An electrochemiluminescence biosensor based on Ag–Ag₂S as an efficient emitter and Zr-MOG as the co-reaction promoter for the ultrasensitive detection of CYFRA21-1

In this work, a highly sensitive electrochemiluminescence (ECL) biosensor was successfully developed for the detection of CYFRA21-1, in which a metal-organic gel (Zr-MOG) was introduced as a novel co-reaction promoter for amplifying the ECL signal of the silver nanoparticle-modified silver sulfide/potassium persulfate (Ag-Ag₂S/K₂S₂O₈) system. Specifically, the incorporation of Ag nanoparticles narrowed the bandgap and enhanced the ECL signals of the composites. As a co-reaction promoter, Zr-MOG accelerated the reduction of S₂O₈^2- to produce abundant sulfate radicals (SO₄˙^-) while increasing the electrode active surface area, which led to a significant enhancement of the Ag-Ag₂S ECL emission. The biosensor constructed based on the dual-signal amplification strategy demonstrated excellent sensitivity, selectivity, and stability, with a wide linear detection range of 0.00005-100 ng mL^-1 and a detection limit as low as 17.66 fg mL^-1 (S/N = 3).