基于金纳米星和生物质多孔碳信号放大策略的新型电化学核酸适配体传感器

Signal amplification strategy for electrochemical aptasensor based on gold nanostars and nitrogen-doped porous carbon derived from biomass

赭曲霉毒素A(ochratoxin A,OTA)是一种由青霉菌和曲霉菌产生的次级代谢产物,具有很强的肾毒性、肝毒性、免疫毒性和致畸致癌作用等,污染范围广泛。因此,建立一种灵敏、有效的分析方法检测OTA,对于维护食品安全及保护人类健康尤为重要。电化学核酸适配体传感器是一种将电化学检测方法与核酸适配体结合起来的新型传感器,具有特异性好、操作简单、易于实现现场检测等优点。制备金纳米星(GNSs)和生物质氮掺杂多孔碳(NDPC)作为双重信号放大策略,构建了一种新型电化学核酸适配体传感器,用于OTA的检测研究。扫描电镜和透射电镜的表征结果表明GNSs和NDPC制备成功。对制备的传感器进行优化,得到OTA核酸适配体链(Apt)的最佳浓度为1.5μmol/L,NDPC的最佳质量浓度为4 mg/mL。在OTA质量浓度为0.001~5.000 ng/mL范围内,电流差值与lg C OTA呈良好的线性关系,检出限为0.22 pg/mL。利用制备的传感器对玉米样品进行加标检测,得到平均回收率为89%~104%,说明该传感器可用于检测实际样品中的OTA。基于核酸适配体可以实现对其他目标物检测,为食品安全检测提供了技术支撑。

As a kind of secondary metabolites mainly produced by Aspergillus and Penicillium,ochratoxin A(OTA)widely exists in cereals,beans,coffee beans,nuts,wine and beer.Toxicology research shows that OTA can cause specific immune dysfunction,and has strong nephrotoxicity,hepatotoxicity,teratogenic,and carcinogenic effects.In order to ensure food safety and human health,it is necessary to establish a sensitive and selective method to detect OTA in food.The electrochemical aptasensor is a novel analysis method combining electrochemical detection technology and nucleic acid aptamer,and has the advantages of good specificity,simple operation,low cost,fast response,and easy on-site detection.In order to improve the sensitivity of electrochemical detection,one type of electrochemical aptasensors were constructed for OTA detection with the aid of signal amplification technologies,including nanomaterials.In this work,a novel electrochemical aptasensor using gold nanostars(GNSs)and nitrogen-doped porous carbon derived from biomass(NDPC)as dual signal amplification strategy was developed for the sensitive detection of OTA.Due to its multi-branched structure,large specific surface area and good electrical conductivity,GNSs were prepared to improve the immobilization amount of OTA aptamer and accelerate the electron transfer on the electrode surface,which played a key role in recognizing the signal amplification.With a large surface area and good biocompatibility,NDPC derived from biomass wheatmeal was prepared and used for increasing the immobilization of complementary DNA and thionine as the second signal amplification strategy.The characterization results of SEM and TEM demonstrated that GNSs and NDPC were successfully prepared.The experimental conditions such as the concentration of Apt and the concentration of NDPC were studied,and the optimum conditions were as follows:the optimum concentration of Apt was 1.5μmol/L;the optimum concentration of NDPC was 4 mg/mL.The proposed aptasensor presented a linear range from 0.001 ng/mL to 5.000 ng/mL with the limit of detection of 0.22 pg/mL toward OTA detection,which was ascribed that the advantages of GNSs and NDPC,including the large surface area,good biocompatibility,good electrical conductivity,and the favorable ability of electron transfer.The prepared Th-NDPC-cDNA/Apt-GNSs/NH 2-AuE sensor was used to detect OTA content in corn sample,and the average recovery rate was 89%-104%,indicating that the prepared sensor was suitable to detect OTA in actual sample.In summary,we have successfully designed a novel signal-off electrochemical aptasensor based on GNSs and NDPC as double signal amplification for the highly sensitive and effective detection of OTA,which can be expanded to other targets based on aptamers,as well as provides a technological support for food safety.