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 the 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 (one kind of carbon black) 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), N2adsorption–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 a 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.