Exopolysaccharides (EPSs) are a diverse class of biopolymers synthesized by microorganisms under environmental stress conditions, such as pH, temperature, light intensity, and salinity. They offer biodegradable and environmentally friendly alternatives to synthetic polymers. Their structural versatility and functional properties make them unique in various industries, including food, pharmaceuticals, biomedicine, cosmetics, textiles, petroleum, and environmental remediation. In this way, among the well-known EPSs, homopolysaccharides like dextran, bacterial cellulose, curdlan, and levan, as well as heteropolysaccharides like xanthan gum, alginate, gellan, and kefiran, have found widespread applications in numerous fields. However, recent attention has focused on the potential role of extremophile bacteria in producing EPSs with novel and unusual protective and biological features under extreme conditions. Therefore, this review provides an overview of the functional properties and applications of the commonly employed EPSs. It emphasizes their importance in various industries and scientific endeavors while highlighting the raised interest in exploring EPSs with novel compositions, structures, and properties, including underexplored protective functionalities. Nevertheless, despite the potential benefits of EPSs, challenges persist. Hence, this review discusses these challenges, explores opportunities, and outlines future directions, focusing on their impact on developing innovative, sustainable, and functional materials.

In recent years, the damaging effects of antimicrobial resistance relating to wound management and infections have driven the ongoing development of composite wound dressing mats containing natural compounds, such as plant extracts and their derivatives. The present research reports the fabrication of novel electrospun Polycaprolactone (PCL)/Polyvinyl Alcohol (PVA)/Chitosan (CS) fiber mats loaded with Eugenol (EUG), an essential oil, known for its therapeutic properties. The electrospun fiber mats were prepared via electrospinning from either water-in-oil (W/O) or oil-in-water (O/W) emulsions and characterized using scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FT-IR), total porosity measurements, and water contact angle. The in vitro EUG release profile and antibacterial activity against Staphylococcus aureus and Pseudomonas aeruginosa were also evaluated. The obtained results proved that the EUG was loaded efficiently into electrospun PCL/PVA/CS fiber mats and the two W/O and O/W emulsions prepared from the PCL/PVA/CS (7 : 3 : 1) and PCL/PVA/CS (3 : 7 : 1) revealed porosity within the ideal range of 60–90%, even when EUG was loaded. The measured contact angle values showed that the O/W emulsion exhibited a more hydrophilic character and the wettability noticeably decreased after adding EUG in both emulsion blends. Furthermore, the electrospun PCL/PVA/CS fiber mats demonstrated a rapid release of EUG during the first 8 hours, which enhanced gradually afterward (up to 120 hours). Moreover, an efficient antibacterial activity against S. aureus (inhibition ratios of 92.43% and 83.08%) and P. aeruginosa (inhibition ratios of 94.68% and 87.85%) was displayed and the in vitro cytotoxic assay demonstrated that the normal human dermal fibroblasts (NHDF) remained viable for at least 7 days, after direct contact with the produced electrospun fiber mats. Therefore, such findings support the biocompatibility and suitability of using these EUG-loaded electrospun PCL/PVA/CS fiber mats as a new innovative wound dressing material with potential for preventing and treating microbial wound infections.

Nowadays, food packaging systems have shifted from a passive to an active role in which the incorporation of antimicrobial compounds into biopolymers can promote a sustainable way to reduce food spoilage and its environmental impact. Accordingly, composite materials based on oxidized-bacterial cellulose (BC) and poly(vinyl alcohol)-chitosan (PVA-CH) nanofibers were produced by needleless electrospinning and functionalized with the bacterial pigment prodigiosin (PG). Two strategies were explored, in the first approach PG was incorporated in the electrospun PVA-CH layer, and TEMPO-oxidized BC was the substrate for nanofibers deposition (BC/PVA-CH_PG composite). In the second approach, TEMPO-oxidized BC was functionalized with PG, and afterward, the PVA-CH layer was electrospun (BC_PG/PVA-CH composite). The double-layer composites obtained were characterized and the nanofibrous layers displayed smooth fibers with average diameters of 139.63 ± 65.52 nm and 140.17 ± 57.04 nm, with and without pigment incorporation, respectively. FTIR-ATR analysis confirmed BC oxidation and revealed increased intensity at specific wavelengths, after pigment incorporation. Moreover, the moderate hydrophilic behavior, as well as the high porosity exhibited by each layer, remained mostly unaffected after PG incorporation. The composites’ mechanical performance and the water vapor transmission rate (WVTR) evaluation indicated the suitability of the materials for certain food packaging solutions, especially for fresh products. Additionally, the red color provided by the bacterial pigment PG on the external surface of a food packaging material is also a desirable effect, to attract the consumers’ attention, creating a multifunctional material. Furthermore, the antimicrobial activity was evaluated and, PVA-CH_PG, and BC_PG layers exhibited the highest antimicrobial activity against Staphylococcus aureus and Pseudomonas aeruginosa. Thus, the fabricated composites can be considered for application in active food packaging, owing to PG antimicrobial potential, to prevent foodborne pathogens (with PG incorporated into the inner layer of the food packaging material, BC/PVA-CH_PG composite), but also to prevent external contamination, by tackling the exterior of food packaging materials (with PG added to the outer layer, BC_PG/PVA-CH composite).

Presently, there are many different types of wound dressings available on the market. Nonetheless, there is still a great interest to improve the performance and efficiency of these materials. Concerning that, new dressing materials containing natural products, such as medicinal plants that protect the wound from infections but also enhance skin regeneration have been or are being developed. Herein, we used for the first time a needleless emulsion electrospinning technique for incorporating Chelidoniummajus L. (C. majus), a medicinal plant widely known for its traditional therapeutic properties, in Polycaprolactone (PCL)/Polyvinyl Alcohol (PVA)_Pectin (PEC) nanofibrous meshes. Moreover, the potential use of these electrospun nanofibers as a carrier for C. majus was also explored. The results obtained revealed that the produced PCL/PVA_PEC nanofibrous meshes containing C. majus extract displayed morphological characteristics similar to the natural extracellular matrix of the skin (ECM). Furthermore, the produced meshes showed beneficial properties to support the healing process. Additionally, the C. majus-loaded PCL/PVA_PEC nanofibrous meshes inhibited Staphylococcus aureus (S. aureus) and Pseudomonas aeruginosa (P. aeruginosa) growth, reaching a 3.82 Log reduction, and showed to be useful for controlled release, without causing any cytotoxic effect on the normal human dermal fibroblasts (NHDF) cells. Hence, these findings suggest the promising suitability of this novel wound dressing material for prevention and treatment of bacterial wound infections.

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. Graphical Abstract

Wounds display particular vulnerability to microbial invasion and infections by pathogenic bacteria. Therefore, to reduce the risk of wound infections, researchers have expended considerable energy on developing advanced therapeutic dressings, such as electrospun membranes containing antimicrobial agents. Among the most used antimicrobial agents, medicinal plant extracts demonstrate considerable potential for clinical use, due primarily to their efficacy allied to relatively low incidence of adverse side-effects. In this context, the present work aimed to develop a unique dual-layer composite material with enhanced antibacterial activity derived from a coating layer of Poly(vinyl alcohol) (PVA) and Chitosan (CS) containing Agrimonia eupatoria L. (AG). This novel material has properties that facilitate it being electrospun above a conventional cotton gauze bandage pre-treated with 2,2,6,6-tetramethylpiperidinyl-1-oxy free radical (TEMPO). The produced dual-layer composite material demonstrated features attractive in production of wound dressings, specifically, wettability, porosity, and swelling capacity. Moreover, antibacterial assays showed that AG-incorporated into PVA_CS’s coating layer could effectively inhibit Staphylococcus aureus (S. aureus) and Pseudomonas aeruginosa (P. aeruginosa) growth. Equally important, the cytotoxic profile of the dual-layer material in normal human dermal fibroblast (NHDF) cells demonstrated biocompatibility. In summary, these data provide initial confidence that the TEMPO-oxidized cotton/PVA_CS dressing material containing AG extract demonstrates adequate mechanical attributes for use as a wound dressing and represents a promising approach to prevention of bacterial wound contamination.