Molecular Dynamic Simulations of the Effects of Trimethylamine-N-oxide/Urea Mixture on the Hydration of Single-Walled Carbon Nanotube Interiors

Urea is known for protein denaturation. The counteracting effect of trimethylamine-N-oxide (TMAO) against urea-induced protein denaturation is also well established. However, what is largely unknown is the mechanism TMAO counteracts urea. In this article, the hydration of the interior of a simple single-walled carbon nanotube in a urea/TMAO mixture is studied as a model system for hydrophobic hydration using molecular dynamic simulations. The results show that TMAO counteracts the hydration effect of urea to the nanotube interior through strong interactions among TMAO, water, and urea. The strong interactions of TMAO and water stabilize the water structure, which counteracts the effects of urea indirectly.