Highly sensitive electrochemical biosensor based on nonlinear hybridization chain reaction for DNA detection

In the present work we demonstrated an ultrasensitive detection platform for specific DNA based on nonlinear hybridization chain reaction (HCR) by triggering chain-branching growth of DNA dendrimers. HCR was initiated by target DNA (tDNA) and finally formed dendritic structure by self-assembly. The electrochemical signal was drastically enhanced by capturing multiple catalytic peroxidase with high-ordered growth. Electrochemical signals were obtained by measuring the reduction current of oxidized 3, 3′, 5, 5′-tetramethylbenzidine sulfate (TMB), which was generated by HRP in the presence of H2O2. This method exhibited ultrahigh sensitivity to tDNA with detection limit of 0.4 fM. Furthermore, the biosensor was also capable of discriminating single-nucleotide difference among concomitant DNA sequences.