A disposable homemade screen printed electrode for famotidine analysis using a computer-designed molecularly imprinted polymer based on the MWCNT-Fe3O4 nanocomposite in simulated real samples†

A home-made screen printed electrode (SPE) was designed with a magnetic multi-walled carbon nanotube composite (MWCNT-Fe₃O₄) and a molecularly imprinted polymer (MIP) for sensitive and selective electrochemical analysis of famotidine (FAM). The SPE was fabricated using non-commercial conductive inks such as carbon and silver inks. The electrodes were printed by a painting technique on polyvinyl chloride (PVC) sheets as a substrate. To optimize the composition of the carbon ink, a mixture design methodology was employed. A computational approach was used to select the functional monomer. The imprinted layer was synthesized by electropolymerization of FAM (template) and pyrrole (PY) (monomer) using cyclic voltammetry (CV) on the working electrode surface modified with the MWCNT-Fe₃O₄ nanocomposite. Differential pulse voltammetry (DPV) was applied to characterize the template removal and rebinding processes. The Plackett–Burman design (PBD) and central composite design (CCD) investigated the effect of parameters on the MIP/MWCNT-Fe₃O₄/SPE performance. The sensor exhibited a linear dynamic range of 1–1000 μM (R² = 0.9919) with a limit of detection (LOD) of 0.027 μM (3s_b, n = 3). It demonstrated good repeatability and reproducibility, with relative standard deviations (RSD) of 3.6 and 4.2, respectively. This disposable and cost-effective sensor successfully detected FAM in simulated real samples and correlated well with high-performance liquid chromatography (HPLC) results.