Influence of environmental media on carbon nanotubes and graphene nanoplatelets towards bacterial toxicity

Functional carbon-based nanomaterials have become important due to their unique combinations of chemical and physical properties, and also because of the increasing research efforts in various fields. A significant gap in nanotechnology is the disregarding of physicochemical transformation under real conditions for the examination and comparison on the effect of carbon based nanomaterials. In this study, the behavior of some carbon based nanomaterials (multi-walled carbon nanotubes and graphene nanoplatelets) in environmental media (sea water, soil, and airborne fine particulate) were evaluated by using the influence on nanomaterial physicochemical properties (size, zeta potential, surface chemistry, morphology and sedimentation) and on the toxicity of bacterium (gram positive and gram negative bacteria) to contribute to their environmental hazard and risk assessment on the environment. The bacteria were exposed to the carbon based nanomaterials, and cultivated on nutrient agar plates including each environmental media, and then counted for the colony forming units. The physicochemical properties of the carbon based nanomaterials dispersed in these environmental media were also investigated. Our results indicated that the toxicity depended on the type of environmental media and their concentration, and the physicochemical properties of the carbon based nanomaterials changed when compared to the results obtained in controlled conditions.