基于辣根过氧化物酶(HRP)及纳米钯(NanoPd)对过氧化氢(H2O2)的双重催化作用放大铁氰化镍(NiHCF)的电化学氧化还原信号构建了一种新型的电化学适体传感器.采用生物兼容性好的壳聚糖(CS)分散石墨烯-碳纳米管复合物(CS-Gra-CNTs)可以大大提高其导电性和比表面积，吸附更多电活性好、化学性质稳定的电子媒介体NiHCF.固定NanoPd并吸附凝血酶适体(TBA)，用HRP封闭非特异性吸附位点后，在含有一定浓度的H2O2的磷酸缓冲溶液(PBS)中可用于高灵敏检测凝血酶(TB).在最优条件下，采用循环伏安法考察该传感器的电化学特性，研究表明，峰电流值与TB浓度在1.0×10-5~3.0×10-2 mol/L成线性关系，检出下限为3.0×10-6 mol/L.并且，该传感器制备简单、操作简便、稳定性好、寿命长、灵敏度高、特异性强.% In this paper, a novel electrochemical aptasensor based on a dual amplification strategy was designed. Recent studies demonstrated that application of graphene-carbon nanotubes (Gra-CNTs) hybrid film can offer a high surface area and more electroactive interaction sites. When dispersed by biocompatible chitosan, the CS-Gra-CNTs composites modified glassy carbon electrode showed strong adsorption capacity for electro-active nickel ferricyanide (NiHCF). After that, the palladium nanoparticals (NanoPd) were modified on the electrode through electrodeposition, which was further used to capture the thrombin aptamer (TBA). Then, the horseradish peroxidase was used to eliminate nonspecific binding. A greatly amplified signal was obtained when H2O2 added to the detection solution, since both horseradish peroxidase and palladium nanoparticals can catalyse H2O2, which can further amplified the current of NiHCF. The aptasensor displayed excellent performance for thrombin with a wide linearity ranging from 1.0 ×10-5~3.0 ×10-2 mol/L with a detection limit of 3.0 ×10-6 mol/L. Moreover, the resulted aptasensor also exhibited good specificity, acceptable reproducibility and stability, indicating that the present strategy could pave a promising way for the wide application of graphene in clinical research.
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