A Bioluminescent Protein-Graphene Oxide Donor-Quencher Pair in DNA Hybridization Assays.

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 used Gaussia luciferase (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.

Monitoring Pathogenic Viable E. coli O157:H7 in Food Matrices Based on the Detection of RNA Using Isothermal Amplification and a Paper-Based Platform.

In recent years, the number of product recalls and contamination incidents involving pathogenic bacteria has significantly increased, and the ensuing infections continue to be an ongoing problem for public health and agriculture. Due to the widespread impact of these pathogens, there is a critical need for rapid, on-site assays that can provide rapid results. In this work, we demonstrate the development of a rapid and simple test based on the combination of reverse transcription with recombinase polymerase amplification followed by lateral flow strip detection of viable Escherichia coli O157:H7 cells by detecting the RNA of the pathogen. The optimized method can be performed for approximately 2 h with a detection limit of 10 CFU/mL of E. coli O157:H7 in buffer, spinach, and ground beef samples. Our assay is sensitive, detecting only E. coli O157:H7 and not nonpathogenic E. coli or other similar pathogens. This strategy was able to distinguish viable from nonviable bacteria and more significantly was able to detect viable but nonculturable bacteria, which is a major issue when using culture-based methods for monitoring pathogenic bacteria. An important advantage of this test is that it can provide timely identification and removal of contaminated consumables prior to distribution without an extensive sample preparation.

On-site detection of food and waterborne bacteria - current technologies, challenges, and future directions.

With the rise in outbreaks of pathogenic bacteria in both food and water resulting in an increased instance of infection, there is a growing public health problem in both developed and developing countries. In this increasing threat the most effective method for control and prevention is rapid and cost-effective detection. Research has shifted in recent years towards the development of rapid and on-site assays for the detection of these kinds of bacteria. However, there are still some limitations in the implementation of these assays in the field. This article discusses the current on-site detection methods. Current scope of advancements and limitations in the development or use of these on-site technologies for food and waterborne bacterial detection is evaluated in this study. With the continued development of these technologies, on-site detection will continue to impact many areas of public health. As these methods continue to improve and diversify further, on-site detection could become more widely implemented in food and water analysis.