Development of a chemiluminescent aptasensor for ultrasensitive and selective detection of aflatoxin B1 in peanut and milk

More and more attention about food safety leads to a research hotspot to develop new detection methods for food contaminant. To address the problems of serious interference and low sensitivity, a chemiluminescent aptasensor for the detection of aflatoxin B1(AFB1) in food was developed in this paper. It is based on horseradish peroxidase (HRP) catalyze the luminol chemiluminescence reaction. The hybridization chain reaction (HCR) signal amplification strategy has been used to improve the detection sensitivity. Magnetic separation could further reduce background signal obviously at the same time. AFB1 as a model of analyte to test the capability of our developed assay system. Under the optimal experimental conditions, CL intensity showed a good linear correlation with the concentrations of AFB1 ranging from 0.5 to 40 ng mL−1. The limit of detection was estimated 0.2 ng mL−1 based on 3 times of the signal-to-noise ratio which is lower than those of the previously reported sensors. It could be used to detect AFB1 content in real samples, such as peanuts and milk which were purchased in local supermarket. The results proved that the sensing system has good anti-interference and selectivity. In all, it has potential for practical application in food safety field. In the present work, we developed an ultrasensitive chemiluminescent aptasensor for selective detection of AFB1 by using horseradish peroxidase (HRP) as catalyst and hybridization chain reaction (HCR) as signal enhancer tool in luminol oxidation process. Aptamers as recognition elements for AFB1 sensing and magnetic beads as separation assist which can greatly increase ratio of signals to noise. First, the capture probe (CP) on the surface of magnetic beads hybridize with the aptamer of the targets to form an DNA duplex structure. In the presence of AFB1, aptamer can combine with AFB1 while exposing the CP probe on the magnetic beads after magnetic separation. Subsequently, HCR was triggered by the sticky end which forming a linear concatemers containing alternating hairpin 1 (H1) and hairpin 2 (H2). H1 are double-labeled with biotin moiety on its terminals for linking with streptavidin-tagged HRP (SA-HRP). Then, amount of HRP can catalyze the luminol-H2O2 reaction to produce strong CL emission. This strategy has been applied to detect AFB1 in peanut and milk samples. It is believed that the strategy possesses great potential for simple, easy and convenient detection of AFB1 residue in food safety field