Imaging mRNA in vitro and in vivo with nanofirecracker probes via intramolecular hybridization chain reaction

Ultrasensitive Electrochemiluminescence Biosensor Based on DNA-Bio-Bar-Code and Hybridization Chain Reaction Dual Signal Amplification for Exosomes Detection

“…The ingenious and rational integration of signal amplification strategies in detection systems can significantly improve the sensitivity, which has received considerable attention in constructing various biosensors for analyzing cancer-related biomarkers. , The distinct programmability and remarkable predictability of the canonical Watson–Crick nuclide acid endow DNA the capacity to fabricate versatile DNA-based systems with precise nanostructures for signal amplification in bioanalysis. − Especially, various enzyme-free isothermal amplification strategies have been regarded as powerful tools for the improvement of sensitivity in the identification and quantification of biological molecules, including entropy-driven catalytic reaction, hybridization chain reaction (HCR), and catalytic hairpin assembly (CHA). − Among them, HCR involves an initiator to trigger the repeated hybridization of two hairpin DNA strands, leading to the “polymerization” into a nicked double helix for the signal amplification. − Taking advantage of the long double-stranded DNA produced by HCR, which provides abundant insertion sites for hemin, we propose a dual signal amplification system combining bio-bar-code amplification (BCA) assay and bio-bar-code DNA initiated HCR for the ultrasensitive electrochemiluminescent detection of breast cancer cell (MCF-7)-derived exosomes.…”

Toehold Strand Displacement-Mediated Exponential HCR for Highly Sensitive and Specific Analysis of miRNA in Living Cells

“…Recently, isothermal nucleic acid amplification technology has attracted widespread attention and has been widely used in miRNA analysis due to its sensitivity, speed, and accuracy. , Isothermal nucleic acid amplification can be divided into enzyme-based and enzyme-free amplification. , Enzyme-based isothermal amplification methods, such as rolling circle amplification (RCA), loop-mediated isothermal amplification (LAMP), and isothermal exponential amplification reaction (EXPAR), are sensitive and efficient, but biological enzymes are difficult to transfect into cells and their activity is easily affected by the complex intracellular environment, which makes these methods inconvenient for intracellular miRNA imaging. , Enzyme-free amplification strategies, such as catalytic hairpin assembly (CHA), hybridization chain reaction (HCR), entropy-driven DNA reaction, and DNAzyme-based sensing, do not involve biological enzymes and allow for the transfection of nucleic acid probes into cells, which have been widely used for miRNA imaging in living cells. − Among them, HCR based on toehold strand displacement technology has attracted much attention due to its simple design and high specificity and has been applied to the analysis of various disease biomarkers in living cells. − However, traditional HCR is a linear amplification model with limited amplification efficiency, which hinders its use for rapid and highly sensitive analysis of trace amounts of miRNAs in living cells. , To solve this problem, we and other groups have integrated HCR with other enzyme-free amplification techniques to achieve theoretically exponential amplification efficiency. − Although these methods have shown improved sensitivity compared to traditional HCR technology to some extent, they require more probe numbers and involve complex probe design, leading to serious background and false positives. Besides, due to the different reaction kinetics of various enzyme-free amplification techniques, strategies for integrating HCR with other enzyme-free amplification techniques also exhibit restricted reaction kinetics and low flexibility.…”