Cupric ion coordination-mediated molecularly imprinted electrochemical sensor for the recognition and ratiometric...

Molecularly imprinted polymers (MIPs) have been widely used as artificial recognition elements in sensing applications. However, their electrochemical sensing performance is generally hampered by limited affinity and uncontrolled condition change. In this work, a novel MIP electrochemical sensor based on metal coordination interaction was prepared and used for the recognition and ratiometric detection of lidocaine (LC). The sensor was constructed by electrodepositing Cu-coordinated MIP on biomass carbon modified glassy carbon electrode. Herein, Cu²⁺ ions acted as anchor for the immobilization of LC during the synthesis process, enabling the orderly formation of molecular recognition sites. Reversely, the metal coordination between Cu²⁺ ions and LC molecules facilitated the recognition of LC. Moreover, the doped cupric ions in the polymer film could provide a reference signal for subsequent ratiometric strategy. Thus the resulting sensor exhibited high selectivity, sensitivity, satisfactory reproducibility, and anti-interference ability. Under the selected conditions, the peak current ratio of LC and cupric ion was linear to LC concentration in the range of 0.008-2.5 μmol L^-1 (R² = 0.9951), and the limit of detection was 1.9 nmol L^-1 (S/N = 3). The practical feasibility of the sensor was evaluated by detecting human serum and pharmaceutical samples, and satisfactory outcomes were obtained.