rGO-Aluminium Substrates as Broad-Spectrum Antimicrobial and Antibiofilm Functional Materials

The intractable prevalence of contact-mediated infections warrants the development of next-generation antimicrobial materials. Since bare metals like aluminum (Al) are prone to limitations such as microbial contamination and corrosion, it is imperative to develop a sustainable substrate using infinitely recyclable aluminum, with robust antimicrobial activity. This study reports broad-spectrum antibiofilm and antimicrobial activity of electro-chemically deposited reduced graphene oxide on aluminum (rGO-Al) substrates toward clinically important pathogens, Gram-negative E. coli, Gram-positive S. aureus, and fungus C. albicans. This further evaluates the knowledge gap by correlating the observed antimicrobial properties of rGO-Al materials to the possible mechanism(s). Next, measurements of water contact angle and 4-probe conductivity tests confirm the hydrophobic and conducting nature of the synthesized substrates respectively. In vitro, experimental results show that rGO-Al substrates can significantly inhibit the growth and viability of test organisms. While scanning electron microscopy (SEM) analyses confirm contact-mediated cell membrane damage, fluorescence microscopy reveals potent antibiofilm activity of test substrates. Alterations in membrane potential and reactive oxygen species (ROS) production provide further evidence for the antimicrobial activity via microbial membrane disruption. Thus, a perspective mechanism is proposed, where the surface hydrophobicity of rGO-Al promotes a stable interaction with the microbes. Further, conductivity-driven-electron transfer induces ROS production leading to membrane damage. Current research will facilitate the development of high-performance aluminum-based nanomaterials that can replace bare Al in the industrial and biomedical sectors. The sustainable nature of rGO-Al substrates will enhance the longevity and functionality of underneath Al surface by inhibiting microbial colonization and concurrent outcomes.