An Aptamer-functionalized Magnetic Relaxation Switch Sensor for the Rapid Detection of Vibrio alginolyticus in Water

A sensitive and rapid method for the detection of Vibrio alginolyticus is always in high demand. In this research, a magnetic relaxation switch sensor for the rapid detection of Vibrio alginolyticus has been successfully developed based on the aptamer-functionalized magnetic nanoparticle. The optimal concentration of aptamer for cross-linking was 6 μM, and the coupling time was 7 h. The optimal detection conditions were as follows: the concentration of Fe3O4@SiO2-AptVA was 0.06 mg/mL, the incubation time was 10 min and the detection could be completed within 15 min. Meanwhile, the dependence of bacteria concentration on different relaxation characteristic signals was compared, and it was clear that ΔT2w exhibited better correlationship. In addition, the maximum NaCl limit for nanoparticles to remain stable is 0.4% (w/w). Under the optimal conditions, the LOD of this method based on ΔT2w is 26 CFU/mL and the recovery is 91.30–113.09%. Good specificity was proved. This method provides new choice for the rapid detection of Vibrio alginolyticus.