Photo-induced antibacterial activity of four graphene based nanomaterials on a wide range of bacteria.

Due to controversial reports concerning antibacterial activity of different graphene based materials it is very important to investigate their antibacterial action on a wide range of Gram-positive and Gram-negative bacteria. In this paper we have investigated the structure induced phototoxic antibacterial activity of four types of graphene based materials: graphene oxide (GO), graphene quantum dots (GQDs), carbon quantum dots (CQDs) and nitrogen doped carbon quantum dots (N-CQDs). Antibacterial activity was tested on 19 types of bacteria. It is found that nanometer-size CQDs and N-CQDs are the most potent agents whereas micrometer-size GO has very poor antibacterial activity. Electron paramagnetic resonance measurements confirmed photodynamic production of singlet oxygen for all types of used quantum dots. Detailed analysis has shown that N-CQDs are an excellent photodynamic antibacterial agent for treatment of bacterial infections induced by Enterobacter aerogenes ( E. aerogenes ), Proteus mirabilis ( P. mirabilis ), Staphylococcus saprophyticus ( S. saprophyticus ), Listeria monocytogenes ( L. monocytogenes ), Salmonella typhimurium ( S. typhimurium ) and Klebsiella pneumoniae .