Hydroxylated-graphitic carbon nitride@graphene oxide composites for sensitive electrochemical determination of COVID-19 drug molnupiravir: Effect of modifier composition

In this research, pencil graphite electrode (PGE) surfaces were modified with a two-dimensional and multifunctional composite material consisting of hydroxylated graphitic carbon nitride (hCN) and graphene oxide (GO) components for sensitive voltammetric determination of coronavirus disease (COVID-19) drug molnupiravir (MLP). The synthesis of carbon nitride, hCN, GO, and the composite material (hCN@GO) included thermal polymerization, hydroxylation, intermediate Hummer's method, and sonochemical processes, respectively. Then, the resulting composite material was electrochemically loaded on the PGE surface. The effects of various experimental parameters, such as the supporting electrolyte, pH, buffer concentration, and scan speed, on the analytical signal were investigated. The most vital one was the composite composition loaded on the PGE. The highest signal was obtained when the PGE surface was coated with the hCN:GO ratio of 30:70 (as weight%). The findings assigned electrode modification with proper composition led to an approximately 17-fold increase in the electrochemically active surface area and a 100-fold decrease in the charge transfer resistance of bare PGE. Thus, it could achieve approximately a 3-fold lower detection limit. The sensor exhibited a linear response in the 7-300 nM MLP concentration range with a detection limit of 2.2 nM without significant interference.