In the present work a highly sensitive and selective aptasensor was developed for the determination of 8-hydroxy-2′-deoxyguanosine (8-OH-dG) based on the hybridization chain reaction (HCR) signal amplification. It was observed that the aptamer of 8-OH-dG could hybridize with the capture DNA immobilized on the gold electrode with a sticky tail left, which initiated the HCR and led to the formation of extended dsDNA structure on the electrode surface. Then the electroactive species ([Ru(NH₃)₆]³⁺, RuHex) intercalated into the dsDNA grooves to generate the amplified signal. However, in the presence of 8-OH-dG, the aptamer containing G-rich nucleic acid sequences would be induced to form a G-quadruplex structure, which made it impossible to continue the HCR. So the detection signal will significantly decrease. Under the optimal conditions, the peak current of RuHex was linear with the logarithm of 8-OH-dG concentration in the range from 10 pM to 100 μM with the detection limit of 2.5 pM. By integrating the merits of enzyme-free amplification power of the HCR and the inherent high sensitivity of the electrochemical technique, the prepared aptasensor not only showed high sensitivity for the detection of 8-OH-dG, but also exhibited good selectivity against to the uric acid, an important interferent in the urine sample. Particularly, the aptasensor was applied to detect 8-OH-dG in urine samples with satisfactory results.

在本工作中，基于杂交链反应（HCR）信号放大，开发了一种高灵敏度和选择性的适体传感器，用于测定8-羟基-2'-脱氧鸟苷（8-OH-dG）。观察到，8-OH-dG的适体可以与固定在金电极上的捕获DNA杂交，并留有粘性尾巴，这会启动HCR，并导致在电极表面形成扩展的dsDNA结构。然后是电活性物质（[Ru（NH ₃）₆ ] ³⁺（RuHex）插入到dsDNA凹槽中以生成放大的信号。然而，在存在8-OH-dG的情况下，将诱导含有富含G的核酸序列的适体形成G-四链体结构，这使得不可能继续HCR。因此，检测信号将大大降低。在最佳条件下，RuHex的峰值电流与8-OH-dG浓度在10 pM至100μM之间的对数呈线性关系，检出限为2.5 pM。通过结合HCR的无酶放大能力和电化学技术固有的高灵敏度，所制备的适体传感器不仅对8-OH-dG的检测具有很高的灵敏度，而且对尿酸具有良好的选择性。酸，尿样中的重要干扰物。特别，