Molecular imprinting technology for sensing foodborne pathogenic bacteria

Sensitive and specific detection of Listeria monocytogenes in food samples using imprinted upconversion fluorescence probe prepared by emulsion polymerization method

Listeria monocytogenes (L. monocytogenes) is a foodborne pathogen with high morbidity and mortality rates, necessitating rapid detection methods. Current techniques, while reliable, are labor-intensive and not amenable to on-site testing. We report the design and synthesis of a novel imprinted upconversion fluorescence probe through Pickering emulsion polymerization for the specific detection of L. monocytogenes. The probe employs trimethylolpropane trimethacrylate and divinylbenzene as cross-linkers, acryloyl-modified chitosan as a functional monomer, and the bacterium itself as the template. The developed probe demonstrated high specificity and sensitivity in detecting L. monocytogenes, with a limit of detection of 72 CFU/mL. It effectively identified the pathogen in contaminated salmon and chicken samples, with minimal background interference. The integration of molecular imprinting and upconversion fluorescence materials presents a potent and reliable approach for the rapid and specific detection of L. monocytogenes, offering considerable potential for on-site food safety testing.

Emerging Biomimetic Sensor Technologies for the Detection of Pathogenic Bacteria: A Commercial Viability Study

Ensuring a rapid and accurate identification of harmful bacteria is crucial in various fields including environmental monitoring, food safety, and clinical diagnostics. Conventional detection methods often suffer from limitations such as long analysis time, complexity, and the need for qualified personnel. Therefore, a lot of research effort is devoted to developing technologies with the potential to revolutionize the detection of pathogenic bacteria by offering rapid, sensitive, and user-friendly platforms for point-of-care analysis. In this light, biosensors have gained significant commercial attention in recent years due to their simplicity, portability, and rapid analysis capabilities. The purpose of this review is to identify a trend by analyzing which biosensor technologies have become commercially successful in the field of bacteria detection. Moreover, we highlight the characteristics that a biosensor must possess to finally arrive in the market and therefore in the hands of the end-user, and we present critical examples of the market applications of various technologies. The aim is to investigate the reason why certain technologies have achieved commercial success and extrapolate these trends to the future economic viability of a new subfield in the world of biosensing: the development of biomimetic sensor platforms. Therefore, an overview of recent advances in the field of biomimetic bacteria detection will be presented, after which the challenges that need to be addressed in the coming years to improve market penetration will be critically evaluated. We will zoom into the current shortcomings of biomimetic sensors based on imprinting technology and aptamers and try to come up with a recommendation for further development based on the trends observed from previous commercial success stories in biosensing.

Multimodal Biosensing of Foodborne Pathogens

Microbial foodborne pathogens present significant challenges to public health and the food industry, requiring rapid and accurate detection methods to prevent infections and ensure food safety. Conventional single biosensing techniques often exhibit limitations in terms of sensitivity, specificity, and rapidity. In response, there has been a growing interest in multimodal biosensing approaches that combine multiple sensing techniques to enhance the efficacy, accuracy, and precision in detecting these pathogens. This review investigates the current state of multimodal biosensing technologies and their potential applications within the food industry. Various multimodal biosensing platforms, such as opto-electrochemical, optical nanomaterial, multiple nanomaterial-based systems, hybrid biosensing microfluidics, and microfabrication techniques are discussed. The review provides an in-depth analysis of the advantages, challenges, and future prospects of multimodal biosensing for foodborne pathogens, emphasizing its transformative potential for food safety and public health. This comprehensive analysis aims to contribute to the development of innovative strategies for combating foodborne infections and ensuring the reliability of the global food supply chain.

Review of Detection Limits for Various Techniques for Bacterial Detection in Food Samples

Foodborne illnesses can be infectious and dangerous, and most of them are caused by bacteria. Some common food-related bacteria species exist widely in nature and pose a serious threat to both humans and animals; they can cause poisoning, diseases, disabilities and even death. Rapid, reliable and cost-effective methods for bacterial detection are of paramount importance in food safety and environmental monitoring. Polymerase chain reaction (PCR), lateral flow immunochromatographic assay (LFIA) and electrochemical methods have been widely used in food safety and environmental monitoring. In this paper, the recent developments (2013-2023) covering PCR, LFIA and electrochemical methods for various bacterial species (Salmonella, Listeria, Campylobacter, Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli)), considering different food sample types, analytical performances and the reported limit of detection (LOD), are discussed. It was found that the bacteria species and food sample type contributed significantly to the analytical performance and LOD. Detection via LFIA has a higher average LOD (24 CFU/mL) than detection via electrochemical methods (12 CFU/mL) and PCR (6 CFU/mL). Salmonella and E. coli in the Pseudomonadota domain usually have low LODs. LODs are usually lower for detection in fish and eggs. Gold and iron nanoparticles were the most studied in the reported articles for LFIA, and average LODs were 26 CFU/mL and 12 CFU/mL, respectively. The electrochemical method revealed that the average LOD was highest for cyclic voltammetry (CV) at 18 CFU/mL, followed by electrochemical impedance spectroscopy (EIS) at 12 CFU/mL and differential pulse voltammetry (DPV) at 8 CFU/mL. LOD usually decreases when the sample number increases until it remains unchanged. Exponential relations (R2 > 0.95) between LODs of Listeria in milk via LFIA and via the electrochemical method with sample numbers have been obtained. Finally, the review discusses challenges and future perspectives (including the role of nanomaterials/advanced materials) to improve analytical performance for bacterial detection.

Lemon essential oil nanoemulsions: Potential natural inhibitors against Escherichia coli

Lemon essential oil (LEO) is a common natural antibacterial substance, and encapsulating LEO into nanoemulsions (NEs) can improve their stability and broaden its application. Our study aimed to investigate the bacterial inhibitory effect of LEO-NEs against Escherichia coli (E. coli). Results showed that the minimum inhibitory concentration (MIC) of LEO-NEs was 6.25 mg/mL, and the time-kill curve showed that E. coli were significantly killed by LEO-NEs after 5 h of treatment at 1MIC. Flow-cytometry analysis showed that LEO-NEs adversely affected the cell-membrane depolarisation, cell-membrane integrity, and efflux pump function of E. coli. Confocal laser scanning microscopy demonstrated that 8MIC of LEO-NEs induced changes in the cell-membrane permeability and cell-wall integrity of E. coli. Proteomic results suggested that the mode of action LEO-NEs against E. coli was to enhance bacterial chemotaxis and significantly inhibit ribosomal assembly. They may also affect butyric acid, ascorbic acid and aldehyde metabolism, and sulphur-relay system pathways. In conclusion, LEO-NEs had potential application as a natural antibacterial agent for the control of E. coli in the food industry.

Advancements in Cortisol Detection: From Conventional Methods to Next-Generation Technologies for Enhanced Hormone Monitoring

The hormone cortisol, released as the end-product of the hypothalamic-pituitary-adrenal (HPA) axis, has a well-characterized circadian rhythm that enables an allostatic response to external stressors. When the pattern of secretion is disrupted, cortisol levels are chronically elevated, contributing to diseases such as heart attacks, strokes, mental health disorders, and diabetes. The diagnosis of chronic stress and stress related disorders depends upon accurate measurement of cortisol levels; currently, it is quantified using mass spectroscopy or immunoassay, in specialized laboratories with trained personnel. However, these methods are time-consuming, expensive and are unable to capture the dynamic biorhythm of the hormone. This critical review traces the path of cortisol detection from traditional laboratory-based methods to decentralised cortisol monitoring biosensors. A complete picture of cortisol biology and pathophysiology is provided, and the importance of precision medicine style monitoring of cortisol is highlighted. Antibody-based immunoassays still dominate the pipeline of development of point-of-care biosensors; new capture molecules such as aptamers and molecularly imprinted polymers (MIPs) combined with technologies such as microfluidics, wearable electronics, and quantum dots offer improvements to limit of detection (LoD), specificity, and a shift toward rapid or continuous measurements. While a variety of different sensors and devices have been proposed, there still exists a need to produce quantitative tests for cortisol ─ using either rapid or continuous monitoring devices that can enable a personalized medicine approach to stress management. This can be addressed by synergistic combinations of technologies that can leverage low sample volumes, relevant limit of detection and rapid testing time, to better account for cortisol's shifting biorhythm. Trends in cortisol diagnostics toward rapid and continuous monitoring of hormones are highlighted, along with insights into choice of sample matrix.

Nanotechnology-based analytical techniques for the detection of contaminants in aquatic products

Food safety of aquatic products has attracted considerable attention worldwide. Although a series of conventional bioassays and instrumental methods have been developed for the detection of pathogenic bacteria, heavy metal residues, marine toxins, and biogenic amines during the production and storage of fish, shrimp, crabs et al., the nanotechnology-based analyses still have their advantages and are promising since they are cost-efficient, highly sensitive and selective, easy to conduct, facial design, often require no sophisticated instruments but with excellent detection performance. This review aims to summarize the advances of various biosensing strategies for bacteria, metal ions, and small molecule contaminants in aquatic products during the last five years, The review highlights the development in nanotechnologies applied for biorecognition process, signal transduction and amplification methods in each novel approach, the nuclease-mediated DNA amplification, nanomaterials (noble metal nanoparticle, metal-organic frameworks, carbon dots), lateral flow-based biosensor, surface-enhanced Raman scattering, microfluidic chip, and molecular imprinting technologies were especially emphasized. Moreover, this study provides a view of current accomplishments, challenges, and future development directions of nanotechnology in aquatic product safety evaluation.

Key steps for improving bacterial SERS signals in complex samples: Separation, recognition, detection, and analysis

Rapid and reliable detection of pathogenic bacteria is absolutely essential for research in environmental science, food quality, and medical diagnostics. Surface-enhanced Raman spectroscopy (SERS), as an emerging spectroscopic technique, has the advantages of high sensitivity, good selectivity, rapid detection speed, and portable operation, which has been broadly used in the detection of pathogenic bacteria in different kinds of complex samples. However, the SERS detection method is also challenging in dealing with the detection difficulties of bacterial samples in complex matrices, such as interference from complex matrices, confusion of similar bacteria, and complexity of data processing. Therefore, researchers have developed some technologies to assist in SERS detection of bacteria, including both the front-end process of obtaining bacterial sample data and the back-end data processing process. The review summarizes the key steps for improving bacterial SERS signals in complex samples: separation, recognition, detection, and analysis, highlighting the principles of each step and the key roles for SERS pathogenic bacteria analysis, and the interconnectivity between each step. In addition, the current challenges in the practical application of SERS technology and the development trends are discussed. The purpose of this review is to deepen researchers' understanding of the various stages of using SERS technology to detect bacteria in complex sample matrices, and help them find new breakthroughs in different stages to facilitate the detection and control of bacteria in complex samples.

Emerging Applications of Nanobiosensors in Pathogen Detection in Water and Food

Food and waterborne illnesses are still a major concern in health and food safety areas. Every year, almost 0.42 million and 2.2 million deaths related to food and waterborne illness are reported worldwide, respectively. In foodborne pathogens, bacteria such as Salmonella, Shiga-toxin producer Escherichia coli, Campylobacter, and Listeria monocytogenes are considered to be high-concern pathogens. High-concern waterborne pathogens are Vibrio cholerae, leptospirosis, Schistosoma mansoni, and Schistosima japonicum, among others. Despite the major efforts of food and water quality control to monitor the presence of these pathogens of concern in these kinds of sources, foodborne and waterborne illness occurrence is still high globally. For these reasons, the development of novel and faster pathogen-detection methods applicable to real-time surveillance strategies are required. Methods based on biosensor devices have emerged as novel tools for faster detection of food and water pathogens, in contrast to traditional methods that are usually time-consuming and are unsuitable for large-scale monitoring. Biosensor devices can be summarized as devices that use biochemical reactions with a biorecognition section (isolated enzymes, antibodies, tissues, genetic materials, or aptamers) to detect pathogens. In most cases, biosensors are based on the correlation of electrical, thermal, or optical signals in the presence of pathogen biomarkers. The application of nano and molecular technologies allows the identification of pathogens in a faster and high-sensibility manner, at extremely low-pathogen concentrations. In fact, the integration of gold, silver, iron, and magnetic nanoparticles (NP) in biosensors has demonstrated an improvement in their detection functionality. The present review summarizes the principal application of nanomaterials and biosensor-based devices for the detection of pathogens in food and water samples. Additionally, it highlights the improvement of biosensor devices through nanomaterials. Nanomaterials offer unique advantages for pathogen detection. The nanoscale and high specific surface area allows for more effective interaction with pathogenic agents, enhancing the sensitivity and selectivity of the biosensors. Finally, biosensors' capability to functionalize with specific molecules such as antibodies or nucleic acids facilitates the specific detection of the target pathogens.

Rising to the surface: capturing and detecting bacteria by rationally-designed surfaces

Analytical microbiology has made substantial progress since its conception, starting from potato slices, through selective agar media, to engineered surfaces modified with capture probes. While the latter represents the dominant approach in designing sensors for bacteria detection, the importance of sensor surface properties is frequently ignored. Herein, we highlight their significant role in the complex process of bacterial transition from planktonic to sessile, representing the first and critical step in bacteria detection. We present the main surface features and discuss their effect on the bio-solid interface and the resulting sensing capabilities for both flat and particulate systems. The concepts of rationally-designed surfaces for enhanced bacterial detection are presented with recent examples of sensors (capture probe-free) relying solely on surface cues.

Triazine-based covalent-organic framework embedded with cuprous oxide as the bioplatform for photoelectrochemical aptasensing Escherichia coli

A superior photoelectrochemical (PEC) aptasensor was manufactured for the detection of Escherichia coli (E. coli) based on a hybrid of triazine-based covalent-organic framework (COF) and cuprous oxide (Cu2O). The COF synthesized using 1,3,5-tris(4-aminophenyl)-benzene (TAPB) and 1,3,5-triformylphloroglucinol (Tp) as building blocks acted as a scaffold for encapsulated Cu2O nanoparticles (denoted as Cu2O@TAPB-Tp-COF), which then was employed as the bioplatform for anchoring E. coli-targeted aptamer. Cu2O@Cu@TAPB-Tp-COF demonstrated enhanced separation of the photogenerated carriers and photoabsorption ability and boosted photoelectric conversion efficiency. The developed Cu2O@TAPB-Tp-COF-based PEC aptasensor exhibited a lower detection limit of 2.5 CFU mL-1 toward E. coli within a wider range of 10 CFU mL-1 to 1 × 104 CFU mL-1 than most of reported aptasensors for determining foodborne bacteria, together with high selectivity, good stability, and superior ability and reproducibility. The recoveries of E. coli spiked into milk and bread samples ranged within 95.3-103.6% and 96.6-102.8%, accompanying with low RSDs of 1.37-4.48% and 1.74-3.66%, respectively. The present study shows a promising alternative for the sensitive detection of foodborne bacteria from complex foodstuffs and pathogenic bacteria-polluted environment.

Imprinting of nanoparticles in thin films: Quo Vadis?

Nanomaterials, and especially nanoparticles, have been introduced to almost any aspect of our lives. This has caused increasing concern as to their toxicity and adverse effects on the environment and human health. The activity of nanoparticles, including their nanotoxicity, is not only a function of the material they are made of but also their size, shape, and surface properties. It is evident that there is an unmet need for simple approaches to the speciation of nanoparticles, namely to monitor and detect them based on their properties. An appealing method for such speciation involves the imprinting of nanoparticles in soft matrices. The principles of imprinting nanoparticles originate from the molecularly imprinted polymer (MIP) approach. This review summarizes the current status of this emerging field, which bridges between the traditional MIP approach and the imprinting of larger entities such as viruses and bacteria. The concepts of nanoparticle imprinting and the requirement of both physical and chemical matching between the nanoparticles and the matrix are discussed and demonstrated.

Responsive Janus droplets as modular sensory layers for the optical detection of bacteria

The field of biosensor development is fueled by innovations in new functional transduction materials and technologies. Material innovations promise to extend current sensor hardware limitations, reduce analysis costs, and ensure broad application of sensor methods. Optical sensors are particularly attractive because they enable sensitive and noninvasive analyte detection in near real-time. Optical transducers convert physical, chemical, or biological events into detectable changes in fluorescence, refractive index, or spectroscopic shifts. Thus, in addition to sophisticated biochemical selector designs, smart transducers can improve signal transmission and amplification, thereby greatly facilitating the practical applicability of biosensors, which, to date, is often hampered by complications such as difficult replication of reproducible selector-analyte interactions within a uniform and consistent sensing area. In this context, stimuli-responsive and optically active Janus emulsions, which are dispersions of kinetically stabilized biphasic fluid droplets, have emerged as a novel triggerable material platform that provides as a versatile and cost-effective alternative for the generation of reproducible, highly sensitive, and modular optical sensing layers. The intrinsic and unprecedented chemical-morphological-optical coupling inside Janus droplets has facilitated optical signal transduction and amplification in various chemo- and biosensor paradigms, which include examples for the rapid and cost-effective detection of major foodborne pathogens. These initial demonstrations resulted in detection limits that rival the capabilities of current commercial platforms. This trend article aims to present a conceptual summary of these initial efforts and to provide a concise and comprehensive overview of the pivotal kinetic and thermodynamic principles that govern the ability of Janus droplets to sensitively and selectively respond to and interact with bacteria.

Molecularly Imprinted Polymer-Based Biomimetic Systems for Sensing Environmental Contaminants, Biomarkers, and Bioimaging Applications

Molecularly imprinted polymers (MIPs), a biomimetic artificial receptor system inspired by the human body's antibody-antigen reactions, have gained significant attraction in the area of sensor development applications, especially in the areas of medical, pharmaceutical, food quality control, and the environment. MIPs are found to enhance the sensitivity and specificity of typical optical and electrochemical sensors severalfold with their precise binding to the analytes of choice. In this review, different polymerization chemistries, strategies used in the synthesis of MIPs, and various factors influencing the imprinting parameters to achieve high-performing MIPs are explained in depth. This review also highlights the recent developments in the field, such as MIP-based nanocomposites through nanoscale imprinting, MIP-based thin layers through surface imprinting, and other latest advancements in the sensor field. Furthermore, the role of MIPs in enhancing the sensitivity and specificity of sensors, especially optical and electrochemical sensors, is elaborated. In the later part of the review, applications of MIP-based optical and electrochemical sensors for the detection of biomarkers, enzymes, bacteria, viruses, and various emerging micropollutants like pharmaceutical drugs, pesticides, and heavy metal ions are discussed in detail. Finally, MIP's role in bioimaging applications is elucidated with a critical assessment of the future research directions for MIP-based biomimetic systems.

Affinity-Based Analysis Methods for the Detection of Aminoglycoside Antibiotic Residues in Animal-Derived Foods: A Review

With the increasingly serious problem of aminoglycoside antibiotic residues, it is imperative to develop rapid, sensitive and efficient detection methods. This article reviews the detection methods of aminoglycoside antibiotics in animal-derived foods, including enzyme-linked immunosorbent assay, fluorescent immunoassay, chemical immunoassay, affinity sensing assay, lateral flow immunochromatography and molecular imprinted immunoassay. After evaluating the performance of these methods, the advantages and disadvantages were analyzed and compared. Furthermore, development prospects and research trends were proposed and summarized. This review can serve as a basis for further research and provide helpful references and new insights for the analysis of aminoglycoside residues. Accordingly, the in-depth investigation and analysis will certainly make great contributions to food safety, public hygiene and human health.

Molecularly imprinted sensor based on poly-o-phenylenediamine-hydroquinone polymer for β-amyloid-42 detection

A sensitive and selective molecularly imprinted polymer (MIP) sensor was developed for the determination of amyloid-β (1-42) (Aβ₄₂). The glassy carbon electrode (GCE) was successively modified with electrochemical reduction graphene oxide (ERG) and poly(thionine-methylene blue) (PTH-MB). The MIPs were synthesized by electropolymerization with Aβ₄₂ as a template and o-phenylenediamine (o-PD) and hydroquinone (HQ) as functional monomers. Cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), chronoamperometry (CC), and differential pulse voltammetry (DPV) were used to study the preparation process of the MIP sensor. The preparation conditions of the sensor were investigated in detail. In optimal experimental conditions, the response current of the sensor was linear in the range of 0.12-10 μg mL^-1 with a detection limit of 0.018 ng mL^-1. The MIP-based sensor successfully detected Aβ₄₂ in commercial fetal bovine serum (cFBS) and artificial cerebrospinal fluid (aCSF).

Molecularly Designed Ion-Imprinted Nanoparticles for Real-Time Sensing of Cu(II) Ions Using Quartz Crystal Microbalance

A molecularly designed imprinting method was combined with a gravimetric nanosensor for the real-time detection Cu(II) ions in aqueous solutions without using expensive laboratory devices. Thus, 1:1 and 2:1 mol-ratio-dependent coordination modes between Cu(II), N-methacyloly-L histidine methyl ester (MAH) functional monomer complexes, and their four-fold and six-fold coordinations were calculated by means of density functional theory molecular modeling. Cu(II)-MIP1 and Cu(II)-MIP2 nanoparticles were synthesized in the size range of 80-100 nm and characterized by SEM, AFM and FTIR. Cu(II)-MIP nanoparticles were then conducted to a quartz crystal microbalance sensor for the real-time detection of Cu(II) ions in aqueous solutions. The effects of initial Cu(II) concentration, selectivity, and imprinting efficiency were investigated for the optimization of the nanosensor. Linearity of 99% was obtained in the Cu(II) ion linear concentration range of 0.15-1.57 µM with high sensitivity. The LOD was obtained as 40.7 nM for Cu(II)-MIP2 nanoparticles. The selectivity and the imprinting efficiency of the QCM nanosensor were obtained significantly in the presence of competitive ion samples (Co(II), Ni(II), Zn(II), and Fe(II)). The results are promising for sensing Cu(II) ions as environmental toxicants in water by combining molecularly designed ion-imprinted nanoparticles and a gravimetric sensor.

Research progress on detection techniques for point-of-care testing of foodborne pathogens

The global burden of foodborne disease is enormous and foodborne pathogens are the leading cause of human illnesses. The detection of foodborne pathogenic bacteria has become a research hotspot in recent years. Rapid detection methods based on immunoassay, molecular biology, microfluidic chip, metabolism, biosensor, and mass spectrometry have developed rapidly and become the main methods for the detection of foodborne pathogens. This study reviewed a variety of rapid detection methods in recent years. The research advances are introduced based on the above technical methods for the rapid detection of foodborne pathogenic bacteria. The study also discusses the limitations of existing methods and their advantages and future development direction, to form an overall understanding of the detection methods, and for point-of-care testing (POCT) applications to accurately and rapidly diagnose and control diseases.

Specific and quantitative detection of bacteria based on surface cell imprinted SERS mapping platform

Non-specificity and poor quantitative ability are the main challenges in surface-enhanced Raman scattering (SERS) technique, especially for the detection of bacteria in real samples. In this study, we presented a surface cell imprinted SERS mapping platform which is competent for the specific and quantitative detection of bacteria. The platform based on the fabrication of a surface cell imprinted substrate (SCIS) by which Escherichia coli (E. coli) can be captured and labelled by SERS tags which produces strong characteristic signal to indicate the capture of targets. We highlighted the specificity of this platform in the detection of E. coli, by comparing the performances toward Salmonella paratyphoid A, Bacillus subtilis, Enterococcus faecalis and Staphylococcus aureus. Upon integrating with SERS mapping technique, the platform displayed good quantitative ability toward E. coli with a wide linear range from 10² to 10⁸ CFU/mL and a low detection limit of ∼1.35 CFU/mL. Moreover, this novel SERS analysis platform was proved to be effective for E. coli detection in real probiotic beverage and chicken breast meat samples. By fabricating different SCISs, this platform can be replicated for the detection of other bacteria, which provides a promising application for real sample testing.

Current Scenario of Pathogen Detection Techniques in Agro-Food Sector

Over the past-decade, agricultural products (such as vegetables and fruits) have been reported as the major vehicles for foodborne diseases, which are limiting food resources. The spread of infectious diseases due to foodborne pathogens poses a global threat to human health and the economy. The accurate and timely detection of infectious disease and of causative pathogens is crucial in the prevention and treatment of disease. Negligence in the detection of pathogenic substances can be catastrophic and lead to a pandemic. Despite the revolution in health diagnostics, much attention has been paid to the agro-food sector regarding the detection of food contaminants (such as pathogens). The conventional analytical techniques for pathogen detection are reliable and still in operation. However, laborious procedures and time-consuming detection via these approaches emphasize the need for simple, easy-to-use, and affordable detection techniques. The rapid detection of pathogens from food is essential to avoid the morbidity and mortality originating from the suboptimal nature of empiric pathogen treatment. This review critically discusses both the conventional and emerging bio-molecular approaches for pathogen detection in agro-food.

Detection of pesticides in food products using paper-based devices by UV-induced fluorescence spectroscopy combined with molecularly imprinted polymers

In this proof-of-concept study, we explore the detection of pesticides in food using a combined power of sensitive UV-induced fingerprint spectroscopy with selective capture by molecularly imprinted polymers (MIPs) and portable cost-effective paper-based analytical devices (PADs). The specific pesticides used herein as model compounds (both pure substances and their application products for spraying), were: strobilurins (i.e. trifloxystrobin), urea pesticides (rimsulfuron), pyrethroids (cypermethrine) and aryloxyphenoxyproponic acid herbicides (Haloxyfop-methyl). Commercially available spraying formulations containing the selected pesticides were positively identified by MIP-PADs swabs of sprayed apple and tomato. The key properties of MIP layer - imprinting factor (IF) and selectivity factor (α) were characterized using trifloxystrobin (IF-3.5, α-4.4) was demonstrated as a potential option for in-field application. The presented method may provide effective help with in-field testing of food and reveal problems such as false product labelling.

Determination of fluoroquinolones in chicken muscle by molecularly imprinted graphitic carbon nitride-based solid-phase extraction and ultra-performance liquid chromatography

A graphitic carbon nitride was synthesised and nalidixic acid (NA) based molecularly imprinted microspheres (MIMs) were polymerised on its surface to create a composite material. After characterisation and evaluation of its absorption ability, the composite was used to prepare a solid-phase extraction (SPE) cartridge for purification of fluoroquinolones in chicken muscle, analysed by ultra-performance liquid chromatography. The cartridge showed high absorption capacities (378-559 μg) and high recoveries (92.1-99.4%) for eight fluoroquinolones, and could be reused at least 20 times. The limits of detection for the 8 drugs were 0.2-0.8 ng g^-1, and recoveries from standard fortified blank chicken muscle samples were 71.9-96.8%. This is the first study reporting the use of molecularly imprinted graphitic carbon nitride composite to determine the residue of veterinary drug in foods of animal origin.

Development of a microfluidic dispensing device for multivariate data acquisition and application in molecularly imprinting hydrogel preparation

Molecularly imprinted polymer (MIP) is the superior material with molecular recognition ability that applies to various applications. In order to get high specificity recognition for target molecules, selecting polymerization conditions,...

Reusable and universal impedimetric sensing platform for the rapid and sensitive detection of pathogenic bacteria based on bacteria-imprinted polythiophene film

A bacteria-imprinted polythiophene film (BIF)-based impedimetric sensor was proposed for the rapid and sensitive detection of S. aureus. A significant improvement is the reduced time for both BIF fabrication (15 min) and bacterial capturing (10 min).

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.

Cross-Linked Polymer Brushes Containing N-Halamine Groups for Antibacterial Surface Applications

Microbial contamination is a significant issue in various areas, especially in the food industry. In this study, to overcome microbial contamination, cross-linked polymer brushes containing N-halamine were synthesized, characterized, and investigated for antibacterial properties. The cross-linked polymer brushes with different N-halamine ratios were synthesized by in-situ cross-linking methods with reversible addition-fragmentation chain transfer (RAFT) polymerization using a bifunctional cross-linker. The RAFT agent was immobilized on an amine-terminated silicon wafer surface and utilized in the surface-initiated RAFT polymerization of [N-(2-methyl-1-(4-methyl-2,5-dioxoimidazolidin-4-yl)propane-2-yl)acrylamide] (hydantoin acrylamide, HA), and N-(2-hydroxypropyl)methacrylamide) (HPMA) monomers. Measurement of film thickness, contact angle, and surface morphology of the resulting surfaces were used to confirm the structural characteristics of cross-linked polymer brushes. The chlorine content of the three different surfaces was determined to be approximately 8-31 × 1013 atoms/cm2. At the same time, it was also observed that the activation-deactivation efficiency decreased during the recharge-discharge cycles. However, it was determined that the prepared N-halamine-containing cross-linked polymer brushes inactivated approximately 96% of Escherichia coli and 91% of Staphylococcus aureus. In conclusion, in the framework of this study, high-performance brush gels were produced that can be used on antibacterial surfaces.

Detection of harmful foodborne pathogens in food samples at the points of sale by MALDT-TOF MS in Egypt

OBJECTIVES

Microbes can contaminate foodstuffs resulting in foodborne illnesses. Investigating microbial hazards in foods at the point of sale with rapid tools is required to avoid foodborne illness outbreaks. The current study aimed to identify the microbial hazards in food samples collected from retail shops at sale points using MALDI-TOF MS.

RESULTS

Food samples were collected from stores and supermarkets in four Delta cities (Tanta, Kutour, Kafr-Elzayat and Benha). Analysis of 178 samples of fish, meat and dairy products revealed 20 different bacterial species. 44.76% of isolates were identified as E. coli, 17.44% were identified as Enterobacter spp., and E. cloacae was predominant. 12.2% were identified as Citrobacter spp., and C. braakii was predominant, and 8.7% were identified as Klebsiella spp., and K. pneumoniae was predominant. Moreover, eight Proteus mirabilis, six Morganella morganii, five Staphylococcus hominis, three Serratia marcescens, two Pseudomonas aeruginosa, one Salmonella typhimurium and one Enterococcus faecalis were detected. Foodstuffs not only be contaminated during production and processing but also during storage and transport. Identification of harmful human pathogens in foodstuffs is alarming and consider threatening to public health. Identification of microbiological hazards in foods using MALDI-TOF MS provides an efficient tool for identifying foodborne pathogens.