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

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. The synergic catalysis can greatly improve the performance of sensor developed.