New perspectives in graphene-based nanomaterials and surface disinfection

BACKGROUND: Chemical disinfection of surfaces and instruments for infection control in dental units is a relevant practice, especially at the time of antibiotic resistance microbes. Resistant bacteria are in fact, involved in the high incidence of healthcare-acquired infections, recognized as critical emergence in hospitals and clinics around the world. Infected patients disseminate and release many multidrug-resistant Gram-negative and Gram–positive species to other ones and to healthy people: such bacteria share the ability to survive on various hospital surfaces for long periods and for this reason they are difficult to eradicate by cleaning and chemical disinfection. In this regard, the use of nanomaterials as novel and non-traditional antibacterial agents offers new insight in the field of disinfection. Here we report the development of carbon based nanomaterials, such as graphene nanoplatelets (GNPs) decorated with Zinc oxide nanorods (ZNGs) to be used as disinfectant agents in dentistry units. METHODS: ZNGs were produced at Sapienza NanoLab by thermal expansion of graphite; ZNGs were obtained by subsequent hydrothermal growth of zinc oxide nanorods on GNPs (graphene nanoplatelets), used as seed layers. These nanomaterials were spray coated on different surfaces with different porosity and the antimicrobial properties were evaluated by the colony forming unit method (CFU), against Staphylococcus aureus and Pseudomonas aeruginosa as main representatives of Gram positive and Gram negative bacteria, respectively. RESULTS: Characterization of ZNGs sprayed on the different surfaces was performed by Field-Emission Scanning Electrone Microscope and XRD analysis. Microscope images showed the nanorods of ZNGs emerging out from the surfaces having average diameter of ~34 nm and length of 300–400 nm. The XRD pattern of ZNGs did not detect any diffraction peaks of impurity, suggesting that the synthesized nanomaterials were of high-purity. Treated surfaces with the above nanomaterial showed a strong antimicrobial power with respect to the untreated surfaces. Indeed, the survival of both types of bacteria was almost less than 10% after 30 minutes in the case of cells inoculated on treated surface. CONCLUSIONS: ZNGs can be exploited as promising antimicrobial agents to be used as disinfectants in dental units.