Nanostructured Fibers Containing Natural or Synthetic Bioactive Compounds in Wound Dressing Applications

Electrospun wound dressings with antibacterial function: a critical review of plant extract and essential oil incorporation

Among the many different types of wound dressings, nanofiber-based materials produced through electrospinning are claimed to be ideal because of their advantageous intrinsic properties and the feasibility of employing several strategies to load bioactive compounds into their structure. Bioactive compounds with antimicrobial properties have been incorporated into different wound dressings to promote healing as well as prevent and treat bacterial infections. Among these, natural products, such as medicinal plant extracts and essential oils (EOs), have proven particularly attractive thanks to their nontoxic nature, minor side effects, desirable bioactive properties, and favorable effects on the healing process. To this end, the present review provides an exhaustive and up-to-date revision of the most prominent medicinal plant extracts and EOs with antimicrobial properties that have been incorporated into nanofiber-based wound dressings. The most common methods used for incorporating bioactive compounds into electrospun nanofibers include: pre-electrospinning (blend, encapsulation, coaxial, and emulsion electrospinning), post-electrospinning (physical adsorption, chemical immobilization, and layer-by-layer assembly), and nanoparticle loading. Furthermore, a general overview of the benefits of EOs and medicinal plant extracts is presented, describing their intrinsic properties and biotechniques for their incorporation into wound dressings. Finally, the current challenges and safety issues that need to be adequately clarified and addressed are discussed.

Patient With Sitosterolemia With Slow Healing Sternal Wound From Coronary Artery Bypass Surgery

BACKGROUND

Sitosterolemia, also known as phytosterolemia, is a rare recessive genetic disorder characterized by accumulation of sitosterol from vegetable oils, nuts, and other plant-based foods in the body. In those with sitosterolemia, there is an increase of fatty deposits in the arteries (atherosclerosis), which may occur in early childhood, impeding blood flow and increasing the risk of a heart attack, stroke, or sudden death at a very early age. Visual signs of sitosterolemia may include small yellowish xanthomas beginning in early childhood. Xanthomas are accumulated lipids that develop in the heels, elbows, and buttocks.

CASE

A clinical case study of a patient with sitosterolemia with slow healing surgical wound from coronary artery bypass surgery is described. Treatment of sitosterolemia is aimed at lowering plasma plant sterol levels with dietary restriction intake of both animal- and plant-based sterols. However, plant-based products (collagen, chitosan, etc) are also used for wound dressings, so alternative wound dressings were selected to decrease the possibility of systemic absorption.

CONCLUSION

This case study describes a young adult male with sitosterolemia who presented with a slow healing surgical incision following coronary artery bypass surgery. Sitosterolemia is often characterized by atherosclerosis of the coronary arteries that occurs in children and early adulthood, especially affecting men. Treatment is aimed at lowering plasma sterol levels with the restriction of animal and plant sterols. There is considerable interest today in natural versus synthetic wound care products. Dressings containing chitosan, cellulose, collagen, etc, to be avoided to decrease the chance of systemic absorption.

PVA/PVP Nanofibres Incorporated with Ecklonia cava Phlorotannins Exhibit Excellent Cytocompatibility and Accelerate Hyperglycaemic Wound Healing

BACKGROUND

Diabetic foot ulcer (DFU) is a major debilitating complication of diabetes. The lack of effective diabetic wound dressings has been a significant problem in DFU management. In this study, we aim to establish a phlorotannin-incorporated nanofibre system and determine its potential in accelerating hyperglycaemic wound healing.

METHODS

The effective dose of Ecklonia cava phlorotannins (ECP) for hyperglycaemic wound healing was determined prior to phlorotannin nanofibre fabrication using polyvinyl-alcohol (PVA), polyvinylpyrrolidone (PVP), and ECP. Vapour glutaraldehyde was used for crosslinking of the PVA/PVP nanofibres. The phlorotannin nanofibres were characterised, and their safety and cytocompatibility were validated. Next, the wound healing effect of phlorotannin nanofibres was determined with 2D wound scratch assay, whereas immunofluorescence staining of Collagen-I (Col-I) and Cytokeratin-14 (CK-14) was performed in human dermal fibroblasts (HDF) and human epidermal keratinocytes (HEK), respectively.

RESULTS

Our results demonstrated that 0.01 μg/mL ECP significantly improved hyperglycaemic wound healing without compromising cell viability and proliferation. Among all nanofibres, PVA/PVP/0.01 wt% ECP nanofibres exhibited the best hyperglycaemic wound healing effect. They displayed a diameter of 334.7 ± 10.1 nm, a porosity of 40.7 ± 3.3%, and a WVTR of 1718.1 ± 32.3 g/m2/day. Besides, the FTIR spectra and phlorotannin release profile validated the successful vapour glutaraldehyde crosslinking and ECP incorporation. We also demonstrated the potential of phlorotannin nanofibres as a non-cytotoxic wound dressing as they support the viability and proliferation of both HDF and HEK. Furthermore, phlorotannin nanofibres significantly ameliorated the impaired hyperglycaemic wound healing and restored the hyperglycaemic-induced Col-I reduction in HDF.

CONCLUSION

Taken together, our findings show that phlorotannin nanofibres have the potential to be used as a diabetic wound dressing.

Composite nanofibrous dressing loaded with Prussian blue and heparin for anti-inflammation therapy and diabetic wound healing

Diabetic ulcer is a severe complication of diabetes that can lead to amputation due to the overproduction of pro-inflammatory factors and reactive oxygen species (ROS). In this study, a composite nanofibrous dressing was developed by combining Prussian blue nanocrystals (PBNCs) and heparin sodium (Hep) through electrospinning, electrospraying, and chemical deposition. The nanofibrous dressing (PPBDH) was designed to take advantage of the excellent pro-inflammatory factor-adsorbing capability of Hep and the ROS-scavenging capabilities of PBNCs, resulting in synergistic treatment. It is worth noting that the nanozymes were firmly anchored to the fiber surfaces through slight polymer swelling caused by the solvent during electrospinning, thereby guaranteeing the preservation of the enzyme-like activity levels of PBNCs. The PPBDH dressing was found to be effective in reducing intracellular ROS levels, protecting cells from ROS-induced apoptosis, and capturing excessive pro-inflammatory factors, including chemoattractant protein-1 (MCP-1) and interleukin-1β (IL-1β). Furthermore, a chronic wound healing evaluation conducted in vivo demonstrated that the PPBDH dressing was able to effectively alleviate the inflammatory response and accelerate wound healing. This research presents an innovative approach to fabricate nanozyme hybrid nanofibrous dressings, which have great potential in accelerating the healing of chronic and refractory wounds with uncontrolled inflammation.

Recent Tissue Engineering Approaches to Mimicking the Extracellular Matrix Structure for Skin Regeneration

Inducing tissue regeneration in many skin defects, such as large traumatic wounds, burns, other physicochemical wounds, bedsores, and chronic diabetic ulcers, has become an important clinical issue in recent years. Cultured cell sheets and scaffolds containing growth factors are already in use but have yet to restore normal skin tissue structure and function. Many tissue engineering materials that focus on the regeneration process of living tissues have been developed for the more versatile and rapid initiation of treatment. Since the discovery that cells recognize the chemical-physical properties of their surrounding environment, there has been a great deal of work on mimicking the composition of the extracellular matrix (ECM) and its three-dimensional network structure. Approaches have used ECM constituent proteins as well as morphological processing methods, such as fiber sheets, sponges, and meshes. This review summarizes material design strategies in tissue engineering fields, ranging from the morphology of existing dressings and ECM structures to cellular-level microstructure mimicry, and explores directions for future approaches to precision skin tissue regeneration.

Electrospun Polycaprolactone/Chitosan Nanofibers Containing Cordia myxa Fruit Extract as Potential Biocompatible Antibacterial Wound Dressings

The goal of the current work was to create an antibacterial agent by using polycaprolactone/chitosan (PCL/CH) nanofibers loaded with Cordia myxa fruit extract (CMFE) as an antimicrobial agent for wound dressing. Several characteristics, including morphological, physicomechanical, and mechanical characteristics, surface wettability, antibacterial activity, cell viability, and in vitro drug release, were investigated. The inclusion of CMFE in PCL/CH led to increased swelling capability and maximum weight loss. The SEM images of the PCL/CH/CMFE mat showed a uniform topology free of beads and an average fiber diameter of 195.378 nm. Excellent antimicrobial activity was shown towards Escherichia coli (31.34 ± 0.42 mm), Salmonella enterica (30.27 ± 0.57 mm), Staphylococcus aureus (21.31 ± 0.17 mm), Bacillus subtilis (27.53 ± 1.53 mm), and Pseudomonas aeruginosa (22.17 ± 0.12 mm) based on the inhibition zone assay. The sample containing 5 wt% CMFE had a lower water contact angle (47 ± 3.7°), high porosity, and high swelling compared to the neat mat. The release of the 5% CMFE-loaded mat was proven to be based on anomalous non-Fickian diffusion using the Korsmeyer–Peppas model. Compared to the pure PCL membrane, the PCL-CH/CMFE membrane exhibited suitable cytocompatibility on L929 cells. In conclusion, the fabricated antimicrobial nanofibrous films demonstrated high bioavailability, with suitable properties that can be used in wound dressings.

A Review on Electrospun Poly(amino acid) Nanofibers and Their Applications of Hemostasis and Wound Healing

The timely and effective control and repair of wound bleeding is a key research issue all over the world. From traditional compression hemostasis to a variety of new hemostatic methods, people have a more comprehensive understanding of the hemostatic mechanism and the structure and function of different types of wound dressings. Electrospun nanofibers stand out with nano size, high specific surface area, higher porosity, and a variety of complex structures. They are high-quality materials that can effectively promote wound hemostasis and wound healing because they can imitate the structural characteristics of the skin extracellular matrix (ECM) and support cell adhesion and angiogenesis. At the same time, combined with amino acid polymers with good biocompatibility not only has high compatibility with the human body but can also be combined with a variety of drugs to further improve the effect of wound hemostatic dressing. This paper summarizes the application of different amino acid electrospun wound dressings, analyzes the characteristics of different materials in preparation and application, and looks forward to the development of directions of poly(amino acid) electrospun dressings in hemostasis.

ELECTROSPUN SODIUM ALGINATE/POLY(ETHYLENE OXIDE) NANOFIBERS FOR WOUND HEALING APPLICATIONS: CHALLENGES AND FUTURE DIRECTIONS

Alginate is an interesting natural biopolymer to be considered for biomedical applications due to its advantages and good biological properties. These biological properties make electrospun alginate nanofibers suitable for various uses in the biomedical field, such as wound healing dressings, drug delivery systems, or both. Unfortunately, the fabrication of alginate nanofibers by electrospinning is very challenging because of the high viscosity of the solution, high surface tension and rigidity in water due to hydrogen bonding, and also their diaxial linkages. This review presents an overview of the factors affecting the electrospinning process of sodium alginate/poly(ethylene oxide) (SA/PEO), the application of SA/PEO in drug delivery systems for wound healing applications, and the degradation and swelling properties of SA/PEO. The challenges and future directions of SA/PEO in the medical field are also discussed.

Antimicrobial and Antibiofilm Activity of Curcumin-Loaded Electrospun Nanofibers for the Prevention of the Biofilm-Associated Infections

Curcumin extracted from the rhizome of Curcuma Longa has been used in therapeutic preparations for centuries in different parts of the world. However, its bioactivity is limited by chemical instability, water insolubility, low bioavailability, and extensive metabolism. In this study, the coaxial electrospinning technique was used to produce both poly (ε-caprolactone) (PCL)-curcumin and core-shell nanofibers composed of PCL and curcumin in the core and poly (lactic acid) (PLA) in the shell. Morphology and physical properties, as well as the release of curcumin were studied and compared with neat PCL, showing the formation of randomly oriented, defect-free cylindrical fibers with a narrow distribution of the dimensions. The antibacterial and antibiofilm potential, including the capacity to interfere with the quorum-sensing mechanism, was evaluated on Pseudomonas aeruginosa PAO1, and Streptococcus mutans, two opportunistic pathogenic bacteria frequently associated with infections. The reported results demonstrated the ability of the Curcumin-loading membranes to inhibit both PAO1 and S. mutans biofilm growth and activity, thus representing a promising solution for the prevention of biofilm-associated infections. Moreover, the high biocompatibility and the ability to control the oxidative stress of damaged tissue, make the synthesized membranes useful as scaffolds in tissue engineering regeneration, helping to accelerate the healing process.

Role of Honey in Advanced Wound Care

Honey is a natural product rich in several phenolic compounds, enzymes, and sugars with antioxidant, anticarcinogenic, anti-inflammatory, and antimicrobial potential. Indeed, the development of honey-based adhesives for wound care and other biomedical applications are topics being widely investigated over the years. Some of the advantages of the use of honey for wound-healing solutions are the acceleration of dermal repair and epithelialization, angiogenesis promotion, immune response promotion and the reduction in healing-related infections with pathogenic microorganisms. This paper reviews the main role of honey on the development of wound-healing-based applications, the main compounds responsible for the healing capacity, how the honey origin can influence the healing properties, also highlighting promising results in in vitro and in vivo trials. The challenges in the use of honey for wound healing are also covered and discussed. The delivery methodology (direct application, incorporated in fibrous membranes and hydrogels) is also presented and discussed.

Electrically Triggered Drug Delivery from Novel Electrospun Poly(Lactic Acid)/Graphene Oxide/Quercetin Fibrous Scaffolds for Wound Dressing Applications

The novel controlled and localized delivery of drug molecules to target tissues using an external electric stimulus makes electro-responsive drug delivery systems both feasible and desirable, as well as entailing a reduction in the side effects. Novel micro-scaffold matrices were designed based on poly(lactic acid) (PLA) and graphene oxide (GO) via electrospinning. Quercetin (Q), a natural flavonoid, was loaded into the fiber matrices in order to investigate the potential as a model drug for wound dressing applications. The physico-chemical properties, electrical triggering capacity, antimicrobial assay and biocompatibility were also investigated. The newly fabricated PLA/GO/Q scaffolds showed uniform and smooth surface morphologies, without any beads, and with diameters ranging from 1107 nm (10%PLA/0.1GO/Q) to 1243 nm (10%PLA). The in vitro release tests of Q from the scaffolds showed that Q can be released much faster (up to 8640 times) when an appropriate electric field is applied compared to traditional drug-release approaches. For instance, 10 s of electric stimulation is enough to ensure the full delivery of the loaded Q from the 10%PLA/1%GO/Q microfiber scaffold at both 10 Hz and at 50 Hz. The antimicrobial tests showed the inhibition of bacterial film growth. Certainly, these materials could be loaded with more potent agents for anti-cancer, anti-infection, and anti-osteoporotic therapies. The L929 fibroblast cells cultured on these scaffolds were distributed homogeneously on the scaffolds, and the highest viability value of 82.3% was obtained for the 10%PLA/0.5%GO/Q microfiber scaffold. Moreover, the addition of Q in the PLA/GO matrix stimulated the production of IL-6 at 24 h, which could be linked to an acute inflammatory response in the exposed fibroblast cells, as a potential effect of wound healing. As a general conclusion, these results demonstrate the possibility of developing graphene oxide-based supports for the electrically triggered delivery of biological active agents, with the delivery rate being externally controlled in order to ensure personalized release.

Nanotechnologies: An Innovative Tool to Release Natural Extracts with Antimicrobial Properties

Site-Specific release of active molecules with antimicrobial activity spurred the interest in the development of innovative polymeric nanocarriers. In the preparation of polymeric devices, nanotechnologies usually overcome the inconvenience frequently related to other synthetic strategies. High performing nanocarriers were synthesized using a wide range of starting polymer structures, with tailored features and great chemical versatility. Over the last decade, many antimicrobial substances originating from plants, herbs, and agro-food waste by-products were deeply investigated, significantly catching the interest of the scientific community. In this review, the most innovative strategies to synthesize nanodevices able to release antimicrobial natural extracts were discussed. In this regard, the properties and structure of the starting polymers, either synthetic or natural, as well as the antimicrobial activity of the biomolecules were deeply investigated, outlining the right combination able to inhibit pathogens in specific biological compartments.

Advances in Osteoporotic Bone Tissue Engineering

The increase in osteoporotic fracture worldwide is urging bone tissue engineering research to find new, improved solutions both for the biomaterials used in designing bone scaffolds and the anti-osteoporotic agents capable of promoting bone regeneration. This review aims to report on the latest advances in biomaterials by discussing the types of biomaterials and their properties, with a special emphasis on polymer-ceramic composites. The use of hydroxyapatite in combination with natural/synthetic polymers can take advantage of each of their components properties and has a great potential in bone tissue engineering, in general. A comparison between the benefits and potential limitations of different scaffold fabrication methods lead to a raised awareness of the challenges research face in dealing with osteoporotic fracture. Advances in 3D printing techniques are providing the ways to manufacture improved, complex, and specialized 3D scaffolds, capable of delivering therapeutic factors directly at the osteoporotic skeletal defect site with predefined rate which is essential in order to optimize the osteointegration/healing rate. Among these factors, strontium has the potential to increase osseointegration, osteogenesis, and healing rate. Strontium ranelate as well as other biological active agents are known to be effective in treating osteoporosis due to both anti-resorptive and anabolic properties but has adverse effects that can be reduced/avoided by local release from biomaterials. In this manner, incorporation of these agents in polymer-ceramic composites bone scaffolds can have significant clinical applications for the recovery of fractured osteoporotic bones limiting or removing the risks associated with systemic administration.

New Insights for Red Propolis of Alagoas-Chemical Constituents, Topical Membrane Formulations and Their Physicochemical and Biological Properties

The main objectives of this study were to evaluate the chemical constitution and allergenic potential of red propolis extract (RPE). They were evaluated, using high performance liquid chromatography (HPLC) and the release of β-hexosaminidase, respectively. A plethora of biologically active polyphenols and the absence of allergic responses were evinced. RPE inhibited the release of β-hexosaminidase, suggesting that the extract does not stimulate allergic responses. Additionally, the physicochemical properties and antibacterial activity of hydrogel membranes loaded with RPE were analyzed. Bio-polymeric hydrogel membranes (M) were obtained using 5% carboxymethylcellulose (M1 and M2), 1.0% of citric acid (M3) and 10% RPE (for all). Their characterization was performed using thermal analysis, Fourier transform infrared (FTIR), total phenolic content, phenol release test and, antioxidant activity through 2,2-diphenyl-1-picrylhydrazyl radical (DPPH) and Ferric Reducing Antioxidant Power (FRAP). The latter appointed to the similar antioxidant capacity of the M1, M2 and M3. The degradation profiles showed higher thermostability to M3, followed by M2 and M1. The incorporation of RPE into the matrices and the crosslinking of M3 were evinced by FTIR. There were differences in the release of phenolic compounds, with a higher release related to M1 and lower in the strongly crosslinked M3. The degradation profiles showed higher thermostability to M3, followed by M2 and M1. The antibacterial activity of the membranes was determined using the disc diffusion assay, in comparison with controls, obtained in the same way, without RPE. The membranes elicited antibacterial activity against Staphylococcus aureus and Staphylococcus epidermidis, with superior performance over M3. The hydrogel membranes loaded with RPE promote a physical barrier against bacterial skin infections and may be applied in the wound healing process.

Development and Optimization of Naringenin-Loaded Chitosan-Coated Nanoemulsion for Topical Therapy in Wound Healing

The potential role of naringenin (NAR), a natural flavonoid, in the treatment of chronic wound has prompted the present research to deliver the drug in nanoemulsion (NE) form, where synergistic role of chitosan was achieved through development of chitosan-coated NAR NE (CNNE). The NE consisted of Capryol 90, Tween 20 and Transcutol P, which was fabricated by low-energy emulsification method to encapsulate NAR within the oil core. The optimization of the formulated NEs was performed using Box-Behnken statistical design to obtain crucial variable parameters that influence globule size, size distribution and surface charge. Finally, the optimized formulation was coated with different concentrations of chitosan and subsequently characterized in vitro. The size of the CNNE was found to be increased when the drug-loaded formulation was coated with chitosan. Controlled release characteristics depicted 67-81% release of NAR from the CNNE, compared to 89% from the NE formulation. Cytotoxicity study of the formulation was performed in vitro using fibroblast cell line (NIH-3T3), where no inhibition in proliferation of the cells was observed with CNNE. Finally, the wound healing potential of the CNNE was evaluated in an abrasion-created wound model in experimental animals where the animals were treated and compared histologically at 0 and 14 days. Significant improvement in construction of the abrasion wound was observed when the animals were treated with formulated CNNE, whereas stimulation of skin regeneration was depicted in the histological examination. Therefore, it could be summarized that the chitosan coating of the developed NAR NE is a potential platform to accelerate healing of wounds.