Recent Advances in Using Natural Antibacterial Additives in Bioactive Wound Dressings

Hydrogel Containing Propolis: Physical Characterization and Evaluation of Biological Activities for Potential Use in the Treatment of Skin Lesions

BACKGROUND

Skin injury affects the integrity of the skin structure and induces the wound healing process, which is defined by a well-coordinated series of cellular and molecular reactions that aim to recover or replace the injured tissue. Hydrogels are a group of promising biomaterials that are able to incorporate active ingredients for use as dressings. This study aimed to synthesize hydrogels with and without propolis extract and evaluate their physical characteristics and biological activities in vitro for potential use as active dressings in the treatment of skin lesions.

METHODS

The antifungal [Candida albicans (C. albicans) and Candida tropicalis (C. tropicalis)] and antibacterial [Staphylococcus aureus (S. aureus), Pseudomonas aeruginosas (P. aeruginosas) and Escherichia coli (E. coli)] activity was assessed by the microdilution method in plates and antioxidant potential by the reduction of the phosphomolybdate complex.

RESULTS

The hydrogels showed good water absorption capacity, high solubility, and high gel fraction, as well as good porosity, water retention, and vapor transmission rates. They revealed a totally amorphous structure. The extract and the hydrogels containing the propolis extract (1.0% and 2.5%) did not inhibit fungal growth. However, they showed antibacterial activity against strains of S. aureus and P. aeruginosas. Regarding the E. coli strain, only the extract inhibited its growth. It showed good antioxidant activity by the evaluation method used.

CONCLUSIONS

Therefore, the hydrogels containing propolis extract can be a promising alternative with antibacterial and antioxidant action for use as dressings for the treatment of skin lesions.

Antibacterial and Antibiofilm Properties of Native Australian Plant Endophytes against Wound-Infecting Bacteria

The wound management field faces significant challenges due to antimicrobial resistance (AMR) and the complexity of chronic wound care. Effective wound treatment requires antimicrobial dressings to prevent bacterial infections. However, the rise of AMR necessitates new antimicrobial agents for wound dressings, particularly for addressing bacterial pathogens like methicillin-resistant Staphylococcus aureus (MRSA). Endophytic fungi, known for producing diverse bioactive compounds, represent a promising source of such new agents. This study tested thirty-two endophytic fungi from thirteen distinct Australian native plants for their antibacterial activity against S. aureus. Ethyl acetate (EtOAc) extracts from fungal culture filtrates exhibited inhibitory effects against both methicillin-sensitive S. aureus ATCC 25923 (MIC = 78.1 µg/mL) and MRSA M180920 (MIC = 78.1 µg/mL). DNA sequence analysis was employed for fungal identification. The most active sample, EL 19 (Chaetomium globosum), was selected for further analysis, revealing that its EtOAc extracts reduced S. aureus ATCC 25923 biofilm formation by 55% and cell viability by 57% to 68% at 12 × MIC. Furthermore, cytotoxicity studies using the brine shrimp lethality test demonstrated low cytotoxicity up to 6 × MIC (25% mortality rate) with an LC50 value of 639.1 µg/mL. Finally, the most active sample was incorporated into polycaprolactone (PCL) fiber mats via electrospinning, with resultant inhibition of S. aureus species. This research underscores the potential of endophytic fungi from Australian plants as sources of substances effective against common wound pathogens. Further exploration of the responsible compounds and their mechanisms could facilitate the development of wound dressings effective against MRSA and innovative biofilm-resistant electrospun fibers, contributing to the global efforts to combat AMR.

In Vitro Biological Evaluation of an Alginate-Based Hydrogel Loaded with Rifampicin for Wound Care

We report a biocompatible hydrogel dressing based on sodium alginate-grafted poly(N-vinylcaprolactam) prepared by encapsulation of Rifampicin as an antimicrobial drug and stabilizing the matrix through the repeated freeze-thawing method. The hydrogel structure and polymer-drug compatibility were confirmed by FTIR, and a series of hydrogen-bond-based interactions between alginate and Rifampicin were identified. A concentration of 0.69% Rifampicin was found in the polymeric matrix using HPLC analysis and spectrophotometric UV-Vis methods. The hydrogel's morphology was evaluated by scanning electron microscopy, and various sizes and shapes of pores, ranging from almost spherical geometries to irregular ones, with a smooth surface of the pore walls and high interconnectivity in the presence of the drug, were identified. The hydrogels are bioadhesive, and the adhesion strength increased after Rifampicin was encapsulated into the polymeric matrix, which suggests that these compositions are suitable for wound dressings. Antimicrobial activity against S. aureus and MRSA, with an increased effect in the presence of the drug, was also found in the newly prepared hydrogels. In vitro biological evaluation demonstrated the cytocompatibility of the hydrogels and their ability to stimulate cell multiplication and mutual cell communication. The in vitro scratch assay demonstrated the drug-loaded alginate-grafted poly(N-vinylcaprolactam) hydrogel's ability to stimulate cell migration and wound closure. All of these results suggest that the prepared hydrogels can be used as antimicrobial materials for wound healing and care applications.

Bacterial Cellulose Applied in Wound Dressing Materials: Production and Functional Modification - A Review

In recent years, the development of new type wound dressings has gradually attracted more attention. Bacterial cellulose (BC) is a natural polymer material with various unique properties, such as ultrafine 3D nanonetwork structure, high water retention capacity, and biocompatibility. These properties allow BC to be used independently or in combination with different components (such as biopolymers and nanoparticles) to achieve diverse effects. This means that BC has great potential as a wound dressing. However, systematic summaries for the production and commercial application of BC-based wound dressings are still lacking. Therefore, this review provides a detailed introduction to the production fermentation process of BC, including various production strains and their biosynthetic mechanisms. Subsequently, with regard to the functional deficiencies of bacterial cellulose as a wound dressing, recent research progress in this area is enumerated. Finally, prospects are discussed for the low-cost production and high-value-added product development of BC-based wound dressings.

Piezoelectric-based bioactive zinc oxide-cellulose acetate electrospun mats for efficient wound healing: an in vitro insight

Being a complex physiological process involving the removal of damaged tissue debris and creating a new microenvironment for host tissue regeneration, wound healing is still a major challenge for healthcare professionals. Disruption of this process can lead to tissue inflammation, pathogenic infections, and scar formation. Current wound healing treatments primarily focus on passive tissue healing, lacking active engagement in the healing process. In recent years, a new class of functional biomaterials based on piezoelectric properties has emerged, which can actively participate in the wound healing process by harnessing mechanical forces generated from body movement. Herein, we have fabricated a bioactive Cellulose Acetate (CA) electrospun nanofibrous mat incorporating zinc oxide (ZnO) and investigated its efficiency for accelerated wound healing. We have characterized the physicochemical properties of the fabricated nanofibrous mats using various assays, including SEM, FTIR, TGA, mechanical testing, degradation analysis, porosity measurement, hemolysis assay, and piezoelectric d33 coefficient measurement. Through our investigation, we discovered the tunned piezoelectric coefficient of fabricated specimens due to incorporating ZnO into the CA fibers. In vitro studies also confirmed enhanced cell adhesion, proliferation, and migration, indicating faster wound healing potential. Overall, our findings support the efficacy of piezoelectric-based ZnO-incorporated bioactive CA nanofibrous mats for efficient wound healing.

Natural and Synthetic Polymeric Biomaterials for Application in Wound Management

Biomaterials are at the forefront of the future, finding a variety of applications in the biomedical field, especially in wound healing, thanks to their biocompatible and biodegradable properties. Wounds spontaneously try to heal through a series of interconnected processes involving several initiators and mediators such as cytokines, macrophages, and fibroblasts. The combination of biopolymers with wound healing properties may provide opportunities to synthesize matrices that stimulate and trigger target cell responses crucial to the healing process. This review outlines the optimal management and care required for wound treatment with a special focus on biopolymers, drug-delivery systems, and nanotechnologies used for enhanced wound healing applications. Researchers have utilized a range of techniques to produce wound dressings, leading to products with different characteristics. Each method comes with its unique strengths and limitations, which are important to consider. The future trajectory in wound dressing advancement should prioritize economical and eco-friendly methodologies, along with improving the efficacy of constituent materials. The aim of this work is to give researchers the possibility to evaluate the proper materials for wound dressing preparation and to better understand the optimal synthesis conditions as well as the most effective bioactive molecules to load.

Transforming Wound Management: Nanomaterials and Their Clinical Impact

Wound healing is a complex process that can be further complicated in chronic wounds, leading to prolonged healing times, high healthcare costs, and potential patient morbidity. Nanotechnology has shown great promise in developing advanced wound dressings that promote wound healing and prevent infection. The review article presents a comprehensive search strategy that was applied to four databases, namely Scopus, Web of Science, PubMed, and Google Scholar, using specific keywords and inclusion/exclusion criteria to select a representative sample of 164 research articles published between 2001 and 2023. This review article provides an updated overview of the different types of nanomaterials used in wound dressings, including nanofibers, nanocomposites, silver-based nanoparticles, lipid nanoparticles, and polymeric nanoparticles. Several recent studies have shown the potential benefits of using nanomaterials in wound care, including the use of hydrogel/nano silver-based dressings in treating diabetic foot wounds, the use of copper oxide-infused dressings in difficult-to-treat wounds, and the use of chitosan nanofiber mats in burn dressings. Overall, developing nanomaterials in wound care has complemented nanotechnology in drug delivery systems, providing biocompatible and biodegradable nanomaterials that enhance wound healing and provide sustained drug release. Wound dressings are an effective and convenient method of wound care that can prevent wound contamination, support the injured area, control hemorrhaging, and reduce pain and inflammation. This review article provides valuable insights into the potential role of individual nanoformulations used in wound dressings in promoting wound healing and preventing infections, and serves as an excellent resource for clinicians, researchers, and patients seeking improved healing outcomes.

Synergistic Inhibition of Methicillin-Resistant Staphylococcus aureus (MRSA) by Melaleuca alternifolia Chell (Tea Tree) and Eucalyptus globulus Labill. Essential Oils in Association with Oxacillin

The presence of antibiotic-resistant bacteria has become a major therapeutic priority. This trend indicates the need for alternative agents to antibiotics, such as natural compounds of plant origin. By assessing membrane permeability, we investigated the antimicrobial activity of Melaleuca alternifolia and Eucalyptus globulus essential oils (EOs) against three strains of methicillin-resistant Staphylococcus aureus (MRSA). Using the checkerboard method, the efficacy of single EOs, in association with each other or in combination with oxacillin, was quantified by calculating the fractional inhibitory concentrations (FIC Index). All EOs showed a reduction in bacterial load, an alteration of membrane permeability which leads to an increase in its function, resulting in the release of nucleic acids and proteins. The treatment with EO-oxacillin combinations and associated EO-EO resulted in a synergistic effect in most of the tests performed. EO-EO association showed a high activity in the alteration of the membrane, increasing the permeability to about 80% in all the MRSA strains treated. In conclusion, the combination of EOs and antibiotics represents a valid therapeutic support against MRSA bacteria, allowing for a decrease in the antibiotic concentration needed for therapeutic use.