An electrochemiluminescence sensor based on lanthanide bimetallic MOFs with a "cascade sensitization mechanism" for the sensitive detection of CA242.

Lanthanide metal-organic frameworks (Ln-MOFs) broaden the optical sensing applications of lanthanide ions due to the antenna effect between organic ligands and metals. However, the sensitization ability of the ligand to metal ions is limited, and maximizing the sensitization of the electrochemiluminescence behavior of Eu is still a challenge for the application of Ln-MOFs. Therefore, under the guidance of the "cascade sensitization mechanism" based on the antenna effect sensitizing the electrochemiluminescence of bimetallic Ln-MOFs, we proposed Eu/Tb-MOFs with high luminescence intensity as a signal probe. According to the antenna effect, the conjugated structure and high extinction coefficient of the benzene ring of 2-amino terephthalic acid (NH-BDC) can enhance the ECL luminescence intensity of Eu/Tb-MOFs. Tb can act as an energy bridge between NH-BDC and Eu, buffering the energy gap. The bimetallic sensitization is formed between Tb and Eu, which can inhibit the reverse internal flow of energy and ensure the high luminous efficiency of Eu. In addition, the nanosphere mixed valence FeO as a co-reactant accelerator promotes the formation of transient free radical SO through the valence change of Fe/Fe. The ECL immunosensor constructed by luminophores Eu/Tb-MOFs and nanosphere FeO provided a new explanation for the ECL self-luminous of Eu/Tb-MOFs.