Visual Detection of Alpha Toxin by Combining Nanometer Microspheres with Smart Phones.

α toxin (CPA) is an important virulence factor that causes livestock hemorrhagic enteritis and food poisoning by contaminated meat products. In this study, the nano-silica microspheres combined with smartphone image processing technology was developed to realize real-time CPA detection. First, the N-terminal and C-terminal domain of the CPA toxin (CPA and CPA) and their anti-sera were prepared. The silica microspheres coupled with the antibody of CPA was prepared to capture the toxin that existed in the detection sample and the fluorescent-labeled antibody of CPA was incubated. Moreover, the fluorescent pictures of gray value were performed in a cell phone app, corresponding to toxin concentration. The new assay takes 90 min to perform and can detect CPA as little as 32.8 ng/mL. Our results showed a sensitive, stable, and convenient CPA detection system, which provides a novel detection method of native CPA in foods.