Construction of chemiluminescence aptasensor platform using magnetic microsphere for ochratoxin A detection based on G bases derivative reaction and Au NPs catalyzing luminol system

In this paper, two kinds of chemiluminescent (CL) aptasensors for detecting Ochratoxin A (OTA) were constructed using Magnetic microsphere (MBs) as separated carrier. For the label-free aptasensor, in presence of the OTA, the OTA aptamer specially bound with it, and this affinity function was stronger than hybridization interaction between OTA aptamer and the paired sequence (capture probe), and resulted in the quantitative reduction of aptamers that bound to the capture probe on the MBs. And thus, according to the CL signals changes which came from the transient reaction between guanine (G) in the OTA aptamer sequence and phenylglyoxal (PG), the OTA could be rapidly detected. Meanwhile, another Au nanoparticle (Au NPs) -labeled aptasensor based on the above-mentioned mechanism of aptamer affinitive substitution was also prepared, analytical target OTA could be sensitively determined with the CL signals which were generated by Au NPs catalyzing luminol chemiluminescence. Under the optimal conditions, the detection limits of two OTA sensors were 0.041 ng/mL and 0.0067 ng/mL, respectively. What is more, these two simple, convenient and low-cost strategies afford high sensitivity, specificity and suitability for detection of OTA in real samples.