E 0.097 ± 0.020 MPa, fracture stress σ_f 0.449 ± 0.025 MPa, and work of fracture W_f 5.75 ± 0.35 MJ·m^-3. The obtained DN hydrogel was strong enough for surgical requirements in the usage of soft tissue scaffolds. In addition, chitin endowed the DN hydrogel with good bacterial resistance and accelerated fibroblast proliferation, which increased the NIH3T3 cell number by nearly five times within 3 days. Subcutaneous implantation studies showed that the DN hydrogel did not induce inflammation after 4 weeks, suggesting a good biosafety in vivo. These results indicated that the hybrid RCN-PEGDE/PAAm DN hydrogel had great prospect as a rapid soft-tissue-repairing material.

Thread Size and Polymer Composition of 3D Printed and Electrospun Wound Dressings Affect Wound Healing Outcomes in an Excisional Wound Rat Model

Thread size and polymer composition are critical properties to consider for achieving a positive healing outcome with a wound dressing. Three-dimensional (3D) printed scaffolds and electrospun mats both offer distinct advantages as replaceable wound dressings. This research aims to determine if the thread size and polymer compositions of the scaffolds affect skin wound healing outcomes, an aspect that has not been adequately explored. Using a modular polymer platform, four polyester direct-write 3D printed scaffolds and electrospun mats were fabricated into wound dressings. The dressings were applied to splinted, full thickness skin wounds in an excisional wound rat model and evaluated against control wounds to which no dressing was applied. Wound closure rates and reduction of the wound bed width were not affected by the thread size or polymer composition. However, epidermal thickness was larger in wounds treated with electrospun dressings and was slightly affected by the polymer composition. Two of the four tested polymer compositions lead to delayed reorganization of granulation tissues. Moreover, enhanced angiogenesis was seen in wounds treated with 3D printed dressings compared to those treated with electrospun dressings. The results from this study can be used to inform the choice of dressing architecture and polymer compositions to achieve positive wound healing outcomes.

Agarose/κ-carrageenan-based hydrogel film enriched with natural plant extracts for the treatment of cutaneous wounds

Hydrogels for complex and chronic wound dressings must be conformable, absorb and retain wound exudates and maintain hydration. They can incorporate and release bioactive molecules that can accelerate the healing process. Wound dressings have to be in contact with the wound and epidermis, even for long periods, without causing adverse effects. Hydrogel dressing formulations based on biopolymers derived from terrestrial or marine flora can be relatively inexpensive and well tolerated. In the present article hydrogel films composed by agarose (1.0 wt%), κ-carrageenan at three different concentrations (0.5, 1.0 and 1.5 wt%) and glycerol (3.0 wt%) were prepared without recourse to crosslinking agents, and characterized for their mechanical properties, morphology, swelling and erosion behavior. The films resulted highly elastic and able to absorb and retain large amounts of fluids without losing their integrity. One of the films was loaded with the aqueous extract from Cryphaea heteromalla (Hedw.) D. Mohr for its antioxidant properties. Absence of cytotoxicity and ability to reduce the oxidative stress were demonstrated on NIH-3T3 fibroblast cell cultures. These results encourage further biological evaluations to assess their impact on the healing process.