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.

Defining wound bed conformability: a new testing methodology to assess the relative swelling rise of foam dressings

OBJECTIVE

Using a dressing that expands and conforms to the wound bed upon exudate absorption is one of the best ways to promote wound healing. While many products claim wound bed conformability, no externally replicated or verified test methodology had been developed to quantify a wound dressing's ability to conform to the wound bed. The Relative Swelling Rise (RSR) test methodology was developed to measure the relative swelling rise of foam dressings upon fluid absorption, and offers a quantifiable and easily replicated method to measure wound bed conformability.

METHOD

The RSR test method was developed, validated and reliability tested by Coloplast A/S, Denmark. External replication was provided by ALS Odense, Denmark (previously DB Lab). Circular fences provide a fixed diameter to apply and contain the fluid and prevent horizontal spreading in the test set-up. The swelling height is quantified relative to the fence's inner diameter, i.e., the ratio alpha (α), and allows evaluation of a material's ability to conform to the wound bed.

RESULTS

Biatain Silicone foam products (n=3, Coloplast A/S, Denmark) were tested, all afforded an average α-ratio from 0.30 to 0.60. The relative standard deviations were between 1-3%, demonstrating the strength of the test. Robustness of the methodology was demonstrated through the internal validation study, the reliability study, and both an internal and external replication study, as well as a systematic literature review and expert review of the construct, content, criterion and generalisability of the method.

CONCLUSION

Having a validated, effective and easily replicable testing method to quantify wound bed conformability of foam dressings is an important step towards achieving better healing outcomes.

Chitosan-based films with cannabis oil as a base material for wound dressing application

This study focuses on obtaining and characterizing novel chitosan-based biomaterials containing cannabis oil to potentially promote wound healing. The primary active substance in cannabis oil is the non-psychoactive cannabidiol, which has many beneficial properties. In this study, three chitosan-based films containing different concentrations of cannabis oil were prepared. As the amount of oil increased, the obtained biomaterials became rougher as tested by atomic force microscopy. Such rough surfaces promote protein adsorption, confirmed by experiments assessing the interaction between human albumin with the obtained materials. Increased oil concentration also improved the films' mechanical parameters, swelling capacity, and hydrophilic properties, which were checked by the wetting angle measurement. On the other hand, higher oil content resulted in decreased water vapour permeability, which is essential in wound dressing. Furthermore, the prepared films were subjected to an acute toxicity test using a Microtox. Significantly, the film's increased cannabis oil content enhanced the antimicrobial effect against A. fischeri for films in direct contact with bacteria. More importantly, cell culture studies revealed that the obtained materials are biocompatible and, therefore, they might be potential candidates for application in wound dressing materials.

In vitro fibroblasts viability and migration stimulation of Acalypha indica: an insight on wound healing activity

Background

The current study investigates the antioxidant activity of Acalypha indica aerial parts and root ethanolic extracts and explore whether these extracts will stimulate fibroblasts viability and ability to migrate.

Results

Aerial parts extract exhibited higher DPPH scavenging activity compared to root extract with IC50 of 62 µg/mL and 206 µg/mL, respectively. Both aerial parts and root extracts showed low cytotoxicity towards fibroblasts with 753 µg/mL LD50 for aerial parts and undetected LD50 for root extract. Additionally, aerial parts extract significantly induces fibroblasts proliferation up to 134%. Wound closure investigation showed a significant closure percentage for aerial parts compared to untreated control with 75% at 1 µg/mL and high closure percentage with 70% at 0.1 µg/mL for root extract compared to only 59% closure percentage for untreated control after 48 h of the study.

Conclusions

This study provided evidence for A. indica to have great wound healing potential. The finding builds the scientific background in future to utilise the high antioxidant activity of A. indica and its ability to stimulate fibroblasts migration and proliferation for further applications.

Perspective on the application of medicinal plants and natural products in wound healing: A mechanistic review

Wound is defined as any injury to the body such as damage to the epidermis of the skin and disturbance to its normal anatomy and function. Since ancient times, the importance of wound healing has been recognized, and many efforts have been made to develop novel wound dressings made of the best material for rapid and effective wound healing. Medicinal plants play a great role in the wound healing process. In recent decades, many studies have focused on the development of novel wound dressings that incorporate medicinal plant extracts or their purified active compounds, which are potential alternatives to conventional wound dressings. Several studies have also investigated the mechanism of action of various herbal medicines in wound healing process. This paper attempts to highlight and review the mechanistic perspective of wound healing mediated by plant-based natural products. The findings showed that herbal medicines act through multiple mechanisms and are involved in various stages of wound healing. Some herbal medicines increase the expression of vascular endothelial growth factor (VEGF) and transforming growth factor-β (TGF-β) which play important role in stimulation of re-epithelialization, angiogenesis, formation of granulation tissue, and collagen fiber deposition. Some other wound dressing containing herbal medicines act as inhibitor of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β) and inducible nitric oxide synthase (iNOS) protein expression thereby inducing antioxidant and anti-inflammatory properties in various phases of the wound healing process. Besides the growing public interest in traditional and alternative medicine, the use of herbal medicine and natural products for wound healing has many advantages over conventional medicines, including greater effectiveness due to diverse mechanisms of action, antibacterial activity, and safety in long-term wound dressing usage.

Chelidoniummajus L. Incorporated Emulsion Electrospun PCL/PVA_PEC Nanofibrous Meshes for Antibacterial Wound Dressing Applications

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.

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.