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

Abstract

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•−. 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 ∼ 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.