Sequence-specific amperometric detection based on a double-probe mode and enzyme-mediated multiple signal electrocatalysis for the double-stranded DNA of PML/RARα-related fusion gene

A new electrochemical DNA biosensor based on double-probe mode and enzyme-mediated multiple signal electrocatalysis is constructed for the highly sensitive determination of double-stranded (ds-) PML/RARα fusion gene. Through the ingenious design of two groups of detection probes, including two thiolated capture probes anchored on dual standalone detection units integrated into one customized gold electrode and four biotinylated reporter probes, hybridizing with different segments of the same target single-stranded DNA (ssDNA) simultaneously, the hybridization efficiency between the probes and target is improved by preventing the reannealing of the two separate target ssDNA. Compared with a single reporter probe, this method can dramatically increase the amount of biotin and introduce numerous streptavidin-labelled horseradish peroxidase (HRP), thereby significantly amplifying electrochemical signals with low background signals. The combination of the dual-probe mode, multiple signal amplification strategy, and the inherent electrocatalytic activity of the HRP results in the prominent electrochemical sensing performance in detecting large-fragment target dsDNA with a detection limit as low as 71 fM. Furthermore, taking advantage of the new detection strategy, polymerase chain reaction (PCR) products and enzyme-digested PCR products from NB4 cells can be effectively analysed, showing great promise for the development of a new class of point-of-care platforms for disease-/drug-related genes.