Zheng Yingning, Chai Yaqin, Yuan Yali, Yuan Ruo
Key Laboratory on Luminescence and Real-Time Analysis, Ministry of Education, College of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715, PR China.
Key Laboratory on Luminescence and Real-Time Analysis, Ministry of Education, College of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715, PR China.
Anal Chim Acta. 2014 Jun 27;834:45-50. doi: 10.1016/j.aca.2014.04.060. Epub 2014 May 2.
Our present work aimed at developing a pseudo triple-enzyme cascade electrocatalytic electrochemical aptasensor for determination of thrombin with the amplification of alcohol dehydrogenase (ADH)-Pt-Pd nanowires bionanocomposite and hemin/G-quadruplex structure that simultaneously acted as NADH oxidase and HRP-mimicking DNAzyme. With the addition of ethanol to the electrolyte, the ADH immobilized on the Pt-Pd nanowires catalyzed ethanol to acetaldehyde accompanied by NAD(+) being converted to NADH. Then the hemin/G-quadruplex firstly served as NADH oxidase, converting the produced NADH to NAD(+) with the concomitant local formation of high concentration of H2O2. Subsequently, the hemin/G-quadruplex acted as HRP-mimicking DNAzyme, bioelectrocatalyzing the produced H2O2. At the same time, the Pt-Pd nanowires employed in our strategy not only provided a large surface area for immobilizing thrombin binding aptamer (TBA) and ADH, but also served as HRP-mimicking DNAzyme which rapidly bioelectrocatalyzed the reduction of the produced H2O2. Thus, such a pseudo triple-enzyme cascade electrochemical aptasensor could greatly promote the electron transfer of hemin and resulted in the dramatic enhancement of electrochemical signal. As a result, a wide dynamic concentration linear range from 0.2 pM to 20 nM with a low detection limit of 0.067 pM for thrombin (TB) determination was obtained. The excellent performance indicated that our strategy was a promising way for ultrasensitive assays in electrochemical aptasensors.
我们目前的工作旨在开发一种用于凝血酶测定的伪三酶级联电化学适体传感器，该传感器利用乙醇脱氢酶（ADH）-铂-钯纳米线生物纳米复合材料和血红素/G-四链体结构进行信号放大，它们同时作为NADH氧化酶和模拟辣根过氧化物酶（HRP）的DNAzyme。向电解质中加入乙醇后，固定在铂-钯纳米线上的ADH催化乙醇生成乙醛，同时NAD(+)转化为NADH。然后，血红素/G-四链体首先作为NADH氧化酶，将生成的NADH转化为NAD(+)，同时局部形成高浓度的H2O2。随后，血红素/G-四链体作为模拟HRP的DNAzyme，对生成的H2O2进行生物电催化。同时，我们策略中使用的铂-钯纳米线不仅为固定凝血酶结合适体（TBA）和ADH提供了大的表面积，还作为模拟HRP的DNAzyme，快速对生成的H2O2的还原进行生物电催化。因此，这种伪三酶级联电化学适体传感器可以极大地促进血红素的电子转移，并导致电化学信号的显著增强。结果，在凝血酶（TB）测定中获得了0.2 pM至20 nM的宽动态浓度线性范围，检测限低至0.067 pM。优异的性能表明我们的策略是电化学适体传感器中超灵敏检测的一种有前途的方法。
