Saccharide Insertion in Carbon Nanotube: Molecular Dynamics Simulation Studies

We have investigated the insertion process of saccharides into nanopores using atomistic molecular dynamic (MD) simulations of the model systems, which consist of three different saccharides (α-d-glucose, sucrose, and γ-cyclodextrin) and carbon nanotubes (CNTs) with various diameters (13.6–21.7 Å). We have observed that unlike small saccharides such as α-d-glucose and sucrose, γ-cyclodextrin shows a nonmonotonic behavior in the absorption free energy with the minimum at the CNT pore of about 16 Å in diameter. In addition, we have decomposed the system energy into several components to understand the driving force of the saccharide insertion into nanopores and found that the nonmonotonic insertion free energy is attributed to several contributions such as the dehydration and the conformational change of saccharides, van der Waals interactions among saccharides, CNT and water molecules, and the entropic effects of water molecules.