Polyurethane-Nanolignin Composite Foam Coated with Propolis as a Platform for Wound Dressing: Synthesis and Characterization

Abstract

This piece of research explores porous nanocomposite polyurethane (PU) foam synthesis, containing nanolignin (NL), coated with natural antimicrobial propolis for wound dressing. PU foam was synthesized using polyethylene glycol, glycerol, NL, and 1, 6-diisocyanato-hexane (NCO/OH ratio: 1.2) and water as blowing agent. The resultant foam was immersed in ethanolic extract of propolis (EEP). PU, NL-PU, and PU-NL/EEP foams were characterized from mechanical, morphological, and chemical perspectives. NL Incorporation into PU increased mechanical strength, while EEP coating showed lower strength than PU-NL/EEP. Morphological investigations confirmed an open-celled structure with a pore diameter of 150–200 μm, a density of nearly 0.2 g/cm3,, and porosity greater than 85%, which led to significantly high water absorption (267% for PU-NL/EEP). The hydrophilic nature of foams, measured by the contact angle, proved to be increased by NL addition and EEP coating. PU and PU-NL did not show important antibacterial features, while EEP coating resulted in a significant antibacterial efficiency. All foams revealed high biocompatibility toward L929 fibroblasts, with the highest cell viability and cell attachment for PU-NL/EEP. In vivo wound healing using Wistar rats’ full-thickness skin wound model confirmed that PU-NL/EEP exhibited an essentially higher wound healing efficacy compared with other foams. Hence, PU-NL/EEP foam could be a promising wound dressing candidate.

Insights into the Design of Polyurethane Dressings Suitable for the Stages of Skin Wound-Healing: A Systematic Review

“…As for the activity against S. aureus , polyurethanes with 2% propolis ethanol extract reached an activity of 5.63 ± 0.87 mm at the highest, followed by polyurethane with 30% propolis water extract 3.89 ± 0.31 mm. Pahlevanneshan et al obtained similar results; they made polyurethanes with ethanolic propolis extract and compared them with the inclusion of water propolis extracts, reporting that higher activity was obtained with ethanolic extracts than with water extracts [ 15 ].…”

“…Malva sylvestris L. ethanolic extract was incorporated at concentrations of 5, 10, 15, and 20% w / w [ 11 ], chitosan in a ratio ranging from 0 to 10, and mupirocin solutions at 0, 2, and 5% ( w / w ) [ 12 ]. For the use of propolis extracts, one of the reports evaluated water extracts at 0%, 10%, 20%, and 30% [ 17 ], and the ethanolic extract was made at a 1:10 ratio (25 g of propolis in 250 mL of ethanol) [ 15 ] and at 0.5, 1, and 2% w / w [ 20 ]. The results of these studies show that polyurethanes do not possess antibacterial activity on their own, which is important for the design of wound dressings.…”

“…Typically, the antibiotics used act on bacteria by disrupting the function of the bacteria’s structure, such as walls, or their metabolic pathways [ 44 ]. The most common pathogens encountered in bacterial wound infection problems are Staphylococcus aureus and Escherichia coli , so the antibacterial evaluation of wound dressings generated has focused on these two [ 15 ].…”

An Up-to-Date Review of Biomaterials Application in Wound Management

“…Alternatively, Pahlevanneshan et al [ 53 ] have developed a porous nanocomposite polyurethane–nanolignin foam coated with ethanol extract of propolis (EEP). The addition of nanolignin and EEP increased the mechanical strength (tensile strength: 0.82 ± 0.09 MPa) and hydrophilicity (water contact angle: 50.1 ± 2.1°) of the dressing.…”

Novel Technologies in Chronic Wound Care

“…The healing process has been well researched, with identification of numerous beneficial factors, including oxygen tension, nutritional status, and external environment which act in various ways to support expedient wound resolution. [2][3][4] In the natural course of healing, a fine balance of these factors is necessary to achieve ultimate healing; however, through the course of ongoing research, numerous products have been designed to take advantage of these factors and promote a more optimal environment and support wound healing. 5 Herein, we present a brief overview of products used to support advancement of the healing process in chronic wounds at our institution.…”