Demonstration of G-quadruplex-assisted hybridization chain reaction for nucleic acid detection

In recent years, the hybridization chain reaction (HCR) has been proposed as an alternative to polymerase chain reaction (PCR) for diagnosis. Unfortunately, the sensitivity of the HCR methods are still far below PCR and researchers focus on ways to improve it by investigating different HCR designs. While earlier designs exploit fluorescently labelled probes for detection, here we propose an HCR system that combines G-quadruplex formation and fluorescence for detection of single stranded DNA sequences with concentrations as low as 20 pM. We show that Cquadruplex-mediated oxidation of Amplex Red results in fluorescence increase and lowers the detection limit by about 10-fold, in comparison to HCR using only fluorescently labelled HCR probes.