Effects of solvent-free amine functionalization of graphene oxide and nanodiamond on bacterial growth

We studied the effect of covalent functionalization of graphene oxide (GO) and nanodiamond (ND) with octadecylamine (ODA) on bacterial growth (a series of experiments was performed also with pristine single-walled carbon nanotubes [SWNTs] for comparison). The bacteria tested wereEscherichia coliandStaphylococcus aureus, which represent Gram-positive and Gram-negative types, respectively, and are of importance for the environment and human health. We found that pristine GO is the most toxic nanomaterial in both bacteria species, which exhibits a dose-dependent behavior. SWNTs show toxicity only againstS. aureusat the higher concentrations of 1.0 and 10 mg/mL. Pristine ND, as expected, was found to be the least toxic against both species of bacteria, and in the experiments withS. aureusit even showed a viability amplifier activity at 10 mg/mL concentration. The use of ODA-functionalized nanomaterials generally changed the toxicity behavior, neutralizing the antibacterial effect of GO (for bothS. aureusandE. coli), but making ODA-functionalized ND more toxic as compared to pristine material (with respect toS. aureus).

Automated summary

The study found that pristine GO is toxic to bacteria, while SWNTs show toxicity only against S. aureus. Pristine ND is non-toxic to both bacteria and even exhibits viability amplifier activity at high concentrations. The use of functionalized nanomaterials can change toxicity behavior, neutralizing the antibacterial effect of GO and making functionalized ND more toxic.