pH dependence of dacarbazine adsorption on activated carbon: DFT study

¹ Instituto de Física del Sur (IFISUR), Departamento de Física, Universidad Nacional del Sur (UNS), CONICET Av. L. N. Alem 1253, B8000CPB - Bahía Blanca, Argentina
² Comisión de Investigaciones Científicas (CIC) - Calle 526 e/10 y 11, 1900 - La Plata, Argentina
³ Universidad Tecnológica Nacional (UTN) - 11 de Abril 461, B8000LMI - Bahía Blanca, Argentina

^(a) ssimonet@uns.edu.ar

Received: 27 March 2019
Accepted: 7 June 2019

Abstract

Density Functional Theory (DFT) methods supply important aspects of dacarbazine adsorption on a carbon surface, by providing atomistic details through molecular modeling. The weak interactions between dacarbazine and pristine carbon surface could limit the medicinal treatment efficiency. Nevertheless, the carboxyl (-COOH) functionalized carbon surface has a significant effect on the adsorption of dacarbazine at neural and lower pH. At low pH, the carboxyl-carbon surface acts as attraction centre for the protonated drug via hydrogen bonding and electrostatic interactions, which result in lower adsorption energy and better controlled release. At pH = 7, they are expected an increased rate and released amount of dacarbazine because the electrostatic interactions decrease between the neutral molecule and the carboxyl functionalized surface. At high pH, the deprotonated drug and the ionized carboxyl-surface present stronger electrostatic repulsion and the highest adsorption energy, which could increase the dacarbazine release rate. Carboxyl functionalized carbon surfaces could improve dacarbazine drug delivery adapting to therapy requirement according to the pH.