Brucella spp. are facultative intracellular bacteria that cause zoonotic disease of brucellosis worldwide. Traditional methods for detection of Brucella spp. take 48–72 h that does not meet the need of rapid detection. Herein, a new rapid detection method of Brucella was developed based on polyclonal antibody-conjugating quantum dots and antibody-modified magnetic beads. First, polyclonal antibodies IgG and IgY were prepared and then the antibody conjugated with quantum dots (QDs) and immunomagnetic beads (IMB), respectively, which were activated by N-(3-dimethylaminopropyl)-N’-ethylcar-bodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS) to form probes. We used the IMB probe to separate the Brucella and labeled by the QD probe, and then detected the fluorescence intensity with a fluorescence spectrometer. The detection method takes 105 min with a limit of detection of 103 CFU/mL and ranges from 10 to 105 CFU/mL (R 2 = 0.9983), and it can be well used in real samples.

The infection and outbreak of Salmonella typhimurium (S. typhimurium) highlight the need for developing a reliable on-site detection strategy fitting to various settings. However, due to the requirement of specialized instruments and trained personnel, traditional detection methods have to be implemented in laboratories and are not ideal for on-site applications. To achieve a sample-to-answer and field-deployable detection for S. typhimurium, we developed an integrated nucleic acid detection platform combining single-vial of loop-mediated isothermal amplification (LAMP)-clustered regularly interspaced short palindromic repeat (CRISPR)/Cas12a system, portable device and smartphone app. This platform enables the extraction, concentration, and purification of DNA, amplification of the target, and output of visual fluorescent signals within 1 h. With this detection platform, 10² CFU/mL of S. typhimurium in food and environmental matrix was able to be accurately detected. This method demonstrated excellent selectivity. Also, an auxiliary smartphone application was developed to achieve simplified result interpretation. Our method exhibited potential to better control and respond to outbreaks of foodborne diseases, especially in low-resource settings.

IMB probe and QD probe were used as separation and fluorescent label to measure the content of V. parahaemolyticus. The detection method with a detection limit of 10² cfu mL⁻¹ has been shown to work satisfactorily in real food samples.