Enzyme-free dual amplification strategy for protein assay by coupling toehold-mediated DNA strand displacement reaction with hybridization chain reaction

DNA Microsystems for Biodiagnosis

“…The following examples demonstrate the use of DNA nanostructures as an active component for proof-of-concept diagnosis. For instance, a recent enzyme-free electrochemical biosensor (Figure 6a) combined two DNA nanotechnology's techniques i.e., DNA strand displacement and hybridization chain reaction (HCR), together with a conventional electrochemical amplification method to detect targeted thrombin, an important molecule in thrombosis and hemostasis [151]. In particular, the first amplification occurs when the target sequence (i.e., TBA) attaches to the protein and releases recognizable outputs (i.e., CP DNA and N3-DNA), which eventually releases the protein for a new reaction cycle.…”

“…Thus, this assay allows highly sensitive detection of biomarkers with a limit of detection (LOD) of 30 fM. In addition, the assay offers high selectivity toward the target protein due to the specificity of the DNA aptamer and, without using active enzymes in the detection, the assay development's cost is reduced [151]. By simply utilizing the DNA strand displacement technique, another proof-of-concept biosensor was capable of organizing proteins with highly diverse and complex logic processes for constructing synthetic protein switches.…”

Ultrasensitive visual detection of DNA with tunable dynamic range by using unmodified gold nanoparticles and target catalyzed hairpin assembly amplification

“…Recently, target catalyzed hairpin assembly was developed for DNA nanostructure organization and also as a promising enzyme-free signal amplification strategy for DNA detection on account of its significant advantages such as simple, costeffective, isothermal and high sensitive (Yin et al, 2008). These two kinds of enzyme-free strategies were both been successfully used to achieve signal amplification for analysis of metal ions, nucleic acids, protein, and small molecules (Huang et al, 2012Liao et al, 2014Qian et al, 2015;Liu et al, 2013;Li et al, 2014;Yang et al, 2015). However, the amplification of HCR was only 2-5 fold/hour much lower than 20-50 fold/hour of catalyzed hairpin assembly (CHA) (Jung and Ellington, 2014).…”

Target-triggered triple isothermal cascade amplification strategy for ultrasensitive microRNA-21 detection at sub-attomole level

“…Among these methods, electrochemical biosensor has been attracted increasing attention owing to simplicity, low cost, high sensitivity, and easy of miniaturization Tran et al, 2014;Hu et al, 2016). To further upgrade the sensitivity of electrochemical detection, a variety of isothermal exponential amplification reaction (EXPAR) based strategies have been developed, such as strand displacement amplification (SDA) (Yang et al, 2015), rolling circle amplification (RCA) (Cheng et al, 2014) and loop-mediated amplification (LAMP) (Zhang et al, 2014b). Among these techniques, SDA has attracted particular attention since it is fast, efficient and requiring no special equipment Ren et al, 2010).…”