Montmorillonite modified with Fe₃O₄ and tannic acid for inhibition of S. aureus and MRSA biofilm formation

In this study we introduce a novel nano-biocomposite, M-MM-TA, composed of clay montmorillonite (MM) modified with magnetic (M) Fe₃O₄ and tannic acid (TA), designed to combat S. aureus, MRSA, and their biofilm. Bacterial attachment and biofilm formation are significant challenges to public health, medicine, and the clinical industry. Staphylococcus aureus (S. aureus), a gram-positive pathogenic bacterium, is known to be the cause of infectious diseases in both humans and animals. Methicillin-resistant Staphylococcus aureus (MRSA), a major cause of healthcare-associated infections, has emerged due to its resistance to antibiotics. Considering MRSA's resistance to antibiotics, it is essential to explore and characterize alternative antibacterial agents. Comprehensive characterization through SEM, SEM-EDS, TEM, TEM-EDS, XPS, XRD and VSM analyses confirmed the successful synthesis of M-MM-TA. To confirm the anti-bacterial effects of nanocomposite, we treated M-MM-TA on S. aureus and MRSA. Then we evaluated the anti-biofilm effect of M-MM-TA by using CV staining and live/dead assay. The results showed that M-MM-TA inhibits biofilm formation against S. aureus and MRSA. Additionally, SEM morphological analysis confirmed that M-MM-TA caused dissociation of the bacteria from biofilms. To confirm the mechanism of anti-biofilm effect, gene expression level was analyzed related to biofilm formation. The results showed that icaA, B, C, D genes are downregulated by the M-MM-TA. Overall, these results demonstrated that M-MM-TA has significant potential as an anti-bacterial agent and inhibits biofilm formation against S. aureus and MRSA. These findings suggest that M-MM-TA can be used in various biomedical applications to inhibit gram-positive bacterial infections.