Recent Advances in Biosensor Development for Foodborne Virus Detection

A CRISPR/Cas12a-powered gold/nickel foam surface-enhanced Raman spectroscopy biosensor for nucleic acid specific detection in foods

Food is a necessary source of energy, but it also serves as a pathway for transmitting infectious pathogens, making food safety a matter of great concern. Rapid, accurate, and specific detection methods for foodborne viruses are crucial. Surface-Enhanced Raman Scattering (SERS), due to its superior sensitivity and characteristic fingerprint spectra, holds enormous potential. However, due to the limitations of SERS, it requires specific conditions to achieve specificity. In order to enhance the specificity and accuracy of nucleic acid detection based on SERS, we have developed a CRISPR-Cas12a-mediated SERS technique to identify target DNA, harnessing the targeting recognition capability of CRISPR-Cas12a and ultra-sensitive SERS tags and successfully addressing SERS' lack of specific detection capability. This system includes a gold/nickel foam substrate (Au-NFs) and a reporter (ssDNA-ROX). The phenomenon of colloidal gold/silver nano-aggregation due to magnesium ions, which is commonly encountered in CRISPR-SERS, was simultaneously solved using AuNFs. The qualitative and quantitative analysis of target DNA in drinking water was performed by monitoring the intensity change of ROX Raman reporter molecules. The results showed that the sensor detected DNA within 30 min and the limit of detection (LOD) was 8.23 fM. This is expected to become one of the alternative methods for nucleic acid detection for its rapid detection and high specificity.

Dual-Mode Virus Detection: Combining Electrochemical and Fluorescence Modalities for Enhanced Sensitivity and Reliability

This study introduces a dual-mode biosensor specifically designed for the quantitative detection of viruses in rapid analysis. The biosensor is unique in its use of both optical (fluorescence) and electrochemical (impedance) detection methods using the same nanocomposites, providing a dual confirmation system for virus (norovirus-like particles) quantification. The system is based on using two antibody-conjugated nanocomposites: CdSeS quantum dots and Au-N,S-GQD nanocomposites. For optical detection, the principle relies on the fluorescence quenching of CdSeS by Au-N,S-GQD in a sandwich structure with the target. Conversely, electrochemical detection is based on the change in impedance caused by the formation of the same sandwich structure. The biosensor demonstrated exceptional sensitivity, capable of detecting norovirus at concentrations of as low as femtomolar in the electrochemical method and picomolar in the optical method. In the dual-responsive concentration range from 10-13 to 10-10 M, the sensor is highly sensitive in both methods, creating significant changes in fluorescence intensity and impedance in the presence of virus. Furthermore, the biosensor exhibits a high degree of specificity, with a negligible response to nontarget proteins, even within complex test solutions. This work represents a significant advancement in the field of biosensor technology, offering a fast, accurate, and reliable method for diagnosing viral infections and diseases.

Common and Potential Emerging Foodborne Viruses: A Comprehensive Review

Human viruses and viruses from animals can cause illnesses in humans after the consumption of contaminated food or water. Contamination may occur during preparation by infected food handlers, during food production because of unsuitably controlled working conditions, or following the consumption of animal-based foods contaminated by a zoonotic virus. This review discussed the recent information available on the general and clinical characteristics of viruses, viral foodborne outbreaks and control strategies to prevent the viral contamination of food products and water. Viruses are responsible for the greatest number of illnesses from outbreaks caused by food, and risk assessment experts regard them as a high food safety priority. This concern is well founded, since a significant increase in viral foodborne outbreaks has occurred over the past 20 years. Norovirus, hepatitis A and E viruses, rotavirus, astrovirus, adenovirus, and sapovirus are the major common viruses associated with water or foodborne illness outbreaks. It is also suspected that many human viruses including Aichi virus, Nipah virus, tick-borne encephalitis virus, H5N1 avian influenza viruses, and coronaviruses (SARS-CoV-1, SARS-CoV-2 and MERS-CoV) also have the potential to be transmitted via food products. It is evident that the adoption of strict hygienic food processing measures from farm to table is required to prevent viruses from contaminating our food.

Mitigating Global Challenges: Harnessing Green Synthesized Nanomaterials for Sustainable Crop Production Systems

Green nanotechnology, an emerging field, offers economic and social benefits while minimizing environmental impact. Nanoparticles, pivotal in medicine, pharmaceuticals, and agriculture, are now sourced from green plants and microorganisms, overcoming limitations of chemically synthesized ones. In agriculture, these green-made nanoparticles find use in fertilizers, insecticides, pesticides, and fungicides. Nanofertilizers curtail mineral losses, bolster yields, and foster agricultural progress. Their biological production, preferred for environmental friendliness and high purity, is cost-effective and efficient. Biosensors aid early disease detection, ensuring food security and sustainable farming by reducing excessive pesticide use. This eco-friendly approach harnesses natural phytochemicals to boost crop productivity. This review highlights recent strides in green nanotechnology, showcasing how green-synthesized nanomaterials elevate crop quality, combat plant pathogens, and manage diseases and stress. These advancements pave the way for sustainable crop production systems in the future.

Surface plasmonic biosensors: principles, designs and applications

Recently, surface plasmon resonance (SPR) biosensors have been widely used in environmental monitoring, food contamination detection and diagnosing medical conditions due to their superior sensitivity, label-free detection and rapid analysis speed. This paper briefly elaborates on the development history of SPR technology and introduces SPR signal sensing principles. A summary of recent applications of SPR sensors in different fields is highlighted, including their figures of merit and limitations. Finally, the personal perspectives and future development trends about sensor preparation and design are discussed in detail, which may be critical for improving the performance of SPR sensors.

Recent Advances in Biosensor Development for the Detection of Viral Particles in Foods: A Comprehensive Review

Viral foodborne diseases cause serious harm to human health and the economy. Rapid, accurate, and convenient approaches for detecting foodborne viruses are crucial for preventing diseases. Biosensors integrating electrochemical and optical properties of nanomaterials have emerged as effective tools for the detection of viruses in foods. However, they still face several challenges, including substantial sample preparation and relatively poor sensitivity due to complex food matrices, which limit their field applications. Hence, the purpose of this review is to provide an overview of recent advances in biosensing techniques, including electrochemical, SERS-based, and colorimetric biosensors, for detecting viral particles in food samples, with emerging techniques for extraction/concentration of virus particles from food samples. Moreover, the principle, design, and advantages/disadvantages of each biosensing method are comprehensively described. This review covers the recent development of rapid and sensitive biosensors that can be used as new standards for monitoring food safety and food quality in the food industry.

A review of rapid food safety testing: using lateral flow assay platform to detect foodborne pathogens

The detrimental impact of foodborne pathogens on human health makes food safety a major concern at all levels of production. Conventional methods to detect foodborne pathogens, such as live culture, high-performance liquid chromatography, and molecular techniques, are relatively tedious, time-consuming, laborious, and expensive, which hinders their use for on-site applications. Recurrent outbreaks of foodborne illness have heightened the demand for rapid and simple technologies for detection of foodborne pathogens. Recently, Lateral flow assays (LFA) have drawn attention because of their ability to detect pathogens rapidly, cheaply, and on-site. Here, we reviewed the latest developments in LFAs to detect various foodborne pathogens in food samples, giving special attention to how reporters and labels have improved LFA performance. We also discussed different approaches to improve LFA sensitivity and specificity. Most importantly, due to the lack of studies on LFAs for the detection of viral foodborne pathogens in food samples, we summarized our recent research on developing LFAs for the detection of viral foodborne pathogens. Finally, we highlighted the main challenges for further development of LFA platforms. In summary, with continuing improvements, LFAs may soon offer excellent performance at point-of-care that is competitive with laboratory techniques while retaining a rapid format.

A review of current effective COVID-19 testing methods and quality control

COVID-19 is a highly infectious disease caused by the SARS-CoV-2 virus, which primarily affects the respiratory system and can lead to severe illness. The virus is extremely contagious, early and accurate diagnosis of SARS-CoV-2 is crucial to contain its spread, to provide prompt treatment, and to prevent complications. Currently, the reverse transcriptase polymerase chain reaction (RT-PCR) is considered to be the gold standard for detecting COVID-19 in its early stages. In addition, loop-mediated isothermal amplification (LMAP), clustering rule interval short palindromic repeats (CRISPR), colloidal gold immunochromatographic assay (GICA), computed tomography (CT), and electrochemical sensors are also common tests. However, these different methods vary greatly in terms of their detection efficiency, specificity, accuracy, sensitivity, cost, and throughput. Besides, most of the current detection methods are conducted in central hospitals and laboratories, which is a great challenge for remote and underdeveloped areas. Therefore, it is essential to review the advantages and disadvantages of different COVID-19 detection methods, as well as the technology that can enhance detection efficiency and improve detection quality in greater details.

Detection Methods for Foodborne Viruses: Current State-of-Art and Future Perspectives

Foodborne viruses have been recognized as important threats to food safety and human health. Rapid and accurate detection is one of the most crucial measures for food safety control. With the development of biology, chemistry, nanoscience, and related interdisciplines, detection strategies have been devised and advanced continuously. This review mainly focuses on the progress of detection methods for foodborne viruses. The current detection methods for foodborne viruses are summarized, including traditional electron microscopy and cultural isolation, immunoassay, molecular technology, biosensors, and newly emerging CRISPR/Cas-based detection technology. Furthermore, a comparison of the detection methods was objectively discussed. This review provides a comprehensive account of foodborne virus detection methods from fundamentals to state-of-the-art and illustrates the advantages and disadvantages of the current methods and proposes the future trends and directions for foodborne virus detection. It is hoped that this review can update current knowledge and present blueprints in order to accelerate futuristic development.

Positively Charged Gold Quantum Dots: An Nanozymatic "Off-On" Sensor for Thiocyanate Detection

The concentration of thiocyanate (SCN⁻) in bodily fluids is a good indicator of potential and severe health issues such as nasal bleeding, goiters, vertigo, unconsciousness, several inflammatory diseases, and cystic fibrosis. Herein, a visual SCN⁻ sensing method has been developed using the enzyme-like nature of positively charged gold quantum dots (Au QDs) mixed with 3,3′,5,5′-tetramethylbenzidine (TMB) and hydrogen peroxide (H₂O₂₎. This research also reports a new method of synthesizing positively charged Au QDs directly from gold nanoparticles through a hydrothermal process. Microscopic imaging has showed that the Au QDs were 3–5 nm in size, and the emission wavelength was at 438 nm. Au QDs did not display any enzyme-like nature while mixed up with TMB and H₂O₂. However, the nanozymatic activity of Au QDs appeared when SCN⁻ was included, leading to a very low detection limit (LOD) of 8 nM and 99–105% recovery in complex media. The steady-state kinetic reaction of Au QDs showed that Au QDs had a lower Michaelis–Menten constant (Km) toward H₂O₂ and TMB, which indicates that the Au QDs had a higher affinity for H₂O₂ and TMB than horseradish peroxidase (HRP). A mechanism study has revealed that the scavenging ability of hydroxyl (•OH) radicals by the SCN⁻ group plays an important role in enhancing the sensitivity in this study. The proposed nanozymatic “Off–On” SCN⁻ sensor was also successfully validated in commercial milk samples.

Viral outbreaks detection and surveillance using wastewater-based epidemiology, viral air sampling, and machine learning techniques: A comprehensive review and outlook

A viral outbreak is a global challenge that affects public health and safety. The coronavirus disease 2019 (COVID-19) has been spreading globally, affecting millions of people worldwide, and led to significant loss of lives and deterioration of the global economy. The current adverse effects caused by the COVID-19 pandemic demands finding new detection methods for future viral outbreaks. The environment's transmission pathways include and are not limited to air, surface water, and wastewater environments. The wastewater surveillance, known as wastewater-based epidemiology (WBE), can potentially monitor viral outbreaks and provide a complementary clinical testing method. Another investigated outbreak surveillance technique that has not been yet implemented in a sufficient number of studies is the surveillance of Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) in the air. Artificial intelligence (AI) and its related machine learning (ML) and deep learning (DL) technologies are currently emerging techniques for detecting viral outbreaks using global data. To date, there are no reports that illustrate the potential of using WBE with AI to detect viral outbreaks. This study investigates the transmission pathways of SARS-CoV-2 in the environment and provides current updates on the surveillance of viral outbreaks using WBE, viral air sampling, and AI. It also proposes a novel framework based on an ensemble of ML and DL algorithms to provide a beneficial supportive tool for decision-makers. The framework exploits available data from reliable sources to discover meaningful insights and knowledge that allows researchers and practitioners to build efficient methods and protocols that accurately monitor and detect viral outbreaks. The proposed framework could provide early detection of viruses, forecast risk maps and vulnerable areas, and estimate the number of infected citizens.

Plasmonic Metasurfaces Based on Pyramidal Nanoholes for High-Efficiency SERS Biosensing

An inverted pyramidal metasurface was designed, fabricated, and studied at the nanoscale level for the development of a label-free pathogen detection on a chip platform that merges nanotechnology and surface-enhanced Raman scattering (SERS). Based on the integration and synergy of these ingredients, a virus immunoassay was proposed as a relevant proof of concept for very sensitive detection of hepatitis A virus, for the first time to our best knowledge, in a very small volume (2 μL), without complex signal amplification, allowing to detect a minimal virus concentration of 13 pg/mL. The proposed work aims to develop a high-flux and high-accuracy surface-enhanced Raman spectroscopy (SERS) nanobiosensor for the detection of pathogens to provide an effective method for early and easy water monitoring, which can be fast and convenient.

Antiviral Potential of Plants against Noroviruses

Human noroviruses, which belong to the enterovirus family, are one of the most common etiological agents of food-borne diseases. In recent years, intensive research has been carried out regarding the antiviral activity of plant metabolites that could be used for the preservation of fresh food, because they are safer for consumption when compared to synthetic chemicals. Plant preparations with proven antimicrobial activity differ in their chemical compositions, which significantly affects their biological activity. Our review aimed to present the results of research related to the characteristics, applicability, and mechanisms of the action of various plant-based preparations and metabolites against norovirus. New strategies to combat intestinal viruses are necessary, not only to ensure food safety and reduce infections in humans but also to lower the direct health costs associated with them.

In situ food-borne pathogen sensors in a nanoconfined space by surface enhanced Raman scattering

The incidence of disease arising from food-borne pathogens is increasing continuously and has become a global public health problem. Rapid and accurate identification of food-borne pathogens is essential for adopting disease intervention strategies and controlling the spread of epidemics. Surface-enhanced Raman spectroscopy (SERS) has attracted increasing interest due to the attractive features including simplicity, rapid measurement, and high sensitivity. It can be used for rapid in situ sensing of single and multicomponent samples within the nanostructure-based confined space by providing molecular fingerprint information and has been demonstrated to be an effective detection strategy for pathogens. This article aims to review the application of SERS to the rapid sensing of food-borne pathogens in food matrices. The mechanisms and advantages of SERS, and detection strategies are briefly discussed. The latest progress on the use of SERS for rapid detection of food-borne bacteria and viruses is considered, including both the labeled and label-free detection strategies. In closing, according to the current situation regarding detection of food-borne pathogens, the review highlights the challenges faced by SERS and the prospects for new applications in food safety.

Graphical abstract

Biosensors as a future diagnostic approach for COVID-19

Biosensors are important devices in clinical diagnostics, food processing, and environmental monitoring for detecting various analytes, especially viruses. These biosensors provide rapid and effective instruments for qualitative and quantitative detection of infectious diseases in real-time. Here, we report the development of biosensors based on various techniques. Additionally, we will explain the mechanisms, advantages, and disadvantages of the most common biosensors that are currently used for viral detection, which could be optical (e.g., surface-enhanced Raman scattering (SERS), Surface plasmon resonance (SPR)) and electrochemical biosensors. Based on that, this review recommends methods for efficient, simple, low-cost, and rapid detection of SARS-CoV-2 (the causative agent of COVID-19) that employ the two types of biosensors depending on attaching hemoglobin β-chain and binding of specific antibodies with SARS-CoV-2 antigens, respectively.

COVID-19 pandemic sheds light on the importance of food safety practices: risks, global recommendations, and perspectives

The outbreak of the coronavirus disease (COVID-19) is global health and humanitarian emergency. To respond effectively to this pandemic, it is mandatory to reaffirm science in its different fields of study, including the food safety area. Presently, we review food safety in times of COVID-19, exploring whether the virus can be transmitted by food or water; recommendations from regulatory agencies; perceptions of food hygiene practices during the pandemic; and post-pandemic perspectives. The review was based on papers published in Web of Science, Scopus, Pubmed, and covered recommendations of public health protection and regulatory agencies around the world. The transmission of the severe acute respiratory syndrome (SARS-CoV-2) by food was not confirmed until the present time. In any case, the protocols already established for food safety were reinforced, emphasizing the proper hygiene of hands after shopping, handling food packages, or before manipulating or eating food, adequate social distance, the use of individual protection equipment, the health of employees, and the proper preparation of food. It is hoped, in the post-pandemic scenario, to reach a better understanding of the particularities that led to greater care with food hygiene. Moreover, it is expected that the food system will creatively adapt the way meals are served.

Recent trends in the utilization of LAMP for the diagnosis of viruses, bacteria, and allergens in food

Foodborne diseases are becoming major scientific struggles for both developing and developed countries. Most foodborne infections are caused by microbial pathogens such as bacteria, viruses, and other food allergens. Hence early and accurate diagnosis of these foodborne pathogens is always preferable. To satisfy these concerns, plenty of isothermal amplification methodologies such as rolling circle amplification (RCA), helicase-dependent amplification (HDA), and recombinase polymerase amplification (RPA) have been developed. Among these, loop-mediated isothermal amplification (LAMP) is a widely usable, potential, and recognizable amplification technique achieved at a constant temperature around 60°C within 30–60 min by using only one kind of enzyme. As a robust gene amplification technique, it can be employed for the detection of bacteria, viruses, and other related food allergens. This technique has its own merits such as cost-effectiveness, facile manufacturing procedure, and consistency. In this chapter, we emphasize recent trends in designing the techniques, challenges, and the future prospects of LAMP in the detection of foodborne pathogens. These effective pathogen detection methods may offer potential benefits compared with existing conventional methods.

Performance of concanavalin A-immobilized on polyacrylate beads for the detection of human norovirus and hepatitis A virus in fecal specimens

Quantitative reverse transcription PCR (qRT-PCR) is a sensitive method for the detection of foodborne viruses in fecal samples. However, the performance of qRT-PCR depends on the efficiency of virus concentration methods. In this study, the effect of Concanavalin A (Con A)-immobilized on polyacrylate beads (Con A-PAB) on the qRT-PCR performance, in terms of sensitivity and specificity to detect foodborne viruses in human fecal specimens was compared with commercial viral RNA extraction kit (VRNA). The detection of foodborne viruses by qRT-PCR was validated by viral genome sequencing. Both Con A-PAB and VRNA methods were equally sensitive and specific for detecting hepatitis A virus in fecal specimens. Even though both methods showed high specificity (100% vs. 100%) for detecting human norovirus (HuNoV), Con A-PAB method exhibited higher sensitivity (100% vs. 42.9%) and accuracy (100% vs. 73.3%) compared to VRNA method. In conclusion, the application of Con A-PAB would improve the performance of qRT-PCR for the detection of HuNoV in fecal samples.

Water safety screening via multiplex LAMP-Au-nanoprobe integrated approach

Contaminated water resources remain a major global concern regarding public health. The majority of water safety protocols include indicators of microbial contamination to evaluate the potential risk to public health and are key elements of quality guidelines. Among these, markers for total coliforms and fecal coliforms are strong indicators of co-contamination with other pathogens. Traditional methods, recurring to slow and cumbersome culture-based approaches, have been gradually replaced by molecular methods, capable of faster and more specific screening. These are usually PCR-based methods that may allow for multiple pathogen detection but require dedicated laboratory equipment, hindering the rapid on-site assessment. Here, we used a multiplex Loop-Mediated Isothermal Amplification (mLAMP) strategy for the amplification of two markers associated with the contamination by total and fecal coliforms (e.g. Escherichia coli) - lacZ and uidA genes, respectively - thus allowing for single tube multiplex detection. The mLAMP products were then subject to an Au-nanoprobe colorimetric detection assay for precise discrimination of targets. This approach was validated in 22 water samples that were also screened for the presence of lacZ and uidA using standard and quantitative PCR, with the capability for discriminating the contamination level, e.g. a semi-quantitative evaluation of water quality.

Foodborne Viruses and Innovative Non-Thermal Food-Processing Technologies

In recent years, several foodborne viruses' outbreaks have been recorded worldwide. Μost of the foodborne viruses have a low infection dose, are stable and can persist and survive in foods for a long time without loss of infectivity. The most important foodborne viruses are: human norovirus (HuNoV), human rotavirus (HRV), hepatitis A virus (HAV), hepatitis E virus (HEV), human astrovirus (HAstV), Aichi virus (AiV), sapovirus (SaV), human adenovirus (HAdV) and enterovirus (EV). In recent years, innovative non-thermal food-processing technologies including high-pressure processing (HPP), cold plasma (CP), ultraviolet light (UV), irradiation and pulsed electric field (PEF) for improving the quality and safety of foods, including foods of animal origin, have been under research. This review presents the recent data on foodborne viruses and reviews the innovative non-thermal technologies for the control of the foodborne viruses in foods.

Current and Emerging Technologies for the Detection of Norovirus from Shellfish

Reports of norovirus infections associated with the consumption of contaminated bivalve molluscan shellfish negatively impact both consumers and commercial shellfish operators. Current virus recovery and PCR detection methods can be expensive and time consuming. Due to the lack of rapid, user-friendly and onsite/infield methods, it has been difficult to establish an effective virus monitoring regime that is able to identify contamination points across the production line (i.e., farm-to-plate) to ensure shellfish quality. The focus of this review is to evaluate current norovirus detection methods and discuss emerging approaches. Recent advances in omics-based detection approaches have the potential to identify novel biomarkers that can be incorporated into rapid detection kits for onsite use. Furthermore, some omics techniques have the potential to simultaneously detect multiple enteric viruses that cause human disease. Other emerging technologies discussed include microfluidic, aptamer and biosensor-based detection methods developed to detect norovirus with high sensitivity from a simple matrix. Many of these approaches have the potential to be developed as user-friendly onsite detection kits with minimal costs. However, more collaborative efforts on research and development will be required to commercialize such products. Once developed, these emerging technologies could provide a way forward that minimizes public health risks associated with shellfish consumption.

Functional chimera aptamer and molecular beacon based fluorescent detection of Staphylococcus aureus with strand displacement-target recycling amplification

A fluorescent detection of Staphylococcus aureus (S. aureus) is established based on a finely designed functional chimera sequence, a molecular beacon (MB), and strand displacement target recycling. The chimera sequence, which consists of the aptamer sequence of S. aureus and the complementary sequence of MB, can form a hairpin structure due to the existence of intramolecular complementary regions. When S. aureus is present, it binds to the aptamer region of the chimera, opens the hairpin and unlocks the complementary sequence of MB. Subsequently, the MB is opened and intensive fluorescence signal is restored. To increase the sensitivity of the detection, signal amplification is achieved through strand displacement-based target recycling. With the catalysis of Nb. Bpu10I nicking endonuclease and Bsm DNA polymerase, the MB sequence can be cleaved and then elongated to form a complete duplex with the chimera, during which S. aureus is displaced from the chimera and proceeded to the next round of the reaction. This assay displays a linear correlation between the fluorescence intensity and the logarithm of the concentration of S. aureus within a broad concentration range from 80 CFU/mL to 8 × 10⁶ CFU/mL. The detection limit of 39 CFU/mL can be derived. The assay was applied to detect S. aureus in different water samples, and satisfactory recovery and repeatability were achieved. Hence the designed chimera sequence and established assay have potential application in environmental pollution monitoring.

Progress in the Development of Intrinsically Conducting Polymer Composites as Biosensors

Biosensors are analytical devices which find extensive applications in fields such as the food industry, defense sector, environmental monitoring, and in clinical diagnosis. Similarly, intrinsically conducting polymers (ICPs) and their composites have lured immense interest in bio-sensing due to their various attributes like compatibility with biological molecules, efficient electron transfer upon biochemical reactions, loading of bio-reagent, and immobilization of biomolecules. Further, they are proficient in sensing diverse biological species and compounds like glucose (detection limit ≈0.18 nm), DNA (≈10 pm), cholesterol (≈1 µm), aptamer (≈0.8 pm), and also cancer cells (≈5 pm mL-1) making them a potential candidate for biological sensing functions. ICPs and their composites have been extensively exploited by researchers in the field of biosensors owing to these peculiarities; however, no consolidated literature on the usage of conducting polymer composites for biosensing functions is available. This review extensively elucidates on ICP composites and doped conjugated polymers for biosensing functions of copious biological species. In addition, a brief overview is provided on various forms of biosensors, their sensing mechanisms, and various methods of immobilizing biological species along with the life cycle assessment of biosensors for various biosensing applications, and their cost analysis.

An Electrochemical Aptasensor Using Coaxial Capillary with Magnetic Nanoparticle, Urease Catalysis and PCB Electrode for Rapid and Sensitive Detection of Escherichia coli O157:H7

The continuous outbreaks of foodborne diseases have drawn public attentions to food safety. Early screening of foodborne pathogens is crucial to prevent and control of foodborne diseases. In this study, a novel electrochemical aptasensor was developed for rapid and sensitive detection of E. coli O157:H7 using the coaxial capillary with immune magnetic nanoparticles (MNPs) for specific separation of the target bacteria, the urease with urea for amplification of the impedance signals, and the PCB gold electrode for measurement of the impedance change. The streptavidin modified MNPs were conjugated with the biotinylated polyclonal antibodies (PAbs) to form the immune MNPs, and captured in the coaxial capillary with the line-up high gradient magnetic fields to separate the bacteria from the large volume of sample. Then, the gold nanoparticles (GNPs) were modified with the aptamers against E. coli and the urease, and injected into the capillary to react with the bacteria and form the MNP-PAb-bacteria-aptamer-GNP-urease complexes. Finally, the urease on the complexes was used to catalyze the hydrolysis of urea into ammonium ions and carbonate ions in the capillary, leading to the decrease in the impedance of the catalysate, which was measured by the gold plating PCB electrode. The impedance change of the catalysate and the concentration of the bacteria had a good linear relationship. This aptasensor was able to detect E. coli as low as 10¹ CFU/mL in 3 h, and the mean recovery of E. coli in the spiked pasteurized milk was ~99%. This proposed aptasensor has the potential for practical applications of foodborne pathogen detection due to its short detection time, high sensitivity and low cost.