Amplified Chemiluminescence Detection of DNA by Strand-Displacement Polymerization Target Recycling and G-quadruplexes/Hemin DNAzyme Catalysis

Abstract

A new strategy based on strand-displacement polymerization target recycling and G-quadruplex DNAzyme catalysis was developed for amplified chemiluminescence detection of DNA. The amplified detection was achieved by using the system consisted of hairpin DNA probe, G-rich DNA, primer, and polymerase Klenow fragment exo−. When the target DNA was introduced the system, the hairpin structure of DNA probe was opened by the hybridizing of target DNA with its complementary sequence, the primer hybridized then with DNA probe and initiated polymerase-aided strand-displacement polymerization reaction, resulting in the release of target DNA and G-rich DNA. The released target DNA again hybridizes with another DNA probe to trigger the next polymerase-aided strand-displacement polymerization, generating large numbers of G-rich DNA. The G-rich DNA assembles with hemin to form the G-quadruplexes/hemin DNAzyme, which can catalyze oxidation of luminol by H2O2, generating chemiluminescence. This unique amplifying strategy gives a detection limit down to 2.5 pM, which is at least two to three orders of magnitude lower than that of unamplified DNA detection methods.