Development of an electrochemical sensor based on Ni-Bio-MOF and a molecular imprinted polymer for determination of diclofenac: electrochemical and DFT investigations

In this work, a metal-organic nickel framework (Ni-MOF) modified with a biological ligand (asparagine) (Ni-Bio-MOF) was synthesized by a hydrothermal method. Asparagine is believed to create defects on the surface of the MOF, thereby increasing its electrocatalytic activity. Then, a Diclofenac (DCF) polymer imprinted with l-methionine (PL-Met) was electrodeposited on a carbon paste electrode (CPE)/Ni-Bio-MOF and used as a new electrochemical sensor for highly selective and sensitive detection of DCF in biological and pharmaceutical samples. The Ni-Bio-MOF/MIP-PL-Met nanocomposite was characterized using the following techniques: FT-IR, FE-SEM, TEM, HR-TEM, XRD, XPS, and EDX. The electrochemical properties and performance of the sensor for the electrooxidation of DCF were assessed using CV, DPV, and EIS techniques. The electrochemical behavior of CPE/Ni-Bio-MOF/MIP-PL-Met and non-imprinted polymer (NIP) with an imprinting factor of 6.64 was investigated, and the influencing parameters in DCF measurement were optimized by cyclic voltammetry (CV). This modified sensor showed three dynamic ranges at 1.0-500.0 pM, 1.0-1000.0 nM, and 1.0-1000.0 μM of DCF with a limited detection (LOD) of 0.17 pM, sensitivity of 2015.5 μA μM^-1 cm^-2, relative standard deviation (RSD) of 3.3%, and reproducibility of 96.2%. Real samples of healthy human blood serum and DCF tablets were used to evaluate the practical application of the CPE/Ni-Bio-MOF/MIP-PL-Met electrochemical sensor. This method is simple, low-cost, with good limited detection, high sensitivity, and selectivity. The interactions of PL-Met with DCF were studied at the B3LYP/6-311++G(d,p) level of theory in both gaseous and aqueous phases. Additionally, the computational methodology investigated the thermodynamic stability of the proposed configurations and the role of hydrogen bonds in this system.