Paper-integrated rotary type sensor for on-site, multiple detection of foodborne pathogens

Abstract

Foodborne pathogens cause hundreds of thousands of deaths worldwide every year and also causes serious economic damage in both public and private sectors. A rapid detection system of pathogens that can be used on-site of food processing facilities can help prevent the outbreak by stopping contaminated products from being distributed. An ideal technology for such purpose is a low-cost, rapid detection system that is easy to operate and can be interpreted without any external equipment. With this goal, a novel method for controlling fluid flow in a paper-based device was first developed. The method was used to demonstrate the sequential delivery of multiple reagents in a three-branch device, which was then applied to perform an automated multistep immunoassay. A more robust and versatile device was then developed to deliver multiple reagents with a specific sequence and duration. The novel handheld rotary device can perform an enzyme-linked immunosorbent assay and detect $5 \times 10^4$ CFU/mL Escherichia coli O157:H7 in 22 min. The device was then modified to utilize gold nanoparticles and gold enhancers, and also to be equipped with two test strips for multiple detection. Detection of Escherichia coli O157:H7, Salmonella typhimurium, Staphylococcus aureus and Bacillus cereus was confirmed without nonspecific signals. To confirm its application in the detection of contaminated foods, lettuces were contaminated with a different number of bacteria, which were then recovered using a novel sample pre-concentration protocol, and then loaded into the device. Without enrichment process, contaminated lettuces that were inoculated with $1.87 \times 10^4$ CFU of Escherichia coli O157:H7 and $1.47 \times 10^4$ CFU of Salmonella typhimurium per gram of lettuce were able to be detected. With 6-hour enrichment of contaminated lettuces in growth media, contamination of 1 CFU of Escherichia coli O157:H7 and 1 CFU of Salmonella typhimurium per gram of lettuce was successfully detected.