A highly sensitive and stable electrochemiluminescence immunosensor for alpha-fetoprotein detection based on luminol-AgNPs@Co/Ni-MOF nanosheet microflowers

Due to their high catalytic effect on the electrochemiluminescence (ECL) of luminol, noble metal nanoparticles (NPs) have been widely used in luminol-based ECL immunosensors. However the aggregation of NPs often resulted in the decrease of ECL signal and affected the stability and durability of the sensor. In this study, a microflower-like structure made of ultrathin Co/Ni-based metal-organic frameworks (MOF) nanosheets were used as a platform for luminol-functionalized AgNPs to construct an immunosensor for tumor marker alpha-fetoprotein. The nanosheet and microflower-like assembly structure of the Co/Ni-MOF greatly improved the ECL performance of the luminol-AgNPs system, attributed to their large surface area, resistance to particle agglomeration and the high catalytic activity of the Co/Ni-MOF. The ultrathin Co/Ni-MOF was full of atomically dispersed cobalt ions and nickel ions, which can catalyze the ECL reaction of luminol and H2O2. The as-fabricated immunosensor has a good sensitivity with detection limit of 0.417 pg mL(-1) (S/N=3), and shows satisfactory performance in practical applications.