Dual-wavelength electrochemiluminescence biosensor based on a multifunctional Zr MOFs@PEI@AuAg nanocomposite with intramolecular self-enhancing effect for simultaneous detection of dual microRNAs

Rapid parallel detection of multi-targets has always been an exploration aim in electrochemiluminescence (ECL) assays. Herein, a multifunctional nanocomposite of Zr metal-organic frameworks (MOFs) @PEI@AuAg nanoclusters (NCs) with intense and stable dual-wavelength ECL was synthesized for the first time, and used to construct a new ECL biosensor for rapid simultaneous detection of dual targets. Notably, the novel ECL emitter Zr MOFs with high-performance was not only integrated with a co-reactant polyethyleneimine (PEI) to form a unique intramolecular self-enhancing structure, but also loaded a large number of another ECL emitter AuAg NCs, furthermore, AuAg NCs with superior electron transfer property can much enhance the electrical conductivity of the composites, thus achieving the goal of "killing three birds with one stone". Moreover, a unique stable and rigid three-dimensional DNA tetrahedron (TDN) structure was connected with two quenching probes BHQ1 and BHQ3 and immobilized on the composites-modified electrode, so ECL emission of the nanocomposites at two wavelengths of 535 nm and 644 nm were both quenched by resonance energy transfer (RET). In the presence of target miRNAs, the efficient DNA cycling double-amplification processes were performed by using exonuclease (T7 Exo) combined with DNA Walker, thus both quenching groups were separated to restore the ECL at two wavelengths, achieving simultaneous and rapid ECL detection of two miRNAs. Therefore, this present work not only opens a unique nanocomplex with dual wavelength ECL and self-enhancing performance, but also develops a highly sensitive ECL biosensor with promising value for rapid multi-target analysis in clinical fields.