Biosensors for rapid detection of bacterial pathogens in water, food and environment

SERS-based approaches in the investigation of bacterial metabolism, antibiotic resistance, and species identification

Surface-enhanced Raman scattering (SERS) is an inelastic scattering phenomenon that occurs when photons interact with substances, providing detailed molecular structure information. It exhibits various advantages including high sensitivity, specificity, and multiple-detection capabilities, which make it particularly effective in bacterial detection and antibiotic resistance research. In this review, we review the recent development of SERS-based approaches in the investigation of bacterial metabolism, antibiotic resistance, and species identification. Although the promising applications have been realized in clinical microbiology and diagnostics, several challenges still limit the further development, including signal variability, the complexity of spectral data interpretation, and the lack of standardized protocols. To overcome these obstacles, more reproducible and standardized methodologies, particularly in nanomaterial design and experimental condition optimization. Furthermore, the integration of SERS with machine learning and artificial intelligence can automate spectral analysis, improving the efficiency and accuracy of bacterial species identification, resistance marker detection, and metabolic monitoring. Combining SERS with other analytical techniques, such as mass spectrometry, fluorescence microscopy, or genomic sequencing, could provide a more comprehensive understanding of bacterial physiology and resistance mechanisms. As SERS technology advances, its applications are expected to extend beyond traditional microbiology to areas like environmental monitoring, food safety, and personalized medicine. In particular, the potential for SERS to be integrated into point-of-care diagnostic devices offers significant promise for enhancing diagnostics in resource-limited settings, providing cost-effective, rapid, and accessible solutions for bacterial infection and resistance detection.

Recent advances and challenges in graphene-based electrochemical biosensors for food safety

Ensuring food safety is a critical global concern, particularly in light of recent pandemics and rising contamination risks from pesticides, antibiotics, toxins, and allergens. These contaminants pose significant health hazards, including neurological disorders, endocrine disruption, antibiotic resistance, and carcinogenic effects. Regulatory agencies such as the Food and Agriculture Organization (FAO), the World Health Organization (WHO), and the United States Food and Drug Administration (FDA) have established strict maximum residue limits (MRLs) to mitigate these risks. However, enforcement remains challenging due to limitations in current detection methods. The increasing global population and limited food resources have exacerbated food security challenges, while contaminants can infiltrate food at various stages, including production, processing, and packaging. Despite consumer awareness, significant amounts of food are discarded due to quality concerns. To address these issues, researchers are actively developing low-cost, reliable sensing technologies for real-time food quality assessment and contamination detection. Among these, graphene-based electrochemical biosensors have emerged as a promising solution due to their high sensitivity, selectivity, and cost-effectiveness. This review provides an in-depth analysis of recent advancements in graphene-based electrochemical biosensors, focusing on their role in detecting foodborne hazards and improving food quality monitoring. By integrating selective layers, these sensors enhance detection efficiency and provide an innovative solution for safeguarding public health. The findings underscore the transformative potential of graphene-derived biosensors in food safety diagnostics, paving the way for more reliable and sustainable food monitoring systems.

A recent review on smart sensor-integrated wound dressings: Real-time monitoring and on-demand therapeutic delivery

Wound management is a critical aspect of healthcare, necessitating continuous monitoring and timely interventions to ensure optimal healing outcomes. In recent years, the integration of sensor technology into wound dressings has emerged as a transformative approach, enabling real-time monitoring of healing parameters and facilitating on-demand treatment delivery. Sensor-based wound dressings leverage various sensing modalities, including temperature, pH, moisture, oxygen, and other biochemical markers, to provide comprehensive insights into the wound microenvironment. These dressings are equipped with miniaturized sensors capable of transmitting the data wirelessly, facilitating remote monitoring and timely interventions. Moreover, some advanced dressings incorporate responsive drug delivery systems, enabling the on-demand release of therapeutics based on real-time sensor feedback. Additionally, the incorporation of on-demand treatment mechanisms allows targeted delivery of therapeutics based on the specific needs of the wound, further enhancing the efficacy of the healing process. This comprehensive approach improves patient outcomes by promoting faster and more effective wound healing and reducing the burden through streamlined monitoring and treatment protocols. This paper presents an overview of recent advancements in sensor technology applied to wound healing, focusing on their role in monitoring wound parameters and delivering targeted therapy. These sensors leverage temperature, pH, and glucose sensing modalities to provide comprehensive insights into the healing process.

Electrochemical biosensors: The beacon for food safety and quality

Electrochemical biosensors transduce chemical reactions into measurable electrical signals by incorporating recognition components. Although they are capable of detecting a broad range of target molecules, their application in complex matrices, such as food, at minimum or no sample preparation, is challenging and requires the introduction of innovative and effective strategies. This review explores the recent advances in electrochemical biosensors for on-site food safety and quality analysis. We first discuss the presence of chemical contaminants and biohazards in food and the need for robust, rapid, low-cost, and point-of-care (POC) analytical techniques. We then address the critical aspects of sensitivity and selectivity of electrochemical biosensors in detecting chemical and biological contaminants in real food samples. We finally investigate the major drawbacks of these biosensors and provide future perspectives on the field.

Genetic engineering of bacteriophage S16 for Salmonella separation, concentration, and detection

Salmonella contamination in food and water poses a major global health risk, creating an urgent need for rapid, reliable, and cost-effective detection methods. Conventional approaches are often expensive, labor-intensive, and time-consuming, and they frequently yield inconclusive or presumptive positive results. A significant bottleneck to rapid detection is the need to separate the target bacteria into smaller, clean, and concentrated samples. Bacteriophages can recognize, bind, and infect specific bacterial hosts. This study presents a genetically engineered S16 Salmonella-specific bacteriophage as a biosensor, optimized for enhanced sensitivity and efficiency in detecting Salmonella. Using CRISPR-Cas12a, the phages were engineered to include a gene for a NanoLuc luciferase reporter and a monomeric streptavidin (mSA) affinity tag fused to the gene for the capsid protein Soc. This design enabled conjugation of the phages to magnetic nanoparticles, facilitating the capture, concentration, and detection of Salmonella from 10 mL water samples. The modified S16 phage exhibited a detection limit of fewer than 10 CFU of Salmonella in 10 mL of water within a typical work shift. This innovative phage-based detection method offers a promising tool for enhancing food and water safety by providing a faster, more sensitive, and cost-effective approach to pathogen monitoring of Salmonella enterica subsp. enterica serovar Typhimurium.

Towards a Rational Design of Biosensors: Engineering Covalently Grafted Interfacial Adlayers as a Testbed Platform for Electrochemical Detection of Epinephrine

The performance of electrochemical (bio)sensors is fundamentally determined by the precise engineering of interfacial layers that govern (bio)analyte-surface interactions. However, elucidating structure-function relationships remains challenging due to the complex architecture of modern sensors and the irregular nanoscale morphology of many high-performance materials. In this study, we present a strategy for designing custom functional interfaces as well-defined platforms for probing interfacial processes. Focusing on epinephrine (EP) detection as an important representative of catecholamines, we compare the interfacial behavior of two carboxy-functionalized electrodes-grafted with either para-aminobenzoic acid (PAB) or 3,4,5-tricarboxybenzenediazonium (ATA)-against atomically flat highly oriented pyrolytic graphite (HOPG) as a control. While both modifiers introduce carboxyl groups, PAB forms disordered multilayers that inhibit surface responsiveness, whereas ATA yields an ultrathin monolayer with accessible COOH groups. Electrochemical analysis reveals that ATA-HOPG significantly enhances EP detection at sub-micromolar levels, facilitated by electrostatic interactions between surface-bound COO- and protonated EP and its redox products. These results demonstrate that nanoscale control of diazonium grafting is crucial for optimizing bioanalyte recognition. More broadly, this work highlights how molecular-level surface engineering on high-quality carbon substrates can serve as a test-bed platform for the rational design of advanced electrochemical sensing interfaces.

Advances in in vitro cultivation techniques for comprehensive analysis of human gut microbiome

The role of gut microbiota in human health and disease is becoming increasingly recognized. Historically, the impact of human gut microbiota on health has been studied using clinical trials and animal models. However, clinical studies often struggle with controlling variables and pinpointing disease-causing factors, while animal models fall short of accurately replicating the human gut environment. Additionally, continuous sample collection for gut microbiota analysis in vivo presents significant ethical and technical challenges. To address these limitations, in vitro fermentation models have emerged as promising alternatives. These models aim to simulate the structural and functional characteristics of the human gut in a controlled setting, offering valuable insights into microbial behavior. This review highlights current knowledge and technological advances in in vitro cultivation systems for human gut microbiota, focusing on key elements such as three-dimensional scaffolds, culture media, fermentation systems, and analytical techniques. By examining these components, the review establishes a framework for improving methods to cultivate and study human gut microbiota, enhancing research methodologies for better understanding microbial interactions, behavior, and adaptation in diverse environments.

The use of faecal indicator organisms to manage microbial health risks in recreational waterways not impacted by point sources of sewage: a systematic review of the epidemiological evidence

This PRISMA review investigated the extent to which epidemiological evidence supports the use of faecal indicator organisms (FIOs) to manage microbial health risks in recreational waters without point sources of sewage. The quality of papers meeting the inclusion criteria was appraised using the Office of Health Assessment and Translation (OHAT) Risk of Bias tool and low-bias studies were synthesised. Studies consistently reported elevated illness risks (particularly gastrointestinal) among bathers compared with non-bathers. However, no FIOs or pathogens were associated consistently with any health outcomes. While enterococci most frequently correlated with a variety of illnesses, the relatively even split of positive and negative associations suggests an overall lack of association. Consequently, applying FIO guidelines derived from epidemiological studies with point sources of sewage could result in type I and type II errors. Overall, results suggest that the sources and drivers of health risks are site-specific. Tools including sanitary surveys, microbial source tracking, epidemiology and quantitative microbial risk assessment provide avenues for characterising site-specific health risks, for those who can afford them. Meanwhile, characterising the site-specific sources/drivers of contamination seems pragmatic as the limited evidence so far suggests that FIO monitoring may not be sufficient to protect health in these waters.

Progress in machine learning-supported electronic nose and hyperspectral imaging technologies for food safety assessment: A review

The growing concern over food safety, driven by threats such as food contaminations and adulterations has prompted the adoption of advanced technologies like electronic nose (e-nose) and hyperspectral imaging (HSI), which are increasingly enhanced by machine learning innovations. This paper aims to provide a comprehensive review on food safety, by combining insights from both e-nose and HSI technologies alongside machine learning algorithms. First, the basic principles of e-nose, HSI, and machine learning, with particular emphasis on artificial neural network (ANN) and deep learning (DL) are briefly discussed. The review then examines how machine learning enhances the performance of e-nose and HSI, followed by an exploration of recent applications in detecting food hazards, including drug residues, microbial contaminants, pesticide residues, toxins, and adulterants. Subsequently, key limitations encountered in the applications of machine learning, e-nose and HSI, along with future perspectives on the potential advancements of these technologies are highlighted. E-nose and HSI technologies have shown their great potential for applications in food safety assessment through machine learning assistance. Despite this, their use is primarily limited to laboratory environments, restricting their real-world applications. Additionally, the lack of standardized protocols hampers their acceptance and the reproducibility of tests in food safety assessments. Thus, further research is essential to address these limitations and enhance the effectiveness of e-nose and HSI technologies in practical applications. Ultimately, this paper offers a detailed understanding of both technologies, highlighting the pivotal role of machine learning and presenting insights into their innovative applications within food safety evaluation.

Fast visual detection of sunflower oil thermal oxidation using Polyacrylonitrile/Congo red nanofiber mats

Lipid oxidation monitoring is essential for food safety and quality, but traditional techniques are expensive and complicated for daily use. This study developed novel nanofiber mats using solution-blowing spinning technology to visually detect the oxidation of sunflower oil that was heated for six hours at 200 °C. These mats (Mat_1-9) are made from polyacrylonitrile (compatible with the used technique) containing various concentrations of Congo red as pH-sensitive dye (0.0025, 0.005, and 0.01 %) and hydroxylamine hydrochloride (0.125, 0.250, and 0.50 %) that react with volatile oxidation compounds to produce a striking color change. Results indicated an increase in peroxide and acid values after six hours. Mat_9 outperformed Mat_1 with a high color change (27.74 ± 0.2) and a response time of only 5 s, whereas Mat_1 took 65 s and had a far lesser response. These mats enable non-experts and food auditors to quickly assess oil quality while efficiently promoting food safety and consumer health.

Immobilization of a novel bacteriophage PpZDSS02 onto the peroxidase-mimicking Cu-MOF for colorimetric sensing of Proteus penneri encompassing both promotion and inhibition mechanisms

A chromogenic system utilizing a novel bacteriophage-integrated nanozyme was established for Proteus penneri detection. Initially, a novel bacteriophage PpZDSS02 was isolated and identified, demonstrating exceptional biological properties and harboring genes that exhibit specific recognition ability. Afterwards, a PpZDSS02-integrated Cu-MOF nanozyme (Cu-MOF@PpZDSS02) with peroxidase-mimicking activity was prepared, catalyzing 3, 3', 5, 5'-tetramethylbenzidine (TMB) chromogenic reaction. Its peroxidase-mimicking activity can be modulated by P. penneri. Interestingly, low concentration of P. penneri can enhance its activity and high concentration of P. penneri inhibits its activity. Based on it, a visual quantification method with high sensitivity and specificity for P. penneri was achieved, offering a low limit of detection (3.3 CFU·mL-1). Moreover, Cu-MOF@PpZDSS02-based chromogenic system shows exceptional performance in the detection of authentic food samples, achieving ideal recoveries (89.00 % ∼ 111.81 %). These results indicate the potential application of Cu-MOF@PpZDSS02-based chromogenic system for colorimetric detection of P. penneri.

Chemically reduced graphene oxide based assembly of Aptasensor for sensitive and probe-free detection of penicillin-G

The widespread use of antibiotics in livestock and poultry leads to antibiotic residues in food, posing public health risks. To ensure food safety, monitoring antibiotic levels in dairy and poultry is essential, especially for Penicillin-G (Pen-G), a frequently used β-lactam antibiotic. This study presents an electrochemical aptasensor for detecting Pen-G in food samples, using chemically reduced graphene oxide (crGO) conjugated with Pen-G-specific aptamer on electrode. The sensors construction was validated via various microscopy and spectroscopy techniques and its performance optimized by adjusting factors such as pH, scan rate, temperature, concentration of aptamer, and reaction time using differential pulse voltammetry (DPV) and cyclic voltammetry (CV). It achieved a detection limit of 1.24 pM, effectively distinguishing Pen-G from other antibiotics in real milk, meat, and egg samples, with stability for up to 3 weeks, making it a valuable tool for antibiotic monitoring in food products.

Sheath-enhanced concentration and on-chip detection of bacteria from an extremely low-concentration level

Microfluidic-based sheath flow focusing methods have been widely used for efficiently isolating, concentrating, and detecting pathogenic bacteria for various biomedical applications due to their enhanced sensitivity and exceptional integration. However, such a microfluidic device usually needs complicated device fabrication and sample dilution, hampering the efficient and sensitive identification of target bacteria. In this study, we develop and fabricate a sheath-assisted and pneumatic-induced nano-sieve device for achieving the improved on-chip concentration and sensitive detection of Staphylococcus aureus (MRSA). The optimized nanochannel design with diverging configuration is beneficial to the regulation of the hydrodynamic flow while the sheath flow is focusing the sample to the confined region as expected. Per the experimental finding, a high flow ratio (sheath flow/sample flow) presents enhanced target concentration by comparing with a low flow ratio. With this setup, MRSA bacteria with an extremely low concentration of ∼100 CFU mL-1 are successfully and sensitively detected under a fluorescence microscope, less than 30 min, demonstrating a reliable sheath-enhanced concentration and on-chip detection for target bacteria. Additionally, the theoretical model introduced here further rationalizes the working principle of our nano-sieve device, potentially guiding the optimization of next generation devices for highly sensitive and accurate on-chip bacteria detection at a much lower concentration level below 100 CFU mL-1.

IoT-Enabled Biosensors in Food Packaging: A Breakthrough in Food Safety for Monitoring Risks in Real Time

The integration of biosensors and the Internet of Things (IoT) in food packaging is gaining significant interest in rapidly enhancing food safety and traceability worldwide. Currently, the IoT is one of the most intriguing topics in the digital and virtual world. Biosensors can be integrated into food packaging to monitor, sense, and identify early signs of food spoilage or freshness. When coupled with the IoT, these biosensors can contribute to data transmission via IoT networks, providing real-time insights into food storage and transportation conditions for stakeholders across each stage of the food supply chain, facilitating proactive decision-making practices. The technologies of combining biosensors with IoT could leverage artificial intelligence (AI) to enhance food safety, quality, and security in food industries, compared to conventional existing food inspection technologies, which are limited to assessing weight, volume, color, and physical appearance. This review focused on highlighting the latest and existing advancements, identifying the knowledge gaps in the applications of biosensors and the IoT, and exploring their opportunities to shape future food packaging, particularly in the context of 21st-century food safety. The review also aims to investigate the role of the IoT in creating smart food ecosystems and examines how data transmitted from biosensors to IoT systems can be stored in cloud-based platforms, in addition to addressing upcoming research challenges. Concerns of data privacy, security, and regulatory compliance in implementing the IoT and biosensors for food packaging are also addressed, along with potential solutions to overcome these barriers.

Metagenomic assembled genomes profile potential pathogens and antibiotic-resistant pathogens in an urban river

The microbiological safety of urban rivers that flow through cities is crucial to local public health. However, detailed insights into the key characteristics of pathogens in urban rivers remain limited due to the lack of efficient high-throughput analysis tools. In this study, a comprehensive profiling of potential pathogens, antibiotic-resistant pathogens (ARPs), and multidrug-resistant pathogens (MDRPs) in the Hai River, which runs through the central city of Tianjin, was conducted using metagenomic assembled genome (MAG) analysis. Of the 436 recovered MAGs assigned to 430 species, 110 MAGs were identified as potential pathogens due to the presence of virulence factors (VFs), whereas 19 MAGs containing both antibiotic resistance genes (ARGs) and VFs, were classified as potential ARPs, predominantly belonging to the genera Kluyvera, Enterobacter, and Klebsiella. Notably, nine species of MDRPs, including Enterobacter kobei, Klebsiella pneumoniae, Morganella morganii, Kluyvera intermedia, Aeromonas salmonicida, Rahnella aceris, Hafnia paralvei, the unidentified species Sep. D_bin46, and Vibrio cholerae, exhibited resistance to multidrug, beta-lactam, polymyxin, bacitracin, tetracycline, other peptide antibiotics, macrolide-lincosamide-streptogramin, aminoglycoside, and chloramphenicol. The unknown pathogen Sep. D_bin46, classified under Aeromonas, showed resistance to both carbapenems and polymyxins. The strong co-occurrence of ARGs, VFs, and mobile genetic elements suggests a significant risk of ARGs and VFs transfers among MDRPs with last-resort ARGs (r > 0.8; p < 0.05). Interestingly, the sampling location significantly influenced the presence of pathogens, ARPs, and MDRPs carrying last-resort ARGs in the water. Notably, their abundance was lower downstream of the Hai River compared to upstream. This observation suggests that urban environmental sanitation facilities may be more effective in reducing contaminants as the river flows from upstream to downstream. Nevertheless, the presence of pathogens, ARPs, and MDRPs with last-resort ARGs in the water underscores the ongoing microbiological risks associated with urban surface water.

Whole-cell aptamer-based techniques for rapid bacterial detection: Alternatives to traditional methods

Controlling the spread of bacterial infectious diseases is a major public health issue, particularly in view of the pandemic of bacterial resistance to antibiotics. In this context, the detection and identification of pathogenic bacteria is a prerequisite for the implementation of control measures. Current reference methods are mainly based on culture methods, which generate a delay in obtaining a result and requires equipment. Consequently, focusing on the detection of the whole bacterium represents a very attractive alternative, since no culture is required. Several techniques have already been deployed to identify whole-cell bacteria. In recent decades, growing interest in nucleic acid aptamers has emerged as a viable alternative to antibodies as recognition elements, offering preferable stability, cost-efficiency, good specificity and affinity. This review explores current alternative methods for the detection of whole-cell bacteria, with particular emphasis on aptamer-based assays. These assays have shown promising results in various transduction mechanisms, including optical, electrochemical, and mechanical approaches, enhancing their versatility in different diagnostic platforms. The integration of aptamers in these detection methods offers rapid, sensitive, versatile and portable solutions for pathogen identification, positioning them as valuable tools in the fight against bacterial infections.

Recent Advances in Paper-Based Nano-Biosensors for Waterborne Pathogen Detection: Challenges and Solutions

Ensuring safe access to water and public health requires the availability of sensitive and fast response detection tools. Traditional detection tools present challenges of duration, procedure intricacy, and the need for trained staff. An advanced approach involves utilizing biosensors and nanomaterials, which have the capacity to detect the target analyte with high sensitivity and specificity in a short time. To date, researchers have created new techniques and materials to improve the sensitivity, detection limit, durability, and real-time analytical capabilities of biosensors. This critical review provides a thorough analysis of recent advances in paper-based nano-biosensors used for detecting waterborne pathogens, along with challenges faced in entering the market and potential solutions. The objective is to provide a comprehensive understanding of the capabilities of biosensors in detecting waterborne diseases, by evaluating technologies based on their range of concentrations and limits of detection. The review analyzed multiple biosensors and evaluated the underlying mechanisms that contribute to their effectiveness in detecting waterborne diseases. The discussion also addressed the influence of including nanomaterials on enhancing the performance of biosensors, specifically in relation to specificity, selectivity, and durability. Additionally, the challenges of translating the proof-of-concept biosensor into market products are discussed with potential solutions. The major findings reveal various biosensor technologies with distinct advantages and limitations. The thorough examination of biosensor technologies and the integration of nanomaterials offers valuable insights for academics, professionals, and policymakers involved in water quality monitoring. Additionally, it advocates for additional research to improve the performance of biosensors and address existing challenges.

Poly(p-Phenyleneethynylene)s-Based Sensor Array for Diagnosis of Clinical Diseases

Inspired by the mammalian taste and olfactory systems, array-based pattern recognition technology has demonstrated significant potential in discerning subtle differences between highly similar compounds and complex mixtures, owing to their unique parallel detection mechanism based on cross-reactive signals. While optical sensor array has been extensively employed in the field of chemical sensing, they encounter significant challenges in non-specific recognition of multiple analytes at low concentrations, particularly in rife environments with complex interferences. Poly(p-phenylene ethynylene)s (PPEs) offer substantial advantages in detecting multi-analytes at low concentrations, owing to its distinctive optical properties, including the "molecular wire" effect, fluorescence super-amplification and super-quenching. This is particularly promising for the parallel detection of ultra-low concentration multi-biomarkers in clinical diseases. As the continuous development of PPEs sensor array, more sensitive methods for rapid detection of clinical disease will be further developed. It will promote the further development of the field of early diagnosis of clinical diseases.

Silk-polyurethane composite based flexible electrochemical biosensing platform for pathogen detection

The upcoming era of flexible and wearable electronics necessitates the development of low-cost, flexible, biocompatible substrates amenable to the fabrication of active devices such as electronic devices, sensors and transducers. While natural biopolymers such as Silk are robust and biocompatible, long-term flexibility is a concern due to the inherent brittle nature of soft Silk thin films. This work elucidates the preparation and characterization of Silk-polyurethane (Silk-PU) composite film that provides long-duration flexibility. More importantly, an electrochemical biosensing platform is developed by creating a three-electrode system using a screen-printing technique. The solvents in the Ink had little impact on the film. As a proof of concept, the detection of E. coli, a highly infectious pathogen, was demonstrated using screen-printed electrodes (SPEs) modified with gold nanoparticles. This method effectively detected E. coli across a wide range of concentrations, with a detection limit of 0.12 CFU/mL. The entire surface functionalization and detection process did not impact the Silk-PU substrate. Even after rigorous bending tests, the results were consistent, demonstrating the robustness and flexibility of the Silk-PU film. The platform demonstrated is scalable and amenable for multi-pathogen detection as it not only can integrate several working electrodes, each catering to detection of a particular pathogen, but also serve as a platform for lab-on-chip devices wherein PDMS-based microfluidics can be seamlessly integrated along with the proposed platform.

Wastewater-borne viruses and bacteria, surveillance and biosensors at the interface of academia and field deployment

Wastewater is a complex, but an ideal, matrix for disease monitoring and surveillance as it represents the entire load of enteric pathogens from a local catchment area. It captures both clinical and community disease burdens. Global interest in wastewater surveillance has been growing rapidly for infectious diseases monitoring and for providing an early warning of potential outbreaks. Although molecular detection methods show high sensitivity and specificity in pathogen monitoring from wastewater, they are strongly limited by challenges, including expensive laboratory settings and prolonged sample processing and analysis. Alternatively, biosensors exhibit a wide range of practical utility in real-time monitoring of biological and chemical markers. However, field deployment of biosensors is primarily challenged by prolonged sample processing and pathogen concentration steps due to complex wastewater matrices. This review summarizes the role of wastewater surveillance and provides an overview of infectious viral and bacterial pathogens with cutting-edge technologies for their detection. It emphasizes the practical utility of biosensors in pathogen monitoring and the major bottlenecks for wastewater surveillance of pathogens, and overcoming approaches to field deployment of biosensors for real-time pathogen detection. Furthermore, the promising potential of novel machine learning algorithms to resolve uncertainties in wastewater data is discussed.

Spectroscopic analysis of bacterial photoreactivation

With the rise of bacterial infections and antibiotic resistance, spectroscopic devices originally developed for bacterial detection have shown promise to rapidly identify bacterial strains and determine the ratio of live to dead bacteria. However, the detection of the photoreactivated pathogens remains a critical concern. This study utilizes fluorescence and Raman spectroscopy to analyze bacterial responses to UV irradiation and subsequent photoreactivation. Our experimental results reveal limitations in fluorescence spectroscopy for detecting photoreactivated bacteria, as the intense fluorescence of tryptophan and tyrosine amino acids masks the fluorescence emitted by thymine molecules. Conversely, Raman spectroscopy proves more effective, showing a detectable decrease in band intensities of E. coli bacteria at 1248 and 1665 cm-1 after exposure to UVC radiation. Subsequent UVA irradiation results in the partial restoration of these band intensities, indicating DNA repair and bacterial photoreactivation. This enhanced understanding aims to improve the accuracy and effectiveness of these spectroscopic tools in clinical and environmental settings.

Aptamer-Modified MOFs (Aptamer@MOF) for Efficient Detection of Bacterial Pathogens: A Review

Detecting pathogenic bacteria is crucial for controlling infectious diseases, safeguarding public health, and ensuring food and water safety. The integration of metal-organic frameworks (MOFs) with aptamers offers a promising approach to enhance bacterial detection. Aptamers provide high specificity for target recognition, while MOFs contribute tunable porous structures and stability, forming robust biosensors. This synergy improves sensitivity, selectivity, and versatility, enabling real-time and quantitative detection. Applications span food safety, environmental monitoring, and point-of-care diagnostics. This review highlights the significance of aptamer@MOF biosensors, discussing various detection techniques and aptamer immobilization methods. It also addresses challenges like enhancing sensitivity, improving selectivity, minimizing interference, ensuring stability, and advancing scalability for real-world applications. Additionally, limitations such as the need for miniaturization, multimode detection, and multiplex analysis are highlighted. Future directions focus on optimizing the design and expanding applications to overcome these limitations. The versatility and potential of aptamer@MOF biosensors underscore their promise as high-performance platforms for bacterial detection in diverse fields.

Microfluidic biosensors: revolutionizing detection in DNA analysis, cellular analysis, and pathogen detection

Microfluidic chips have emerged as versatile and powerful tools that enable the precise manipulation of fluids and bioparticles at the microscale. Their impact on detection applications is profound, offering advantages such as miniaturization, enhanced sensitivity, multiplexing capability, and integrated functions. These chips can be customized for specific techniques, such as DNA analysis, immunoassays, chemical sensing, and cell-based assays. With a wide range of types available, including Lab-on-a-Chip, droplet-based, paper-based, electrochemical, optical, and magnetic chips, they find applications in diverse fields such as medical diagnostics, DNA analysis, cell analysis, food safety testing, environmental monitoring, and industrial processes. This powerful technology replicates laboratory capabilities on miniature chip-scale devices, resulting in time and cost savings while enabling portability and field-use capability. Its impact spans genetic analysis, proteomic analysis, cell culture, biosensors, pathogen detection, and point-of-care diagnostics, playing a pivotal role in advancing chemical and biological analysis. The overall aim of this review is to provide an overview of the development of microfluidic biochips for biological detection and discuss their various applications.

Quantification of Viruses in Wastewater on a Centrifugal Microfluidic Disc

Rapid and onsite detection of pathogens in water is a critical first step in preventing the spread of infectious diseases from the environment to humans. However, current microbial monitoring practices are tedious, expensive, and slow. These limitations significantly impede our ability to promptly identify potential risks to public health, leading to delays in implementing the necessary interventions. In this study, we report the development of a portable centrifugal microfluidic disc (CD) that integrates sample concentration, purification, and a droplet digital reverse transcription LAMP (ddRT-LAMP) assay as a lab-on-a-chip system for rapid virus detection in the environment. Coupled with the pseudo- and nonpseudo forces generated during the CD rotation or oscillation, the assay steps for sample purification, concentration, and quantification were completed in less than 1.5 h. The results showed that the on-CD sample preparation procedures are comparable to the traditional in-tube sample preparation assay. Furthermore, the indigenous pepper mild mottle virus (PMMoV) in raw sewage at concentrations ranging from 6.0 × 104 to 2.1 × 107 copies/ml was successfully quantified using the complete on-CD assay, which includes on-CD sample preparation procedures and on-CD ddRT-LAMP. The concentrations of PMMoV detected by the CD assay matched well with those detected by the state-of-the-art virus nucleic acid extraction and ddRT-PCR assay for wastewater and wastewater-spiked environmental water samples, demonstrating the potential of this CD platform for environmental applications.

Bacterial Bioaerosol-Specific Capture and In Situ Detection Using an Immune ZIF-8-Melamine Foam-Functionalized Colorimetric Biosensor

Bioaerosol infections containing pathogenic viruses and bacteria have resulted in significant economic losses and posed a serious threat to public health, as evidenced by outbreaks of coronavirus disease and avian influenza. Consequently, the sampling and screening of bioaerosols are crucial for the prevention of bioaerosol-borne diseases. In this study, an ultrasensitive biosensor based on zeolitic imidazolate framework-8-melamine foam (ZIF-8-MF) was innovatively developed for the specific capture and in situ detection of bioaerosols. The bacterial bioaerosols were collected by a wet cyclone into phosphate-buffered saline (PBS) buffer at a high collection rate, achieving a satisfactory collection efficiency of ∼80% within 10 min. The target bacteria collected in the PBS buffer were specifically captured and effectively concentrated using immune ZIF-8-MF. The gold@platinum nanozymes (GPNs) were employed to specifically label the captured target bacteria and efficiently amplify the biological signal. And the resulting colorimetric signal was analyzed via a self-developed smartphone application (App). This biosensor demonstrated the capability to detect bioaerosols containing Salmonella typhimurium in the range of 1.6 × 102-1.6 × 105 CFU/m3 within 1.5 h, with a detection limit as low as 100 CFU/m3. Compared with other bioaerosol detection methods, the biosensor offered advantages such as high collection rate, specific capture, efficient concentration, and in situ detection, positioning it as a highly promising and practical tool for the monitoring of bioaerosols containing diverse pathogenic bacteria.

Multiplexed Pathogenic Bacteria Detection via a Two-Dimensional Encoded Fluorescent Microsphere System

We developed an advanced microscopy imaging platform enabling amplification-free, multiplex detection of pathogenic bacteria in food and clinical samples, eliminating the need for DNA extraction. This platform leverages two-dimensional encoded polystyrene (PS) microspheres and an Argonaute-based decoding system to create multiplexed signal libraries. Each PS microsphere probe, encoded with spectrally distinct fluorophores and differing particle sizes, achieves high fluorescence through a tetrahedral DNA-enhanced hybridization chain reaction (TDNA-HCR), significantly enhancing signal intensity and reducing reaction time by 67%. Pathogenic bacteria identification relies on aptamer-specific recognition, which transduces pathogenic bacteria presence into guide DNA (gDNA) signals that activate Clostridium butyricum Argonaute (CbAgo) for precise DNA cleavage, encoding pathogenic bacteria type and concentration in the color, size, and count of fluorescent PS probes. A custom computer vision-powered algorithm processes these signals, offering sensitive detection at 102 CFU/mL within 1.5 h, demonstrating significant potential for food safety and clinical diagnostic applications.

Development and application of hydrogels in pathogenic bacteria detection in foods

Hydrogels are 3D networks of water-swollen hydrophilic polymers. It possesses unique properties (e.g., carrying biorecognition elements and creating a micro-environment) that make it highly suitable for bacteria detection (e.g., expedited and effective bacteria detection) and mitigation of bacterial contamination in specific environments (e.g., food systems). This study first introduces the materials used to create hydrogels for bacteria detection and the mechanisms for detection. We also summarize different hydrogel-based detection methods that rely on external stimuli and biorecognition elements, such as enzymes, temperature, pH, antibodies, and oligonucleotides. Subsequently, a range of widely utilized bacterial detection technologies were discussed where recently hydrogels are being used. These modifications allow for precise, real-time diagnostics across varied food matrices, responding effectively to industry needs for sensitivity, scalability, and portability. After highlighting the utilization of hydrogels and their role in these detection techniques, we outline limitations and advancements in the methods for the detection of foodborne pathogenic bacteria, especially the potential application of hydrogels in the food industry.

Machine Learning-Enhanced Bacteria Detection Using a Fluorescent Sensor Array with Functionalized Graphene Quantum Dots

Pathogenic bacteria are the source of many serious health problems, such as foodborne diseases and hospital infections. Timely and accurate detection of these pathogens is of vital significance for disease prevention, control of epidemic spread, and protection of public health security. Rapid identification of pathogenic bacteria has become a research focus in recent years. In contrast to traditional large-scale detection equipment, the fluorescent sensor array developed in this study can detect bacteria within just five min and is cost-effective. The array employs nitrogen- and sulfur-doped graphene quantum dots (NS-GQDs) synthesized through a simple hydrothermal process, making it environmentally friendly by avoiding toxic metal elements. Functionalized with antibiotics, spectinomycin, kanamycin, and polymyxin B, the NS-GQDs (renamed as S-NS-GQDs, K-NS-GQDs, and B-NS-GQDs) exhibit variable affinities for different bacteria, enabling broad-spectrum detection without targeting specific species. Upon binding with bacteria, the fluorescence intensity of the functionalized NS-GQDs decreases significantly. The sensor array exhibits distinct fluorescence responses to different bacterial species, which can be distinguished by using various machine learning algorithms. The results demonstrate that the platform can quickly and accurately identify and quantify five bacterial species, showing excellent performance in terms of accuracy, sensitivity, and stability. This makes it a promising tool with great practical application prospects in pathogenic bacterial detection.

Identification of Salmonella Enteritidis, Salmonella Typhimurium, Bacillus cereus, Bacillus subtilis, and Clostridium perfringens in hospital food

Despite conducting studies to investigate food contamination in hospitals in different parts of Iran in recent years, there have been no reliable studies to identify Salmonella Enteritidis, Salmonella Typhimurium, Bacillus cereus, Bacillus subtilis, and Clostridium perfringens in hospital food in Mashhad. Therefore, this study was conducted with the aim of investigating some major foodborne pathogens in hospital food. In this study, 360 food samples were randomly selected from 12 different menus from 13 hospitals affiliated with Mashhad University of Medical Sciences, Mashhad, Iran. Microbial culture methods for the recovery/isolation or enumeration of Salmonella spp., Bacillus spp. and C. perfringens as well as toxinotyping of C. perfringens using the PCR method were performed. B. cereus and C. perfringens were detected in 4 out of 360 food samples, 2 (0.55%) of which were B. cereus and, the remaining 2 (0.55%) were C. perfringens; B. subtilis was not detected in any of the food samples. Furthermore, Salmonella was found in 21 (5.82%) food samples, 12 (3.33%) of which were S. Typhimurium, 4 (1.11%) were S. Enteritidis, and 5 (1.38%) belonged to other Salmonella species. The most contaminated foods were salad, kebab, and rice samples, which accounted for 36%, 16%, and 12% of the contaminated foods, respectively. In our study, two strains of S. Typhimurium and S. Enteritidis, were the primary causative agents of food contamination among the investigated pathogens. More stringent control measures should be implemented in hospital catering, particularly for unprocessed foods such as salads.

CRISPR/Cas12a dual-mode biosensor for Staphylococcus aureus detection via enzyme-free isothermal amplification

Accurate and reliable detection of Staphylococcus aureus (S. aureus) is essential for preventing infections, particularly in healthcare and food safety contexts. This work presents a novel dual-mode biosensor that integrates the CRISPR/Cas12a system with an enzyme-free isothermal amplification method for detecting S. aureus. Hybridization chain reaction (HCR) and catalytic hairpin assembly (CHA) amplify the aptamer-triggered response, significantly enhancing sensitivity. CRISPR/Cas12a's nuclease activity is utilized in two modes: cis cleavage generates a fluorescence signal, while trans cleavage produces an electrochemical signal, enabling dual-mode detection. The biosensor demonstrates outstanding performance, with a limit of detection (LOD) as low as 5.7 CFU mL-1 in electrochemical mode and 133.7 CFU mL-1 in fluorescence mode, showcasing excellent accuracy, stability, and sensitivity. It has been successfully applied to detecting actual samples, confirming its practical applicability. This innovative approach offers a powerful tool for the swift and precise identification of S. aureus and paves the way for developing next-generation dual-mode biosensors for various analytes. Future research will aim to simplify the detection process further, making it more accessible for use in resource-limited settings.

Trends of Nanobiosensors in Modern Agriculture Systems

Sustainable agriculture and the provision of food for all become dependent on the availability of efficient diagnostic techniques for the prompt identification of plant diseases. Current scientific findings suggest that nanotechnology can positively affect the agrifood industry by reducing the adverse effects of agricultural practices on human health and the environment, increasing food security and productivity, and fostering social and economic justice. Nanomaterials' unique physical and chemical characteristics have made it possible to employ them as cutting-edge, effective diagnostic instruments for various plant infections and other significant disease biomarkers. By creating diagnostic instruments and methods, nanobiosensors significantly contribute to the revolution of farming. In real time, nanobiosensors can detect infections, metabolites, pesticides, nutrient levels, soil moisture, and temperature. This helps with precision farming techniques and maximises resource use. To better address agricultural concerns, we have included the most recent research on the concept, types, applications, commercial aspects, and future scope of nanobiosensors in this review.

Engineering Stimuli-Responsive Materials for Precision Medicine

Over the past decade, precision medicine has garnered increasing attention, making significant strides in discovering new therapeutic drugs and mechanisms, resulting in notable achievements in symptom alleviation, pain reduction, and extended survival rates. However, the limited target specificity of primary drugs and inter-individual differences have often necessitated high-dosage strategies, leading to challenges such as restricted deep tissue penetration rates and systemic side effects. Material science advancements present a promising avenue for these issues. By leveraging the distinct internal features of diseased regions and the application of specific external stimuli, responsive materials can be tailored to achieve targeted delivery, controllable release, and specific biochemical reactions. This review aims to highlight the latest advancements in stimuli-responsive materials and their potential in precision medicine. Initially, we introduce disease-related internal stimuli and capable external stimuli, elucidating the reaction principles of responsive functional groups. Subsequently, we provide a detailed analysis of representative pre-clinical achievements of stimuli responsive materials across various clinical applications, including enhancements in the treatment of cancers, injury diseases, inflammatory diseases, infection diseases, and high-throughput microfluidic biosensors. Finally, we discuss some clinical challenges, such as off-target effects, long-term impacts of nano-materials, potential ethical concerns, and offer insights into future perspectives of stimuli-responsive materials.

Highly Sensitive Lateral Flow Immunodetection of the Insecticide Imidacloprid in Fruits and Berries Reached by Indirect Antibody-Label Coupling

A highly sensitive lateral flow immunoassay (LFIA) for imidacloprid, a widely used neonicotinoid insecticide, has been developed. The LFIA realizes the indirect coupling of anti-imidacloprid antibodies and gold nanoparticle (GNP) labels directly in the course of the assay. For this purpose, the common GNPs conjugate with anti-imidacloprid antibodies and are changed into a combination of non-modified, anti-imidacloprid antibodies, and the GNPs conjugate with anti-species antibodies. The given approach provides the possibility of selecting independent concentrations of GNPs and anti-imidacloprid antibodies to obtain the influence of minimal imidacloprid concentrations in the samples on the formation of detected, labeled immune complexes. A comparative study of imidacloprid LFIAs with common and indirect antibody-label coupling was implemented. The second variant reduced the limit of detection (LOD) of imidacloprid 20 times, reaching 0.2 ng/mL and 0.002 ng/mL for visual and instrumental detection, respectively, thus surpassing the existing LFIAs for imidacloprid. The developed highly sensitive LFIA was tested for imidacloprid detection in freshly squeezed fruits and berries without any additional sample preparation. The imidacloprids revealed were in the range of 75-97% for grape, 75-85% for orange, and 86-97% for apple samples. The time of the testing was 15 min.

Phage probe on RAFT polymer surface for rapid enumeration of E. coli K12

This study presents a simple, fast, and sensitive label-free sensing assay for the precise enumeration of modeled pathogenic Escherichia coli K12 (E. coli K12) bacteria for the first time. The method employs the covalent binding bacteriophage technique on the surface of a reversible addition-fragmentation chain transfer (RAFT) polymer film. The Nyquist plots obtained from electrochemical impedance spectroscopy (EIS) identified the charge transfer resistance Rct was calculated from a suitable electrochemical circuit model through an evaluation of the relevant parameter after the immobilization of the bacteriophage and the binding of specific E. coli K12. The impedimetric biosensor reveals specific and reproducible detection with sensitivity in the linear working range of 104.2-107.0 CFU/mL, a limit of detection (LOD) of 101.3 CFU/mL, and a short response time of 15 min. The SERS response validates the surface roughness and interaction of the SERS-tag with E. coli K12-modified electrodes. Furthermore, the covalently immobilized active phage selectivity was proved against various non-targeting bacterial strains in the presence of targeted E.coli K12 with a result of 94 % specificity and 98 % sensitivity. Therefore, the developed phage-based electrode surface can be used as a disposable, label-free impedimetric biosensor for rapid and real-time monitoring of serum samples.

Biosensor in smart food traceability system for food safety and security

The burden of food contamination and food wastage has significantly contributed to the increased prevalence of foodborne disease and food insecurity all over the world. Due to this, there is an urgent need to develop a smarter food traceability system. Recent advancements in biosensors that are easy-to-use, rapid yet selective, sensitive, and cost-effective have shown great promise to meet the critical demand for onsite and immediate diagnosis and treatment of food safety and quality control (i.e. point-of-care technology). This review article focuses on the recent development of different biosensors for food safety and quality monitoring. In general, the application of biosensors in agriculture (i.e. pre-harvest stage) for early detection and routine control of plant infections or stress is discussed. Afterward, a more detailed advancement of biosensors in the past five years within the food supply chain (i.e. post-harvest stage) to detect different types of food contaminants and smart food packaging is highlighted. A section that discusses perspectives for the development of biosensors in the future is also mentioned.

Impact of Metabolites from Foodborne Pathogens on Cancer

Foodborne pathogens are microorganisms that cause illness through contamination, presenting significant risks to public health and food safety. This review explores the metabolites produced by these pathogens, including toxins and secondary metabolites, and their implications for human health, particularly concerning cancer risk. We examine various pathogens such as Salmonella sp., Campylobacter sp., Escherichia coli, and Listeria monocytogenes, detailing the specific metabolites of concern and their carcinogenic mechanisms. This study discusses analytical techniques for detecting these metabolites, such as chromatography, spectrometry, and immunoassays, along with the challenges associated with their detection. This study covers effective control strategies, including food processing techniques, sanitation practices, regulatory measures, and emerging technologies in pathogen control. This manuscript considers the broader public health implications of pathogen metabolites, highlighting the importance of robust health policies, public awareness, and education. This review identifies research gaps and innovative approaches, recommending advancements in detection methods, preventive strategies, and policy improvements to better manage the risks associated with foodborne pathogens and their metabolites.

Influence of surface texture: A comparative study on antibacterial activities of morphologically tailored zinc oxide

The morphology-dependent antibacterial activity of zinc oxide (ZnO) nanoparticles with three different morphologies, nanowall (NW), nanosphere (NS), and, nanorod (NR) was rigorously investigated to elucidate the influence of shape and size on their performance. Their morphological, surface, and structural characteristics were meticulously analyzed using SEM, BET, and XRD techniques. The antibacterial activity of synthesized ZnO samples was initially investigated and validated through in silico docking studies against nine bacterial strains, specifically targeting 1GCI, 2DCJ, 6KMM and 3T07, 6KVQ, 1MWT from gram-positive Bacillus sp. and Staphylococcus sp. respectively, 6N38, 6CRT, 6GRH from gram-negative E. coli. The docking simulations were performed using Autodock 4.2 software, yielding promising results characterized by negative binding energies, indicative of favorable interactions. The invitro studies were assessed against three same bacteria mentioned above using the disk diffusion method. The results demonstrated a pronounced dependency of antibacterial activity on the surface area, average crystallite size, and surface roughness of ZnO samples. ZnO (NW) exhibited markedly superior antibacterial properties. This enhanced efficacy is attributed to their higher surface area to volume ratio, smaller average crystallite size and increased surface roughness facilitating more efficient interactions with bacterial cell membranes. ZnO (NR) nanoparticles exhibited enhanced antibacterial activity despite minimal surface area.

Application of the Electrical Microbial Growth Analyzer Method for Efficiently Quantifying Viable Bacteria in Ready-to-Eat Sea Cucumber Products

Accurate and efficient quantification of viable bacteria in ready-to-eat food products is crucial for food safety and public health. The rapid and accurate assessment of foodborne bacteria in complex food matrices remains a significant challenge. Herein a culture-based approach was established for easily quantifying viable bacteria in ready-to-eat sea cucumber (RSC) products. Samples of the liquid companion within the package were directly transferred into test tubes to determine bacterial growth curves and growth rate curves, utilizing the electrical microbial growth analyzer. Viable bacteria in the samples were then quantified based on the time required to attain the maximum growth rate indicated on the growth rate curve. At a concentration of 5.0 × 103 CFU/mL of viable bacteria in the liquid companion, the recovery rates were 108.85-112.77% for Escherichia coli (E. coli) and 107.01-130.54% for Staphylococcus aureus (S. aureus), with standard deviations of 1.60 and 3.92, respectively. For the solid content in the package, the quantification was performed using the same methodology following an additional homogenization step. At a concentration of 5.0 × 103 CFU/mL of viable bacteria in the sample, the recovery rates were 91.94-102.24% for E. coli and 81.43-104.46% for S. aureus, with standard deviations of 2.34 and 2.38, respectively. In instances where the viable bacterial concentration was 5.0 × 103 CFU/mL in RSC products, the total time required for the quantification did not exceed 10.5 h. This method demonstrated advantages over traditional plate counting and PCR methods regarding simplicity and efficiency, representing a promising alternative for the quantification of viable bacteria in food like RSC products.

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).

Colorimetric-SERS dual-mode aptasensor for Staphylococcus aureus based on MnO2@AuNPs oxidase-like activity

The nanozyme-linked aptamer-sorbent assay (NLASA) is a rapid way to screen and characterize aptamer binding to targets. In this paper, a MnO2@AuNPs@aptamer (Apt) based NLASA coupled with colorimetric-SERS dual-mode for Staphylococcus aureus (S. aureus) detection is presented. Cu,Fe-CDs were used as the reducing agent to synthesize MnO2 and gold nanoparticles (AuNPs). Then, they were fabricated to obtain MnO2@AuNPs with oxidase (OXD)-like and SERS activities. The S. aureus aptamer was conjugated to MnO2@AuNPs and enhanced the OXD-like activity, which realized the specific capture of S. aureus in food matrices. In addition, S. aureus improves the oxidation of 2,2'-azino-bis (3-ethylbenzthiazoline-6-sulfonic acid (ABTS) but inhibits 3,3',5,5'-tetramethylbenzidine (TMB) to generate Raman-active oxTMB with MnO2@AuNPs@Apt. This sensor was used for detections of S. aureus in a concentration ranged from 101 to 107 CFU/mL with a detection limit of 0.926 CFU/mL (colorimetric) and 1.561 CFU/mL (SERS), and the recovery is 85%-105% in real samples.

Bioinks and biofabrication techniques for biosensors development: A review

3D bioprinting technologies and bioink development are enabling significant advances in miniaturized and integrated biosensors. For example, bioreceptors can be immobilized within a porous 3D structure to significantly amplify the signal, while biocompatible and mechanically flexible systems uniquely enable wearable chem- and bio-sensors. This advancement is accelerating translation by enabling the production of high performance, reproducible, and flexible analytical devices. The formulation of the bioink plays a crucial role in determining the bio-functionality of the resulting printed structures, e.g., the porosity that allows the analyte to diffuse through the 3D structure, the affinity and avidity of the receptors, etc. This review explores the next generation of advanced bioinks for biosensor development and provides insights into the latest cutting-edge bioprinting technologies. The bioprinting methods available for biosensor fabrication including inkjet, extrusion, and laser-based bioprinting, are discussed. The advantages and limitations of each method are analysed, and recent advancements in bioprinting technologies are presented. The review then delves into the properties of advanced bioinks, such as biocompatibility, printability, stability, and applicability. Different types of advanced bioinks are explored, including multicomponent, stimuli-responsive, and conductive bioinks. Finally, the next generation of bioinks for biosensors is considered, identifying possible new opportunities and challenges. Overall, this literature review highlights the combined importance of bioink formulation and bioprinting methods for the development of high-performance analytical biosensors.

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

Concern about food safety triggers demand on rapid, accurate and on-site detection of foodborne pathogens. Among various fluorescent probes for detection, carbon dots (CDs) prepared by carbonization of carbon-rich raw materials show extraordinary performance for their excellent and tailorable photoluminescence property, as well as their facilely gained specificity by surface customization and modification. CDs-based fluorescent probes play a crucial role in many pathogenic bacteria sensing systems. In addition, microfluidic technology with characteristics of portability and functional integration is expected to combine with CDs-based fluorescent probes for point-of-care testing (POCT), which can further enhance the detection property of CDs-based fluorescent probes. Here, this paper reviews CDs-based bacterial detection methods and systems, including the structural modulation of fluorescent probes and pathogenic bacteria detection mechanisms, and describes the potential of combining CDs with microfluidic technology, providing reference for the development of novel rapid detection technology for pathogenic bacteria in food.

Recent advances in portable devices for environmental monitoring applications

Environmental pollution remains a major societal problem, leading to serious impacts on living organisms including humans. Human activities such as civilization, urbanization, and industrialization are major causes of pollution. Imposing stricter rules helps control environmental pollutant levels, creating a need for reliable pollutant monitoring in air, water, and soil. The application of traditional analytical techniques is limited in low-resource areas because they are sophisticated, expensive, and bulky. With the development of biosensors and microfluidics technology, environmental monitoring has significantly improved the analysis time, low cost, portability, and ease of use. This review discusses the fundamentals of portable devices, including microfluidics and biosensors, for environmental control. Recently, publications reviewing microfluidics and biosensor device applications have increased more than tenfold, showing the potential of emerging novel approaches for environmental monitoring. Strategies for enzyme-, immunoassay-, and molecular-based analyte sensing are discussed based on their mechanisms and applications. Microfluidic and biosensor platforms for detecting major pollutants, including metal ions, pathogens, pesticides, and antibiotic residues, are reviewed based on their working principles, advantages, and disadvantages. Challenges and future trends for the device design and fabrication process to improve performance are discussed. Miniaturization, low cost, selectivity, sensitivity, high automation, and savings in samples and reagents make the devices ideal alternatives for in-field detection, especially in low-resource areas. However, their operation with complicated environmental samples requires further research to improve the specificity and sensitivity. Although there is a wide range of devices available for environmental applications, their implementation in real-world situations is limited. This study provides insights into existing issues that can be used as references and a comparative analysis for future studies and applications.

Dynamic simulation and experimental studies of molecularly imprinted label-free sensor for determination of milk quality marker

Bovine serum albumin (BSA) has emerged as a biomarker for mammary gland health and cow quality, being recognized as a significant allergenic protein. In this study, a novel flexible molecular imprinted electrochemical sensor by surface electropolymerization using pyrrole (Py) as functional monomer, which can be better applied to the detection of milk quality marker BSA. Based on computational results, with regard to all polypyrrole (PPy) conformations and amino-acid positions within the protein, the BSA molecule remained firmly embedded into PPy polymers with no biological changes. The molecular imprinted electrochemical sensor displayed a broad linear detection range from 1.0 × 10-4 to 50 ng·mL-1 (R2 = 0.995) with a low detection limit (LOD) of 4.5 × 10-2 pg·mL-1. Additionally, the sensor was highly selective, reproducible, stable and recoverable, suggesting that it might be utilized for the evaluation of milk quality.

A rapid LAMP assay for the diagnosis of oak wilt with the naked eye

BACKGROUND

Oak wilt disease, caused by Bretziella fagacearum is a significant threat to oak (Quercus spp.) tree health in the United States and Eastern Canada. The disease may cause dramatic damage to natural and urban ecosystems without management. Early and accurate diagnosis followed by timely treatment increases the level of disease control success.

RESULTS

A rapid assay based on loop mediated isothermal amplification (LAMP) was first developed with fluorescence detection of B. fagacearum after 30-minute reaction time. Six different primers were designed to specifically bind and amplify the pathogen's DNA. To simplify the use of this assay in the field, gold nanoparticles (AuNPs) were designed to bind to the DNA amplicon obtained from the LAMP reaction. Upon inducing precipitation, the AuNP-amplicons settle as a red pellet visible to the naked eye, indicative of pathogen presence. Both infected and healthy red oak samples were tested using this visualization method. The assay was found to have high diagnostic sensitivity and specificity for the B. fagacearum isolate studied. Moreover, the developed assay was able to detect the pathogen in crude DNA extracts of diseased oak wood samples, which further reduced the time required to process samples.

CONCLUSIONS

In summary, the LAMP assay coupled with oligonucleotide-conjugated gold nanoparticle visualization is a promising method for accurate and rapid molecular-based diagnosis of B. fagacearum in field settings. The new method can be adapted to other forest and plant diseases by simply designing new primers.

Optimized detection of Salmonella typhimurium using aptamer lateral flow assay

Salmonella typhimurium, a pathogenic bacterium with significant implications in medicine and the food industry, poses a substantial threat by causing foodborne illnesses such as typhoid fever. Accurate diagnosis of S. typhimurium is challenging due to its overlap symptoms with various diseases. This underscores the need for a precise and efficient diagnostic approach. In this study, we developed a biosensor using the Taguchi optimization method based on aptamer lateral flow assay (LFA) for the detection of S. typhimurium. Therefore, signal probe and nanobioprobe were designed using anti-Salmonella aptamer, conjugated with gold nanoparticles (GNPs), and used in LFA. The strategy of this test is based on a competitive format between the bacteria immobilized on the membrane and the bacteria present in the tested sample. Moreovere, the optimization of various factors affecting the aptamer LFA, including the concentration of bacteria (immobilized and into the sample) and the concentration of nanobioprop, were performed using the Taguchi test designing method. The data showed that the optimal conditions for the LFA reaction was 108 CFU/mL of immobilized bacteria and 1.5 μg/μL of nanobioprop concentration. Then, the visual detection limit of S. typhimurium was estimated as 105 CFU/mL. The reaction results were obtained within 20 min, and there were no significant cross-reactions with other food pathogens. In conclusion, the aptamer-LFA diagnostic method, optimized using the Taguchi approach, emerges as a reliable, straightforward, and accurate tool for the detection of S. typhimurium. Overall, this method can be a portable diagnostic kit for the detection and identification of bacteria.

Microfluidic sensors for the detection of emerging contaminants in water: A review

In recent years, numerous emerging contaminants have been identified in surface water, groundwater, and drinking water. Developing novel sensing methods for detecting diverse emerging pollutants in water is urgently needed, as even at low concentrations, these pollutants can pose a serious threat to human health and environmental safety. Traditional testing methods are based on laboratory equipment, which is highly sensitive but complex to operate, costly, and not suitable for on-site monitoring. Microfluidic sensors offer several benefits, including rapid evaluation, minimal sample usage, accurate liquid manipulation, compact size, automation, and in-situ detection capabilities. They provide promising and efficient analytical tools for high-performance sensing platforms in monitoring emerging contaminants in water. In this paper, recent research advances in microfluidic sensors for the detection of emerging contaminants in water are reviewed. Initially, a concise overview is provided about the various substrate materials, corresponding microfabrication techniques, different driving forces, and commonly used detection techniques for microfluidic devices. Subsequently, a comprehensive analysis is conducted on microfluidic detection methods for endocrine-disrupting chemicals, pharmaceuticals and personal care products, microplastics, and perfluorinated compounds. Finally, the prospects and future challenges of microfluidic sensors in this field are discussed.

A 3D-Printed Integrated Handheld Biosensor for the Detection of Vibrio parahaemolyticus

Vibrio parahaemolyticus (V. parahaemolyticus) is one of the important seafood-borne pathogens that cause a serious gastrointestinal disorder in humans. Recently, biosensors have attracted serious attention for precisely detecting and tracking risk factors in foods. However, a major consideration when fabricating biosensors is to match the low cost of portable devices to broaden its application. In this study, a 3D-printed integrated handheld biosensor (IHB) that combines RPA-CRISPR/Cas12a, a lateral flow strip (LFS), and a handheld device was developed for the ultrasensitive detection of V. parahaemolyticus. Using the preamplification of RPA on tlh gene of V. parahaemolyticus, a specific duplex DNA product was obtained to activate the trans-cleavage activity of CRISPR/Cas12a, which was then utilized to cleave the ssDNA probe. The ssDNA probe was then detected by the LFS, which was negatively correlated with the content of amplified RPA products of the tlh gene. The IHB showed high selectivity and excellent sensitivity for V. parahaemolyticus detection, and the limit of detection was 4.9 CFU/mL. The IHB also demonstrated great promise for the screening of V. parahaemolyticus in samples and had the potential to be applied to the rapid screening of other pathogen risks for seafood and marine environmental safety.

A Dual-mode platform for the rapid detection of Escherichia coli O157:H7 based on CRISPR/Cas12a and RPA

Escherichia coli O157:H7 (E. coli O157:H7) is a foodborne pathogenic microorganism that is commonly found in the environment and poses a significant threat to human health, public safety, and economic stability worldwide. Thus, early detection is essential for E. coli O157:H7 control. In recent years, a series of E. coli O157:H7 detection methods have been developed, but the sensitivity and portability of the methods still need improvement. Therefore, in this study, a rapid and efficient testing platform based on the CRISPR/Cas12a cleavage reaction was constructed. Through the integration of recombinant polymerase amplification and lateral flow chromatography, we established a dual-interpretation-mode detection platform based on CRISPR/Cas12a-derived fluorescence and lateral flow chromatography for the detection of E. coli O157:H7. For the fluorescence detection method, the limits of detection (LODs) of genomic DNA and E. coli O157:H7 were 1.8 fg/µL and 2.4 CFU/mL, respectively, within 40 min. Conversely, for the lateral flow detection method, LODs of 1.8 fg/µL and 2.4 × 102 CFU/mL were achieved for genomic DNA and E. coli O157:H7, respectively, within 45 min. This detection strategy offered higher sensitivity and lower equipment requirements than industry standards. In conclusion, the established platform showed excellent specificity and strong universality. Modifying the target gene and its primers can broaden the platform's applicability to detect various other foodborne pathogens.