Functionalized metal–organic frameworks based on multi-catalyst ordered assembly for electrochemical stripping chemiluminescent immunoassay

Abstract

The catalytic efficiency of catalysts may be greatly improved by their ordered assembly. To verify this assumption, metal–organic frameworks (MOFs) were selected as the model. In this work, three catalysts of the luminol–hydrogen peroxide (H₂O₂) system were employed for the construction of gold nanoparticle functionalized Cu–hemin MOFs (Au@MOFs), which were later used as labels for the electrochemical stripping chemiluminescent (ESCL) detection of cardiac troponin I (cTnI). Au@MOFs, with a three-dimensional flower spherical structure, good conductivity, open active centers and catalytic sites, could greatly accelerate the decomposition of H₂O₂, enhancing the electrochemiluminescent (ECL) signal of the luminol–H₂O₂ system significantly. Further combined with the electrochemical stripping of copper ions, the ESCL process with three-component synergistic amplification could be realized. Based on the excellent catalytic performance of Au@MOFs, a “sandwich-type” ESCL immunosensor was developed for the determination of cTnI. The constructed ESCL sensor exhibited good stability and repeatability with a low limit of detection down to 0.78 fg mL⁻¹, and had been successfully used for the detection of human serum samples with satisfactory results.