Laser-Induced Graphene Papers with Tunable Microstructures as Antibacterial Agents

Laser-induced graphene (LIG) has recently been attracting attention as a highly efficient method to process antimicrobial materials with scalable sizes and tunable properties. In this work, freestanding graphene papers are systematically investigated to study their process- and structure-dependent antibacterial activities against both Gram-positive and Gram-negative species. In addition to microscopy analyses for qualitative discussion of live and dead cells, a colony counting assay is applied to precisely quantify the loss of viability of bacteria treated by various laser-induced graphene papers (LIGPs) with tunable microstructures. Remarkably, the 1.25 W-processed LIGPs (LIGP-1.25 W) exhibit the highest reduction rate of 92.8% for Escherichia coli (E. coli) and 95.2% for Staphylococcus aureus (S. aureus), compared with LIGPs processed under 0.75 W (LIGP-0.75 W) and 1.75 W (LIGP-1.75 W). In addition to proving the combined membrane stress and reactive oxygen species (ROS)-independent oxidative stress-related mechanisms, the specific interconnected open-cell network with the highest specific surface area (171.6 m2/g) is found to be the determinant with fruitful bacteria trapping sites. Finally, corrosion resistance test is applied for demonstrating the capability of LIGPs for protecting the aluminum alloy sheet against immersion invasion of E. coli suspension up to 3 weeks, suggesting their great potentiality for facilitating advanced environmental protection activities.