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Foodborne bacteria have persisted as a significant threat to public health and to the food and agriculture industry. Due to the widespread impact of these pathogens, there has been a push for the development of strategies that can rapidly detect foodborne bacteria on-site. Shiga toxin-producing E. coli strains (such as E. coli O157:H7, E. coli O121, and E. coli O26) from contaminated food have been a major concern. They carry genes stx1 and/or stx2 that produce two toxins, Shiga toxin 1 and Shiga toxin 2, which are virulent proteins. In this work, we demonstrate the development of a rapid test based on an isothermal recombinase polymerase amplification reaction for two Shiga toxin genes in a single reaction. Results of the amplification reaction are visualized simultaneously for both Shiga toxins on a single lateral flow paper strip. This strategy targets the DNA encoding Shiga toxin 1 and 2, allowing for broad detection of any Shiga toxin-producing bacterial species. From sample to answer, this method can achieve results in approximately 35 min with a detection limit of 10 CFU/mL. This strategy is sensitive and selective, detecting only Shiga toxin-producing bacteria. There was no interference observed from non-pathogenic or pathogenic non-Shiga toxin-producing bacteria. A detection limit of 10 CFU/mL for Shiga toxin-producing E. coli was also obtained in a food matrix. This strategy is advantageous as it allows for timely identification of Shiga toxin-related contamination for quick initial food contamination assessments. 

Despite fluorescent quenching with graphene oxide (GO) having shown great success in various applications ‐ bioluminescent quenching has not yet been demonstrated using GO as a quencher. To explore the ability of GO to quench bioluminescence, we usedGaussialuciferase (Gluc) as a donor and GO as a quencher and demonstrated its application in sensing of two target analytes, HIV‐1 DNA and IFN‐γ. We demonstrated that the incubation of Gluc conjugated HIV‐1 and IFN‐γ oligonucleotide probes with GO provided for monitoring of probe‐target interactions based on bioluminescence measurement in a solution phase sensing system. The limits of detection obtained for IFN‐γ and HIV‐1 DNA detection were 17 nM and 7.59 nM, respectively. Both sensing systems showed selectivity toward the target analyte. The detection of IFN‐γ in saliva matrix was demonstrated. The use of GO as a quencher provides for high sensitivity while maintaining the selectivity of designed probes to their respective targets. The use of GO as a quencher provides for an easy assay design and low cost, environmentally friendly reporter.