Exposure-Dependent Antimicrobial Activity and Oxidative Properties of Polymer-Based Graphene Oxide Nanocomposites
Bacterial proliferation and biofilm formation has emerged as a significant concern in the long-term use of industrial apparatus. This study describes the antimicrobial properties of a novel chitosan-polyethyleneimine-graphene oxide (CS-PEI-GO) nanocomposite against E. coli. The nanocomposite is a stable material with minimal dispersibility in storage water after more than 7 days. The antimicrobial activity is contact-time-dependent, with direct contact (92% bacterial inactivation after 3h exposure) having superior results compared with dynamic contact (~50% inactivation after 3h exposure). In addition, the incorporation of GO also translated to enhanced production of ROS—oxidation of GSH was higher in CS-PEI-GO (31.78%) as compared to CS-PEI alone (5.69%). This may be attributed to previously proposed mechanisms of mechanical membrane damage and reactive oxygen species production that may be more pronounced with prolonged contact. This may be due to the positively charged chitosan and the negatively charged cell membrane facilitating the coating of cells that could allow the oxygen-containing functional groups of GO to induce oxidative stress and lead to cell death.