Key Laboratory on Luminescence and Real-Time Analysis, Ministry of Education, College of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715, PR China.
Biosens Bioelectron. 2011 Jun 15;26(10):4236-40. doi: 10.1016/j.bios.2011.03.038. Epub 2011 Apr 8.
A simple electrochemical aptasensor for sensitive detection of thrombin was fabricated with G-quadruplex horseradish peroxidase-mimicking DNAzyme (hemin/G-quadruplex system) and blocking reagent-horseradish peroxidase as dual signal-amplification scheme. Gold nanoparticles (nano-Au) were firstly electrodeposited onto single wall nanotube (SWNT)-graphene modified electrode surface for the immobilization of electrochemical probe of nickel hexacyanoferrates nanoparticles (NiHCFNPs). Subsequently, another nano-Au layer was electrodeposited for further immobilization of thrombin aptamer (TBA), which later formed hemin/G-quadruplex system with hemin. Horseradish peroxidases (HRP) then served as blocking reagent to block possible remaining active sites and avoided the non-specific adsorption. In the presence of thrombin, the TBA binded to thrombin and the hemin released from the hemin/G-quadruplex electrocatalytic structure, increasing steric hindrance of the aptasensor and decomposing hemin/G-quadruplex electrocatalytic structure, which finally decreased the electrocatalytic efficiency of aptasensor toward H(2)O(2) in the presence of NiHCFNPs with a decreased electrochemical signal. On the basis of the synergistic amplifying action, a detection limit as low as 2 pM for thrombin was obtained.
一种简单的电化学适体传感器，用于灵敏检测凝血酶，是利用 G-四链体辣根过氧化物酶模拟 DNA 酶（血红素/G-四链体系统）和封闭试剂-辣根过氧化物酶作为双重信号放大方案构建的。首先将金纳米粒子（纳米 Au）电沉积到单壁碳纳米管（SWNT）-石墨烯修饰电极表面，用于固定电化学探针镍六氰合铁纳米粒子（NiHCFNPs）。随后，再电沉积一层纳米 Au 以进一步固定凝血酶适体（TBA），随后 TBA 与血红素形成血红素/G-四链体系统。辣根过氧化物酶（HRP）随后作为封闭试剂来封闭可能存在的剩余活性位点，并避免非特异性吸附。在凝血酶存在的情况下，TBA 与凝血酶结合，血红素从血红素/G-四链体电催化结构中释放出来，增加了适体传感器的空间位阻，并分解了血红素/G-四链体电催化结构，最终降低了在 NiHCFNPs 存在下对 H2O2 的电催化效率，电化学信号降低。基于协同放大作用，凝血酶的检测限低至 2 pM。
