Highly Efficient Electrochemiluminescence of MnS:CdS@ZnS Core-Shell Quantum Dots for Ultrasensitive Detection of MicroRNA.

In this work, a novel electrochemiluminescence (ECL) biosensor was developed for ultrasensitive detection of microRNA let-7a (miRNA let-7a) based on MnS:CdS@ZnS core-shell quantum dots (QDs) as ECL luminophores with high ECL efficiency. Impressively, compared to the CdS:Mn@ZnS QDs prepared by ionic doping with ECL efficiency of 0.87%, MnS:CdS@ZnS QDs synthesized by bimetallic clusters (Cd2Mn2O4) doping exhibited high ECL efficiency of up to 15.84% with S2O82- as cathodic coreactant due to the elimination of the dopants size mismatch and "self-purification" effect, which could achieve the surface defect passivation of MnS:CdS@ZnS QDs for effectively improving the ECL emission. Furthermore, with the help of strand displacement amplification (SDA), the trace target miRNA let-7a was able to be converted to a number of output DNA labeled with ferrocene (Fc) to construct an ultrasensitive ECL biosensor. The well-designed ECL biosensor for miRNA let-7a exhibited high stability and excellent sensitivity of a concentration variation from 10 aM to 1 nM and a low detection limit of 4.1 aM, which was further applied to the analysis of miRNA let-7a from cancer cell (MCF-7) lysate. Thus, this strategy provides a novel method to prepare high-efficient ECL emitters for the construction of ECL biosensing platforms in biological fields and clinical diagnosis.

High-Efficient Electrochemiluminescence of BCNO Quantum Dot-Equipped Boron Active Sites with Unexpected Catalysis for Ultrasensitive Detection of MicroRNA.

Herein, the boron radical active sites of boron carbon oxynitride quantum dots (BCNO QDs) are electrically excited to produce boron radicals (B•) for catalyzing peroxydisulfate (S2O82-) as a coreactant to accelerate the generation of abundant sulfate radicals (SO4•-) for significant enhancement in the electrochemiluminescence (ECL) efficiency of BCNO QDs, which overcome the defect of traditional carbon-based QDs with low ECL efficiency. Impressively, under extremely low concentration of S2O82- solution, the BCNO QDs/S2O82- system could exhibit high ECL emission, realizing environmental friendliness and excellent biocompatibility for sensitive bioanalysis. As a proof-of-concept, BCNO QDs, a new generation of ECL emitters with high ECL efficiency, were successfully used in the ultrasensitive determination of microRNA-21, which pushes the exploration of new ECL emitters and broadens the application in the field of clinical diagnosis, ECL imaging, and molecular devices.

Three-Dimensional Cadmium Telluride Quantum Dots-DNA Nanoreticulation as a Highly Efficient Electrochemiluminescent Emitter for Ultrasensitive Detection of MicroRNA from Cancer Cells.

In this work, a novel three-dimensional cadmium telluride quantum dots-DNA nanoreticulation (3D CdTe QDs-DNA-NR) was used as a signal probe with the dual-legged DNA walker circular amplification as target conversion strategy to establish a pioneering electrochemiluminescence (ECL) biosensing strategy for ultrasensitive detection of microRNA-21 form cancer cells. Herein, such a 3D luminous nanomaterial with reticular structure not only supported abundant CdTe QDs to avoid the inner filter effect for obtaining a high ECL efficiency but also contained the hemin/G-quadruplex as coreaction accelerator in the 3D CdTe QDs-DNA-NR/S2O82- system for the enhancement of ECL intensity. Furthermore, with the target-induced dual-legged DNA walker circular amplification strategy, a mass of output DNA was produced to connect with the 3D CdTe QDs-DNA-NR for the construction of the ECL biosensor, which realized the ultrasensitive detection of microRNA-21 from 100 aM to 100 pM and the detection limit down to 34 aM. Significantly, this work could be readily extended for the detection of other biomolecules to provide a neoteric channel for disease diagnosis.