Electrochemical detection of DNA hybridization based on signal DNA probe modified with Au and apoferritin nanoparticles

A novel and ultrasensitive electrochemical approach for sequence-specific DNA detection based on signal dual-amplification with Au NPs and marker-loaded apoferritin NPs was reported. Target DNA was sandwiched between capture DNA coupled to magnetic beads and signal DNA self-assembled on Au NPs which were incorporated with marker-loaded apoferritin NPs. Subsequent electrochemical stripping analysis of the electroactive markers released from apoferritin NPs in acidic buffers provided a means to quantify the concentration of target DNA. In this means, one target signal could be transformed into multiple redox signals of the markers since a single Au NP could be loaded with dozens of apoferritin NPs, and an apoferritin NP could be loaded with thousands of markers. Under the optimum conditions, the linear range was from 2.0 x 10(-16) to 1.0 x 10(-14) M and the detection limit was 5.1 x 10(-17) M by using the cadmium as a model marker. The proposed DNA biosensor not only exhibited excellent sensitivity but also had good reproducibility and selectivity against two-base mismatched DNA. (C) 2010 Elsevier B.V. All rights reserved.