Chemiluminescent Aptasensors Based On Magnetic Separation Technology For Detection Of Ochratoxin A

Ochratoxin A(OTA) is one of the most important mycotoxins, which toxicity is the second in mycotoxins family only afer aflatoxin. In nature, OTA is frequently present in a cereal crops and animal product foods, which is severe threat to human health. Food safety problems are closely related to the security of the whole society which deserves the world’s attention, so it is particularly important to establish a rapid analytic method for OTA with highly sensitivity. We designed three kinds of aptasensors for detection of OTA by chemiluminescence(CL) based on different sensor models and CL mechanism. The three kinds of aptasensor are all built on the surface of magnetic beads which used as a carrier for separation and immobilization. The paper is mainly composed of three sections as follow.1. In section one,we designed a label-free chemiluminescent OTA aptasensor using OTA aptamer as tracer based on the instantaneous derivative reaction between guanine nucleobeses(G) of OTA aptamer strands and CL reagent phenylglyoxal(PG). In the sensing mode, we can quantificationally analyze OTA utilizing the inverse correlation between the decrease of CL signal and concentration of OTA. Under the optimal conditions, the aptasensor showed a good linear response to the logarithmic value of concentration of OTA in a broad dynamic detection range of 0.1 to 50 ng/m L( r~2=0.9952) and a limit of detection of 0.1ng/m L. In spiked red wine samples, the recoveries is between 103.3%~112.5% and the RSDs is between 4.2%~7.2%(n=3). The aptasensor was confirmed to have high specificity to OTA.2. In section two,an AuNPs-labeled chemiluminescent OTA aptasensor was established using AuNPs as a label, which can achieve quantitative detection of OTA by catalyzing the luminol-chemiluminescence system. Due to a competition binding between OTA and AuNPs-labeled reporter DNA to the OTA aptamer which as the stationaryphase immobilized on the surface of magnetic beads, there is the negative correlation between CL signal and concentration of OTA. Thus the quantitative analysis of OTA was achieved. Under the optimal conditions, the CL signal of the aptasensor decreased linearly with the the logarithm of concentration of OTA range from 0.01 to 20 ng/m L with a detection limit of 0.01ng/ml(r~2=0.9922). In spiked red wine samples, the recoveries is between 104.1%~112.7% and the RSDs is between 5.9%~8.7%(n=3). The aptasensor showed a high specificity to OTA.3. Based on the principle of section 2, a chemiluminescent OTA aptasensor was assembled using horse radish peroxidase(HRP) as tracer which similarly can catalyzed the luminol-chemiluminescence system. We implemented the quantitative detection of OTA by the aptasensor based on a reverse relationship between the CL signal produced by HRP and the concentration of OTA. Under the optimal conditions, the CL signal of aptasensor decreased linearly with the the logarithm of concentration of OTA range from 0.01 to 50ng/m L with a detection limit of 0.01ng/ml(r~2=0.9898). In spiked red wine samples, the recoveries is between 98.5%~109.3% and the RSDs is between 5.2%~7.7%(n=3). Through investigation, the aptasensor have been supported to have a high specificity to OTA.