Colorimetric Enzyme-linked Aptamer Assay for Determination of Staphylococcal Enterotoxin A in Foods
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Abstract:
In this study, an enzyme-linked aptamer assay (ELAA) was developed for detection of staphylococcus enterotoxin A (SEA) based on sandwich-type format strategy. Several experimental conditions have been investigated, including the concentration of aptamer, BSA and streptavidin-horseradish peroxidase (SA-HRP), reactionsystem, blocking conditions, and incubation time between SEA and aptamer. The results showed that the optimal conditions for ELAA were as follows: aptamers concentration of 40 nmol/L; BSA concentration of 1%; blocking time of 4 h; SEA aptamer screening buffer was used as the reaction system; the dilution volume ratio of streptavidin-horseradish peroxidase (SA-HRP) was 1:40000; and the incubation time between SEA and aptamers was 30 min. Under the optimal conditions, the calibration curves for SEA showed good linearity in the range of 5~500 ng/mL with correlation coefficients (R) better than 0.996. The limit of detection (LOD) for SEA was 0.18 ng/mL. The recoveries of SEA in food samples were in the range of 91.22%~101.30%. There lative standard deviation (RSD) of intra-assay and inter-assay were in the range of 2.82%~7.50%. Subsequently, the proposed method was applied to measure SEA in real samples, and was validated using official standard method. A good correlation (R=0.994) was obtained between the results of the two methods. These results suggest that the proposed method had good sensitivity, accuracy and specificity. This study provides a simple, economical and high-throughput new rapid detection technology for SEA detection in food.
