Sensitive and Programmable “Signal-Off” Electrochemiluminescence Sensing Platform Based on Cascade Amplification and Multiple Quenching Mechanisms

Abstract

A versatile and sensitive quantum dot (QD)-based "signal-off" electrochemiluminescence (ECL) sensing system was constructed using target-initiated dual Mg 2+ -dependent DNAzyme (MNAzyme) recycling and catalytic hairpin assembly (CHA) amplification strategies. After the cascade amplification, numerous ferrocene-labeled Y-shaped DNA complexes generated on the QDmodified electrode surface. In the presence of hemin, moreover, the terminal sequence of the formed complex could assemble into hemin/G-quadruplex. Therefore, the highly efficient ECL quenching was achieved due to the multiple quenching mechanisms, including electron/energy transfer between ferrocene and QDs, the steric hindrance effects, and the horseradish peroxidasemimicking activity of hemin/G-quadruplex. Furthermore, owing to the flexibility in regulating the recognition sequences of MNAzyme, the assaying targets can be programmed. Based on the cascade amplification and multiple ECL quenching mechanisms, the developed programmable "signal-off" ECL sensing platform demonstrates excellent sensitivity and the detection limits of 35.00 aM, 3.71 fM, and 0.28 pM (S/N = 3) for target DNA, aptamer substrate (ATP as a model), and ion (Ag + as a model), respectively.

Cooperative Amplification of Au@FeCo as Mimetic Catalytic Nanozymes and Bicycled Hairpin Assembly for Ultrasensitive Electrochemical Biosensing

“…Owing to simplified design, easy operation, and nonsusceptibility of environmental conditions, enzyme-free isothermal amplifications are extremely attractive, such as the hybridization chain reaction, 19−21 strand displacement, 22,23 and catalytic hairpin assembly (CHA). 24,25 Among them, CHA is basically operated by a specific DNA or miRNA trigger to initiate the selfassembly of two metastable hairpins, in which the trigger is repeatedly recycled for the amplified output of dsDNA duplexes. The inherent programming flexibility and diversity of CHA have aroused it to keep searching for wider applications for specific recognition, input transduction, and signaling readout via diverse methodologies.…”

“…The introduction of amplification techniques in sensor designs is crucial to improve the detection sensitivity of disease-related biomarkers at low abundance. Owing to simplified design, easy operation, and nonsusceptibility of environmental conditions, enzyme-free isothermal amplifications are extremely attractive, such as the hybridization chain reaction, − strand displacement, , and catalytic hairpin assembly (CHA). , Among them, CHA is basically operated by a specific DNA or miRNA trigger to initiate the self-assembly of two metastable hairpins, in which the trigger is repeatedly recycled for the amplified output of dsDNA duplexes. The inherent programming flexibility and diversity of CHA have aroused it to keep searching for wider applications for specific recognition, input transduction, and signaling readout via diverse methodologies. − However, traditional CHA involving two hairpins inevitably shared the shortcomings of slow reaction kinetics, low conversion, and nonspecific background leakage. , So, some fascinating strategies have been explored via a two-layer cascade amplification mode, where the upstream CHA routes were activated by an input to induce a second layer of hybridization reactions, distinctly increasing the input–output reaction rate and conversion efficiency.…”

Matching Capacitors to Self-Powered Biosensors for Signal Amplification: Toward Ultrasensitive Electrochemical Detection for MicroRNA-21-Triggered Catalytic Hairpin Assembly

“…Furthermore, for further improving the sensitivity of the sensor system, biomagnification techniques, such as catalytic hairpin assembly (CHA), have been usually applied in the fabrication of biosensors. CHA characterized by enzyme-free and isothermal reactions is an attractive amplification strategy. , In CHA, DNA hairpins open when the target RNA or DNA is added, leading to the production of abundant double-strand DNA, which offers 100-fold signal amplification …”

“…CHA characterized by enzyme-free and isothermal reactions is an attractive amplification strategy. 25,26 In CHA, DNA hairpins open when the target RNA or DNA is added, leading to the production of abundant double-strand DNA, which offers 100-fold signal amplification. 27 Using smart materials to effectively enrich the loading of oligonucleotide strands is another effective way to improve the sensitivity of EBFCs.…”

Electrochemical α-fetoprotein immunosensor based on Fe3O4NPs@covalent organic framework decorated gold nanoparticles and magnetic nanoparticles including SiO2@TiO2

“…Metal nanoparticles as a significant catalyst in biosensor applications have been frequently used owing to a simple synthesis process with minimal waste, efficient surface modification, and high stability [24,25]. They have been usually incorporated into two-(2D) or three-dimensional (3D) nanomaterials via chemical reduction reaction since they can prevent aggregation, thanks to their high surface energies [26,27].…”