Organic conducting polymer electrode based sensors for detection of Salmonella infecting bacteriophages

Principles, Methods, and Real-Time Applications of Bacteriophage-Based Pathogen Detection

Bacterial pathogens in water, food, and the environment are spreading diseases around the world. According to a World Health Organization (WHO) report, waterborne pathogens pose the most significant global health risks to living organisms, including humans and animals. Conventional bacterial detection approaches such as colony counting, microscopic analysis, biochemical analysis, and molecular analysis are expensive, time-consuming, less sensitive, and require a pre-enrichment step. However, the bacteriophage-based detection of pathogenic bacteria is a robust approach that utilizes bacteriophages, which are viruses that specifically target and infect bacteria, for rapid and accurate detection of targets. This review shed light on cutting-edge technologies about the novel structure of phages and the immobilization process on the surface of electrodes to detect targeted bacterial cells. Similarly, the purpose of this study was to provide a comprehensive assessment of bacteriophage-based biosensors utilized for pathogen detection, as well as their trends, outcomes, and problems. This review article summaries current phage-based pathogen detection strategies for the development of low-cost lab-on-chip (LOC) and point-of-care (POC) devices using electrochemical and optical methods such as surface-enhanced Raman spectroscopy (SERS).

Bacteriophage-Based Biosensors: A Platform for Detection of Foodborne Bacterial Pathogens from Food and Environment

Foodborne microorganisms are an important cause of human illness worldwide. Two-thirds of human foodborne diseases are caused by bacterial pathogens throughout the globe, especially in developing nations. Despite enormous developments in conventional foodborne pathogen detection methods, progress is limited by the assay complexity and a prolonged time-to-result. The specificity and sensitivity of assays for live pathogen detection may also depend on the nature of the samples being analyzed and the immunological or molecular reagents used. Bacteriophage-based biosensors offer several benefits, including specificity to their host organism, the detection of only live pathogens, and resistance to extreme environmental factors such as organic solvents, high temperatures, and a wide pH range. Phage-based biosensors are receiving increasing attention owing to their high degree of accuracy, specificity, and reduced assay times. These characteristics, coupled with their abundant supply, make phages a novel bio-recognition molecule in assay development, including biosensors for the detection of foodborne bacterial pathogens to ensure food safety. This review provides comprehensive information about the different types of phage-based biosensor platforms, such as magnetoelastic sensors, quartz crystal microbalance, and electrochemical and surface plasmon resonance for the detection of several foodborne bacterial pathogens from various representative food matrices and environmental samples.

Decontamination of N95 and surgical masks using a treatment based on a continuous gas phase-Advanced Oxidation Process

A gas-phase Advanced Oxidation Process (gAOP) was evaluated for decontaminating N95 and surgical masks. The continuous process was based on the generation of hydroxyl-radicals via the UV-C (254 nm) photo-degradation of hydrogen peroxide and ozone. The decontamination efficacy of the gAOP was dependent on the orientation of the N95 mask passing through the gAOP unit with those positioned horizontally enabling greater exposure to hydroxyl-radicals compared to when arranged vertically. The lethality of gAOP was independent of the applied hydrogen peroxide concentration (2-6% v/v) but was significantly (P<0.05) higher when H2O2 was introduced into the unit at 40 ml/min compared to 20 ml/min. A suitable treatment for N95 masks was identified as 3% v/v hydrogen peroxide delivered into the gAOP reactor at 40 ml/min with continuous introduction of ozone gas and a UV-C dose of 113 mJ/cm2 (30 s processing time). The treatment supported >6 log CFU decrease in Geobacillus stearothermophilus endospores, > 8 log reduction of human coronavirus 229E, and no detection of Escherichia coli K12 on the interior and exterior of masks. There was no negative effect on the N95 mask fitting or particulate efficacy after 20 passes through the gAOP system. No visual changes or hydrogen peroxide residues were detected (<1 ppm) in gAOP treated masks. The optimized gAOP treatment could also support >6 log CFU reduction of endospores inoculated on the interior or exterior of surgical masks. G. stearothermophilus Apex spore strips could be applied as a biological indicator to verify the performance of gAOP treatment. Also, a chemical indicator based on the oxidative polymerization of pyrrole was found suitable for reporting the generation of hydroxyl-radicals. In conclusion, gAOP is a verifiable treatment that can be applied to decontaminate N95 and surgical masks without any negative effects on functionality.

Development of biohybrid immuno-selective membranes for target antigen recognition

Membranes are gaining increasing interest in solid-phase analytical assay and biosensors applications, in particular as functional surface for bioreceptors immobilization and stabilization as well as for the concentration of target molecules in microsystems. In this work, regenerated cellulose immuno-affinity membranes were developed and they were used for the selective capture of interleukin-6 (IL-6) as targeted antigen. Protein G was covalently linked on the membrane surface and it was successfully used for the oriented site-specific antibody immobilization. The antibody binding capacity of the protein G-coupled membrane was evaluated. The specific anti IL-6 antibody was immobilized and a quantitative analysis of the amount of IL-6 captured by the immuno-affinity membrane was performed. The immobilization procedure was optimized to eliminate the non-specific binding of antigen on the membrane surface. Additionally, the interaction between anti IL-6 antibody and protein G was stabilized by chemical cross-linking with glutaraldehyde and the capture ability of immuno-affinity membranes, with and without the cross-linker, was compared. The maximum binding capacity of the protein G-coupled membrane was 43.8µg/cm² and the binding efficiency was 88%. The immuno-affinity membranes showed a high IL-6 capture efficiency at very low antigen concentration, up to a maximum of 91%, the amount of captured IL-6 increased linearly as increasing the initial concentration. The cross-linked surface retained the antigen binding capacity demonstrating its robustness in being reused, without antibody leakage or reduction in antibody binding capacity. The overall results demonstrated the possibility of a reliable application of the immuno-affinity membrane developed for biosensors and bioassays also in multiple use.

A Review of Membrane-Based Biosensors for Pathogen Detection

Biosensors are of increasing interest for the detection of bacterial pathogens in many applications such as human, animal and plant health, as well as food and water safety. Membranes and membrane-like structures have been integral part of several pathogen detection platforms. Such structures may serve as simple mechanical support, function as a part of the transduction mechanism, may be used to filter out or concentrate pathogens, and may be engineered to specifically house active proteins. This review focuses on membrane materials, their associated biosensing applications, chemical linking procedures, and transduction mechanisms. The sensitivity of membrane biosensors is discussed, and the state of the field is evaluated and summarized.

Bacteriophages: biosensing tools for multi-drug resistant pathogens

Pathogen detection is of utmost importance in many sectors, such as in the food industry, environmental quality control, clinical diagnostics, bio-defence and counter-terrorism. Failure to appropriately, and specifically, detect pathogenic bacteria can lead to serious consequences, and may ultimately be lethal. Public safety, new legislation, recent outbreaks in food contamination, and the ever-increasing prevalence of multidrug-resistant infections have fostered a worldwide research effort targeting novel biosensing strategies. This review concerns phage-based analytical and biosensing methods targeted towards theranostic applications. We discuss and review phage-based assays, notably phage amplification, reporter phage, phage lysis, and bioluminescence assays for the detection of bacterial species, as well as phage-based biosensors, including optical (comprising SPR sensors and fiber optic assays), electrochemical (comprising amperometric, potentiometric, and impedimetric sensors), acoustic wave and magnetoelastic sensors.

Comparative study of thermal stability of magnetostrictive biosensor between two kinds of biorecognition elements

Magnetostrictive biosensors specific to Salmonella typhimurium were prepared by immobilizing antibody or phage as biorecognition elements onto the magnetostrictive sensor platform. The sensors were stored at temperatures of 25 °C (room temperature), 45 °C and 65 °C, respectively, and the ability to bind S. typhimurium was detected by testing the resonant frequency shift using a HP network analyzer after exposure to 1 mL of 1×10(9) cfu/mL of S. typhimurium at a predetermined schedule. The binding of S. typhimurium to biosensors was confirmed by Scanning Electron Microscopy (SEM). The results showed that there existed an initial sudden drop in the average density of S. typhimurium bound to the biosensor surface versus duration at different temperatures for the two kinds of recognition elements, and the binding ability to S. typhimurium of phage-immobilized biosensors was much better than that of antibody-immobilized biosensors, with longevity longer than 30 days at all tested temperatures, though decreasing gradually over the testing period. While the longevity of antibody-immobilized biosensors was only about 30, 8 and 5 days at room temperature (25 °C), 45 °C and 65 °C, respectively. Meanwhile, the activation energy of the two kinds of biosensors was investigated, and it was found that phage immobilized sensors showed much higher activation energy than antibody immobilized sensors, which resulted in less dependency on temperature and thus having much better thermal stability than antibody immobilized sensors.

Critical issues in sensor science to aid food and water safety

The stability of food and water supplies is widely recognized as a global issue of fundamental importance. Sensor development for food and water safety by nonconventional assays continues to overcome technological challenges. The delicate balance between attaining adequate limits of detection, chemical fingerprinting of the target species, dealing with the complex food matrix, and operating in difficult environments are still the focus of current efforts. While the traditional pursuit of robust recognition methods remains important, emerging engineered nanomaterials and nanotechnology promise better sensor performance but also bring about new challenges. Both advanced receptor-based sensors and emerging non-receptor-based physical sensors are evaluated for their critical challenges toward out-of-laboratory applications.

Bacteriophage based probes for pathogen detection

Rapid and specific detection of pathogenic bacteria is important for the proper treatment, containment and prevention of human, animal and plant diseases. Identifying unique biological probes to achieve a high degree of specificity and minimize false positives has therefore garnered much interest in recent years. Bacteriophages are obligate intracellular parasites that subvert bacterial cell resources for their own multiplication and production of disseminative new virions, which repeat the cycle by binding specifically to the host surface receptors and injecting genetic material into the bacterial cells. The precision of host recognition in phages is imparted by the receptor binding proteins (RBPs) that are often located in the tail-spike or tail fiber protein assemblies of the virions. Phage host recognition specificity has been traditionally exploited for bacterial typing using laborious and time consuming bacterial growth assays. At the same time this feature makes phage virions or RBPs an excellent choice for the development of probes capable of selectively capturing bacteria on solid surfaces with subsequent quick and automatic detection of the binding event. This review focuses on the description of pathogen detection approaches based on immobilized phage virions as well as pure recombinant RBPs. Specific advantages of RBP-based molecular probes are also discussed.

Recent advances in recognition elements of food and environmental biosensors: a review

A sensitive monitoring of contaminants in food and environment, such as chemical compounds, toxins and pathogens, is essential to assess and avoid risks for both, human and environmental health. To accomplish this, there is a high need for sensitive, robust and cost-effective biosensors that make real time and in situ monitoring possible. Due to their high sensitivity, selectivity and versatility, affinity-based biosensors are interesting for monitoring contaminants in food and environment. Antibodies have long been the most popular affinity-based recognition elements, however recently a lot of research effort has been dedicated to the development of novel recognition elements with improved characteristics, like specificity, stability and cost-efficiency. This review discusses three of these innovative affinity-based recognition elements, namely, phages, nucleic acids and molecular imprinted polymers and gives an overview of biosensors for food and environmental applications where these novel affinity-based recognition elements are applied.