An intra-stimuli resonance energy transfer-based electrochemiluminescence biosensor for DNA methylation detection

Aberrant DNA methylation, as one of the promising biomarkers, is intimately connected to a variety of genetic and tumor diseases. Herein, we constructed an innovative intra-stimuli electrochemiluminescence resonance energy transfer (ECL-RET) biosensor for methylated DNA detection with high sensitivity and accuracy. Glucose oxidase (GOD) was modified at the terminal of assist DNA as functional conjugation (assist DNA-GOD), which then hybridized with methylated target DNA and hairpin DNA to form Y-shaped DNA ternary conjugate. Ru (bpy)32+ 3 2 + encapsulated silica nanospheres (RuSiO2 2 NPs) were uniformly coated with silver nanoparticles (Ag NPs) and the formed RuSiO2@Ag 2 @Ag nanocomposites were introduced to the terminal of hairpin DNA via amide bond. The combination of the ECL donor (RuSiO2 2 NPs) and acceptor (Ag NPs) on one nanostructure yielded an intramolecular ECL-RET. Afterward, the presence of H2O2 2 O 2 as the product of GOD catalyzing glucose induced the etching of Ag NPs and subsequent recovery of ECL signal from RuSiO2 2 NPs. Thus, due to the dependence of the ECL enhancement on the target concentration, this method achieved the quantitative analysis of methylated target DNA with good selectivity, repeatability, and practical utility.