Copper doped terbium metal organic framework as emitter for sensitive electrochemiluminescence detection of CYFRA 21-1

Lanthanide metal organic frameworks (L-MOFs) are emerging as promising electrochemiluminescence (ECL) emitters for bioanalysis. This work proposed a copper doped terbium MOF as a luminescent tag for construction of a "signal-on" ECL immunosensing method. The Tb-Cu-PA MOF was prepared using Tb3+ and Cu2+ ions as metal linkers and m-phthalic acid as bridge ligand, and exhibited strong ECL emission with K2S2O8 as a coreactant. The immunosensor was prepared by immobilizing capture antibody on Pd nanoparticles modified Ni-Co layered double hydroxide (Pd-ZIF-67@LDH) nanoboxes, which showed strong electrocatalytic activity toward the reduction of S2O82- for amplifying the ECL signal. Upon the sandwich-typed immunoreactions, Tb-Cu-PA MOF labeled antibody was introduced onto the immunosensor for sensitive ECL detection of target protein. Using cytokeratin 19 fragment 21-1 (CYFRA21-1), a representative lung cancer biomarker, as target model, the ECL immunosensing method showed a linear range of 0.01-100 ng/mL and a detection limit of 2.6 pg/mL (S/N = 3). This immunosensing strategy highlighted the advances of using luminescent and electroactive MOFs in the developments of highly efficient immunosensors for bioanalysis.