Computational design of molecularly imprinted polymer for electrochemical sensing and stability indicating study of sofosbuvir

Abstract

In this work, a biomimetic electrochemical sensor for sofosbuvir (SOFO) was designed and optimized for its determination in pure forms, pharmaceutical formulations, urine besides forced degradation products. Computational calculations, based on density functional theory (DFT) at the B3LYP/6-31G(d) level, were initially employed to screen some of the commonly used electropolymerizable functional monomers including para-aminothiophenol (PTP), ortho-aminophenol (OAP), ortho-phenylenediamine (OPD), and pyrrole (PY). Based on the computational calculations, the imprinted sensor active sites were engineered via electropolymerization of OAP, which was found to show the highest binding efficiency to the target drug, on a glassy carbon electrode (GCE) modified with functionalized multi-walled carbon nanotubes (f-MWCNTs) and reduced graphene oxide (RGO) nanocomposite for sensitive determination of SOFO. The fabrication variables of the sensor such as accumulation time, (f-MWCNTs&RGO) loading amount, number of electropolymerization cycles, variation of (template: monomer) ratio, pH, extraction solvent, and binding and rebinding conditions were optimized. The proposed electrchemical sensor was characterized using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and atomic force microscopy (AFM). Differential pulse voltammetry (DPV) was employed for obtaining the calibration curve and optimization of significant factors that control the sensor performance. To prepare the sensor, 2.5 µL of (f-MWCNTs&GO) were first casted on GCE where GO was reduced electrochemically to RGO followed by 20 electropolymerization cycles of a mixture that is (1:11) SOFO: OAP then a mixture of methanol and 0.5 M H2SO4 (4:1 V/V) can be used for template removal after almost 1 min of incubation with the sensor, while 5 min were enough for rebinding with SOFO once more at pH 7. The proposed sensor exhibited a linear range of (0.53–74.13) ng/mL and significant detection limit at 0.05 ng/mL (S/N = 3) using DPV in addition to good reproducibility and selectivity. Finally, the imprinted sensor was successfully applied for the analysis of SOFO in pure samples, urine, two different pharmaceutical formulations, and electrochemical stability indicating study.