In the present study, molecular dynamics (MD) simulations and density functional theory (DFT) were applied to monitor the sensing procedure of some alkaloid molecules by cucurbit[n]urils (CB[n]s, [n] is the number of glycoluril unit). The stability of alkaloid molecules inside the CB[n] complexes, which are shown as alkaloid@CB[n], were investigated after 50 nanosecond MD simulations. An acceptable selectivity for thebaine in the presence of CB[8] and CB[10] was confirmed in water and methanol, respectively. DFT calculations confirmed the dispersion interaction as an effective driving force for the alkaloid encapsulation inside CB[n]s. Different analyses of natural bond orbital, quantum theory of atoms in molecules and density of states were applied to have an insight into the electronic processes during the alkaloid@CB[n] complex formation and feasibility of alkaloid sensing. Finally, to determine the role of graphene oxide (GO) in the designing of the new chemo-sensors, a CB[n]/GO composite was proposed and simulated by MD method. On the basis of the theoretical results, graphene oxide improves the encapsulation ability of CB[n]s toward the studied alkaloids, especially CB[10]/GO against Codeine.

Keywords