▎ 摘　　要

Herein, a dual-signal ratiometric fluorescence-based p53 gene sensing strategy was developed for the first time. Nitrogen doped graphene quantum dots (NGQDs) were firstly bound with a single-stranded DNA (P1 DNA), which contains berberine aptamer sequence and p53 gene complementary sequence (C-p53 DNA). With the addition of berberine, berberine will bind to berberine aptamer in P1 DNA, and a dual-signal ratiometric fluorescence probe NGQDs/P1 DNA/berberine was established, which displays two fluorescence peaks at 440 nm and 537 nm corresponding to NGQDs and berberine, respectively. P1 DNA can be hydrolyzed by Exonuclease I (Exo I) when target p53 gene was absent, resulting in the release of berberine and the decrease of fluorescence intensity at 537 nm. When target p53 gene was present, C-p53 DNA sequence in P1 DNA can specifically bind to p53 gene and form double-stranded DNA, so the hydrolysis of P1 DNA by Exo I was blocked, and the fluorescence intensity at 537 nm was recovered. The fluorescence of NGQDs at 440 nm does not affected from Exo I and target p53 gene, and was employed as reference. The sensing strategy showed a good linear response to p53 gene in the range of 0.2-30.0 nM with a detection limit (LOD) of 0.06 nM, and it performed well in human serum samples. (C) 2019 Published by Elsevier B.V.