ASABE Technical Library - Abstract

Abstract. Foodborne diseases are a growing public health problem. In recent years, many rapid detection methods have been reported, but most are still in lab research and not practical for use in the field. In this study, a portable and automatic biosensing instrument was designed and constructed for simultaneous detection of multiple target pathogens in food samples using nanobead-based magnetic separation and quantum dots (QDs)-based fluorescence measurement. The instrument consisted of a laptop with LabVIEW software, a data acquisition card (DAQ), a fluorescent detector, micro-pumps, stepper motors, and 3D printed holds of tubes. First, a sample in a syringe was mixed with magnetic nanobead-antibody (MNB-Ab) conjugates and then injected to a low binding tube. After incubation and magnetic separation, target bacterial cells were captured and collected and the solution was pumped out. Then the QDs-antibody (QD-Ab) conjugates were pumped into the reaction tube and after incubation, the MNB-Ab-cell-Ab-QD complexes were collected by magnetic separation and resuspended in PBS buffer solution through air pressure control. Finally, the sample was pushed out to the detection tube by an air pump and the fluorescence intensity was measured using the fluorescent detector. A virtual instrument (VI) was programmed using LabVIEW software to form a platform for magnetic separation, fluorescent measurement, data processing, and control. The DAQ was used for data communication. The results showed the separation efficiency of this instrument was 78.3 ± 3.4 % for E. coli O157:H7, and the fluorescence signal was detectable for E. coli O157:H7at different concentrations. More tests are being conducted for other three target pathogenic bacteria. The instrument was portable and automatic with great potential to serve as more effective tool for in-field/on-line detection of foodborne pathogenic bacteria.