Detection of Vibrio parahaemolyticus Based on Magnetic and Upconversion Nanoparticles Combined with Aptamers

Vibrio parahaemolyticusis a halophilic and heat-labile gram-negative bacterium and is the most prevalent foodborne bacterium in seafood. In order to develop a rapid and sensitive method for detecting the foodborne pathogenic bacteriumVibrio parahaemolyticus, an aptamer-modified magnetic nanoparticle and an aptamer-modified upconversion nanoparticle were synthesised and used as a capture probe and a signal probe, respectively. The aptamer-modified magnetic nanoparticle,V. parahaemolyticuscell, and aptamer-modified upconversion nanoparticle formed a sandwich-like complex, which was rapidly separated from a complex matrix using a magnetic force, and the bacterial concentration was determined by fluorescence intensity analysis. The results showed that the fluorescence intensity signal correlated positively with the concentration ofV. parahaemolyticusin the range of 3.2 × 102to 3.2 × 105CFU/mL, with a linear equation of y = 296.40x − 217.67 and a correlation coefficient of R2= 0.9610. The detection limit of the developed method was 4.4 CFU/mL. There was no cross-reactivity with other tested foodborne pathogens. This method is highly specific and sensitive for the detection ofV. parahaemolyticus, and can achieve the qualitative detection of this bacterium in a complex matrix.Keywords:Vibrio parahaemolyticus;aptamer;magnetic nanoparticles;upconversion nanoparticles;detection