Dual signal-amplification electrochemical detection of DNA sequence based on molybdenum selenide nanorod and hybridization chain reaction

A new electrochemical biosensor based on the hybridization chain reaction and layered molybdenum selenide (MoSe2) stacked nanorod for dual-signal amplification is developed for the highly sensitive detection of the DNA sequences of Human Immunodeficiency Virus type 1 (HIV-1). The MoSe2 nanorod was prepared using a facile hydrothermal method. The glassy carbon electrode was first modified with MoSe2 nanorods and then Au nanoparticles (AuNPs) were electrodeposited on the electrode. The DNA probe was then immobilized on the electrode by an Au–S bond. As the initiator strands, auxiliary DNA can propagate a chain reaction of hybridization events between the two hairpin probes (Aux 1, Aux 2), and long nicked DNA polymers can be formed on the modified electrode. The biotin-labeled dsDNA polymers can then introduce numerous avidin-labeled horseradish peroxidases on the electrode, resulting in a significantly amplified electrochemical signal through the electrocatalysis of horseradish peroxidase. The target DNA is detected on the basis of the enzymatic oxidization of Fe2+ by H2O2. The electrochemical signals have a good linear relationship with the logarithm of target DNA concentration in the range from 10 fM to 0.1 pM, reaching a detection limit of the target DNA as low as 4.0 fM. This method shows good specificity for target DNA detection with the capability to discriminate single-base-pair mismatched DNA mutations. Moreover, the developed strategy was applied successfully in a real sample, which demonstrated the potential applications in clinical diagnostics.