Bioadhesive polymeric films based on usnic acid for burn wound treatment: Antibacterial and cytotoxicity studies

A biguanide chitosan-based hydrogel adhesive accelerates the healing of bacterial-infected wounds

The development of tissue adhesives with good biocompatibility and potent antimicrobial properties is crucial for addressing the high incidence of surgical site infections in emergency and clinical settings. Herein, an injectable hydrogel adhesive composed of chitosan biguanidine (CSG), oxidized dextran (ODex) and tannin (TA) was synthesized primarily through Schiff-base reactions, hydrogen bonding, and electrostatic interactions. TA was introduced into the CSG/ODex hydrogel to prepare a physicochemically double cross-linked hydrogel. The hydrogel formulation incorporating 2 wt% TA (CSG/ODex-TA2) exhibited rapid gelation, moderate mechanical properties, good tissue adhesion, and sustained release behavior of TA. Both in vitro and in vivo studies demonstrated that CSG/ODex-TA2 showed significantly enhanced adhesion and antibacterial effectiveness compared to the CSG/ODex hydrogel and commercial fibrin glue. Leveraging the positive charge of CSG, the CSG/ODex-TA2 hydrogel demonstrated a strong contact antibacterial effect, while the sustained release of TA provided diffusion antibacterial capabilities. By integrating contact and diffusion antibacterial mechanisms into the hydrogel, a promising approach was developed to boost antibacterial efficiency and accelerate the healing of wounds infected with methicillin-resistant Staphylococcus aureus (MRSA). The CSG/ODex-TA2 hydrogel has excellent biocompatibility, hemostatic properties, and antibacterial capabilities, making it a promising candidate for improving in vivo wound care and combating bacterial infections.

Exploring Cationic Guar Gum: Innovative Hydrogels and Films for Enhanced Wound Healing

Background/Objectives: This study developed and characterized hydrogels (HG-CGG) and films (F-CGG) based on cationic guar gum (CGG) for application in wound healing. Methods: HG-CGG (2% w/v) was prepared by gum thickening and evaluated for pH, stability, spreadability, and viscosity. F-CGG was obtained using an aqueous dispersion of CGG (6% w/v) and the solvent casting method. F-CGG was characterized for thickness, weight uniformity, morphology, mechanical properties, hydrophilicity, and swelling potential. Both formulations were evaluated for bioadhesive potential on intact and injured porcine skin, as well as antioxidant activity. F-CGG was further studied for biocompatibility using hemolysis and cell viability assays (L929 fibroblasts), and its wound-healing potential by the scratch assay. Results: HG-CGG showed adequate viscosity and spreadability profiles for wound coverage, but its bioadhesive strength was reduced on injured skin. In contrast, F-CGG maintained consistent bioadhesive strength regardless of skin condition (6554.14 ± 540.57 dyne/cm2 on injured skin), presenting appropriate mechanical properties (flexible, transparent, thin, and resistant) and a high swelling capacity (2032 ± 211% after 6 h). F-CGG demonstrated superior antioxidant potential compared to HG-CGG (20.50 mg/mL ABTS+ radical scavenging activity), in addition to exhibiting low hemolytic potential and no cytotoxicity to fibroblasts. F-CGG promoted the proliferation of L929 cells in vitro, supporting wound healing. Conclusions: Therefore, CGG proved to be a promising material for developing formulations with properties suitable for cutaneous use. F-CGG combines bioadhesion, antioxidant activity, biocompatibility, cell proliferation, and potential wound healing, making it promising for advanced wound treatment.

Enhancing Wound Healing and Bactericidal Efficacy: A Hydrogel Membrane of Bacterial Cellulose and Sanxan Gel for Accelerating the Healing of Infected Wounds

Bacterial cellulose is an extracellular polysaccharide produced by microorganisms, offering advantages such as high water-holding capacity, flexibility, and biocompatibility. However, its lack of bactericidal activity hampers its wide application. Usnic acid, a secondary metabolite derived from lichens of the Usnea genus, is recognized for its antibacterial and anti-biofilm efficiency, coupled with anti-inflammatory properties. Its water insolubility presents challenges for wide utilization and stable release. Sanxan gel, a novel polysaccharide, exhibits exceptional freeze-thaw stability, suspension properties, and high elasticity, rendering it effective as a suspending agent to improve the bioavailability of water-insoluble drugs. In this study, a hydrogel membrane is designed by combining bacterial cellulose and usnic acid suspended in sanxan gel through a simple in situ microorganism fermentation. The obtained membranes demonstrate excellent ability for sustained drug release, strong eradication capability against tested bacteria in both in vitro and in vivo experiments, effective inhibition of biofilm formation, and excellent hemocompatibility and cytocompatibility. Additionally, the composite membranes promote wound healing with reduced inflammation and bacterial infection in a full-thickness wound infection model in mice. This study provides innovative insights and strategies for the development of functional dressings for infected wounds in future clinical applications.

Bioadhesives with Antimicrobial Properties

Bioadhesives with antimicrobial properties enable easier and safer treatment of wounds as compared to the traditional methods such as suturing and stapling. Composed of natural or synthetic polymers, these bioadhesives seal wounds and facilitate healing while preventing infections through the activity of locally released antimicrobial drugs, nanocomponents, or inherently antimicrobial polers. Although many different materials and strategies are employed to develop antimicrobial bioadhesives, the design of these biomaterials necessitates a prudent approach as achieving all the required properties including optimal adhesive and cohesive properties, biocompatibility, and antimicrobial activity can be challenging. Designing antimicrobial bioadhesives with tunable physical, chemical, and biological properties will shed light on the path for future advancement of bioadhesives with antimicrobial properties. In this review, the requirements and commonly used strategies for developing bioadhesives with antimicrobial properties are discussed. In particular, different methods for their synthesis and their experimental and clinical applications on a variety of organs are reviewed. Advances in the design of bioadhesives with antimicrobial properties will pave the way for a better management of wounds to increase positive clinical outcomes.

Formulation and In Vivo Evaluation of Biofilm Loaded with Silver Sulfadiazine for Burn Healing

Infected burned skin is a life-threatening condition, which may lead to sepsis. The aims of this work are to formulate a biofilm composed of silver sulfadiazine (SSD), chitosan (CS), and sodium alginate (SA), and to evaluate its wound-healing effectiveness. A full factorial design was used to formulate different matrix formulations. The prepared biofilm was tested for physicochemical, and in vitro release. The optimized formulation is composed of 0.833% of CS and 0.75% of SA. The release of SSD almost reached 100% after 6 h. The mechanical properties of the optimized formula were reasonable. The antibacterial activity for the optimized biofilm was significantly higher than that of blank biofilm, which is composed of CS and SA, p = 1.53922 × 10-12. Moreover, the in vivo study showed a 75% reduction in wound width when using the formulated SSD biofilm compared to standard marketed cream (57%) and the untreated group (0%).

Electrospun PVA Fibers for Drug Delivery: A Review

Innovation in biomedical science is always a field of interest for researchers. Drug delivery, being one of the key areas of biomedical science, has gained considerable significance. The utilization of simple yet effective techniques such as electrospinning has undergone significant development in the field of drug delivery. Various polymers such as PEG (polyethylene glycol), PLGA (Poly(lactic-co-glycolic acid)), PLA(Polylactic acid), and PCA (poly(methacrylate citric acid)) have been utilized to prepare electrospinning-based drug delivery systems (DDSs). Polyvinyl alcohol (PVA) has recently gained attention because of its biocompatibility, biodegradability, non-toxicity, and ideal mechanical properties as these are the key factors in developing DDSs. Moreover, it has shown promising results in developing DDSs individually and when combined with natural and synthetic polymers such as chitosan and polycaprolactone (PCL). Considering the outstanding properties of PVA, the aim of this review paper was therefore to summarize these recent advances by highlighting the potential of electrospun PVA for drug delivery systems.

Karaya/Gellan-Gum-Based Bilayer Films Containing 3,3'-Diindolylmethane-Loaded Nanocapsules: A Promising Alternative to Melanoma Topical Treatment

This study aimed to incorporate nanocapsules containing 3,3'-diindolylmethane (DIM) with antitumor activity into a bilayer film of karaya and gellan gums for use in topical melanoma therapy. Nanocarriers and films were prepared by interfacial deposition of the preformed polymer and solvent casting methods, respectively. Incorporating DIM into nanocapsules increased its antitumor potential against human melanoma cells (A-375) (IC50 > 24.00 µg/mL free DIM × 2.89 µg/mL nanocapsules). The films were transparent, hydrophilic (θ < 90°), had homogeneous thickness and weight, and had a DIM content of 106 µg/cm2. Radical ABTS+ scavenger assay showed that the DIM films presented promising antioxidant action. Remarkably, the films showed selective bioadhesive potential on the karaya gum side. Considering the mechanical analyses, the nanotechnology-based films presented appropriate behavior for cutaneous application and controlled DIM release profile, which could increase the residence time on the application site. Furthermore, the nanofilms were found to increase the permeation of DIM into the epidermis, where melanoma develops. Lastly, the films were non-hemolytic (hemolysis test) and non-irritant (HET-CAM assay). In summary, the combination of karaya and gellan gum in bilayer films that contain nanoencapsulated DIM has demonstrated potential in the topical treatment of melanoma and could serve as a viable option for administering DIM for cutaneous melanoma therapy.

Electrospun Nanofibrous Mesh Based on PVA, Chitosan, and Usnic Acid for Applications in Wound Healing

Injuries and diseases of the skin require accurate treatment using nontoxic and noninvasive biomaterials, which aim to mimic the natural structures of the body. There is a strong need to develop biodevices capable of accommodating nutrients and bioactive molecules and generating the process of vascularization. Electrospinning is a robust technique, as it can form fibrous structures for tissue engineering and wound dressings. The best way of forming such meshes for wound healing is to choose two polymers that complement each other regarding their properties. On the one hand, PVA is a water-soluble synthetic polymer widely used for the preparation of hydrogels in the field of biomedicine owing to its biocompatibility, water solubility, nontoxicity, and considerable mechanical properties. PVA is easy to subject to electrospinning and can offer strong mechanical stability of the mesh, but it is necessary to improve its biological properties. On the other hand, CS has good biological properties, including biodegradability, nontoxicity, biocompatibility, and antimicrobial properties. Still, it is harder to electrospin and does not possess as good mechanical properties as PVA. As these structures also allow the incorporation of bioactive agents due to their high surface-area-to-volume ratio, the interesting point was to incorporate usnic acid into the structure as it is a natural and suitable alternative agent for burn wounds treatment which avoids an improper or overuse of antibiotics and other invasive biomolecules. Thus, we report the fabrication of an electrospun nanofibrous mesh based on PVA, chitosan, and usnic acid with applications in wound healing. The obtained nanofibers mesh was physicochemically characterized by Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM). In vitro biological assays were performed to evaluate the antimicrobial properties of the samples using the MIC (minimum inhibitory concentration) assay and evaluating the influence of fabricated meshes on the Staphylococcus aureus biofilm development, as well as their biocompatibility (demonstrated by fluorescence microscopy results, an XTT assay, and a glutathione (GSH) assay).

Benzofuran as a promising scaffold for the synthesis of novel antimicrobial agents

INTRODUCTION

The benzofuran moiety constitutes a main component of enormous biologically active natural and synthetic heterocycles. Such heterocycles have distinctive therapeutic potential and are employed in various clinical drugs. A number of publications have dealt with the synthesis and extraction of benzofuran-based heterocycles to investigate their antimicrobial potential.

AREAS COVERED

This review describes the antimicrobial activity of various natural and synthetic benzofuran scaffolds. The antimicrobial activity of benzofurans is thoroughly investigated against several bacterial (Gram-positive and Gram-negative) and fungal microorganisms compared with several reference antibiotic drugs. The effects of the electronic nature of substituents on the activity of benzofurans through SAR study were reported. This article also highlights the recent natural and synthetic benzofuran-based organic molecules between 2019-2022 that have had success in terms of their antimicrobial activity.

EXPERT OPINION

Many of the described benzofurans are promising candidates as antimicrobial agents based on their activity. Most used antibiotics target infections caused by the gram-positive pathogen S. aureus. Interestingly, most of the described benzofurans are promising inhibitors against S. aureus with either equipotent or more potent activity than the reference antibiotic drugs. These findings will encourage medicinal chemists to explore these new avenues for human health promotion to reduce suffering.

Advances in Research on Bioactivity, Toxicity, Metabolism, and Pharmacokinetics of Usnic Acid In Vitro and In Vivo

Lichens are among the most widely distributed plants on earth and have the longest growth cycle. Usnic acid is an abundant characteristic secondary metabolite of lichens and the earliest lichen compound used commercially. It has diverse pharmacological activities, such as anti-inflammatory, antibacterial, antiviral, anticancer, antioxidant, and photoprotective effects, and promotes wound healing. It is widely used in dietary supplements, daily chemical products (fodder, dyes, food, perfumery, and cosmetics), and medicine. However, some studies have found that usnic acid can cause allergic dermatitis and drug-induced liver injury. In this paper, the bioactivity, toxicity, in vivo and in vitro metabolism, and pharmacokinetics of usnic acid were summarized. The aims were to develop and utilize usnic acid and provide reference for its future research.

Novel Pullulan/Gellan Gum Bilayer Film as a Vehicle for Silibinin-Loaded Nanocapsules in the Topical Treatment of Atopic Dermatitis

In this study a novel gellan gum/pullulan bilayer film containing silibinin-loaded nanocapsules was developed for topical treatment of atopic dermatitis (AD). The bilayer films were produced by applying a pullulan layer on a gellan gum layer incorporated with silibinin nanocapsules by two-step solvent casting method. The bilayer formation was confirmed by microscopic analysis. In vitro studies showed that pullulan imparts bioadhesitvity for the films and the presence of nanocapsules increased their occlusion factor almost 2-fold. Besides, the nano-based film presented a slow silibinin release and high affinity for cutaneous tissue. Moreover, this film presented high scavenger capacity and non-hemolytic property. In the in vivo study, interestingly, the treatments with vehicle film attenuated the scratching behavior and the ear edema in mice induced by 2,4-dinitrochlorobenzene (DNCB). However, the nano-based film containing silibinin modulated the inflammatory and oxidative parameters in a similar or more pronounced way than silibinin solution and vehicle film, as well as than hydrocortisone, a classical treatment of AD. In conclusion, these data suggest that itself gellan gum/pullulan bilayer film might attenuate the effects induced by DNCB, acting together with silibinin-loaded nanocapsules, which protected the skin from oxidative damage, improving the therapeutic effect in this AD-model.

Designing Deferoxamine-Loaded Flaxseed Gum and Carrageenan-Based Controlled Release Biocomposite Hydrogel Films for Wound Healing

In this study, biocomposite hydrogel films made from flaxseed gum (FSG)/kappa carrageenan (CGN) were fabricated, using potassium chloride as a crosslinker and glycerol as a plasticizer. The composite films were loaded with deferoxamine (DFX), an iron chelator that promotes neovascularization and angiogenesis for the healing of wounds. The properties of the biocomposite hydrogel films, including swelling, solubility, water vapor transmission rate, tensile strength, elongation at break, and Young’s modulus studies, were tested. The films were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). In addition, drug release studies in PBS at pH 7.2 were investigated. In vivo analysis was performed by assessing the wound contraction in a full-thickness excisional wound rat model. Hematoxylin & eosin (H & E) and Masson’s trichome staining were performed to evaluate the effect of the films on wound healing progress. The visual and micro-morphological analysis revealed the homogenous structure of the films; however, the elongation at break property decreased within the crosslinked film but increased for the drug-loaded film. The FTIR analysis confirmed the crosslinking due to potassium chloride. A superior resistance towards thermal degradation was confirmed by TGA for the crosslinked and drug-loaded films. Drug release from the optimum film was sustained for up to 24 h. In vivo testing demonstrated 100% wound contraction for the drug-loaded film group compared to 72% for the pure drug solution group. In light of the obtained results, the higher potential of the optimized biocomposite hydrogel film for wound healing applications was corroborated.

Antibiotic and Nematocidal Metabolites from Two Lichen Species Collected on the Island of Lampedusa (Sicily)

The antibiotic and nematocidal activities of extracts from two coastal lichen species collected on Lampedusa Island (Sicily), Ramalina implexa Nyl. and Roccella phycopsis Ach., were tested. Methyl orsellinate, orcinol, (+)-montagnetol, and for the first time 4-chlororcinol were isolated from Roccella phycopsis. (+)-Usnic acid was obtained from Ramalina implexa. The crude organic extract of both lichen species showed strong antibiotic activity against some bacterial species and nematocidal activity. Among all the pure metabolites tested against the infective juveniles (J2) of the root-knot nematode (RKN) Meloydogine incognita, (+)-usnic acid, orcinol, and (+)-montagnetol had significant nematocidal activity, comparable with that of the commercial nematocide Velum^® Prime, and thus they showed potential application in agriculture as a biopesticide. On the contrary, methyl orsellinate and 4-chlororcinol had no nematocidal effect. These results suggest that the substituent pattern at ortho-para-position in respect to both hydroxyl groups of resorcine moiety, which is present in all metabolites, seems very important for nematocidal activity. The organic extracts of both lichens were also tested against some Gram-positive and Gram-negative bacteria. Both extracts were active against Gram-positive species. The extract of Ramalina implexa showed, among Gram-negative species, activity against Escherichia coli and Acinetobacter baumannii, while that from Roccella phycopsis was effective towards all test strains, with the exception of Pseudomonas aeruginosa. The antimicrobial activity of (+)-usnic acid, methyl orsellinate, and (+)-montagnetol is already known, so tests were focused on orcinol and 4-chlororcinol. The former showed antibacterial activity against all Gram positive and Gram-negative test strains, with the exception of A. baumannii and K. pneumoniae, while the latter exhibited a potent antibacterial activity against Gram-positive test strains and among Gram-negative strains, was effective against A. baumannii and K. pneumonia. These results suggest, for orcinol and 4-chlororcinol, an interesting antibiotic potential against both Gram-positive and Gram-negative bacterial strains.

Development of antibacterial and superabsorbent wound composite sponges containing carboxymethyl cellulose/gelatin/Cu-doped ZnO nanoparticles

This study aimed to develop a novel antibacterial and superabsorbent dressing by introducing the Cu-doped ZnO nanoparticles into the carboxymethyl cellulose/gelatin glutaraldehyde-crosslinked composite sponge that is fabricated by lyophilization method. Undoped and Cu-doped ZnO (Zn_1-xCu_xO, x = 0.03 and 0.05) nanoparticles were synthesized through the stabilizing agent-used precipitation process and characterized by XRD, FESEM, FTIR, and ICP-OES techniques. The XRD evaluation determined that the concentration of copper in ZnO is limited to below 5%. Additionally, The ICP-OES analysis confirmed the effect of the doping process on the ZnO crystalline structure by releasing more zinc and copper ions from Cu-doped ZnO, which resulted to improve antibacterial activity against Staphylococcus aureus and Escherichia coli bacterial strains. The effect of ZnO nanoparticles on the physical and mechanical performance of the optimized composite sponge indicated that the incorporation of 3 wt% ZnO nanoparticles produces a well-interconnected porous structure (~156 µm) with high water absorption (~3089%) and proper elongation (~49%) in a wet medium. The incorporation of Cu-doped ZnO nanoparticles enhanced antibacterial potential of the composite sponge. Meanwhile, all sponge groups are safe for viability, proliferation and adhesion of human dermal fibroblast cells. Overall, the obtained data has proved the potential of carboxymethyl cellulose/gelatin/Cu-doped ZnO dressing as a promising candidate for managing infected wounds.

Enhanced wound-healing capability with inherent antimicrobial activities of usnic acid incorporated poly(ε-caprolactone)/decellularized extracellular matrix nanofibrous scaffold

An extracellular matrix-mimicking, biodegradable tissue-engineered skin substitute with improved antibacterial, antibiofilm, and wound healing capabilities is essential in skin tissue regeneration applications. The purpose of this study was to develop a novel biodegradable composite nanofibrous poly(ε-caprolactone) (PCL)/decellularized extracellular matrix (dECM) scaffolds loaded with usnic acid (UA); (PEU), where UA is employed as an antibacterial agent as well as a wound-healing accelerator. The architecture and fiber structure of the scaffolds were examined using scanning electron microscopy, and the results revealed that the average diameters decreased as the dECM content increased. The chemical composition, changes in the crystalline structure, homogeneity, and thermal stability of the nanofiber scaffolds with different material compositions were determined using Fourier-transform infrared spectroscopy, X-ray diffraction, differential scanning calorimetry, and thermogravimetric analysis, respectively. The composite nanofibrous scaffolds exhibited strong antibacterial activity against various bacterial species, such as Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus mutans, and Cutibactrium acnes, and fungal pathogens (such as Candida albicans). Additionally, the composite nanofibrous scaffolds exhibited biofilm inhibition properties against Klebsiella pneumoniae and Pseudomonas aeruginosa. An evaluation of the appearance of in vivo full-thickness excisional wounds treated with the composite nanofiber scaffolds, as well as a histological analysis of the wounds 21 days after surgery, revealed that treatment with nanofibrous PEU scaffolds enhanced wound healing. This study reveals that the proposed composite nanofibrous PEU scaffold has substantial potential for treating infectious full-thickness wounds.

Solid Dispersions Incorporated into PVP Films for the Controlled Release of Trans-Resveratrol: Development, Physicochemical and In Vitro Characterizations and In Vivo Cutaneous Anti-Inflammatory Evaluation

Trans-resveratrol can promote various dermatological effects. However, its high crystallinity decreases its solubility and bioavailability. Therefore, solid dispersions have been developed to promote its amorphization; even so, they present as powders, making cutaneous controlled drug delivery unfeasible and an alternative necessary for their incorporation into other systems. Thus, polyvinylpyrrolidone (PVP) films were chosen with the aim of developing a controlled delivery system to treat inflammation and bacterial infections associated with atopic dermatitis. Four formulations were developed: two with solid dispersions (and trans-resveratrol) and two as controls. The films presented with uniformity, as well as bioadhesive and good barrier properties. X-ray diffraction showed that trans-resveratrol did not recrystallize. Fourier-transform infrared spectroscopy (FT-IR) and thermal analysis evidenced good chemical compatibilities. The in vitro release assay showed release values from 82.27 ± 2.60 to 92.81 ± 2.50% (being a prolonged release). In the in vitro retention assay, trans-resveratrol was retained in the skin, over 24 h, from 42.88 to 53.28%. They also had low cytotoxicity over fibroblasts. The in vivo assay showed a reduction in inflammation up to 66%. The films also avoided Staphylococcus aureus’s growth, which worsens atopic dermatitis. According to the results, the developed system is suitable for drug delivery and capable of simultaneously treating inflammation and infections related to atopic dermatitis.

Wound dressing adherence: a review

Wound dressing adherence is an important problem that is frequently encountered in wound care, and is associated with both clinical and economic burdens. However, only a few review articles have focused on this issue. The objective of this review was to present a comprehensive discussion of wound dressing adherence, including the mechanism of dressing adherence, adverse consequences (clinical burdens and economic burdens), factors affecting adherence (dressing-, patient- and wound-related factors, and factors related to the wound care procedure), tests to assess dressing adherence (in vitro assay, in vivo assay and clinical trials), and reduction of wound adherence (modification of dressing adherence and special care in particular patients). Accordingly, this review article emphasises an awareness of dressing adherence, and is intended to be an informative source for the development of new dressings and for wound management.

Antimicrobial peptides/ciprofloxacin-loaded O-carboxymethyl chitosan/self-assembling peptides hydrogel dressing with sustained-release effect for enhanced anti-bacterial infection and wound healing

Bacteria-induced wound infections and multifunctional hydrogels have received widespread attention in wound repair. In this study, self-assembling peptides (SAPs) were grafted on O-carboxymethyl chitosan (O-CMCS), and compact spatial structure and good drug sustained-release effect on mel-d1, a new AMP designed based on melittin with the same antimicrobial activity but lower cytotoxicity and ciprofloxacin (CIP) were obtained. In vivo test showed that the O-CMCS/SAP hydrogel loaded with CIP and mel-d1 accelerated the wound closure speed caused by infection of Escherichia coli and skin tissue regeneration. Both of the enhanced interaction between O-CMCS/SAP and CIP/Mel-d1 because of the hydrophobic interaction and π-π stacking, and the potential tissue healing ability of SAP played important roles. This study provided a rational design method of O-CMCS by grafting SAPs to give a wider range of biological functions.

Development of sodium carboxymethyl cellulose based polymeric microparticles for in situ hydrogel wound dressing formation

18β-glycyrrhetinic acid (Gly), a natural compound obtained from licorice, is known both for the anti-inflammatory and antioxidant activities and for this reason useful for wound treatment. Due to its poor solubility, Gly is not suitable for formulations used in conventional topical products such as gels, foams and creams. Polymeric bioadhesive microparticles (MP), loaded with Gly, were developed to be introduced in the wound bed and swell, once in contact with the exudate, to form a hydrogel in situ able to close the wound. The MP were prepared by spray drying method from the polymeric solution of polysaccharide sodium carboxymethyl cellulose (CMC) and copolymer Soluplus® (SL). Soluplus® introduction in MP composition, using a 3:1 ratio (CMC/SL wt./wt.), allowed to stabilize Gly in non-crystalline form, favoring the improvement of water solubility, and to obtain a spherical with rugged surface MP morphology. Ex vivo studies showed these MP maintain high swelling capability and are able to form in situ a hydrogel for wound repair. The controlled release of Gly from the hydrogel stimulates keratinocyte growth, potentially supporting the physiological healing processes.

Sustained dual release of ciprofloxacin and lidocaine from ionic exchange responding film based on alginate and hyaluronate for wound healing

This study presents a new antibiotic-anesthetic film (AA-film) based on natural polyelectrolytes ionically complexed with lidocaine and ciprofloxacin to manage pain associated with infected wounds. The rational selection of the components resulted in the AA-films being transparent, compatible with wound skin pH and highly water vapor permeable. The drug release properties evaluated in saline solution and water revealed an ionic exchange mechanism for the release of both drugs and showed that ciprofloxacin acts as a cross-linker, as was confirmed by rheological evaluation. The in vitro antimicrobial efficacy against S. aureus and P. aeruginosa was demonstrated. Furthermore, AA-films exhibit a high fluid absorption capacity and act as a physical barrier for microorganisms. This work highlights the great potential of this smart system as an attractive dressing for skin wounds, surpassing currently available treatments.

Development and Characterization of Xanthan Gum and Alginate Based Bioadhesive Film for Pycnogenol Topical Use in Wound Treatment

Pycnogenol (PYC) is a concentrate of phenolic compounds derived from French maritime pine; its biological activity as antioxidant, anti-inflammatory and antibacterial suggests its use in the treatment of open wounds. A bioadhesive film, loaded with PYC, was prepared by casting, starting with a combination of two biopolymer acqueous solutions: xanthan gum (1% wt/wt) and sodium alginate (1.5% wt/wt), in a 2.5/7.5 (wt/wt) ratio. In both solutions, glycerol (10% wt/wt) was added as plasticizing agent. The film resulted in an adhesive capable to absorb a simulated wound fluid (~ 65% wt/wt within 1 h), therefore suitable for exuding wounds. The mechanical characterization showed that the film is deformable (elastic modulus E = 3.070 ± 0.044 MPa), suggesting adaptability to any type of surface and resistance to mechanical solicitations. PYC is released within 24 h by a sustained mechanism, achieving a maximum concentration of ~0.2 mg/mL, that is safe for keratinocytes, as shown by cytotoxicity studies. A concentration of 0.015 mg/mL is reached in the first 5 min after application, at which point PYC stimulates keratinocyte growth. These preliminary results suggest the use of PYC in formulations designed for topical use.

Films from poly-γ-glutamic acid and poly-ε-lysine as the potential wound dressings – formulation, preparation and evaluation

Film wound dressings represent one of the options in wound therapy. Various polymers can be used for their production. Currently, research focuses on materials of natural origin, more friendly to the human body, which are in many cases able to participate actively in the wound healing process. These include polyamino acids of bacterial origin, substances that are biodegradable, non-toxic, and have a great potential for an application not only in the medical field. From the point of view of film wound dressing formulation, poly-γ-glutamic acid (PGA), as a film-forming agent, and poly-ε-lysine (PL), characterized by antimicrobial activity, are of interest from this group. Therefore, the aim of our experiment was to prepare films consisting of PGA or a combination of PGA and PL with the addition of different plasticizers. The films were prepared by solvent evaporation method and then evaluated for their organoleptic (appearance, colour, transparency, ease of handling), physicochemical (thickness, density, opacity, surface pH), and mechanical properties (tensile strength and tear resistance). As a result, films showing mutual compatibility between the two polymers were obtained, with satisfactory properties for wound application.

A review of the properties and applications of bioadhesive hydrogels

Due to their outstanding properties, bioadhesive hydrogels have been extensively studied by researchers in recent years.

Usnic-Acid-Functionalized Silk Fibroin Composite Scaffolds for Cutaneous Wounds Healing

Despite the progress in chronic wound treatment, antibacterial cutaneous scaffold with high efficiency in wound healing is still the hot spot in the field. In present study, a functionalized silk fibroin (SF) cutaneous scaffold incorporated with natural medicine usnic acid (UA) is investigated, in which UA is used as an antibacterial and wound-healing reagent. Via electrospinning, UA-SF mixture is fabricated into UA-SF composite scaffold (USCS), which is composed of uniform nanofibers with average diameters of around 360 ± 10 nm. The interwoven nanofibers form mesh structure providing sufficient moisture permeability for scaffold. With methanol treatment, USCS presents improved mechanical properties and stability to protease XIV. In the presence of USCS, the growth rate of both Gram-positive and Gram-negative bacteria, including Staphylococcus aureus, Streptococci pyogenes, Escherichia coli, and Pseudomonas aeruginosa, is significantly inhibited in plate culture and suspension assays. In a cutaneous excisional mouse wound model, USCS presents a significant increase of wound closure rate, compared with pure SF scaffold and commercial dressing, Tegaderm Hydrocolloid ^3M . The histological assessments further prove that USCS can enhance re-epithelialization, vascularization, and collagen deposition in wound site to promote the wound-healing process, which indicates the potential application of USCS in chronic wound treatment.

Pilot study for the evaluation of safety profile of a potential inhibitor of SARS-CoV-2 endocytosis

BACKGROUND AND AIM OF THE WORK

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is responsible for the current pandemics of coronavirus disease. This virus is able to attack the cells of the airway epithelium by binding to the transmembrane angiotensin I converting enzyme 2 (ACE2). We developed an oral spray that could inhibit the SARS-CoV-2 endocytosis. The spray contains hydroxytyrosol for its anti-viral, anti-inflammatory and anti-oxidant properties, and α-cyclodextrin for its ability to deplete sphingolipids, that form the lipid rafts where ACE2 localizes. The aim of the present pilot multi-centric open non-controlled observational study was to evaluate the safety profile of the "Endovir Stop" spray.

METHODS

An MTT test was performed to evaluate cytotoxicity of the spray in two human cell lines. An oxygen radical absorbance capacity assay was performed to evaluate the antioxidant capacity of the spray. The spray was also tested on 87 healthy subjects on a voluntary basis.

RESULTS

The MTT test revealed that the spray is not cytotoxic. The ORAC assay showed a good antioxidant capacity for the spray. Endovir Stop tested on healthy volunteers showed the total absence of side effects and drug interactions during the treatment.

CONCLUSIONS

We demonstrated that Endovir Stop spray is safe. The next step would be the administration of the efficacy of the spray by testing it to a wider range of people and see whether there is a reduced infection rate of SARS-CoV-2 in the treated subjects than in the non-treated individuals.

Polymeric Bioadhesive Patch Based on Ketoprofen-Hydrotalcite Hybrid for Local Treatments

Ketoprofen (KET) represents one of the most common drugs used in the topical treatment of pain and inflammations. However, its potential is rather limited due to the very low solubility and photochemical instability. The local administration of KET by conventional products, such as gels, emulgels, creams, and foams, does not guarantee an efficacious and safe treatment because of its low absorption (due to low solubility) and its sensitivity to UV rays. The photodegradation of KET makes many photoproducts responsible for different adverse effects. In the present work, KET was intercalated into the lamellar anionic clay ZnAl-hydrotalcite (ZnAl-HTlc), obtaining the hybrid ZnAl-KET with improved stability to UV rays and water solubility in comparison to the crystalline form (not intercalated KET). The hybrid was then formulated in autoadhesive patches for local pain treatment. The patches were prepared by casting method starting from a hydrogel based on the biocompatible and bioadhesive polymer NaCMC (Sodium carboxymethycellulose) and glycerol as a plasticizing agent. The introduction of ZnAl-KET in the patch composition demonstrated the improvement in the mechanical properties of the formulation. Moreover, a sustained and complete KET release was obtained within 8 h. This allowed reducing the frequency of anti-inflammatory administration, compared to the conventional formulations.

Bactericidal Activity of Usnic Acid-Chitosan Nanoparticles against Persister Cells of Biofilm-Forming Pathogenic Bacteria

The present study aimed to prepare usnic acid (UA)-loaded chitosan (CS) nanoparticles (UA-CS NPs) and evaluate its antibacterial activity against biofilm-forming pathogenic bacteria. UA-CS NPs were prepared through simple ionic gelification of UA with CS, and further characterized using Fourier transform infrared spectroscopy, X-ray diffraction, and field-emission transmission electron microscopy. The UA-CS NPs presented a loading capacity (LC) of 5.2%, encapsulation efficiency (EE) of 24%, and a spherical shape and rough surface. The maximum release of UA was higher in pH 1.2 buffer solution as compared to that in pH 6.8 and 7.4 buffer solution. The average size and zeta potential of the UA-CS NPs was 311.5 ± 49.9 nm in diameter and +27.3 ± 0.8 mV, respectively. The newly prepared UA-CS NPs exhibited antibacterial activity against persister cells obtained from the stationary phase in batch culture, mature biofilms, and antibiotic-induced gram-positive and gram-negative pathogenic bacteria. Exposure of sub-inhibitory concentrations of UA-CS NPs to the bacterial cells resulted in a change in morphology. The present study suggests an alternative method for the application of UA into nanoparticles. Furthermore, the anti-persister activity of UA-CS NPs may be another possible strategy for the treatment of infections caused by biofilm-forming pathogenic bacteria.

Bioadhesive Polymeric Films Based on Red Onion Skins Extract for Wound Treatment: An Innovative and Eco-Friendly Formulation

The onion non-edible outside layers represent a widely available waste material deriving from its processing and consumption. As onion is a vegetable showing many beneficial properties for human health, a study aiming to evaluate the use of extract deriving from the non-edible outside layers was planned. An eco-friendly extraction method was optimized using a hydroalcoholic solution as solvent. The obtained extract was deeply characterized by in vitro methods and then formulated in autoadhesive, biocompatible and pain-free hydrogel polymeric films. The extract, very soluble in water, showed antioxidant, radical scavenging, antibacterial and anti-inflammatory activities, suggesting a potential dermal application for wounds treatment. In vitro studies showed a sustained release of the extract from the hydrogel polymeric film suitable to reach concentrations necessary for both antibacterial and anti-inflammatory activities. Test performed on human keratinocytes showed that the formulation is safe suggesting that the projected formulation could be a valuable tool for wound treatment.

A Role for Neutral Sphingomyelinase in Wound Healing Induced by Keratinocyte Proliferation upon 1α, 25-Dihydroxyvitamin D3 Treatment

The skin has many functions, such as providing a barrier against injury and pathogens, protecting from ultraviolet light, and regulating body temperature. Mechanical causes and many different pathologies can lead to skin damage. Therefore, it is important for the skin to be always adaptable and renewable and for cells to undergo proliferation. Here, we demonstrate that 1α, 25-dihydroxyvitamin D₃ (VD3) stimulates keratinocyte proliferation, leading to wound closure in a simulation model of injury. Functionally, our results show that VD3 acts by stimulating cyclin D1, a cyclin that promotes the G1/S transition of the cell cycle. The study on the mechanism underlying cyclin D1 expression upon VD3 stimulation clearly demonstrates a key role of neutral sphingomyelinase. The enzyme, whose gene and protein expression is stimulated by VD3, is itself able to induce effects on cyclin D1 and wound healing similar to those obtained with VD3. These results could be very useful in the future to better understand wound mechanisms and improve therapeutic interventions.