Molecular Dynamics Insight into the Urea Effect on Tretinoin Encapsulation into Carbon Nanotube

Molecular dynamics simulations at 270 and 310 K rationalized the effect of urea, temperature and the size of the carbon nanotube, on the insertion of Tretinoin into nanotubes with chirality (10, 7) and (8, 5). Concentrations of 0.9 mmol L-1 and 2 mol L-1 of urea are studied, that are less and more than the normal range of blood urea content, respectively. Results show that encapsulation of Tretinoin could be ascribed to the flow of the waters via hydrophilic and van der Waals interactions and diameter of the nanotube. Heat capacity, diffusion coefficient, free energy and contact coefficient change with the temperature and urea. Tretinoin molecule locates inside the nanotube due to the partial pi-pi interactions between oxygen atom of Tretinoin and the conjugated aromatic rings of nanotube. Finally, high concentration of urea causes the striking phenomenon of inducing the drying of nanotube that result in urea wires and instability of encapsulation.