Amperometric galectin-3 immunosensor-based gold nanoparticle-functionalized graphitic carbon nitride nanosheets and core–shell Ti-MOF@COFs composites

Antigen galectin-3 (GL-3), a member of β-galactoside proteins indicates cardiac fibrosis and is a significant biomarker for monitoring heart failure risk and death risk. In this study, a novel sensitive amperometric method for antigen GL-3 detection is developed based on gold nanoparticle-functionalized graphitic carbon nitride nanosheets (g-C₃N₄@Au NPs) as the sensor platform and Ti-based metal organic framework (Ti-MOF, NH₂-MIL-125)@covalent organic frameworks (COFs) composite for the signal amplification. The Ti-MOF@COF composite not only facilitates the penetration of antibody proteins into pore channels, but also the highly stable antigen-antibody interactions. The prepared sensor platform and signal amplification material are characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD) method, X-ray photoelectron spectroscopy (XPS), UV-vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The amperometric technique is utilized to achieve antigen GL-3 detection in plasma samples. The immunosensor demonstrates a wide linearity range (0.0001-20.0 ng mL^-1) and a low detection limit (0.025 pg mL^-1). Finally, the prepared immunosensor shows high stability and selectivity under optimum conditions.