Application of carboxylated carbon nanotubes as artificial channels to facilitate n-decane transport through bacterial cell membranes

Abstract

Facilitating the transport of hydrocarbons across bacterial cell membranes can improve the efficiency and rate of bioremediation processes. In this study, we evaluated the potential of carbon nanotubes (CNTs), particularly functionalized CNTs (CNT–COOH), as artificial membrane channels to enhance the uptake of hydrophobic compounds into bacterial cells. The toxicity of CNTs was firstly assayed using Bacillus subtilis and Pseudomonas aeruginosa strains, and the obtained results revealed that the toxicity of carboxylated CNTs was reduced significantly. Molecular dynamics simulations further confirmed a stable CNT integration into the bilayer membrane model in terms of interaction energies. Our results suggested that a short (around 10 nm), carboxylated CNT system would adopt a perpendicular alignment to the membrane, thus forming an artificial channel. Hydrocarbon uptake experiments using n-decane demonstrated enhanced internalization in the presence of CNT–COOH, with intracellular n-decane levels increasing by 32% and 41% for B. subtilis and P. aeruginosa, respectively, in comparison with the blank tests. It was disclosed that the CNT–COOH can be used as an effective tool for constructing nanoscale membrane channels to increase hydrocarbon transport into bacterial cells for bioremediation applications.