Homogeneous electrochemical sensing is a modification-free approach, in which the biochemical reactions occur in a homogeneous solution rather than on a limited electrode interface. Homogeneous sensing strategies are high-efficient but yet suffer from high background signals, since the free indicators can diffuse upon the electrode to generate signals. In this work, a magnetic graphene oxide (M-GO) assisted homogeneous electrochemiluminescence (ECL) aptasensor was developed for the highly sensitive detection of okadaic acid (OA). The aptamer and Ru(bpy)₃²⁺ were adsorbed in M-GO to prepare the composite ECL probe. When the OA dissociated aptamer from M-GO, Ru(bpy)₃²⁺ was proportionally released from M-GO to generate the ECL signal. With the assistance of deoxyribonuclease I (DNase I), the cyclic dissociation and degradation of aptamers induced much more free Ru(bpy)₃²⁺ for signal amplification. But the unreleased Ru(bpy)₃²⁺ were still adsorbed in M-GO and magnetically separated. So the background signal was decreased, and the sensitivity was further improved. Results showed that the ECL intensity enhanced with the increasing logarithmic concentration of OA in the range of 0.01 ∼ 10.0 ng/mL, and the limit of detection was 4 pg/mL. The aptasensor illuminates a cost-effective approach for the highly sensitive detection of marine toxins.

均质电化学传感是一种无修饰的方法，其中生化反应在均质溶液中而不是在有限的电极界面上发生。均质感测策略是高效的，但是却遭受高背景信号的困扰，因为自由指示剂会扩散到电极上以产生信号。在这项工作中，开发了一种磁性氧化石墨烯（M-GO）辅助的均相电化学发光（ECL）适体传感器，用于冈田酸（OA）的高灵敏度检测。将适体和Ru（bpy）₃ ²⁺吸附在M-GO中以制备复合ECL探针。当OA从M-GO解离适体时，Ru（bpy）₃ ²⁺从M-GO按比例释放以生成ECL信号。借助于脱氧核糖核酸酶I（DNase I），适体的循环解离和降解诱导了更多的游离Ru（bpy）₃ ²⁺用于信号放大。但是未释放的Ru（bpy）₃ ²⁺仍被吸附在M-GO中并被磁分离。因此降低了背景信号，并进一步提高了灵敏度。结果表明，在OA的对数浓度为0.01〜10.0 ng / mL范围内，ECL强度随OA对数浓度的增加而增强，检出限为4 pg / mL。适体传感器为高灵敏度检测海洋毒素提供了一种经济有效的方法。