Bacterial adsorption with graphene family materials compared to nano-alumina

The present study investigates the bio-activity and bio-adsorption properties of graphene family materials (GFMs) in comparison to nano-Al2O3 (12 nm, gamma phase). This is the first study that determines the type of solid adsorbent (GFMs or nano-Al2O3) preferred by living bacteria cells. The investigated GFMs were: graphene, graphene oxide (GO) and reduced graphene oxide ( RGO). The SEM images indicated that bacterial preferences depended on the particular strain, the type of GFM and the composition of the suspension. Generally, bacteria preferred to colonize the GFMs surfaces in the presence of nano-Al2O3 which resulted in no changes of zeta potential (zeta) measured for bacteria cells due to the fact that carbon is known as a good nourishment for microorganisms. There were however few exceptions from that rule i.e. the Sarcina bacteria preferred to adsorb on the surface of nano-Al2O3 when suspended with RGO flakes, and the E. coli preferred to colonize the surface of nano-Al2O3 when suspended with graphene sheets. For this suspension, zeta of bacteria cells decreased suggesting their starving state on the surface of nano-Al2O3. We also found disruptions in morphology of almost all E. coli cells, when attached to all investigated adsorbents.