Signal amplification based on DNA hybridization-dehybridization reaction on the surface of magnet submicrobeads for...

A new signal amplification strategy based on DNA hybridization-dehybridization reaction on the surface of magnetic submicrobeads (MSBs) for fluorescence detection of ultrasensitive DNA was developed. In this strategy, MSBs modified with probe DNA (DNAp-MSBs) were bound to target DNA (t-DNA) (with a ratio of 1 : 1) captured to a substrate. The DNAp-MSBs were released from the substrate via DNA dehybridization and then hybridized with Cy5-labeled detection DNA (Cy5-DNAd). After the Cy5-DNAd and DNAp-MSBs were separated by dehybridization, the Cy5-DNAd was collected. The DNAp-MSBs were then hybridized with other Cy5-DNAd to initiate the next hybridization-dehybridization round. This recycling of the hybridization-dehybridization process on the surface of the DNAp-MSBs was repeated multiple times to accumulate Cy5-DNAd. Finally, fluorescence intensity of the collected Cy5-DNAd was measured. Using this strategy, the limit of detection for determination of t-DNA was 8.5 × 10(-15) mol L(-1) for 11 cycles. The ultrasensitive assay was used to quantify ribosomal protein, large, P2 (RPLP2) mRNA in human breast cancer cells.