An electrochemiluminescence sensor based on the antenna effect of lanthanide bimetallic-organic framework and europium(III) electrocatalyst as a co-reactant accelerator for sensitive detection of serum amyloid A.

Serum amyloid A (SAA) is a more sensitive indicator for the early detection of infections compared to traditional biomarkers like C-reactive protein. This study aimed to construct a highly sensitive electrochemiluminescence (ECL) immunosensor employing lanthanide bimetallic-organic framework (Eu/Tb-MOF) in conjunction with CoSn(OH)6-Au nanocomposites for precise quantification of SAA. The sensor was constructed using an Eu/Tb-MOF, where Eu3+ and Tb3+ functioned as the central metal ions and 1,3,5-tris(4-carboxyphenyl)benzene (H3BTB) served as the organic ligand. H3BTB transmits its energy to Eu3+ and Tb3+ through the antenna effect and europium(III) is used as an electrocatalyst, leading to significant amplification of their characteristic ECL emissions. CoSn(OH)6-bound gold nanoparticles provide binding sites for the antibodies, with simultaneous improvement in the interfacial electron transfer rate of CoSn(OH)6. Under optimal conditions, the engineered immunosensor platform exhibited a linear range from 10 fg‧mL-1 to 100 ng‧mL-1 and achieved a detection limit as low as 2.6 fg‧mL-1. Method validation revealed quantitative recoveries (98.20-102.5 %) and exceptional reproducibility (relative standard deviation ≤ 1.7 %), validating the excellent operational stability and target-specific recognition capability of the assay in complex serum matrices. Therefore, the proposed immunosensor can be successfully applied for detecting SAA in biological specimens and also provides a promising approach for detecting other biomarkers.