Renewable Electrochemiluminescence Biosensor Based on Eu-MOGs as a Highly Efficient Emitter and a DNAzyme-Mediated Dual-drive DNA Walker as a Signal Amplifier for Ultrasensitive Detection of miRNA-222

Abstract

Herein, novel europium metal−organic gels (Eu-MOGs) with excellent cathode electrochemiluminescence (ECL) emission are first used to construct biosensors for the ultrasensitive detection of miRNA-222. Impressively, N and O elements of organic ligand 2,2′:6,2″-terpyridine 4,4′,4″-tricarboxylic acid (H3-tctpy) can perfectly coordinate with Eu 3+ to form Eu-MOGs, which not only reduce nonradiative transition caused by the intramolecular free rotation of phenyl rings in other MOGs to enhance the ECL signal with extraordinary ECL efficiency as high as 37.2% (vs the [Ru(bpy) 3 ] 2+ /S 2 O 8 2− ECL system) but also reinforce ligand-to-metal charge transfer (LMCT) by the strong affinity between Eu 3+ and N and O elements to greatly improve the stability of ECL signals. Besides, an improved nucleic acid cascade amplification reaction is developed to greatly raise the conversion efficiency from target miRNA-222 to a DNAzyme-mediated dual-drive DNA walker as output DNA, which can simultaneously shear the specific recognition sites from two directions. In that way, the proposed biosensor can further enhance the detection sensitivity of miRNA-222 with a linear range of 10 aM−1 nM and a detection limit (LOD) of 8.5 aM, which can also achieve an accurate response in cancer cell lysates of MHCC-97L and HeLa. Additionally, the biosensor can be self-regenerated by the folding/unfolding of related triplets with pH changes to simplify experimental operations and reduce the cost. Hence, this work proposed novel MOGs with stable and intense ECL signals for the construction of a renewable ECL biosensor, supplying a reliable detection method in biomarker analysis and disease diagnosis.

Cu Single-Atom Nanozyme-Mediated Electrochemiluminescence Biosensor for Highly Sensitive Detection of MicroRNA-622

“…In an attempt to optimize the reliability, reproducibility, and sensitivity of its detection, we aimed to construct a new type of electrochemiluminescence (ECL) biosensor. − ECL is a redox-triggered light emission process . The specific luminescent mechanism and electrochemical reaction process have led to the rapid development of ECL detection technology with the remarkable advantages of outstanding sensitivity and near-zero background. − Additionally, the excellent luminescence quantum yield and stability of luminol have made it a crucial luminophore in the development of ECL systems for biosensing and bioimaging. , In the conventional luminol ECL system, the introduction of hydrogen peroxide (H 2 O 2 ) as the coreactant facilitates the generation of reactive oxygen species (ROSs), such as the hydroxyl radical (OH • ), superoxide radical (O 2 •– ), and singlet oxygen ( 1 O 2 ), which accelerate the oxidation of luminol and amplify the ECL singal. , For this reason, there is a pressing demand for the introduction of efficient catalysts to facilitate the generation of interfacial ROS and construct high-performance ECL biosensors.…”