Fabrication of molecularly imprinted electrochemical sensors for sensitive codeine detection

Codeine (COD) is a natural opiate alkaloid obtained from hashish or prepared by methylation from morphine, widely used as an analgesic, antitussive, and antidiarrheal drug. A sensitive and selective electrochemical sensor based on molecular imprinting polymer (MIP) was developed to detect COD in tablet form and biological fluid samples. The polymeric thin film on the glassy carbon electrode (GCE) surface was formed using template molecule COD, a functional monomer based on amino acid N-methacryloyl-L-tryptophan (MA-Trp), basic monomer 2-hydroxyethyl methacrylate (HEMA), cross-linker ethylene glycol dimethacrylate (EGDMA), and the pore-making sacrificial material zinc oxide (ZnO). The developed MIP-based electrochemical sensor (MA-Trp@MIP/GCE) was characterized by scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FT-IR), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS) methods. The electrochemical properties of the sensor were examined using differential pulse voltammetry (DPV). Under optimum experimental conditions, the dynamic linear range of the developed sensor was calculated as 0.1–1.0 pM and the detection limit of 0.0150 pM. The current electrochemical sensor technique also demonstrated outstanding recovery in human urine, synthetic serum samples, and tablet form, with relatively high recoveries of 98.5%, 101.4%, and 101.5%, respectively. Moreover, the MA-Trp@MIP/GCE sensor exhibited good reproducibility, repeatability, stability, and fast response time for the electrochemical analysis of COD. The presented sensor successfully determined COD in tablet and biological fluid samples.