Characterising the Antimicrobial Performance of Engineered Layered Double Hydroxide Surfaces for Biofilm Control

Area of Science:

• Materials Science
• Nanotechnology
• Biomedical Engineering

Background:

• Antimicrobial resistance (AMR) is a critical global health issue, exacerbated by bacterial biofilm formation that hinders treatment efficacy.
• Developing novel surface-based strategies to prevent biofilm formation is essential for combating AMR.
• Layered Double Hydroxides (LDHs) are 2D nanomaterials with tunable properties, offering potential for antimicrobial surface applications due to their ease of synthesis and scalability.

Purpose of the Study:

• To evaluate the efficacy of Layered Double Hydroxide (LDH) thin-film coatings as intrinsic antimicrobial surfaces.
• To investigate the combined influence of chemical composition, nanotopography, and wettability on biofilm formation of key bacterial species.
• To assess the potential of LDH coatings for clinical applications in preventing bacterial colonization.

Main Methods:

• Synthesis of four aluminum-based LDHs (ZnAl-NO3, ZnAl-Cl2, MgAl-NO3, MgAl-Cl2) using coprecipitation or in situ growth on aluminum substrates.
• Characterization of synthesized materials using X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDS), and contact angle measurements.
• Assessment of antimicrobial performance by quantifying colony-forming units (CFU mL-1) after exposure to *Escherichia coli*, *Staphylococcus aureus*, and *Pseudomonas aeruginosa*.

Main Results:

• ZnAl-LDH surfaces demonstrated significant antimicrobial activity against *E. coli* and *S. aureus*, effectively reducing biofilm formation.
• MgAl-LDH coatings showed no significant antimicrobial effect and, in some cases, promoted bacterial growth.
• No tested LDH surfaces exhibited substantial antimicrobial activity against the *P. aeruginosa* strain used in the study.
• The antimicrobial efficacy of ZnAl-LDH was linked to the synergistic effects of surface chemistry, wettability, and nanotopography.

Conclusions:

• ZnAl-LDH coatings represent a promising material for developing intrinsic antimicrobial surfaces.
• The findings highlight the importance of material composition and surface properties in designing effective anti-biofilm strategies.
• ZnAl-LDH coatings hold potential for translational research in clinical settings for antimicrobial surface development.