A Novel Bilayer Wound Dressing Composed of a Dense Polyurethane/Propolis Membrane and a Biodegradable Polycaprolactone/Gelatin Nanofibrous Scaffold

Antibacterial and in vivo toxicological studies of Bi2O3/CuO/GO nanocomposite synthesized via cost effective methods

In this research work, Bi₂O₃, Bi₂O₃/GO and Bi₂O₃/CuO/GO nanocomposites have been synthesized via an eco-friendly green synthesis technique, solgel route and co-precipitation method respectively for the assessment of antibacterial activity as well as in vivo toxicity. The XRD patterns confirm the formation of Bi₂O₃, Bi₂O₃/GO and Bi₂O₃/CuO/GO nanocomposites showing monoclinic structures. Crystallite size and lattice strain are calculated by Scherrer equation, Scherrer plot and Willimson Hall plot methods. Average crystallite size measured for Bi₂O₃, Bi₂O₃/GO and Bi₂O₃/CuO/GO nanocomposites by Scherrer equation, Scherrer plot and WH-plot methods are (5.1, 13.9, 11.5)nm, (5.4, 14.2, 11.3)nm and (5.2, 13.5, 12.0)nm respectively. Optical properties such as absorption peaks and band-gap energies are studied by UV–vis spectroscopy. The FTIR peaks at 513 cm⁻¹, 553 cm⁻¹ and 855 cm⁻¹ confirms the successful synthesis of Bi₂O₃, Bi₂O₃/GO and Bi₂O₃/CuO/GO nanocomposites. The antibacterial activity of synthesized Bi₂O₃, Bi₂O₃/GO and Bi₂O₃/CuO/GO nanocomposites is examined against two gram-negative (Escherichia coli and pseudomonas) as well as gram-positive bacteria (Bacillus cereus and Staphylococcus aureus) at dose 25 mg/kg and 40 mg/kg by disk diffusion technique. Zone of inhibition for Bi₂O₃, Bi₂O₃/GO and Bi₂O₃/CuO/GO at dose 40 mg/kg against E. coli (gram − ve) are 12 mm, 17 mm and 18 mm respectively and against Pseudomonas (gram − ve) are 28 mm, 19 mm and 21 mm respectively. While the zone of inhibition for Bi₂O₃/GO and Bi₂O₃/CuO/GO at dose 40 mg/kg against B. cereus (gram + ve) are 8 mm and 8.5 mm respectively and against S. aureus (gram + ve) are 5 mm and 10.5 mm respectively. These amazing results reveal that Bi₂O₃, Bi₂O₃/GO and Bi₂O₃/CuO/GO nanocomposite as a kind of antibacterial content, have enormous potential for biomedical applications. In addition, the in vivo toxicity of synthesized Bi₂O₃/CuO/GO nanocomposite is investigated on Swiss Albino mice at dose of 20 mg/kg by evaluating immune response, hematology and biochemistry at the time period of 2, 7, 14 and 30 days. No severe damage is observed in mice during whole treatment. The p value calculated by statistical analysis of hematological and biochemistry tests is nonsignificant which ensures that synthesized nanocomposites are safe and non-toxic as they do not affect mice significantly. This study proves that Bi₂O₃/CuO/GO nanocomposites are biocompatible and can be explored further for different biomedical applications.

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

Full-thickness wounds are difficult to heal spontaneously. Scaffolds, meant for treating full-thickness wounds, should ensure proper tissue regeneration, both structurally and functionally. An ideal scaffold should mimic the physical, mechanical and biochemical properties of natural skin. However, available mono- or bi-layer skin scaffolds lack in the precise architecture and functionality, thus, failing to provide scar-free regeneration of full-thickness skin wounds. These unmet challenges of scar-free skin regeneration have been addressed in the present study for the first time. This research deals with the synthesis of a low-cost, structurally and functionally graded single unit biodegradable polymeric scaffold. The functional gradient in this scaffold was achieved by varying polymer concentration and electrospinning parameters. This gradient in the scaffold provided the required microenvironment for proper functional and structural reconstruction of all the layers of natural skin. The mechanical property of the scaffold matched that of the natural skin. Besides, the degradation kinetics of the scaffold was in coordination with the regeneration time for the full-thickness wound. The porosity and hydrophilicity gradients of the scaffold helped it mimic the in vivo hypodermal, dermal and epidermal microenvironments of the skin, simultaneously. Co-culturing PCS-201 (dermal fibroblasts) and HaCaT (keratinocytes) on the scaffold resulted in successful regeneration through cellular proliferation, differentiation and organization of the skin tissue. The scaffold also displayed better wound healing in vivo, in terms of speedy wound closure and proper tissue regeneration, in comparison to the standard treatment. Altogether, this study successfully established a simple, one-step synthesis process of a functionally graded, bioresorbable scaffold for scar-free, native-like, structural and functional regeneration of full-thickness skin wounds. Due to cost-effectiveness, easy synthesis process and microarchitectural features, the designed scaffold possesses a potential of translation to a good commercial wound healing product.

Bilayer Hydrogels for Wound Dressing and Tissue Engineering

A large number of different skin diseases such as hits, acute, and chronic wounds dictate the search for alternative and effective treatment options. The wound healing process requires a complex approach, the key step of which is the choice of a dressing with controlled properties. Hydrogel-based scaffolds can serve as a unique class of wound dressings. Presented on the commercial market, hydrogel wound dressings are not found among proposals for specific cases and have a number of disadvantages—toxicity, allergenicity, and mechanical instability. Bilayer dressings are attracting great attention, which can be combined with multifunctional properties, high criteria for an ideal wound dressing (antimicrobial properties, adhesion and hemostasis, anti-inflammatory and antioxidant effects), drug delivery, self-healing, stimulus manifestation, and conductivity, depending on the preparation and purpose. In addition, advances in stem cell biology and biomaterials have enabled the design of hydrogel materials for skin tissue engineering. To improve the heterogeneity of the cell environment, it is possible to use two-layer functional gradient hydrogels. This review summarizes the methods and application advantages of bilayer dressings in wound treatment and skin tissue regeneration. Bilayered hydrogels based on natural as well as synthetic polymers are presented. The results of the in vitro and in vivo experiments and drug release are also discussed.

Three-layered PCL-collagen nanofibers containing melilotus officinalis extract for diabetic ulcer healing in a rat model

Active wound dressing with physicochemical and biological characteristics is more effective in healing diabetic foot ulcer (DFU). In this study, a 3-layer electrospun nanofiber wound dressings was fabricated, while its outer, middle and inner layers of the scaffold were made of PCL, PCL/collagen and collagen nanofibers, respectively. Various amounts of Melilotus officinalis extract were also loaded in the collagen nanofibers as a biologically active compound. The diameter and morphology of the obtained nanofibers were investigated by scanning electron microscopy (SEM) and FT-IR spectroscopy to analyse the composition of prepared dressings. The efficacy of the fabricated dressings as wound healing agent was assessed in streptozotocin-induced diabetic rats. The results demonstrated that the mean diameter of nanofibers are 373 ± 179 nm, 266 ± 108 nm, 160 ± 52 nm, and 393 ± 131 nm for PCL, PCL/collagen, pure collagen, and collagen nanofibers containing 0.08 g extract, respectively. The histo-pathology and histomorphometry assessments demonstrate the herbal extract-loaded electrospun dressings (especially containing 0.08 g of the extract) are promising in improving the diabetic ulcer healing. Our results indicated that the combination of drug did not compromise the physicochemical characteristics of wound dressing, while improving its biological activities.

Recent technological advances in the management of chronic wounds: A literature review

Background

Wound treatment comprises a substantial portion of the healthcare budgets in developed countries. Studies suggest that about 50% of patients admitted to hospitals have wounds, while 1%−2% of the general population in the developed world suffers from chronic wounds. Chronic wounds fail to repair themselves within the expected period of 30 days. Technologies have been developed to address challenges encountered during wound care with the aim of alleviating pain, promoting healing, or controlling wound infections.

Objective

The objective of this study was to explore the technological improvements that have been made in this field over time.

Methods

To gain insight into the future of wound management, a systematic review of literature on the subject was conducted in scientific databases (PubMed, Scopus, Web of Science, Medline, and Clinical Trials).

Results and Discussion

Results indicate that wound dressings have evolved from the traditional cotton gauze to composite materials embedded with appropriate ingredients such as metal‐based nanoparticles. Studies on biodegradable dressing materials are also underway to explore their applicability in dressing large and irregular wounds. On the other hand, conventional drugs and traditional formulations for the management of pain, inflammation, infections, and accelerating healing have been developed. However, more research needs to be carried out to address the issue of microbial resistance to drugs. Drugs for managing other ailments also need to be designed in such a way that they can augment wound healing. In addition, it has been demonstrated that a coordinated integration of conventional and traditional medicine can produce laudable results in chronic wound management.

Conclusion

Accordingly, collaborative efforts and ingenuity of all players in the field can accelerate technological advances in the wound care market to the benefit of the patients.

Wounds affect about 50% of patients admitted to hospitals.

Technologies have been developed including biodegradable dressing materials to address underlying challenges.

Technological advancement, rising incidences of chronic wounds, growing government support, and a rising elderly population will drive wound market growth.

A careful combination of recent research outputs can greatly change wound care technologies.

This review highlights the recent research advances and opportunities in the wound care field.

The future lies in biodegradable dressing materials, probably embedded with selected nanoparticles and which shall be combined in predetermined ratios.

Biomaterials-Based Regenerative Strategies for Skin Tissue Wound Healing

Skin tissue wound healing proceeds through four major stages, including hematoma formation, inflammation, and neo-tissue formation, and culminates with tissue remodeling. These four steps significantly overlap with each other and are aided by various factors such as cells, cytokines (both anti- and pro-inflammatory), and growth factors that aid in the neo-tissue formation. In all these stages, advanced biomaterials provide several functional advantages, such as removing wound exudates, providing cover, transporting oxygen to the wound site, and preventing infection from microbes. In addition, advanced biomaterials serve as vehicles to carry proteins/drug molecules/growth factors and/or antimicrobial agents to the target wound site. In this review, we report recent advancements in biomaterials-based regenerative strategies that augment the skin tissue wound healing process. In conjunction with other medical sciences, designing nanoengineered biomaterials is gaining significant attention for providing numerous functionalities to trigger wound repair. In this regard, we highlight the advent of nanomaterial-based constructs for wound healing, especially those that are being evaluated in clinical settings. Herein, we also emphasize the competence and versatility of the three-dimensional (3D) bioprinting technique for advanced wound management. Finally, we discuss the challenges and clinical perspective of various biomaterial-based wound dressings, along with prospective future directions. With regenerative strategies that utilize a cocktail of cell sources, antimicrobial agents, drugs, and/or growth factors, it is expected that significant patient-specific strategies will be developed in the near future, resulting in complete wound healing with no scar tissue formation.

Elastomer–Hydrogel Systems: From Bio-Inspired Interfaces to Medical Applications

Novel advanced biomaterials have recently gained great attention, especially in minimally invasive surgical techniques. By applying sophisticated design and engineering methods, various elastomer–hydrogel systems (EHS) with outstanding performance have been developed in the last decades. These systems composed of elastomers and hydrogels are very attractive due to their high biocompatibility, injectability, controlled porosity and often antimicrobial properties. Moreover, their elastomeric properties and bioadhesiveness are making them suitable for soft tissue engineering. Herein, we present the advances in the current state-of-the-art design principles and strategies for strong interface formation inspired by nature (bio-inspiration), the diverse properties and applications of elastomer–hydrogel systems in different medical fields, in particular, in tissue engineering. The functionalities of these systems, including adhesive properties, injectability, antimicrobial properties and degradability, applicable to tissue engineering will be discussed in a context of future efforts towards the development of advanced biomaterials.

An Overview on the Recent Advances in the Treatment of Infected Wounds: Antibacterial Wound Dressings

A wound can be surgical, cuts from an operation or due to accident and trauma. The infected wound, as a result of bacteria growth within the damaged skin, interrupts the natural wound healing process and significantly impacts the quality of life. Wound dressing is an important segment of the skincare industry with its economic burden estimated at $ 20.4 billion (in 2021) in the global market. The results of recent clinical trials suggest that the use of modern dressings can be the easiest, most accessible, and most cost-effective way to treat chronic wounds and, hence, holds significant promise. With the sheer number of dressings in the market, the selection of correct dressing is confusing for clinicians and healthcare workers. The aim of this research was to review widely used types of antibacterial wound dressings, as well as emerging products, for their efficiency and mode of action. In this review, we focus on introducing antibiotics and antibacterial nanoparticles as two important and clinically widely used categories of antibacterial agents. The perspectives and challenges for paving the way for future research in this field are also discussed. This article is protected by copyright. All rights reserved.

Bee-Derived Products: Chemical Composition and Applications in Skin Tissue Engineering

Skin tissue regeneration is one of the population’s most common problems, and the complications that may appear in the healing process can have detrimental consequences. An alternative to conventional treatments could be represented by sustainable materials based on natural products, such as honey and its derivates (propolis, royal jelly, bee pollen, beeswax, and bee venom). They exhibit significant inhibitory activities against bacteria and have great potential in dermal tissue regeneration. Research in the pharmaceutical field demonstrates that conventional medication combined with bee products can deliver better results. The advantages include minimizing side effects and maintaining the same effectiveness by using low concentrations of antibiotic, anti-inflammatory, or chemotherapy drugs. Several studies suggested that bee products can replace the antimicrobial activity and efficiency of antibiotics, but further investigation is needed to establish a topical mixture’s potential, including honey, royal jelly, and propolis. Bee products seem to complete each other’s deficiencies, and their mixture may have a better impact on the wound healing process. The topic addressed in this paper highlights the usefulness of honey, propolis, royal jelly, bee pollen, beeswax, and bee venom in the re-epithelization process and against most common bacterial infections.

Dual Spinneret Electrospun Polyurethane/PVA-Gelatin Nanofibrous Scaffolds Containing Cinnamon Essential Oil and Nanoceria for Chronic Diabetic Wound Healing: Preparation, Physicochemical Characterization and In-Vitro Evaluation

In this study, a dual spinneret electrospinning technique was applied to fabricate a series of polyurethane (PU) and polyvinyl alcohol-gelatin (PVA/Gel) nanofibrous scaffolds. The study aims to enhance the properties of PU/PVA-Gel NFs loaded with a low dose of nanoceria through the incorporation of cinnamon essential oil (CEO). The as-prepared nCeO2 were embedded into the PVA/Gel nanofibrous layer, where the cinnamon essential oil (CEO) was incorporated into the PU nanofibrous layer. The morphology, thermal stability, mechanical properties, and chemical composition of the produced NF mats were investigated by STEM, DSC, and FTIR. The obtained results showed improvement in the mechanical, and thermal stability of the dual-fiber scaffolds by adding CEO along with nanoceria. The cytotoxicity evaluation revealed that the incorporation of CEO to PU/PVA-Gel loaded with a low dose of nanoceria could enhance the cell population compared to using pure PU/PVA-Gel NFs. Moreover, the presence of CEO could inhibit the growth rate of S. aureus more than E. coli. To our knowledge, this is the first time such nanofibrous membranes composed of PU and PVA-Gel have been produced. The first time was to load the nanofibrous membranes with both CEO and nCeO2. The obtained results indicate that the proposed PU/PVA-Gel NFs represent promising platforms with CEO and nCeO2 for effectively managing diabetic wounds.

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

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

Polysaccharide-Based Membrane Biocompatibility Study of Anacardium occidentale L. and Polyvinyl Alcohol after Subcutaneous Implant in Rats

Polymeric membranes are a viable and sustainable option for the biotechnology industry from an economic and environmental point of view. In this study, we evaluated tissue response and tolerance to the implantation of a polymeric membrane prepared with cashew gum polysaccharide (CGP) associated with polyvinyl alcohol (PVA). The objective was to characterize the biocompatibility of the CGP/PVA membrane in vivo. Following the evaluation criteria of the ISO 10993-6 standard, we demonstrated that the CGP/PVA membrane showed moderate tissue reaction, with a non-irritating ISO pattern, a thinner fibrous capsule, and a smaller amount of collagen compared to the positive control group. At 30 and 60 days, the membrane presented a similar amount of mast cells to that observed in the negative control group. The data demonstrate that the CGP/PVA membrane presents biocompatibility in accordance with the ISO 10993-6 standard.

A Biomimetic Composite Bilayer Dressing Composed of Alginate and Fibroin for Enhancing Full-Thickness Wound Healing

Full-thickness skin wound dressings are critically important for acute cutaneous wound healing. In this study, we developed a bilayer sheet originating from biological macromolecules, mimicking skin hierarchy structure. This sheet was composed of a steady silk fibroin (SF)/sodium alginate (SA) composite scaffold as the bottom regenerative layer and a SA film as the protective top layer. SEM analysis revealed the thickness of the top layer was ∼25 μm and was tightly adhered to the composite scaffold layer with interconnected pores (∼150 μm). The bilayer sheets displayed suitable water uptake capacity and high stability in water. The mass retention percentage of the bilayer sheets was approximately 50% during three weeks of PBS degradation in vitro. The tensile strength of the bilayer sheets significantly increased from 13.41 ± 3.75 kPa (single scaffold) to 59.81 ± 5.98 kPa. The composite scaffolds were more conducive to the growth and proliferation of human dermal microvascular endothelial cells. The experiment results in vivo demonstrated superior and faster epithelialisation and dermal regeneration in the wound treated with bilayer sheets because the sheets accelerated wound closure, reduced the inflammatory response, and promoted protein synthesis in the extracellular matrix and blood vessel ingrowth. This article is protected by copyright. All rights reserved.

Honey Bee Products: Preclinical and Clinical Studies of Their Anti-inflammatory and Immunomodulatory Properties

Inflammation is a defense process triggered when the body faces assaults from pathogens, toxic substances, microbial infections, or when tissue is damaged. Immune and inflammatory disorders are common pathogenic pathways that lead to the progress of various chronic diseases, such as cancer and diabetes. The overproduction of cytokines, such as interleukin (IL)-1β, IL-6, and tumor necrosis factor-α, is an essential parameter in the clinical diagnosis of auto-inflammatory diseases. In this review, the effects of bee products have on inflammatory and autoimmune diseases are discussed with respect to the current literature. The databases of Google Scholar, PubMed, Science Direct, Sci-Finder and clinical trials were screened using different combinations of the following terms: “immunomodulatory”, “anti-inflammatory”, “bee products”, “honey”, “propolis”, “royal jelly”, “bee venom”, “bee pollen”, “bee bread”, “preclinical trials”, “clinical trials”, and “safety”. Honey bee products, including propolis, royal jelly, honey, bee venom, and bee pollen, or their bioactive chemical constituents like polyphenols, demonstrate interesting therapeutic potential in the regulation of inflammatory mediator production as per the increase of TNF-α, IL-1β, IL-6, Il-2, and Il-7, and the decrease of reactive oxygen species (ROS) production. Additionally, improvement in the immune response via activation of B and T lymphocyte cells, both in in vitro, in vivo and in clinical studies was reported. Thus, the biological properties of bee products as anti-inflammatory, immune protective, antioxidant, anti-apoptotic, and antimicrobial agents have prompted further clinical investigation.

An Up-to-Date Review of Biomaterials Application in Wound Management

Whether they are caused by trauma, illness, or surgery, wounds may occur throughout anyone's life. Some injuries' complexity and healing difficulty pose important challenges in the medical field, demanding novel approaches in wound management. A highly researched possibility is applying biomaterials in various forms, ranging from thin protective films, foams, and hydrogels to scaffolds and textiles enriched with drugs and nanoparticles. The synergy of biocompatibility and cell proliferative effects of these materials is reflected in a more rapid wound healing rate and improved structural and functional properties of the newly grown tissue. This paper aims to present the biomaterial dressings and scaffolds suitable for wound management application, reviewing the most recent studies in the field.

Antibacterial Effect of Pre-constructed 3D Bone Scaffolds before and after Modification with Propolis

AIM: This study was to determine and compare the antibacterial activity of different scaffold materials before and after their modification with ethanolic extract of Egyptian propolis ethanolic extract of propolis (EEP). SETTINGS AND DESIGN: Preparation of the dry mass of propolis, preparation of EEP, preparation of the scaffolds, and antibacterial activity testing. MATERIALS AND METHODS: Four bacterial strains were used to determine the antibacterial activity of two different scaffold materials before and after their modification with EEP (15% and 25% by weight). RESULTS: Tricalcium phosphate + gelatin binder modified by 25% EEP exhibited the highest antibacterial activity against Escherichia coli. While, tricalcium phosphate + (alginate and cellulose nanowhiskers) binder modified by 25% EEP demonstrated the highest antibacterial activity Staphylococcus aureus, Streptococcus mutans, and Lactobacillus casei. CONCLUSIONS: It can be concluded that EEP had a significant effect on the antibacterial activity of both scaffold materials; the antibacterial activity was higher against Gram-positive bacteria.

Hydrogels Based on Alginates and Carboxymethyl Cellulose with Modulated Drug Release-An Experimental and Theoretical Study

New hydrogels films crosslinked with epichlorohydrin were prepared based on alginates and carboxymethyl cellulose with properties that recommend them as potential drug delivery systems (e.g., biocompatibility, low toxicity, non-immunogenicity, hemostatic activity and the ability to absorb large amounts of water). The characterization of their structural, morphological, swelling capacity, loading/release and drug efficiency traits proved that these new hydrogels are promising materials for controlled drug delivery systems. Further, a new theoretical model, in the framework of Scale Relativity Theory, was built with to offer insights on the release process at the microscopic level and to simplify the analysis of the release process.

A novel multifunctional bilayer scaffold based on chitosan nanofiber/alginate-gelatin methacrylate hydrogel for full-thickness wound healing

Due to their lack of multifunctionality, the majority of traditional wound dressings do not support all the clinical requirements. Bilayer wound dressings with multifunctional properties can be attractive for effective skin regeneration. In the present study, we designed a multifunctional bilayer scaffold containing Chitosan-Polycaprolactone (PC) nanofiber and tannic acid (TA) reinforced methacrylate gelatin (GM)/alginate (Al) hydrogel (GM/Al/TA). PC nanofibers were coated with GM/Al/TA hydrogel to obtain a bilayer nanocomposite scaffold (Bi-TA). The GM/Al/TA hydrogel layer of Bi-TA showed antibacterial, free radical scavenging, and biocompatibility properties. Also, PC nanofiber acted as a barrier for preventing bacterial invasion and moisture loss of the hydrogel layer. The wound healing performance of the Bi-TA scaffold was investigated via a full-thickness wound model. In addition, the histopathological and immunohistochemical (IHC) stainings of transforming growth factor-β1(TGF-β1) and tumor necrosis factor-α (TNF-α) were assessed. The results indicated an enhanced wound closure rate, effective collagen deposition, quick re-epithelialization, more skin appendages, and replacement of defect area with normal skin tissue by Bi-TA scaffold compared to other groups. Additionally, the regulation of TGF-β1 and TNF-α was observed by Bi-TA dressing. Overall, the Bi-TA with appropriate structural and multifunctional properties can be an excellent candidate for developing effective dressings for wound healing applications.

Microstructure and Biological Properties of Electrospun In Situ Polymerization of Polycaprolactone-Graft-Polyacrylic Acid Nanofibers and Its Composite Nanofiber Dressings

In this study, polycaprolactone (PCL)- and poly(acrylic acid) (PAA)-based electrospun nanofibers were prepared for the carriers of antimicrobials and designed composite nanofiber mats for chronic wound care. The PCL- and PAA-based electrospun nanofibers were prepared through in situ polymerization starting from PCL and acrylic acid (AA). Different amounts of AA were introduced to improve the hydrophilicity of the PCL electrospun nanofibers. A compatibilizer and a photoinitiator were then added to the electrospinning solution to form a grafted structure composed of PCL and PAA (PCL-g-PAA). The grafted PAA was mainly located on the surface of a PCL nanofiber. The optimization of the composition of PCL, AA, compatibilizer, and photoinitiator was studied, and the PCL-g-PAA electrospun nanofibers were characterized through scanning electron microscopy and 1H-NMR spectroscopy. Results showed that the addition of AA to PCL improved the hydrophilicity of the electrospun PCL nanofibers, and a PCL/AA ratio of 80/20 presented the best composition and had smooth nanofiber morphology. Moreover, poly[2 -(tert-butylaminoethyl) methacrylate]-grafted graphene oxide nanosheets (GO-g-PTA) functioned as an antimicrobial agent and was used as filler for PCL-g-PAA nanofibers in the preparation of composite nanofiber mats, which exerted synergistic effects promoted by the antibacterial properties of GO-g-PTA and the hydrophilicity of PCL-g-PAA electrospun nanofibers. Thus, the composite nanofiber mats had antibacterial properties and absorbed body fluids in the wound healing process, thereby promoting cell proliferation. The biodegradation of the PCL-g-PAA electrospun nanofibers also demonstrated an encouraging result of three-fold weight reduction compared to the neat PCL nanofiber. Our findings may serve as guidelines for the fabrication of electrospun nanofiber composites that can be used mats for chronic wound care.

Chitosan/PEO nanofibers containing Calendula officinalis extract: Preparation, characterization, in vitro and in vivo evaluation for wound healing applications

Wound healing is a complex pathophysiological process, highlighting the importance of effective and thorough wound care along with the prevention of wound infection, a major barrier that can slow down or even disrupt the healing process. To date, there are plenty of herbal plants well known and historically supernatural, showing profound wound healing effects. Application of such herbal extracts/ingredients in electrospun nanofiber platforms has shown promising outcomes in improving wound healing process. Based on these facts, we loaded Calendula officinalis extract (CO) in chitosan/polyethylene oxide scaffolds (CS/PEO) by electrospinning. Using SEM, morphology of electrospun scaffolds showed a narrow range of fiber diameter, around 143--252 nm, with uniform and bead-free appearance. FT-IR spectroscopy confirmed the presence of CO extract in nanofibrous scaffolds. Of importance, incorporation of CO extract improved mechanical properties of CS/PEO nanofibers. A 1602 cP reduction in viscosity and a 0.892 ms/cm increase in the conductivity of the solution was observed after addition of the CO extract. CO extract showed strong antibacterial properties with 96% and 94% reduction in Gram positive and Gram negative bacteria, respectively. In vitro studies with fibroblast cells confirmed enhanced proliferation, growth and attachment of the cells. The in vivo and histological analysis of rat wounds, revealed excellent wound healing ability of CS/PEO/CO dressings (87.5 % wound closure after 14 days) via improving collagen synthesis, re-epithelization and remodeling of the tissue. In sum, our findings show that CS/PEO/CO scaffolds can be used as a promising dressing for the treatment of skin wounds.

JK-2 loaded electrospun membrane for promoting bone regeneration

Hydrogen sulfide (H₂S) has been as an essential gasotransmitter and a potential therapeutic approach for several biomedical treatments such as cardiovascular disorders, hypertension, and other diseases. The endogenous and exogenous H₂S also plays a crucial role in the bone anabolic process and a protective mechanism in cell signalling. In this study, we have utilized two types of polymers, polycaprolactone (PCL) and gelatin (Gel), for the fabrication of JK-2 (H₂S donor) loaded nanofibrous scaffold via electrospinning process for bone healing and bone tissue engineering. Comparing the PCL/Gel and PCL/Gel-JK-2 scaffolds, the latter demonstrated enhanced cell adhesion and proliferation capabilities. Furthermore, both experimental scaffolds have been subjected to an in vivo experiment for 4 and 8 weeks in a bone-defect model of a rabbit to determine their biological responses under physiological conditions. There was an obvious increase in bone regeneration in the PCL/Gel-JK-2 group compared to the control and PCL/Gel groups. These results indicate the use of PCL/Gel scaffolds loaded with JK-2 should be considered for possible bone regeneration.

A bifunctional electrospun nanocomposite wound dressing containing surfactin and curcumin: In vitro and in vivo studies

A double-nozzle electrospinning technique was adopted in the present study to yield a novel bifunctional wound dressing composed of curcumin (Cur) and surfactin (Sur)-loaded poly(ε-caprolactone) (PCL)-gelatin (Gel). To comprehensively unveil the effect of both composition and drug molecules on the applicability, different dressings composed of PCL, Gel, and combination of the polymers with the drug molecules were fabricated. Besides the physicochemical properties, the in vitro and in vivo biological properties of prepared wound dressings were assessed. The results showed that increasing in the Cur from 0 to 3% (w/w) and Sur from 0 to 0.2 mg/mL caused a decrease in the elastic modulus on the one hand. On the other hand, the tensile strength and elongation at break experienced an increase in their values. The wettability, swelling capacity, and degradation rate of PCL improved significantly when both Gel and the drug molecules had been added. The dressings encompassing Sur (0.2 mg/mL) exhibited an excellent antibacterial activity after 24 h (>99%). Moreover, a sustained release of Cur up to 14 days was obtained. The in vitro cell compatibility tests implied a desirable result for all dressings without taking the composition into consideration. To complement the in vitro studies, the PCL/0.2Sur-Gel/3%Cur dressing was further assessed in vivo and the results revealed a significant improvement in the healing rate compared to control groups proofing its great potential for accelerated wound healing applications.

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.

Gelatin-Based Hybrid Scaffolds: Promising Wound Dressings

Wound care is a major biomedical field that is challenging due to the delayed wound healing process. Some factors are responsible for delayed wound healing such as malnutrition, poor oxygen flow, smoking, diseases (such as diabetes and cancer), microbial infections, etc. The currently used wound dressings suffer from various limitations, including poor antimicrobial activity, etc. Wound dressings that are formulated from biopolymers (e.g., cellulose, chitin, gelatin, chitosan, etc.) demonstrate interesting properties, such as good biocompatibility, non-toxicity, biodegradability, and attractive antimicrobial activity. Although biopolymer-based wound dressings display the aforementioned excellent features, they possess poor mechanical properties. Gelatin, a biopolymer has excellent biocompatibility, hemostatic property, reduced cytotoxicity, low antigenicity, and promotes cellular attachment and growth. However, it suffers from poor mechanical properties and antimicrobial activity. It is crosslinked with other polymers to enhance its mechanical properties. Furthermore, the incorporation of antimicrobial agents into gelatin-based wound dressings enhance their antimicrobial activity in vitro and in vivo. This review is focused on the development of hybrid wound dressings from a combination of gelatin and other polymers with good biological, mechanical, and physicochemical features which are appropriate for ideal wound dressings. Gelatin-based wound dressings are promising scaffolds for the treatment of infected, exuding, and bleeding wounds. This review article reports gelatin-based wound dressings which were developed between 2016 and 2021.

Evaluation of Nigella sativa oil loaded electrospun polyurethane nanofibrous mat as wound dressing

Electrospun nanofibers have a natural wound healing effect due to their similarity to the extracellular matrix (ECM). Nigella sativa oil, which has therapeutic properties, is used for a wide variety of applications in traditional medicine. The aim of this study was to investigate the release characteristic and wound healing performance of Nigella sativa oil (NSO) loaded polyurethane (PU) electrospun nanofibrous mats in wound dressing applications. In addition, the antibacterial activity and cytotoxicity of the electrospun mats were studied. Analyses using a scanning electron microscope (SEM) showed that PU/NSO nanofibrous mat with an average fiber diameter of 416 ± 66 nm were successfully fabricated. NSO was released at a maximum ratio of 30% from the electrospun mat, and the Korsmeyer-Peppas model was identified as best for determining the release mechanism. Significant antibacterial activity was observed against Staphylococcus aureus (90.26%) and Escherichia coli (95.75%). The developed PU/NSO nanofibrous mat increased the cell viability more than 100% in human umbilical vein endothelial cell line (HUVEC) cell line. The NSO loaded PU nanofibrous mat significantly promoted the wound healing process on a rat wound model, and its wound closure reached approximately 85% compared to the control groups on the 9^th day (p < 0.01). The results indicated PU/NSO nanofibrous mat is a suitable candidate for a wound dressing.

Bioactives from Bee Products and Accompanying Extracellular Vesicles as Novel Bioactive Components for Wound Healing

In recent years, interest has surged among researchers to determine compounds from bee products such as honey, royal jelly, propolis and bee pollen, which are beneficial to human health. Mass spectrometry techniques have shown that bee products contain a number of proven health-promoting compounds but also revealed rather high diversity in the chemical composition of bee products depending on several factors, such as for example botanical sources and geographical origin. In the present paper, we present recent scientific advances in the field of major bioactive compounds from bee products and corresponding regenerative properties. We also discuss extracellular vesicles from bee products as a potential novel bioactive nutraceutical component. Extracellular vesicles are cell-derived membranous structures that show promising potential in various therapeutic areas. It has been extensively reported that the use of vesicles, which are naturally formed in plant and animal cells, as delivery agents have many advantages. Whether the use of extracellular vesicles from bee products represents a new solution for wound healing remains still to be elucidated. However, promising results in specific applications of the bee products in wound healing and tissue regenerative properties of extracellular vesicles provide a good rationale to further explore this idea.

Propolis loaded and genipin-crosslinked PVA/chitosan membranes; characterization properties and cytocompatibility/genotoxicity response for wound dressing applications

Loading propolis by a simple process using genipin as a crosslinking agent and fabrication of a novel PVA/Chitosan-Propolis membrane scaffolds were reported for wound dressing applications. The research is focused on the effects of propolis on characterization properties of membrane such as chemical structure, surface morphology, degradation ratio, crystallinity, hydrophilicity, water uptake capacity, water vapour transmission rate and mechanical aspect. It was noticed that water uptake capacity and hydrophilicity properties of membrane considerably affected by the propolis. By addition of (0.50, % v/v) propolis, the contact angle of the PVA/Chitosan membrane was remarkably decreased from 86.29° ± 3 to 45 ± 2°. 3-(4,5-dimethylthiazoyl-2-yl)-2,5-diphenylte-trazolium (MTT) bromide test and SEM were used to analyse the cytocompatibility of the membranes and morphology of cells on membrane. The propolis incorporated membrane showed cell proliferation rate 176 ± 13%, 775 ± 1%, and 853 ± 23%, at 24 h, 27 h and 120 h, respectively. SEM images also supported the cell behaviour on membrane. DNA fragmentation was also investigated with genotoxicity test. The studies on the interactions between membranes and MEF cells revealed that the incorporation of propolis into membrane promoted cell proliferation. These overall results presented that propolis incorporated membranes could have potentially appealing application as scaffolds for wound healing applications.

Co-electrospun nanofibrous mats loaded with bitter gourd (Momordica charantia) extract as the wound dressing materials: in vitro and in vivo study

BACKGROUND

Interactive dressings are innovatively designed to interact with the wound surface and alter the wound environment to promote wound healing. In the current study, we integrated the physicochemical properties of Poly (caprolactone)/ Poly (vinyl alcohol)/Collagen (PCL/PVA/Col) nanofibers with the biological activities of Momordica charantia pulp extract to develop an efficient wound dressing. The electrospinning method was applied to fabricate the nanofibers, and the prepared wound dressings were thoroughly characterized.

RESULTS

SEM imaging showed that the nanofibers were uniform, straight, without any beds with a diameter in the range of 260 to 480 nm. Increasing the concentration of the extract increased the diameter of the nanofibers and also the wettability characteristics while reduced the ultimate tensile strength from 4.37 ± 0.90 MPa for PCL/PVA/Col to 1.62 ± 0.50 MPa for PCL/PVA/Col/Ex 10% (p < 0.05). The in vivo studies showed that the application of the wound dressings significantly enhanced the healing process and the highest wound closure, 94.01 ± 8.12%, was obtained by PCL/PVA/Col/Ex 10% nanofibers (p < 0.05).

CONCLUSION

The incorporation of the extract had no significant effects on nanofibers' porosity, water vapor permeability, and swelling characteristics. The in vitro evaluations showed that the fabricated nanofibers were hemocompatible, cytocompatible, and prevent bacterial penetration through the dressing. These findings implied that the PCL/PVA/Col/Ex nanofibers can be applied as the wound dressing materials.

Regeneration potential of decellularized periodontal ligament cell sheets combined with 15-deoxy-Δ12,14-prostaglandin J2 nanoparticles in a rat periodontal defect

Periodontitis is a chronic inflammatory disease characterized by loss of attachment and destruction of the periodontium. Decellularized sheet, as an advanced tissue regeneration engineering biomaterial, has been researched and applied in many fields, but its effects on periodontal regeneration remain unclear. In this study, the biological properties of decellularized human periodontal ligament cell (dHPDLC) sheets were evaluated in vitro. Polycaprolactone/gelatin (PCL/GE) nanofibers were fabricated as a carrier to enhance the mechanical strength of the dHPDLC sheet. 15-deoxy-[Formula: see text]-prostaglandin J₂ (15d-PGJ₂) nanoparticles were added for anti-inflammation and regeneration improvement. For in vivo analysis, dHPDLC sheets combined with 15d-PGJ₂ nanoparticles, with or without PCL/GE, were implanted into rat periodontal defects. The periodontal regeneration effects were identified by microcomputed tomography (micro-CT) and histological staining, and immunohistochemistry. The results revealed that DNA content was reduced by 96.6%. The hepatocyte growth factor, vascular endothelial growth factor, and basic fibroblast growth factor were preserved but reduced. The expressions or distribution of collagen I and fibronectin were similar in dHPDLC and nondecellularized cell sheets. The dHPDLC sheets maintained the intact structure of the extracellular matrix. It could be recellularized by allogeneic human periodontal stem ligament cells and retain osteoinductive potential. Newly formed bone, cementum, and PDL were observed in dHPDLC sheets combined with 15d-PGJ₂ groups, with or without PCL/GE nanofibers, for four weeks post-operation in vivo. Bringing together all these points, this new construct of dHPDLC sheets can be a potential candidate for periodontal regeneration in an inflammatory environment of the oral cavity.

Standardized User-Independent Confocal Microscopy Image Acquisition and Analysis for Thickness Measurements of Microscale Collagen Scaffolds

The ability to accurately and precisely measure the thickness of biomaterial constructs is critical for characterizing both specific dimensional features and related mechanical properties. However, in the absence of a standardized approach for thickness measurements, a variety of imaging modalities have been employed, which have been associated with varying limits of accuracy, particularly for ultrathin hydrated structures. Electron microscopy (EM), a commonly used modality, yields thickness values for extensively processed and nonhydrated constructs, potentially resulting in overestimated mechanical properties, including elastic modulus and ultimate tensile strength. Confocal laser scanning microscopy (CLSM) has often been used as a nondestructive imaging alternative. However, published CLSM-derived image analysis protocols use arbitrary signal intensity cutoffs and provide minimal information regarding thickness variability across imaged surfaces. To address the aforementioned limitations, we present a standardized, user-independent CLSM image acquisition and analysis approach developed as a custom ImageJ macro and validated with collagen-based scaffolds. In the process, we also quantify thickness discrepancies in collagen-based scaffolds between CLSM and EM techniques, further illustrating the need for improved strategies. Employing the same image acquisition protocol, we also demonstrate that this approach can be used to estimate the surface roughness of the same scaffolds without the use of specialized instrumentation.

Preparation of Multipurpose Polyvinylidene Fluoride Membranes via a Spray-Coating Strategy Using Waterborne Polymers

As reported herein, the waterborne polymers poly(glycidyl methacrylate-co-poly(ethylene glycol) methyl ether methacrylate) P(GMA-co-mPEGMA) and polyethyleneimine (PEI) were used to prepare multipurpose polyvinylidene fluoride (PVDF) membranes via a direct spray-coating method. P(GMA-co-mPEGMA) and PEI were alternately sprayed onto the PVDF membrane to yield stable cross-linked copolymer coatings. The successful coating of polymers onto the membrane surface was verified by scanning electron microscopy, attenuated total reflectance-Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy characterization. The coated membrane exhibited oil rejection rates that exceeded 99.0% for oil water mixture separation and 98.0% for oil/water emulsion separation. The flux recovery ratio reached 96.7% after bovine serum albumin filtration and washing with water. The removal efficiencies of the coated membrane M3 for Congo red, methyl orange, methylene blue, and crystal violet, Pb(II), Cu(II), and Cd(II) were 82.4, 83.9, 6.3, 26.8, 90.6, 91.3, and 86.2%, respectively. Thus, it can be used for the removal of dyes and heavy metal ions from wastewater. The antibacterial activities of the coated membranes were also confirmed by the inhibition zone tests and confocal laser scanning microscopy analysis. In addition, the cross-linking strategy provides the coated membranes with excellent durability and repeatability. More importantly, the use of water as the solvent can ensure that the application of these membrane coatings proceeds via a very safe and environmentally friendly coating process.

In-vitro Characterization of a Hernia Mesh Featuring a Nanostructured Coating

Abdominal hernia repair is a frequently performed surgical procedure worldwide. Currently, the use of polypropylene (PP) surgical meshes for the repair of abdominal hernias constitutes the primary surgical approach, being widely accepted as superior to primary suture repair. Surgical meshes act as a reinforcement for the weakened or damaged tissues and support tissue restoration. However, implanted meshes could suffer from poor integration with the surrounding tissues. In this context, the present study describes the preliminary evaluation of a PCL-Gel-based nanofibrous coating as an element to develop a multicomponent hernia mesh device (meshPCL-Gel) that could overcome this limitation thanks to the presence of a nanostructured biomimetic substrate for enhanced cell attachment and new tissue formation. Through the electrospinning technique, a commercial PP hernia mesh was coated with a nanofibrous membrane from a polycaprolactone (PCL) and gelatin (Gel) blend (PCL-Gel). Resulting PCL-Gel nanofibers were homogeneous and defect-free, with an average diameter of 0.15 ± 0.04 μm. The presence of Gel decreased PCL hydrophobicity, so that membranes average water contact angle dropped from 138.9 ± 1.1° (PCL) to 99.9 ± 21.6°, while it slightly influenced mechanical properties, which remained comparable to those of PCL (E = 15.7 ± 2.7 MPa, σ R = 7.7 ± 0.6 ε R = 118.8 ± 13.2%). Hydrolytic and enzymatic degradation was conducted on PCL-Gel up to 28 days, with maximum weight losses around 20 and 40%, respectively. The meshPCL-Gel device was obtained with few simple steps, with no influences on the original mechanical properties of the bare mesh, and good stability under physiological conditions. The biocompatibility of meshPCL-Gel was assessed by culturing BJ human fibroblasts on the device, up to 7 days. After 24 h, cells adhered to the nanofibrous substrate, and after 72 h their metabolic activity was about 70% with respect to control cells. The absence of detectable lactate dehydrogenase in the culture medium indicated that no necrosis induction occurred. Hence, the developed nanostructured coating provided the meshPCL-Gel device with chemical and topographical cues similar to the native extracellular matrix ones, that could be exploited for enhancing the biological response and, consequently, mesh integration, in abdominal wall hernia repair.

Convergence of 3D printed biomimetic wound dressings and adult stem cell therapy

Biomimetically designed medical-grade polycaprolactone (mPCL) dressings are 3D-printed with pore architecture and anisotropic mechanical characteristics that favor skin wound healing with reduced scarring. Melt electrowritten mPCL dressings are seeded with human gingival tissue multipotent mesenchymal stem/stromal cells and cryopreserved using a clinically approved method. The regenerative potential of fresh or frozen cell-seeded mPCL dressing is compared in a splinted full-thickness excisional wound in a rat model over six weeks. The application of 3D-printed mPCL dressings decreased wound contracture and significantly improved skin regeneration through granulation and re-epithelialization compared to control groups. Combining 3D-printed biomimetic wound dressings and precursor cell delivery enhances physiological wound closure with reduced scar tissue formation.

Historical and modern research on propolis and its application in wound healing and other fields of medicine and contributions by Polish studies

ETHNOPHARMACOLOGICAL RELEVANCE

The history of medical application of propolis (also known as bee glue) dates back to the times of ancient Greeks, Romans, Persians and Egyptians. Honey and other bee products, including propolis, occupy an important place in Polish folk medicine. Scientific research on propolis in Poland began in the early 1960s in Zabrze and continues until now.

AIM OF THE REVIEW

The aim of this review is to provide an overview of information on Polish research on propolis and its medical application with particular emphasis on studies concerning wound healing. Consequently, our goal is also to shed a new light on therapeutic potential of Polish propolis in order to support future research in the field.

MATERIALS AND METHODS

A systematic review of scientific literature on propolis and its medical application was performed by using the literature databases (PubMed, Web of Science, Google Scholar). We paid special attention to papers describing the effect of propolis on skin wound healing as well as to Polish contribution to research on propolis.

RESULTS

Professor Stan Scheller was the first Polish scientist dealing with propolis and its medical potential. His legacy was continued by several research teams that studied the topic in various aspects. They analyzed propolis composition, its antioxidant, anti-inflammatory, antimicrobial, antiapoptotic and anticancer properties as well as its application in dentistry and wound treatment. Burn wound healing physiology after propolis administration was thoroughly studied on pig model, whereas research on patients proved the efficacy of propolis in chronic venous leg ulcer treatment.

CONCLUSION

Polish scientists have made a significant contribution to the research on propolis, its biological properties and influence on wound healing. Propolis ointments can effectively accelerate the healing process and improve healing physiology, so they can be recommended as a promising topical medication for wound treatment in the future clinical and preclinical trials.

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.