Dual-strategy ECL biosensor based on rare Eu(II,III)-MOF as probe with antenna effect and sensitization for CYFRA 21-1 trace analysis

The choices of luminophore and coreactant accelerator are crucial in a constructed electrochemiluminescence (ECL) biosensor. In this work, a mixed-valence Eu-MOF (Sr(HCOO)(2):Eu2+/Eu3+) as luminophore was synthesized based on the precursor of eight-coordinated Sr(HCOO)(2) with P41212 space group and tetragonal crystal structure. The doped Eu3+ was in-situ reduced to Eu2+ by efficient reductant combined with ligand 2-aminoterephthalic acid and solvent thermal decomposition product dimethylamine, then the Eu2+ substitutively coordinated Sr (HCOO)(2) due to the same ion radius and coordination environment between Eu2+ and Sr2+. Through UV-vis, fluorescence spectra and density functional theory (DFT) calculations, the specific luminescence mechanisms of Sr(HCOO)(2):Eu2+/Eu3+ with the antenna effect and sensitization were verified. Thanks to the strongest catalysis of Ag to K2S2O8 and the high active sites, the AgCl rice roll-shaped nanoclusters (AgCl RRNCs) as coreactant accelerator encouraged the production of more SO4 center dot- . Thereout, the constructed ECL biosensor showed high performance in trace detection of cytokeratin 19 fragment 21-1 (CYFRA 21-1) with low limit of detection (2.73 fg/mL) and wide detection range (5 fg/mL similar to 100 ng/mL), which met the requirement for diagnosis and postoperative monitoring non-small-cell lung cancer in clinical treatment completely. These strategies also provided feasible ideas for efficient and stable other biosensors except ECL.

Automated summary

The choice of luminophore and coreactant accelerator is crucial in an ECL biosensor. In this study, a mixed-valence Eu-MOF was synthesized as the luminophore and AgCl RRNCs were used as the coreactant accelerator. The ECL biosensor showed high performance in detecting CYFRA 21-1 in clinical treatment.