Probing the adsorption and release mechanisms of cytarabine anticancer drug on/from dopamine functionalized graphene oxide as a highly efficient drug delivery system

In this work, the chemical modification of the graphene oxide surface was done via covalent functionalization with dopamine (fGO). The density functional theory (DFT) and molecular dynamics (MD) simulations were applied to study the adsorption of cytarabine (CYT) anticancer drugs on the fGO surface. The DFT calculations demonstrate that the adsorption energy for fGO/CYT complexes is negative which proposes the adsorption process of CYT molecule onto the fGO surface is energetically favorable and the optimized geometries are stable. The electronic and structural properties of cytarabine molecules interacting with fGO were studied using the DFT method. QTAIM calculations confirm the nature of interaction between CYT and fGO nano-sheet is partially covalent and partially electrostatic. It was found in the most stable configuration related to the CYT/fGO interaction, the hydrogen bond (HB) interactions predominate between the CYT molecule and the functional group of fGO. As well as, the MD simulations at various drug concentrations (3, 5, and 10) and in the water solution were examined to assess the dynamics of drug adsorption on the fGO surface. MD simulation results confirm that CYT drugs were strongly adsorbed on the fGO surface by increasing the drug concentration from 3 to 10 molecules, as confirmed by the high number of H-bonds between fGO and al- and the most negative van der Waals (vdW) and electrostatic interaction energies. Finally, the effect of pH in the adsorption and release of drug molecules from the fGO surface was investigated. (C) 2020 Elsevier B.V. All rights reserved.