Improved triple-module fluorescent biosensor for the rapid and ultrasensitive detection of Campylobacter jejuni in livestock and dairy

Campylobacter jejuni (C. jejuni) is a major pathogen responsible for the food-borne illness, campylobacteriosis. To comply with regulatory requirements, its total concentration in food and animal feces must be extremely low. As a result, monitoring this bacterium requires an immediate and cost-effective approach that meets the requirements of the food and livestock industries. The current study reports the development of an improved biosensor comprising three modules viz. a novel transducing module (1), a bi-functional binding/actuating module (2), and an enrichment module (3), synthesized using commercially available components. Module 3, composed of magnetic beads functionalized with a C. jejuni-specific aptamer, utilizes magnetic separation to isolate and enrich C. jejuni from samples. The resulting module 3-C. jejuni complexes can bind module 2 copolymer to form ternary complexes. When these ternary complexes are separated and reacted with module 1, composed of a ferric ion/fluorescein sodium (Fe3+/FLNa) pair, they chelate Fe3+ ions, resulting in the recovery of FLNa after magnetic separation via fluorescence. The as-synthesized biosensor demonstrated a high sensitivity range of 10-107 CFU/mL, and a detection limit of 3 CFU/mL. Additionally, microfluidics was used to eliminate interferences resulting from the module 3-enriched products, while detecting C. jejuni in real-world samples. Herein, the biosensor demonstrated an actual limit of detection (LOD) of 101 CFU/mL within & AP;60 min. Thus, the biosensor and the assisting treatments offer a rapid and ultrasensitive platform for detecting C. jejuni in livestock and dairy industries, outperforming conventional approaches.

Automated summary

The study developed an improved biosensor for the rapid detection of Campylobacter jejuni in food and animal feces. The biosensor demonstrated high sensitivity and a low detection limit, with the ability to detect 101 CFU/mL within 60 minutes. Microfluidics was used to eliminate interferences and enhance the accuracy of the detection.