Abstract: Using adenosine as model analyte, a novel homogeneous fluorescent method with high sensitivity and specificity was proposed. It involves two kinds of DNA probe conjugated nanoparticles-aptamer modified magnetic nanoparticles and capture DNA probe derivatized gold nanoparticles(GNPs), which were connected together via hybridization. The conformational transition of aptamer induced by adenosine-aptamer complex contributes to the displacement of probe conjugated GNP, which further catalyzes the reduction of Cu²⁺ by ascorbic acid, causing the deposition of Cu atom on the surface of GNP. The fluorescence quenching of calcein was restored as the consumption of Cu²⁺. The experimental results demonstrated that the dynamic range for adenosine detection was from 100 pmol/L to 10 nmol/L, with a detection limit of 80 pmol/L. The proposed method shows high selectivity for the specific recognition of adenosine by its aptamer.

Key words: Gold nanoparticles, Catalytic deposition, Magnetic nanoparticles, Aptamer, Inhibition of fluorescence quenching