Dual-functional monomers in molecularly imprinted polymer synthesis for electrochemical detection of bisacodyl in biological samples based on lab-made screen-printed carbon electrode

In this study, the utilization of two monomers, specifically pyrrole (PY) and thiophene (TH), was investigated for the synthesis of dual-monomer molecularly imprinted polymer (DMMIP) used in the electrochemical detection of bisacodyl (BIS) in biological samples. To examine the impact of each monomer individually and in combination on the formation of DMMIP, a density functional theory (DFT) approach was utilized. This calculation was employed to enhance the selectivity of the MIP towards the target molecule BIS. The DMMIP was electropolymerized using cyclic voltammetry (CV) of monomers and template on a lab-made screen-printed carbon electrode (SPCE) that had been modified with graphene oxide (GO). Differential pulse voltammetry (DPV) was then utilized for the accurate determination of BIS levels. The influencing factors in the DMMIP synthesis, such as the PY to BIS ratio, the TH to BIS ratio, pH, scan rate, and the number of scans, were optimized using a Taguchi array. In addition, other parameters such as the stirring rate, loading time, and the amount of GO were analyzed using the one-factor-at-a-time (OFAT) approach. Under optimized conditions, the sensor demonstrated a linear dynamic range from 0.1 to 1000 µM (R² = 0.9984) with limits of detection and quantification of 0.063 µM (S/N = 3) and 0.21 µM (S/N = 10), respectively. The sensor also exhibited good repeatability and reproducibility, with relative standard deviations (RSD) of 1.4% and 2.7%, respectively. Moreover, this sensor successfully detected BIS in real samples and showed a good agreement with high-performance liquid chromatography (HPLC) results.