AbstractAn aptamer based assay is described for the colorimetric detection of adenosine. The presence of adenosine triggers the deformation of hairpin DNA oligonucleotide (HP1) containing adenosine aptamer and then hybridizes another unlabeled hairpin DNA oligonucleotide (HP2). This leads to the formation of a double strand with a blunt 3′ terminal. After exonuclease III (Exo III)-assisted degradation, the guanine-rich strand (GRS) is released from HP2. Hence, the adenosine-HP1 complex is released to the solution where it can hybridize another HP2 and initiate many cycles of the digestion reaction with the assistance of Exo III. This leads to the generation of a large number of GRS strands after multiple cycles. The GRS stabilize the red AuNPs against aggregation in the presence of potassium ions. If, however, GRS forms a G-quadruplex, it loses its ability to protect gold nanoparticles (AuNPs) from salt-induced AuNP aggregation. Therefore, the color of the solution changes from red to blue which can be visually observed. This colorimetric assay has a 0.13 nM detection limit and a wide linear range that extends from 5 nM to 1 μM. Graphical abstractSchematic presentation of a colorimetric aptamer biosensor for adenosine detection based on DNA cycling amplification and salt-induced aggregation of gold nanoparticles.

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基于DNA循环扩增和盐诱导金纳米颗粒聚集的比色腺苷适体传感器

摘要描述了一种基于适配体的测定，用于比色检测腺苷。腺苷的存在触发含有腺苷适体的发夹 DNA 寡核苷酸 (HP1) 的变形，然后与另一个未标记的发夹 DNA 寡核苷酸 (HP2) 杂交。这导致形成具有钝 3' 末端的双链。在核酸外切酶 III (Exo III) 辅助降解后，富含鸟嘌呤的链 (GRS) 从 HP2 中释放出来。因此，腺苷-HP1 复合物被释放到溶液中，在那里它可以与另一个 HP2 杂交，并在 Exo III 的帮助下启动消化反应的许多循环。这导致在多次循环后产生大量 GRS 链。在钾离子存在的情况下，GRS 可以稳定红色 AuNP 以防止聚集。然而，如果 GRS 形成 G-四链体，它失去了保护金纳米粒子 (AuNPs) 免受盐诱导 AuNP 聚集的能力。因此，溶液的颜色从红色变为蓝色，可以用肉眼观察。这种比色测定具有 0.13 nM 的检测限和从 5 nM 到 1 μM 的宽线性范围。基于 DNA 循环扩增和盐诱导的金纳米颗粒聚集的用于腺苷检测的比色适体生物传感器的示意图。