Highly sensitive electrochemical sensor for the detection of Shiga toxin-producing E. coli (STEC) using interdigitated micro-electrodes selectively modified with a chitosan-gold nanocomposite

Advances in DNA-based electrochemical biosensors for the detection of foodborne pathogenic bacteria

The detection of foodborne pathogenic bacteria is critical in preventing foodborne diseases. DNA-based electrochemical biosensors, with the merits of high sensitivity and short detection time, provide an effective detecting method for foodborne pathogens, attracting significant interest for the past few years. This review mainly describes the important research progress of DNA-based electrochemical biosensors for the detection of foodborne pathogenic bacteria through four perspectives: representative foodborne pathogens detection using electrochemical approaches, DNA immobilization strategies of aptamers, DNA-based signal amplification strategies used in electrochemical DNA sensors, and functional DNA used in electrochemical DNA sensors. Finally, perspectives and challenges are presented in this field. This review will contribute to DNA-based electrochemical biosensor in enhancing the nucleic acid signal amplification.

Synthesis of carbon nanotubes-chitosan nanocomposite and immunosensor fabrication for myoglobin detection: An acute myocardial infarction biomarker

The use of single-walled carbon nanotubes (SWCNTs) in biomedical applications is limited due to their inability to disperse in aqueous solutions. In this study, dispersed -COOH functionalized CNTs with N-succinylated chitosan (CS), greatly increasing the water solubility of CNTs and forming a uniformly dispersed nanocomposite solution of CNTs@CS. Coupling reagent EDC/NHS was used as a linker with the -COOH groups present on the N-succinylated chitosan which significantly improved the affinity of the CNTs for biomolecules. Myoglobin (Mb) is a promising biomarker for the precise assessment of cardiovascular risk, type 2 diabetes, metabolic syndrome, hypertension and several types of cancer. A high level of Mb can be used to diagnose the mentioned pathogenic diseases. The CNTs@CS-FET demonstrates superior sensing performance for Mb antigen fortified in buffer, with a wide linear range of 1 to 4000 ng/mL. The detection limit of the developed Mb immunosensor was estimated to be 4.2 ng/mL. The novel CNTs@CS-FET immunosensor demonstrates remarkable capability in detecting Mb without being affected by interferences from nonspecific antigens. Mb spiked serum showed a recovery rate of 100.262 to 118.55 % indicating great promise for Mb detection in clinical samples. The experimental results confirmed that the CNTs@CS-FET immunosensor had excellent selectivity, reproducibility and storage stability.

Disposable impedance sensors based on novel hybrid MoS2 nanosheets and microparticles to detect Escherichia Coli DNA

The rapid and accurate detection of pathogenic bacteria is essential for food safety and public health. Conventional detection techniques, such as nucleic acid sequence-based amplification and polymerase chain reaction, are time-consuming and require specialized equipment and trained personnel. Here, we present quick, disposable impedance sensors based on the novel hybrid MoS2 nanomaterial for detecting Escherichia coli DNA. Our results indicate that the proposed sensors operate linearly between 10- 20 and 10-15 M concentrations, achieving an impressive detection limit of 10-20 M with the highest sensitivity observed at a 0.325 nM probe concentration sensor. Furthermore, the electrochemical impedance spectroscopy biosensors exhibited potential selectivity for Escherichia coli DNA over Bacillus subtilis and Vibrio proteolyticus DNA sequences. The findings offer a promising avenue for efficient and precise DNA detection, with potential implications for broader biotechnology and medical diagnostics applications.

Label-Free Electrochemical Methods for Disease Detection

Label-free electrochemical biosensing leverages the advantages of label-free techniques, low cost, and fewer user steps, with the sensitivity and portability of electrochemical analysis. In this review, we identify four label-free electrochemical biosensing mechanisms: (a) blocking the electrode surface, (b) allowing greater access to the electrode surface, (c) changing the intercalation or electrostatic affinity of a redox probe to a biorecognition unit, and (d) modulating ion or electron transport properties due to conformational and surface charge changes. Each mechanism is described, recent advancements are summarized, and relative advantages and disadvantages of the techniques are discussed. Furthermore, two avenues for gaining further diagnostic information from label-free electrochemical biosensors, through multiplex analysis and incorporating machine learning, are examined.

Nanostructured biosensing platforms for the detection of food- and water-borne pathogenic Escherichia coli

Pathogenic bacterial infection is one of the principal causes affecting human health and ecosystems. The accurate identification of bacteria in food and water samples is of significant interests to maintain safety and health for humans. Culture-based tests are practically tedious and may produce false-positive results, while viable but non-culturable microorganisms (NCMs) cannot be retrieved. Thus, it requires fast, reliable, and low-cost detection strategies for on-field analysis and point-of-care (POC) monitoring. The standard detection methods such as nucleic acid analysis (RT-PCR) and enzyme-linked immunosorbent assays (ELISA) are still challenging in POC practice due to their time-consuming (several hours to days) and expensive laboratory operations. The optical (surface plasmon resonance (SPR), fluorescence, and surface-enhanced Raman scattering (SERS)) and electrochemical-based detection of microbes (early stage of infective diseases) have been considered as alternative routes in the emerging world of nanostructured biosensing since they can attain a faster and concurrent screening of several pathogens in real samples. Moreover, optical and electrochemical detection strategies are opening a new route for the ability of detecting pathogens through the integration of cellphones, which is well fitted for POC analysis. This review article covers the current state of sensitive mechanistic approaches for the screening and detection of Escherichia coli O157:H7 (E. coli) pathogens in food and water samples, which can be potentially applied in clinical and environmental monitoring.

Immunosensors for Assay of Toxic Biological Warfare Agents

An immunosensor for the assay of toxic biological warfare agents is a biosensor suitable for detecting hazardous substances such as aflatoxin, botulinum toxin, ricin, Shiga toxin, and others. The application of immunosensors is used in outdoor assays, point-of-care tests, as a spare method for more expensive devices, and even in the laboratory as a standard analytical method. Some immunosensors, such as automated flow-through analyzers or lateral flow tests, have been successfully commercialized as tools for toxins assay, but the research is ongoing. New devices are being developed, and the use of advanced materials and assay techniques make immunosensors highly competitive analytical devices in the field of toxic biological warfare agents assay. This review summarizes facts about current applications and new trends of immunosensors regarding recent papers in this area.