Colorimetric Detection of Class A Soybean Saponins by G-Quadruplex-Based Hybridization Chain Reaction

Scheme 1

Schematic diagram of hybridization chain reaction. (a)Target fragment and structure of hairpin probes. The target should be single-stranded DNA. Sequences marked with the same number with or without a single quote (’) are complementary to each other, and the punctuation (^) indicates that there is only one base difference between them.(b) The process of detecting GmSg-1 by HCR reaction. In the absence of target, the structures of hairpin probes GA1 and GA2 are metastable and G-quadruplex is enclosed in the loop. Once the target is present, probes GA1 and GA2 are opened successively and hybridization chain reaction was generated, lots of G-quadruplex are released and combined with hemin to catalyze the oxidation of ABTS by H₂O₂ to green ABTS⁺.

(a)

(b)