文摘
The hybridization chain reaction (HCR) is implemented for the development of amplified electrochemical DNA sensing platforms. The target analyte hybridizes with a probe oligonucleotide-functionalized electrode and triggers on the HCR process in the presence of the hairpins HA and HB. The formation of the analyte-triggered HCR chains is followed by Faradaic impedance spectroscopy or chronocoulometry using Fe(CN)63–/4– or Ru(NH3)63+ as redox labels, respectively. By using two different probe-functionalized electrodes and a mixture of four hairpins, HA:HB and HC:HD, the parallel analysis of two analytes is demonstrated. Through the structural design of the hairpin structures to include caged G-quadruplex subunits, the analyte/probe hybrid associated with the electrode triggers on the HCR process, leading to G-quadruplex-functionalized HCR chains. The association of hemin to the matrix yields electrocatalytic hemin/G-quadruplex units that provide a secondary amplification path for the detection of DNA through an electrocatalyzed reduction of H2O2. The system allows the detection of the analyte DNA with a detection limit corresponding to 0.2 nM.