Point-of-Care Diagnostic Devices for Detection of Escherichia coli O157:H7 Using Microfluidic Systems: A Focused Review

Single-Walled Carbon Nanotube-Modified Gold Leaf Immunosensor for Escherichia coli Detection

The requirement to prevent foodborne illnesses underscores the need for reliable detection tools, stimulating biosensor technology with practical solutions for in-field applications. This study introduces a low-cost immunosensor based on a single-walled carbon nanotube (SWCNT)-modified gold leaf electrode (GLE) for the sensitive detection of Escherichia coli. The immunosensor is realized with a layer-by-layer (LbL) assembly technique, creating an electrostatic bond between positively charged polyethylenimine (PEI) and negatively charged carboxyl-functionalized SWCNTs on the GLE. The structural and functional characterization of the PEI-SWCNT film was performed with Raman spectroscopy, high-resolution scanning electron microscopy (HRSEM), and electrical measurements. The PEI-SWCNT film was used as a substrate for antibody immobilization, and the electrochemical sensing potential was validated using electrochemical impedance spectroscopy (EIS). The results showed a wide dynamic range of E. coli detection, 101-108 cfu/mL, with a limit of detection (LOD) of 1.6 cfu/mL in buffer and 15 cfu/mL in the aqueous solution used for cleansing fresh lettuce leaves, affirming its efficiency as a practical and affordable tool in enhancing food safety.

Research progress on the detection of foodborne pathogens based on aptamer recognition

Foodborne diseases caused by bacterial contamination are a serious threat to food safety and human health. The classical plate culture method has the problems of long detection cycle, low sensitivity and specificity, and complicated operation, which cannot meet the growing demand for rapid quantitative detection of pathogenic bacteria. The frequent outbreak of foodborne diseases has put forward higher requirements for rapid and simple detection technology of foodborne pathogens. Aptamer is a kind of oligonucleotide fragment that can recognize targets with the advantages of high affinity and good specificity. The target can be range from proteins, small molecules, cells bacteria, and even viruses. Herein, the latest advances in sensitive and rapid detection of foodborne pathogens based on aptamer recognition was reviewed. Special attention has been paid to the obtained sequences of aptamers to various foodborne pathogens, the optimization of sequences, and the mechanism of aptamer recognition. Then, the research progress of biosensors for the detection of pathogenic bacteria based on aptamer recognition were summarized. Some challenges and prospects for the detection of foodborne pathogens based on aptamer recognition were prospected. In summary, with the further deepening of aptamer research and improvement of detection technology, aptamer-based recognition can meet the needs of rapid, sensitive, and accurate detection in practical applications.

Conductometric immunosensor for specific Escherichia coli O157:H7 detection on chemically funcationalizaed interdigitated aptasensor

Escherichia coli O157:H7 is a strain of Escherichia coli known for causing foodborne illness through the consumption of contaminated or raw food. To detect this pathogen, a conductometric immunosensor was developed using a conductometric sensing approach. The sensor was constructed on an interdigitated electrode and modified with a monoclonal anti-Escherichia coli O157:H7 aptamer. A total of 200 electrode pairs were fabricated and modified to bind to the target molecule replica. The binding replica, acting as the bio-recognizer, was linked to the electrode surface using 3-Aminopropyl triethoxysilane. The sensor exhibited excellent performance, detecting Escherichia coli O157:H7 in a short time frame and demonstrating a wide detection range of 1 fM to 1 nM. Concentrations of Escherichia coli O157:H7 were detected within this range, with a minimum detection limit of 1 fM. This innovative sensor offers simplicity, speed, high sensitivity, selectivity, and the potential for rapid sample processing. The potential of this proposed biosensor is particularly beneficial in applications such as drug screening, environmental monitoring, and disease diagnosis, where real-time information on biomolecular interactions is crucial for timely decision-making and where cross-reactivity or interference may compromise the accuracy of the analysis.

Hybrid Impedimetric Biosensors for Express Protein Markers Detection

Impedimetric biosensors represent a powerful and promising tool for studying and monitoring biological processes associated with proteins and can contribute to the development of new approaches in the diagnosis and treatment of diseases. The basic principles, analytical methods, and applications of hybrid impedimetric biosensors for express protein detection in biological fluids are described. The advantages of this type of biosensors, such as simplicity and speed of operation, sensitivity and selectivity of analysis, cost-effectiveness, and an ability to be integrated into hybrid microfluidic systems, are demonstrated. Current challenges and development prospects in this area are analyzed. They include (a) the selection of materials for electrodes and formation of nanostructures on their surface; (b) the development of efficient methods for biorecognition elements' deposition on the electrodes' surface, providing the specificity and sensitivity of biosensing; (c) the reducing of nonspecific binding and interference, which could affect specificity; (d) adapting biosensors to real samples and conditions of operation; (e) expanding the range of detected proteins; and, finally, (f) the development of biosensor integration into large microanalytical system technologies. This review could be useful for researchers working in the field of impedimetric biosensors for protein detection, as well as for those interested in the application of this type of biosensor in biomedical diagnostics.

Electromicrofluidic Device for Interference-Free Rapid Antibiotic Susceptibility Testing of Escherichia coli from Real Samples

Antimicrobial resistance (AMR) is a global health threat, progressively emerging as a significant public health issue. Therefore, an antibiotic susceptibility study is a powerful method for combating antimicrobial resistance. Antibiotic susceptibility study collectively helps in evaluating both genotypic and phenotypic resistance. However, current traditional antibiotic susceptibility study methods are time-consuming, laborious, and expensive. Hence, there is a pressing need to develop simple, rapid, miniature, and affordable devices to prevent antimicrobial resistance. Herein, a miniaturized, user-friendly device for the electrochemical antibiotic susceptibility study of Escherichia coli (E. coli) has been developed. In contrast to the traditional methods, the designed device has the rapid sensing ability to screen different antibiotics simultaneously, reducing the overall time of diagnosis. Screen-printed electrodes with integrated miniaturized reservoirs with a thermostat were developed. The designed device proffers simultaneous incubator-free culturing and detects antibiotic susceptibility within 6 h, seven times faster than the conventional method. Four antibiotics, namely amoxicillin-clavulanic acid, ciprofloxacin, ofloxacin, and cefpodoxime, were tested against E. coli. Tap water and synthetic urine samples were also tested for antibiotic susceptibility. The results show that the device could be used for antibiotic resistance susceptibility testing against E. coli with four antibiotics within six hours. The developed rapid, low-cost, user-friendly device will aid in antibiotic screening applications, enable the patient to receive the appropriate treatment, and help to lower the risk of anti-microbial resistance.