Enzyme- and label-free amplified fluorescence DNA detection using hairpin probes and SYBR Green I

We report an enzyme- and label-free scheme for amplified fluorescence DNA detection by using two complementary hairpin probes (HPs, HP1 and HP2). SYBR Green I, which fluoresces when binding with double stranded DNA, was used for signal generation. In this scheme, the target DNA is repeatedly used to trigger continuous HP1–HP2 hybridizations, leading to amplified fluorescence after SYBR Green I reacts with the HP1–HP2 duplexes. The detection limit of this approach was experimentally obtained as 80 pM, which is comparable to other methods employing expensive enzymes or requiring complex labeling procedures. The current method also showed excellent selectivity, making it a promising platform for DNA-related molecular diagnosis.