A microfluidic platform for foodborne pathogenic bacteria detections

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Outbreaks of foodborne diseases in recent years have led to the growth in demand for rapid, sensitive, and high-throughput methods and instrumentation for foodborne pathogens from food safety inspection authorities and food industries. A low-cost, robust, reliable and high-throughput pathogen detection platform can meet this increasing demand and allow food safety authorities to quickly respond to events such as foodborne disease outbreaks and bioterrorist attacks on our food supply chains. To this end, this research program is to develop a sensitive and low cost microfludics-based detection system that can circumvent the need for culture enrichment process and complete the whole testing of real-world foods within a short period of time. ******The proposed program integrates sample preparation and sample detection on-chip functionalities. It includes a separator to remove large food particles from the homogenized real-world food sample, a concentrator to remove liquid from the sample, and a detector for efficient capture and detection of target bacteria. As such, an input sample can be processed and subsequently analyzed in this continuous flow fashion within the system. For the current Discovery Grant (DG) application, the main objective is to develop an ultra sensitive microfluidic device that offers both sensitive and rapid detections. To achieve this, we propose to surface modify the microfluidic channel walls with dendrimers and conjugate target bacteria-specific aptamers. This will not only reduce the background signals due to non-specific bindings to the microchannel walls, but also provide multiple reaction sites to subsequently attach bacteria capturing aptamers. Studies will be advanced to investigate aptamers with different types of linkers at different linkage length to the anchoring surfaces. To further enhance detection, rolling circle amplification (RCA) signal intensifications will also be used, effectively enhancing detection signals. Finally, microfluidics flow patterns will be studied to improve detection efficiency. ******Anticipated significance of the work: The proposed detection system is novel in that it offers not only rapid and sensitive detections, but also possibilities to integrate with other microfluidic on-chip functionalities, such as separator and concentrators. The proposed studies is a key component of the overall proposed detection system. If successfully implemented, the fully integrated detection platform will significantly reduce detection time and lower detection cost, thereby allowing safety authorities to extend their testing coverage and frequencies and playing more proactive roles in identifying possible contaminations and suspicious activities.