Rapid Detection of Salmonella via Off-on Composite Fluorescent Probe Based on Fluorescence Resonance Energy Transfer

Immunomagnetic beads were prepared by coupling the functional magnetic beads modified by silanization and amination with Salmonella specific antibodies. The properties and biological activities of the beads were characterized by near infrared spectroscopy, fluorescence spectroscopy and absorption spectroscopy. Aminated magnetic beads, antibodies and quantum dots (QDs) were assembled in an orderly manner to construct a magnetic-bead-antibody-QDs composite fluorescent nanoprobe with magnetic collection and separation abilities for rapid detection of Salmonella. off-on fluorescence was realized through the fluorescence resonance energy transfer (FRET) effect between the QDs and gold nanoparticles (AuNPs), and an off-on fluorescent probe analytical method for rapidly detecting Salmonella was established. The results showed that the degree of fluorescence recovery of the composite fluorescent nanoprobe showed a good linear relationship with logarithm of bacterial concentration, and the linear regression equation was y = 103.5x + 121.4 (R-2 = 0.9956). Moreover, the detection limit of the probe was 10(2) CFU/mL, and its detection time was less than 2 h. The proposed method features good specificity, low detection limit and high sensitivity,and can be used to rapidly detect Salmonella in food.