Abstract
Staphylococcal enterotoxin A (SEA) is a worldwide public health problem accounting for the majority of food poisoning which is produced by Staphylococcus aureus, threatening human health and leading to various foodborne diseases. Therefore, it is of great significance to develop a sensitive detection method for SEA to ensure food safety and prevent foodborne diseases in humans. In this study, an adaptive fluorescence biosensor for the detection of staphylococcal enterotoxin A (SEA) was designed and developed by combining DNA silver nanoclusters (DNA-AgNCs) with polypyrrole nanoparticles (PPyNPs). Fluorescent AgNCs, synthesized using aptamers as templates, were used as fluorescence probes, whose fluorescence was quenched by PPyNPs. In the presence of the target SEA, DNA-AgNCs were forced to desorb from the surface of PPyNPs through the binding of SEA with the aptamer-DNA-AgNCs, thereby resulting in fluorescence recovery. Under the optimized conditions, the relative fluorescence intensity (FI) showed a linear relationship with the SEA concentration in the range from 0.5 to 1000 ng/mL (Y = 1.4917X + 0.9100, R2 = 0.9948) with a limit of detection (LOD) of 0.3393 ng/mL. The sensor was successfully used to evaluate the content of SEA in milk samples, and the recovery efficiency of SEA was between 87.70% and 94.65%. Thus, the sensor shows great potential for application in food analysis. In short, the proposed platform consisted of an aptamer fluorescent sensor that can be used for the ultrasensitive detection of various toxins by taking advantage of the excellent affinity and specificity of corresponding aptamers.
Highlights
Food safety is a major global public health concern, especially the hazards caused by foodborne pathogens, among which Staphylococcus aureus, a Gram-positive bacteria that can produce a variety of enterotoxins, neurotoxins, and cytotoxins, is one of the most common pathogens [1,2,3]
Since dairy products are often contaminated with enterotoxin, milk was selected as the actual sample to evaluate the performance of the biosensors in complex media
The results showed that the detection system has excellent selectivity of bovine serum albumin (BSA), for Staphylococcal enterotoxin A (SEA)
Summary
Food safety is a major global public health concern, especially the hazards caused by foodborne pathogens, among which Staphylococcus aureus, a Gram-positive bacteria that can produce a variety of enterotoxins, neurotoxins, and cytotoxins, is one of the most common pathogens [1,2,3]. Various biosensors such as quartz crystal microbalances [20], electrochemical immunosensors [21,22], enzyme-linked immunosorbent assays [23], chemiluminescence enzyme immunoassay (CLEIA) [24], surface plasmon resonance (SPR) [25], capillary electrophoresis with laser-induced fluorescence detection [26], and others were developed to detect SEA [10,18,24,27,28] The disadvantages of these methods are the extraction and concentration of enterotoxins prior to analysis, time consumption, and personal skills. After the target SEA is added, the appropriate fragment of SEA and DNA-AgNCs causes the release of the DNA-AgNCs from the PPyNP surface and restores the fluorescence, which is measured and used for quantitation
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