Density functional theory calculations. and molecular dynamics simulations of the adsorption of ellipticine anticancancer drug on graphenc oxide surface in aqueous medium as well as under controlled pH conditions

In this study, the solvent effects on the geometric structures and electronic properties of ellipticine (EPT) anticancer drug on the surface of graphene oxide nanosheet (GONS) as adsorbents are studied by density functional theory calculation. To study of the solvent effects, three polar solvents (water with epsilon = 78.39 as a green and natural solvent, dimethyl sulfoxide (DMSO) with epsilon = 46.7 and ethanol with epsilon = 24. 5) have been selected using the polarizable continuum model (PCM). The results show that the adsorption of ellipticine onto GONS is exothermic and energetically more favorable. Moreover, solvation energy values demonstrate that the stability is more in the water among the selected solvents. The theory of Atoms in Molecules (AIM) analysis indicates closed shell (non-covalent) interactions between EPT and GO nanosheet. The calculation of charge transfer by employing NBO method shows that EPT is donor and GO nanosheet is acceptor. These results illustrate that GONS may be a promising candidate as an appropriate adsorbent for adsorbing. Moreover, molecular dynamic simulations are examined to understand the effect of pH on the EPT loading and release on graphene oxide. Our results confirm the favorable drug loading at the neutral blood pH level and its release at acidic pH levels of the environment surrounding a cancerous tumor. The results would motivate the researchers to examine the molecular mechanisms of EPT loading and release under the influence of pH. (C) 2018 Published by Elsevier B.V.