Portable foodborne pathogen detection via ratiometric fluorescence nanoprobe for adenosine triphosphate quantification based on DNA-functionalized metal-organic framework.

The potential for foodborne infectious disease outbreaks has increased not only on a local scale but also on a regional and international scale. Simple, rapid, and accurate methods to enumerate pathogenic bacteria in food and drink are required to prevent the spread of these bacteria. Here, I describe applications of a microfluidic device for on-chip fluorescent staining and semiautomated counting of target bacteria in food samples.

CRISPR-Cas12a-based nanoparticle biosensor for detection of pathogenic bacteria in food

Carbon dots-based fluorescent probe for detection of foodborne pathogens and its potential with microfluidics

Effective monitoring of contaminants present in food is of great significance for ensuring food safety and maintaining public health. Sensing platforms have been recognized as efficient and reliable tools for the rapid, convenient, and sensitive determination of food contaminants. Among multifarious sensing materials, zirconium‐based metal–organic frameworks (Zr‐MOFs) have attracted enormous attention for the construction of sensing platforms in food safety owning to their excellent chemical stability, high surface area, structural diversity, and tunable functionality. This article presents a comprehensive review of recent advances in Zr‐MOFs‐based sensors for food safety applications. Specifically, the rational construction strategies of Zr‐MOFs for the development of sensing platform are discussed. Then, a detailed analysis of reported Zr‐MOFs as sensing platforms for the detection of food contaminants are summarized. Finally, the current challenges and future opportunities for Zr‐MOF‐based sensor systems are highlighted. This review provides references to functional Zr‐MOFs design and sensing applications in food safety monitoring.

Highlights: Eschericia colli was the most contaminant bacteria among food samples from Warmadewa Cafeterias Further suggestions to increase the hygiene in food processing must be offered. Abstract : Foodborne diseases still remain a problem especially in public areas. This study aimed to identify pathogenic bacteria in foods sold at the cafeterias of Universitas Warmadewa, Denpasar, Indonesia. The presence of pathogenic bacteria in the food samples was identified using the brain heart infusion (BHI) agar for the growth of Escherichia coli and Streptococcus aureus, selenite for Shigella and Salmonella, and alkaline peptone for Vibrio cholerae, then bacterial culture was conducted to identify the species. The results showed that Escherichia coli were found in two food samples, kangkong and jinggo rice, with the colony counts of 50-118. Escherichia coli was the most commonly found contaminant in food samples from the Warmadewa Cafeterias. Further suggestions must be offered to increase hygiene in the food processing by advising the stalls’ owners to serve good foods and conducting regular inspections to assess the food quality.

Carbon dots (CDs) emitting red fluorescence (610nm) were synthesized by solvent thermal treatment of p-phenylenediamine in toluene. Upon 440nm excitation, quercetin (QCT) alone endowed slight effects on the red fluorescence of CDs. Once Zn2+ was further introduced, the QCT-Zn2+ complex wasquickly formed. This complex absorbs excitation light and emits bright green fluorescence at 480nm. The red fluorescence of CDs was greatly quenched owing to the inner-filter effect. The ratio of fluorescence intensity at 480nm and 610nm (I480/I610) gradually increases with increasing concentration (c) of Zn2+. Al3+ exhibits the same phenomen like Zn2+. Fluoride ionsform a more stable complex with Al3+ than QCT-Al3+ complex but have anegligible effect on the QCT-Zn2+ complex. The possible interference of Al3+ on Zn2+ can thusbe avoided by adding certain amount of F-. The CD-QCT-F- system was constructed as a ratio-metric fluorescent nanoprobe toward Zn2+ with determination range of 0.14-30μM and limit of detection (LOD) of 0.14μM. Due to the stronger affinity of adenosine triphosphate (ATP) to Zn2+ than QCT, the I480/I610 value of CD-QCT-F--Zn2+ system gradually decreaseswith increasing cATP. The ratiometric fluorescent nanoprobe toward ATP was established with detection ranges of 0.55-10 and 10-35μM and a LOD of 0.55μM. The above two probes enablethe quantitative determination of Zn2+ and ATP in tap and lake water samples with satisfactory recoveries. Graphical abstract Schematic representation of the ratiometric fluorescent nanoprobes based on the carbon dots (CDs)-quercetin (QCT) system towards Zn2+ and adenosine triphosphate (ATP) with high selectivity and sensitivity.

The simple, rapid, and simultaneous detection of multiple foodborne pathogens in food is crucial for ensuring public safety. In this study, a rational design strategy for lanthanide-based metal-organic frameworks (Ln-MOFs), informed by theoretical calculations, was proposed. The calculated results were experimentally verified to screen out the optimal Ln-MOF for fluorescence efficiency. The selected Ln-MOFs were coupled with phages that exhibit specific pathogen recognition to develop phage@Ln-MOF fluorescent probes, while the magnetic nanoparticles were conjugated with phages to form capture probes. On this basis, a fluorescent biosensor was developed for the simultaneous detection of three major foodborne pathogens-Escherichia coli (E. coli), Staphylococcus aureus (S. aureus), and Salmonella. This sensor facilitated the detection of all three pathogens within 15 min, with limit of detection (LOD) as low as 1 CFU/mL. Moreover, this fluorescent biosensor was compatible with on-site visual detection, utilizing a self-designed portable dark box and smartphone-assisted visualization, achieving an LOD of approximately 1-2 CFU/mL for E. coli, S. aureus, and Salmonella. This work demonstrates a novel approach for the rapid on-site detection of multiple foodborne pathogens, which holds promise for advancing field-ready diagnostic tools in food safety monitoring.

·ATP-enhanced PB@MIL-100(Fe) nanozyme enables dual-mode ratiometric colorimetric and smartphone-based hydrogel detection of nitrite in food samples.

Palm-size wireless piezoelectric immune-biosensing system for rapid E. coli O157:H7 detection

This study deals with the rapid detection and differentiation of Escherichia coli, Salmonella, and Campylobacter, which are the most commonly identified commensal and pathogenic bacteria in foods, using fluorescence spectroscopy and multivariate analysis. Each bacterial sample cultured under controlled conditions was diluted in physiologic saline for analysis. Fluorescence spectra were collected over a range of 200-700 nm with 0.5 nm intervals on the PerkinElmer Fluorescence Spectrometer. The synchronous scan technique was employed to find the optimum excitation (lambda(ex)) and emission (lambda(em)) wavelengths for individual bacteria with the wavelength interval (Deltalambda) being varied from 10 to 200 nm. The synchronous spectra and two-dimensional plots showed two maximum lambda(ex) values at 225 nm and 280 nm and one maximum lambda(em) at 335-345 nm (lambda(em) = lambda(ex) + Deltalambda), which correspond to the lambda(ex) = 225 nm, Deltalambda = 110-120 nm, and lambda(ex) = 280 nm, Deltalambda = 60-65 nm. For all three bacterial genera, the same synchronous scan results were obtained. The emission spectra from the three bacteria groups were very similar, creating difficulty in classification. However, the application of principal component analysis (PCA) to the fluorescence spectra resulted in successful classification of the bacteria by their genus as well as determining their concentration. The detection limit was approximately 10(3)-10(4) cells/mL for each bacterial sample. These results demonstrated that fluorescence spectroscopy, when coupled with PCA processing, has the potential to detect and to classify bacterial pathogens in liquids. The methodology is rapid (>10 min), inexpensive, and requires minimal sample preparation compared to standard analytical methods for bacterial detection.

Rapid detection of foodborne pathogens is critical to ensure food safety. New biosensor technologies provide promising opportunities for rapidly detecting pathogenic bacteria in foods. In this study, a portable biosensor was developed for rapid, specific, and sensitive detection of foodborne pathogens using Escherichia coli O157:H7 as a model target. The biosensor was based on the use of an antibody-modified capillary column as a bio-separator as well as a bio-reactor. An innovative delivery system employing miniature pump and multiposition valves was designed to minimize cross-contamination and/or non-specific binding. The biosensor was connected to a laptop computer via a USB port. A Visual Basic 6 program was written for instrument control as well as for data acquisition and processing. Some pre-programmed modules with special functions could be called flexibly to customize any specific task for the biosensor test. A defined task could be executed with real-time display of measured signals in a dynamic graph. The biosensor could detect E. coli O157:H7 down to 100 CFU/mL in one hour.

Food-borne pathogenic bacteria cause infection and death in humans, and impose great economic losses in the food industry worldwide annually. Therefore, researchers have turned to the use of different types of antimicrobials to control pathogenic bacteria in foods. Due to the side effects of synthetic antimicrobials, much attention has recently been paid to natural ones. Endolysins, enzymes coded by bacteriophages, and their derivatives have been known as natural and safe antimicrobials which may be used to eliminate or reduce pathogenic bacteria in foods and their processing environments. Endolysins are remarkably stable under different conditions, and therefore they may have broader use in the food industry. In addition to describing the structure and production of endolysins, this review provides almost comprehensive information on using endolysins as antimicrobials against food-borne pathogens in vitro and in food models, and against their biofilms. According to the results of published studies, endolysins can be considered as a very suitable alternative to synthetic antimicrobials. The use of endolysins to control food-borne pathogens and increase food safety assurance level have been emphasized due to the rapid and specific action of the endolysins, their good stability, and lack of resistance development to endolysins in bacteria.

Recently, two rapid methods using bacteria-specific DNA or oligonucleotide fragments have been developed for the detection of pathogenic bacteria in food samples. These methods are the DNA-DNA hybridization method, using DNA or oligonucleotide probes, and the polymerase chain reaction (PCR) method, using pairs of oligonucleotide primers. This chapter shows the methods to isolate the salmonella-specific DNA fragment as well as the designation of oligonucleotide probes and PCR primers specific for the detection of all salmonellae serotypes in foods. Relative to the detection sensitivity for such PCR methods, the DNA from one cell could be detected unambiguously. Therefore, in using the PCR method for detection of Salmonella food samples could be used directly for examination, without any enrichment step; thereby considerably shortening the total time required to complete the detection. Although DNA hybridization is a rapid method for bacterial detection, the method is not reliable for some food samples if a suitable enrichment step was not performed before the hybridization step.

Electrochemical biosensors for the detection of pathogenic bacteria in food

Introduction: The clean label trend emphasizes the need for natural approaches to combat pathogenic bacteria in food. This study explores the potential of inducing prophages within bacterial genomes as a novel strategy to control pathogenic and spoilage bacterial growth.Methods: A luminescence-based high-throughput assay was developed to identify natural compounds capable of inducing prophages. Bioactive compounds from four chemical libraries were screened at a final concentration of 10 µM. The assay measured luminescence production in Escherichia coli BR513, a genetically modified strain producing β-galactosidase upon prophage λ induction. Luminescence values were normalized to cell concentration (OD600) and the interquartile mean of each 384-well plate. A cut-off for normalized luminescence values, set at 2.25 standard deviations above the mean, defined positive prophage induction.Results: Four naturally-derived compounds (osthol, roccellic acid, galanginee, and sclareol) exhibited positive prophage induction, along with previously identified inducers, rosemary, and gallic acid. Dose-response experiments were conducted to determine optimal concentrations for prophage induction. However, the results could not distinguish between prophage-induced cell death and other mechanisms, making it challenging to identify ideal concentrations.Discussion: The high-throughput luminescent prophage induction assay serves as a valuable tool for the initial screening of natural bioactive compounds that have the potential to enhance food safety and quality by inducing prophages. Further research is required to understand the mechanism of bacterial cell death and to establish optimal concentrations for prophage induction in a food preservation context.