Functionalized Single-Walled Carbon Nanotubes and Nanographene Oxide to Overcome Antibiotic Resistance in Tetracycline-Resistant Escherichia coli

Antibiotic resistance is a significant and growing public health problem. This work investigated the use of two different carbon nanomaterials, single-walled carbon nanotubes (SWNTs) and nanographene oxide (NGO), as a means of delivering the antibiotic tetracycline to a strain of Escherichia coli bacterium with an efflux pump resistance mechanism. Both SWNTs and NGO carrying tetracycline were found to inhibit the resistant strain of Escherichia coli, though the amount of tetracycline delivered was much lower than the minimum inhibitory concentration of free tetracycline. Attachment of the tetracycline to the nanomaterials was found to be necessary for the inhibition of bacterial growth, indicating that the nanomaterials were transporting the antibiotic into the cells and subverting the efflux pump. SWNTs were observed to have greater efficacy in delivering tetracycline than graphene oxide, which is attributed to the SWNTs' needle-like shape. This work demonstrates both the use of carbon nanomaterials as antibiotic-delivery vehicles and the effect of nanomaterial shape on their efficacy. More importantly, it demonstrates that nanomaterials can successfully extend the life of existing antibiotics, making them an important tool for combatting antibiotic resistance mediated by an efflux pump mechanism.