A sensitive immunosensor via Pd@Au 0.85 Pd 0.15 in situ electrocatalysis generating H 2 O 2 for quenching electrochemiluminescence of Ir(pbi) 2 (acac)@Ti 3 C 2 T x MXene-PVA.

The establishment of rapid target analysis methods for cytokeratin fragment antigen 21-1 (CYFRA 21-1) is urgently needed. [Ir(pbi)2 (acac)] (pbi = 2-(4-bromophenyl)-1-hydrogen -benzimidazole, acac = acetylacetonate) as traditional electrochemiluminescence (ECL) luminophores has been confined due to its non-negligible dark toxicity and poor water solubility leading to poor biocompatibility and electrical conductivity as an organic molecule. Hence, to overcome this limitation, [Ir(pbi)2 (acac)] can be effectively loaded on the polyvinyl alcohol hydrogel modified Ti3 C2 Tx MXene surface (Ir@Ti3 C2 Tx -PVA) as sensing platform which can emit high ECL signals. Then, a quenching strategy was proposed to fabricate an ECL sandwich immunosensor using H2 O2 as quencher molecules which can generated by [email protected] Pd0.15 . Especially, the generation of O2 to H2 O2 can be achieved through a two-electron (2e- ) reaction pathway by [email protected] Pd0.15 , to overcome the restriction that the H2 O2 was virtually impossible to label or immobilize on the non-enzyme nanomaterials. The proposed ECL assay achieves a response to CYFRA 21-1 within the range of 0.1 pg/mL-100 ng/mL, with a detection limit of 8.9 fg/mL (S/N = 3). This work provided a feasible tactic to seek superior-performance ECL luminophore and quencher consequently set up a novel means to makeup ultrasensitive ECL biosensor, which extended the utilization potential of Ir(pbi)2 (acac) in ECL assays.