“…Described as sheets of graphene rolled up into cylinders (with several micrometres in length and nanometres in diameter), they can be classified as single-(SWCNTs) and multi-walled CNTs (MWCNTs), accordingly to the number of graphene layers [19,20]. Because of their outstanding properties, such as electrical conductivity, high aspect ratio and mechanical strength, flexibility, high surface energy density, chemical stability, and the possibility of functionalization with a wide variety of moieties (antimicrobial drugs and other bioactive molecules), CNT-based surfaces have been widely applied in the medical field, and in particular for the manufacture of medical devices [18,21]. Although there is still little consensus regarding the mechanisms behind the CNTs' antimicrobial activity, different influencing factors have been described, including CNT diameter and length, purity, electronic structure, CNT aggregation and surface functional groups, as well as CNT type (SWCNT or MWCNT) [22].…”