Evaluation of the anti-biofilm activities of bacterial cellulose-tannic acid-magnesium chloride composites using an <i>in vitro</i> multispecies biofilm model

Abstract

Chronic wounds are a serious worldwide problem, which are often accompanied by wound infections. In this study, bacterial cellulose (BC)-based composites introduced with tannic acid (TA) and magnesium chloride (BC-TA-Mg) were fabricated for anti-biofilm activities. The prepared composites' surface properties, mechanical capacity, thermal stability, water absorption and retention property, releasing behavior, anti-biofilm activities and potential cytotoxicity were tested. Results showed that TA and MgCl₂ particles closely adhered to the nanofibers of BC membranes, thus increasing surface roughness and hydrophobicity of the membranes. While the introduction of TA and MgCl₂ did not influence the transparency of the membranes, making it beneficial for wound inspection. BC-TA and BC-TA-Mg composites displayed increased tensile strength and elongation at break compared to pure BC. Moreover, BC-TA-Mg exhibited higher water absorption and retention capacity than BC and BC-TA, suitable for the absorption of wound exudates. BC-TA-Mg demonstrated controlled release of TA and good inhibitory effect on both singly cultured <i>Staphylococcus aureus and Pseudomonas aeruginosa</i> biofilm and co-cultured biofilm of <i>S. aureus and P. aeruginosa</i>. Furthermore, the cytotoxicity grade of BC-TA-6Mg membrane was eligible based on standard toxicity classifications. These indicated that BC-TA-Mg is potential to be used as wound dressings combating biofilms in chronic wounds.