一种高灵敏检测贝类中大田软海绵酸的可抛式核酸适配体传感器

A Disposable Aptasensor for Sensitive Detection of Okadaic Acid in Shellfish

以能够特异性识别大田软海绵酸(Okadaic acid,OA)的核酸适配体作为识别探针,先利用磁力吸附将核壳型纳米金磁微粒(Fe_3O_4@Au)固定在丝网印刷金电极(Screen-printed gold electrode,SPGE)的表面,然后利用AuS键固定核酸适配体,构建了可抛式核酸适配体传感器,用于贝类中OA的高灵敏测定。采用电化学阻抗谱进行测试,利用核酸适配体与OA结合前后工作电极表面电子传递阻抗值的变化量与OA浓度对数值之间的线性关系,实现贝类中OA的定量检测。此传感器制备简单,采用Fe_3O_4@Au修饰传感界面,通过增大工作电极的比表面积提高核酸适配体的组装量,提高了方法的灵敏度;将核酸适配体作为识别探针,相比抗体的使用大大降低了方法成本;一次性可抛SPGE的应用,省去传统电极使用前必需的繁杂抛光过程。采用此传感器进行贝类中OA的检测,线性范围为1～800μg/kg,检出限为1μg/kg;回收率在92.0%～118.6%范围内,相对标准偏差为5.8%～11.6%。本方法简便高效且重现性良好,可实现大批量样品的筛查与定量分析。

Based on the specific combination between aptamer and its target analyte, a disposable aptasensor was built for the sensitive detection of okadaic acid(OA)(a main constituent of diarrhetic shellfish poisoning) in shellfish. The aptamer was employed as the probe and screen-printed gold electrodes(SPGE) as the support. Electrochemical impedance spectroscopy(EIS) was performed to test the change of electron transfer resistances(Ret) of SPGE before and after binding with OA and OA in shellfish samples could be thus quantified. In order to improve the sensitivity of the method, Fe3O4@Au was introduced into the fabrication of SPGE since it could enhance the gold working electrode’s surface areas. Compared with antibody, the use of aptamer was cheaper, and SPGE avoided the polish step which was needed of traditional electrodes. The change of Ret was linearly correlated with the natural logarithm of concentration of OA from 1 μg/kg to 800 μg/kg. The limit of detection was 1 μg/kg. Recoveries in diarrhetic shellfish at different spiked levels were in the range of 92.0%-118.6%, and relative standard deviations(RSDs) were less than 12%. The proposed disposable aptasensor was efficient and sensitive with good repeatability, and was suitable for screening and quantification of shellfish samples.