L-lysine-structure-directed MIL-88A and its application in electrochemical sensing of cholylglycine via molecular imprinting technique

Abstract In this work, we develop a novel strategy to synthesize MIL-88A (an iron-based metal-organic framework) by adding L-lysine as structural directing agent under ambient conditions, and L-lysine could be thoroughly removed after reaction finished. It was discovered that L-lysine could effectively regulate the size of MIL-88A. The prepared MIL-88A particles, combining with XC-72 and molecularly imprinted polymer (MIP) films, were applied to fabricate a sensitive electrochemical sensor for the detection of cholylglycine (CG, a biomarker of hepatocellular carcinoma). The surface morphologies of modified electrodes were characterized by scanning electron microscope (SEM). Furthermore, X-ray diffraction (XRD), transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR), N2 adsorption-desorption were used to further characterize the prepared MIL-88A particles. A 5 mM [Fe(CN)6]3-/4- (containing 0.1 M KCl) solution was used as redox probe, and differential pulse voltammetry (DPV) was applied to quantitatively detect CG. The linear response range of CG was 1×10-11 to 5×10-8 M with a detection limit of 3.4×10-12 M (S/N=3). The MIP sensor was successfully applied to detect CG in human serum with satisfactory results.