Coupling WO3−x dots-encapsulated metal-organic frameworks and template-free branched polymerization for dual signal-amplified electrochemiluminescence biosensing

Developing accurate and sensitive DNA methyltransferase (MTase) analysis methods is essential for early clinical diagnosis and development of antimicrobial drug targets. In this work, by coupling WO3−x dots-encapsulated metal-organic frameworks (MOFs) as co-reactants and terminal deoxynucleotidyl transferase (TdT)-mediated template-free branched polymerization, a dual signal-amplified electrochemiluminescent (ECL) biosensor was constructed to detect DNA adenine methylation (Dam) MTase. The employment of WO3−x dots-encapsulated MOFs (i.e., NH2-UIO66@WO3−x) was not only beneficial for biomolecule conjugation because of the abundant amino groups but also led to a 7-fold enhanced ECL response due to the increased loading of WO3−x. Moreover, TdT-mediated template-free branched polymerization promoted the capture of ECL emitters on the electrode surface, achieving 20-fold enhanced signal amplification. The presented ECL biosensor demonstrated a low detection limit of 2.4 × 10−4 U/mL, and displayed high reliability for the detection of Dam MTase in both spiked human serum and E. coli cell samples, and for the screening of potential inhibitors. This study opens a new avenue for designing a dual signal amplification-based ECL bioassay for Dam MTase and screening inhibitors in the fields of clinical diagnosis and drug development.2.4 × 10−4.