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.%在一定条件下,磁性纳米颗粒上修饰的腺苷核酸适体与纳米金标记的核酸探针杂交；再加入目标物腺苷诱导适体构象变换,并置换出金标探针；经磁场分离后,游离的金标探针进一步用于催化抗坏血酸还原铜离子,使铜离子对钙黄绿素的荧光猝灭得到抑制,由于极少量的纳米金能够催化大量铜离子还原并沉积在其表面,铜离子浓度急剧降低,从而改变钙黄绿素的荧光信号.实验结果表明,腺苷的动力学响应浓度范围为100 pmol/L ～10 nmol/L,检出限低至80 pmol/L.核酸适体的高度特异识别性能保证了该方法具有良好的选择性.
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