Facile synthesis of 2D Europium-metal organic frameworks nanosheets for highly efficient electrochemiluminescence in DNA detection

Lanthanide metal organic frameworks (Ln-MOFs) with self-luminous behavior are considered promising emitters of electrochemiluminescence (ECL) due to their unique antenna effects. In this study, the novel 2D Europium-metal organic frameworks (Eu-MOFs) nanosheets were synthesized by simply blending 1, 10-phenanthroline-2, 9-dicarboxylic acid (PDA) and Eu salts at room temperature. When N, N-diethylethylenediamine (DEAEA) was used as the efficient co-reactant, the 2D Eu-MOFs exhibited stronger and steadier ECL performance compared with 2D Europium-metal organic gels (Eu-MOGs) synthesized using similar steps, due to their rigid skeletons and higher crystalline degree, which facilitated electron transfer. In addition, we designed a switching mode ECL biosensor, which was combined with an exonuclease-assisted DNA walker cycling signal amplification strategy, enabled the ultra-sensitive detection of the I27L gene, which was significantly associated with an increased risk of maturity-onset diabetes of the young (MODY). When the target DNA was present, DNA walker recycle amplification occurred driven by exonuclease III (Exo III). Subsequently, the ECL intensity of the system was reduced by introducing the ferrocene-labeled probe (H2-Fc) as a signal quencher. Under the optimal experimental conditions, a wide detection linear range of the target DNA was observed from 1 fM to 10 nM with a low detection limit of 447 aM. This research provided new possibilities for a gentle and simple method to obtain 2D MOFs with stable ECL signals for the sensitive detection of specific DNA sequences.