Electrochemical biosensor for p53 gene based on HRP-mimicking DNAzyme-catalyzed deposition of polyaniline coupled with hybridization chain reaction

In this work, an electrochemical biosensor for p53 gene detection was proposed based on the in situ deposition of polyaniline (PANI) catalyzed by G-quadruplex/hemin horseradish peroxidase- (HRP-) mimicking DNAzyme. G-quadruplex structure was formed through hybridization chain reaction (HCR) amplification strategy. First of all, the target p53 DNA hybridizes with the capture DNA assembled on gold (Au) electrode. Then, the released sequences in capture DNA trigger the HCR between two hairpin DNA probes including one-fourth and three-fourth split- G-quadruplex sequences, resulting in the formation of G-quadruplex in the presence of K+. After interacting with hemin, HRP-mimicking DNAzyme forms, which catalyzes the oxidation of aniline to PANI with H2O2 and leads to a measurable “turn-on” electrochemical signal. The electrochemical response of PANI is dependent on the concentration of target DNA. The constructed analysis platform exhibits a good linear response toward p53 DNA sequence in a wide range of concentration from 1.0 fM to 100 pM with the detection limit of 0.5 fM. In addition, this amplified electrochemical biosensor demonstrates specific recognition capacity to discriminate base-mismatched sequences. Furthermore, it has an excellent performance for target DNA detection in real sample and has a great potential for application in bioanalysis and clinical early diagnosis.