▎ 摘　　要

Anovel luminescence `Turn-On' nanoplatform for the sensitive sensing of Ag+ was fabricated based on luminescence resonance energy transfer technique between sodium citrate functionalized upconversion nanoparticles (Cit-UCNPs, energy donor) and graphene quantum dots (GQDs, energy acceptor). Amino-labeled single-strandedDNA(NH2-ssDNA) containing a number of cytosine (C) was conjugated on the surface of the Cit-UCNPs to capture Ag+ ions. Due to the p-p stacking interaction betweenNH(2)-ssDNA and GQDs, the upconversion luminescence can be quenched. However, upon the addition of Ag+, the p-p stacking interaction weakens due to the formation of the hairpin structure of C-Ag+-Con the UCNPs. As a result, GQDs will leave the surface of the UCNPs and the upconversion luminescence can be enhanced (Turn-On). Based on this fact, the sensor was developed for the detection of Ag+ with a linear concentration range from 2 x 10(-4) to 1 mu Mand a detection limit as low as 60 pM. The assay method is fairly simple with high selectivity and sensitivity, which can be used for the determination of Ag+ in environmental water samples.