▎ 摘　　要

We report an amplified chemiluminescence (CL) biosensing platform for ultrasensitive DNA detection. It is based on exonuclease III-assisted target recycling amplification and the super quenching efficiency of graphene oxide (GO). In the presence of target DNA, the target-probe hybrid forms a double-stranded structure, and exonuclease III catalyzes the stepwise removal of mononucleotides from the fluorescein-labeled probe DNA, resulting in the recycling of the target DNA and CL signal amplification of the luminol-H2O2-HRP-fluorescein chemiluminescence resonance energy transfer (CRET) system. The detection limit of target DNA was estimated to be as low as 9 fM, and the sensitivity was about 3 orders of magnitude better than that of GO-based fluorescence resonance energy transfer (FRET) sensors for DNA with exonuclease III-assisted amplification. This CL biosensor offers the advantages of being facile, sensitive, rapid and cost-effective.