Graphene oxide-based fluorescent “turn-on” strategy for Hg2+ detection by using catalytic hairpin assembly for amplification

We have reported an enzyme-free amplification fluorescent strategy for ultra-sensitive detection of Hg2+ based on graphene oxide (GO) and catalytic hairpins self-assembly. Three fluorophore labled metastable hairpin DNA probes can be closely adsorbed onto GO surface via π−π stacking to quench the fluorescent signal. T-Hg2+-T interaction was utilized to induce the catalytic self-assembly of hairpins with the aid of helper DNA. The formed rigid DNA triangles containing double strand DNA (dsDNA) was stiffer, and released from the surface of GO to cause a “turn-on” fluorescent signal. The limit of detection was 25 pM, which was comparable with those reported amplification strategies. This strategy showed good selectivity for Hg2+, and promising application for real samples.