Dual-Hemin-Labelled Catalytic Molecular Beacon: A Monomer-Dimer Switching Probe for Sensitive Chemiluminescence Detection of Biomolecules

摘要

The stem-loop structure of molecular beacon (MB) makes it a powerful nucleic acid probe for homogenous and highly specific bioanalysis. Tradition MBs have an intrinsic limitation on sensitivity because one target molecule converts only one beacon molecule to its fluorescent conformation. Herein, taking full advantages of the self-dimerization behavior and catalytic characteristic of hemin, we engineered a new class of catalytic MB. Both ends of MB are labeled with hemin, and then targetinduced opening of stem-loop structure switches hemin dimer to monomer. Hemin dimer exhibits a low peroxidase activity, whereas hemin monomer with high catalytic activity can produce strong chemiluminescence (CL) emission in the presence of luminol and H2O2. Thus, this catalytic MB can highly specifically report target in homogeneous solution by hemindriven CL signal. One target can introduce two catalytic cycles, exhibiting a higher sensitivity than traditional MB. The formation of hemin dimer further strengthens the stability of stem-loop structure, which greatly reduces the background and improves the specificity. More importantly, the assay can also be adapted for colorimetric and fluorescent readout by changing the catalytic substrate. Therefore, this catalytic MB is a novel and promising probe for developing sensitive and diverse biosensing platform.