A portable biosensing device is developed for detection of Salmonella Typhimurium in poultry. A previously developed optical biosensing method has been converted into a portable biosensing device to achieve simple, rapid and quantitative detection of Salmonella Typhimurium. The device consisted of a microfluidic control module, a magnetic separation module, and a fluorescent detection module. The bacteria sample, immuno-magnetic nanoparticles and immuno-quantum dot beads were added into a microfluidic chip, and were fully mixed in the microfluidic control module. Then, the sample was moved to the magnetic separation module to automatically separate and concentrate the target bacteria. Finally, the fluorescence intensity was measured by the fluorescent detection module to determine the concentration of the target bacteria. The device was able to perform separation and detection of Salmonella with minimal manual operations with a detection limit of 5.4×10² CFU/mL in 1 h. The device also showed good specificity against four selected non-target bacteria.

An LSPR biosensing method for rapid, sensitive and specific detection of enrofloxacin (ENRO) residues in poultry is developed, using polydopamine molecular imprinted polymer (PDA-MIP) as the biological recognition element. The modified sensor chip was used to selectively capture ENRO in samples. To amplify LSPR detection signals of small ENRO molecules, BSA-ENRO conjugates were synthesized, served as competitors, and reacted with the residual binding sites on the PDA-MIP film. The detection time was 20 min, with a detection range of 25 to 1,000 ng/mL and a limit of detection (LOD) of 60 ng/mL. The PDA-MIP film demonstrated a higher binding capacity to ENRO than the corresponding non-imprinted polymer (NIP) film, and discriminated ENRO among structural analogues. Good reusability was achieved within 7 binding-regeneration cycles, with a relative standard deviation (RSD) of 6.9%.

The group members have submitted the manuscript “A Portable Biosensing Device with Magnetic Separation and Quantum Dot Bead Labeling for Simple, Rapid and Quantitative Detection of Salmonella Typhimurium” to Transactions of the ASABE, and another manuscript “Rapid Detection of Enrofloxacin Using a Localized Surface Plasmon Resonance Sensor Based on Polydopamine Surface Imprinted Recognition Polymer” to Talanta for publication. Two abstracts of the conference papers have been accepted: One paper titled “Magnetic separation of bacteria in large-volume samples: A review” for ASABE 2020 Annual International Meeting, July 12-15, 2020 in Omaha, Nebraska; and another paper titled “Application of polydopamine molecular imprinted polymer on a localized surface plasmon resonance sensor for detection of multi-antibiotics in chicken meat” for IAFP 2020 Annual Meeting, August 2-5, 2020 in Cleveland, Ohio. Due to the COVID-19, it is likely that these meetings will be held virtually online, and available to potential participants whose travels are limited.