LED Photoactive Antibacterial Carbon Nanomaterial Surfaces

Carbon-based nanomaterials are potentially antimicrobial in water treatment, healthcare, and environmental applications. The antibacterial properties of various carbon nanomaterial surfaces have been investigated; however, studies including direct comparisons between carbon nanomaterials with different morphology, chemistry, and wettability are few. Moreover, photoenhanced surface antibacterial activity is not fully understood. Here, we show that simple light-emitting diodes (LEDs) can enhance the antibacterial surface activity of three carbon nanomaterials with diverse surface morphologies, including laser-induced graphene (LIG), vertically aligned carbon nanotubes (VACNT), and carbon nanofibers (CNF). After 40 min of exposure to low-energy LED light, VACNTs showed the highest bacterial killing activity (93.4%), followed by CNFs (72.5%) and then LIG surfaces (69.0%). Moreover, when hydrophilicity was increased using atmospheric plasma treatment, the LED-activated antibacterial activity of all surfaces was further enhanced, with only 20 min of LED exposure resulted in 99.1%, 92.6%, and 46.1% bacterial killing efficacies for CNF, VACNT, and LIG surfaces, respectively. The LED treatment was the predominant activator of cell toxicity, resulting in reactive oxygen species and bacterial membrane permeability, although morphological factors were also seen, including an increased antibacterial efficacy of VACNT surfaces as the length of the CNTs increased and differences between the various carbon surfaces. These findings provide valuable insights into the roles of various parameters in carbon nanomaterial surfaces in antimicrobial applications.