This work utilized ultrathin metal-organic layer (MOL) to immobilize luminophores for effectively shortening the ion/electron-transport distance and relieving the diffusional constraints of ion/electron, which greatly enhanced the ECL efficiency and intensity. Moreover, the MOL's immobilization amount of luminophores should be higher than these of bulk MOFs because MOLs possess more accessible postmodification sites for the luminophores with minimal diffusion barriers. As expected, our proof-of-concept experiment indicated that the Hf-MOL's loading number of Ru(bpy)2(mcpbpy)2+ was about 1.74 times that of a 3D mesoporous MOF (PCN-777), and the ECL efficiency and intensity of PEI@Ru-Hf-MOL were around 1.27 times and 14.5 times those of PEI@Ru-PCN-777, respectively. In view of these merits, this work utilized the prepared PEI@Ru-Hf-MOL as a highly efficient sensing platform for simple, rapid and sensitive detection of mucin 1, which exhibited a broad linearity from 1 fg/mL to 10 ng/mL and a low detection limit of 0.48 fg/mL. This work provided a practicable strategy to develop high-performance ECL materials, and therefore opened up a new avenue to design ultrasensitive ECL biosensors, which expanded the application potential of MOLs in ECL assays.
Keywords: 2D metal-organic layers; ECL immunosensor; MUC1; Ru(bpy)(3)(2+) derivatives.
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