设计一种基于双链核酸适体的非标记夹心式电化学适体传感器,建立简单、高灵敏度的可卡因分析方法.首先将末端巯基修饰的捕获适体探针组装在金电极表面,构建可卡因适体传感器.该传感器与目标分子可卡因和部分互补的检测适体探针作用后,在电极表面形成适体/可卡因/适体复合物.以六氨合钌为信号分子,基于单链适体和适体/可卡因/适体复合物对六氨合钌吸附量的不同,通过计时电量法检测电极表面吸附六氨合钌的还原电量,进行可卡因的分析检测.在优化的条件下,还原电量与可卡因浓度在1～50μmol/L范围内呈良好的线性关系,检出限为0.1μmol/L.用于血清中可卡因的检测,回收率为96.4%～104%.该方法简单,灵敏度高,可作为一种通用型的适体传感器模型.%A label-free and sandwich aptamer-based electrochemical biosensor for simple and sensitive de-termination of cocaine was developed based on double-strand nucleotide aptamer.Capture ss-DNA was immobilized on gold surfaces by means of self-assembly technique to fabricate cocaine aptamer-based bio-sensor.In the presence of target cocaine and detected aptamer probe,two fragments folded with cocaine and formed a sandwich complex on the electrode surface.Based on the difference binding ability of [Ru（NH3）6]3＋ to ss-DNA and sandwich complex,a simple and highly sensitive electrochemical method was developed for the determination of cocaine by detecting the charge of [Ru（NH3）6]3＋ adsorbed on the elec-trode surface by chronocoulometry.Under the optimized conditions,the charge response was linear with the concentration of cocaine from 1 ？mol/L to 50 ？mol/L.The detection limit was 0.1 ？mol/L.The developed method allows the detection of cocaine in a serum sample with recovery in 96.4%～104%.This design strategy is easy to generalize for any aptamer without prior knowledge of its secondary or tertiary structure,and would be used as a simple,sensitive and general tool for biomolecule detection.
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