Single walled carbon nanotube-based junction biosensor for detection of Escherichia coli

Aptamer-modified paper-based analytical devices for the detection of food hazards: Emerging applications and future perspective

Food analysis plays a critical role in assessing human health risks and monitoring food quality and safety. Currently, there is a pressing need for a reliable, portable, and quick recognition element for point-of-care testing (POCT) to better serve the demands of on-site food analysis. Aptamer-modified paper-based analytical devices (Apt-PADs) have excellent characteristics of high portability, high sensitivity, high specificity, and on-site detection, which have been widely used and concerned in the field of food safety. The article reviews the basic components and working principles of Apt-PADs, and introduces their representative applications detecting food hazards. Finally, the advantages, challenges, and future directions of Apt-PADs-based sensing performance are discussed, to provide new directions and insights for researchers to select appropriate Apt-PADs according to specific applications.

Enhancing Intracellular Optical Performance and Stability of Engineered Nanomaterials via Aqueous Two-Phase Purification

Supramolecular hybrids of DNA and single-walled carbon nanotubes (SWCNTs) have been introduced in numerous biosensing applications due to their unique optical properties. Recent aqueous two-phase (ATP) purification methods for SWCNTs have gained popularity by introducing specificity and homogeneity into the sensor design process. Using murine macrophages probed by near-infrared and Raman microscopies, we show that ATP purification increases the retention time of DNA-SWCNTs within cells while simultaneously enhancing the optical performance and stability of the engineered nanomaterial. Over a period of 6 h, we observe 45% brighter fluorescence intensity and no significant change in emission wavelength of ATP-purified DNA-SWCNTs relative to as-dispersed SWCNTs. These findings provide strong evidence of how cells differentially process engineered nanomaterials depending on their state of purification, lending to the future development of more robust and sensitive biosensors with desirable in vivo optical parameters using surfactant-based ATP systems with a subsequent exchange to biocompatible functionalization.

Absorbance biosensors-based hybrid [Formula: see text] nanosheets for Escherichia coli detection

Detecting Escherichia coli is essential in biomedical, environmental, and food safety applications. In this paper, we have developed a simple, rapid, sensitive, and selective E. coli DNA sensor based on the novel hybrid-type [Formula: see text] and [Formula: see text] nanosheets. The sensor uses the absorbance measurement to distinguish among the DNA of E. coli, Vibrio proteolyticus, and Bacillus subtilis when implemented in conjunction with [Formula: see text]-probes. Our experiments showed that the absorbance increased when sensors detected E. coli DNA, whereas it decreased when sensors detected V. proteolyticus and B. subtilis DNA. To the best of authors' knowledge, there are no reports using the novel hybrid-[Formula: see text] and [Formula: see text] materials for differentiating three types of DNA using cost-effective and rapid absorbance measurements. In addition, the label-free E. coli DNA biosensor exhibited a linear response in the range of 0 fM to 11.65 fM with a limit of detection of 2 fM. The effect of [Formula: see text]-probes on our sensors' working performance is also investigated. Our results will facilitate further research in pathogen detection applications, which have not been fully developed yet.

Selective Detection of Escherichia coli K12 and Staphylococcus aureus in Mixed Bacterial Communities Using a Single-Walled Carbon Nanotube (SWCNT)-Functionalized Electrochemical Immunosensor with Dielectrophoretic Concentration

An electrochemical immunosensor has been developed for the rapid detection and identification of potentially harmful bacteria in food and environmental samples. This study aimed to fabricate a microwire-based electrochemical immunosensor (MEI sensor) for selective detection of Escherichia coli and Staphylococcus aureus in microbial cocktail samples using dielectrophoresis (DEP)-based cell concentration. A gold-coated tungsten microwire was functionalized by coating polyethylenimine, single-walled carbon nanotube (SWCNT) suspension, streptavidin, biotinylated antibodies, and then bovine serum albumin (BSA) solutions. Double-layered SWCNTs and 5% BSA solution were found to be optimized for enhanced signal enhancement and nonspecific binding barrier. The selective capture of E. coli K12 or S. aureus cells was achieved when the electric field in the bacterial sample solution was generated at a frequency of 3 MHz and 20 V_pp. A linear trend of the change in the electron transfer resistance was observed as E. coli concentrations increased from 5.32 × 10² to 1.30 × 10⁸ CFU/mL (R² = 0.976). The S. aureus MEI sensor fabricated with the anti-S. aureus antibodies also showed an increase in resistance with concentrations of S. aureus (8.90 × 10²-3.45 × 10⁷ CFU/mL) with a correlation of R² = 0.983. Salmonella typhimurium and Listeria monocytogenes were used to evaluate the specificity of the MEI sensors. The functionalization process developed for the MEI sensor is expected to contribute to the sensitive and selective detection of other harmful microorganisms in food and environmental industries.

Carbon Nanotube-Based Biosensors Using Fusion Technologies with Biologicals & Chemicals for Food Assessment

High-sensitivity sensors applied in various diagnostic systems are considered to be a promising technology in the era of the fourth industrial revolution. Biosensors that can quickly detect the presence and concentration of specific biomaterials are receiving research attention owing to the breakthroughs in detection technology. In particular, the latest technologies involving the miniaturization of biosensors using nanomaterials, such as nanowires, carbon nanotubes, and nanometals, have been widely studied. Nano-sized biosensors applied in food assessment and in in vivo measurements have the advantages of rapid diagnosis, high sensitivity and selectivity. Nanomaterial-based biosensors are inexpensive and can be applied to various fields. In the present society, where people are paying attention to health and wellness, high-technology food assessment is becoming essential as the consumer demand for healthy food increases. Thus, biosensor technology is required in the food and medical fields. Carbon nanotubes (CNTs) are widely studied for use in electrochemical biosensors. The sensitive electrical characteristics of CNTs allow them to act as electron transfer mediators in electrochemical biosensors. CNT-based biosensors require novel technologies for immobilizing CNTs on electrodes, such as silicon wafers, to use as biosensor templates. CNT-based electrochemical biosensors that serve as field-effect transistors (FET) increase sensitivity. In this review, we critically discuss the recent advances in CNT-based electrochemical biosensors applied with various receptors (antibodies, DNA fragments, and other nanomaterials) for food evaluation, including pathogens, food allergens, and other food-based substances.

A Novel Activated Biochar-Based Immunosensor for Rapid Detection of E. coli O157:H7

E. coli O157:H7, one of the major foodborne pathogens, can cause a significant threat to the safety of foods. The aim of this research is to develop an activated biochar-based immunosensor that can rapidly detect E. coli O157:H7 cells without incubation in pure culture. Biochar was developed from corn stalks using proprietary reactors and then activated using steam-activation treatment. The developed activated biochar presented an enhanced surface area of 830.78 m²/g. To develop the biosensor, the gold electrode of the sensor was first coated with activated biochar and then functionalized with streptavidin as a linker and further immobilized with biotin-labeled anti-E. coli polyclonal antibodies (pAbs). The optimum concentration of activated biochar for sensor development was determined to be 20 mg/mL. Binding of anti-E. coli pAbs with E. coli O157:H7 resulted in a significant increase in impedance amplitude from 3.5 to 8.5 kΩ when compared to an only activated biochar-coated electrode. The developed immunosensor was able to detect E. coli O157:H7 cells with a limit of detection of 4 log CFU/mL without incubation. Successful binding of E. coli O157:H7 onto an activated biochar-based immunosensor was observed on the microelectrode surface in scanning electron microscopy (SEM) images.

Studies on the Detection of Oleuropein from Extra Virgin Olive Oils Using Enzymatic Biosensors

Oleuropein (OLEU) is an important indicator of the quality and authenticity of extra virgin olive oils (EVOO). Electrochemical sensors and biosensors for the detection of oleuropein can be used to test the adulteration of extra virgin olive oils. The present study aimed at the qualitative and quantitative determination of oleuropein in commercial EVOO samples by applying electrochemical techniques, cyclic voltammetry (CV) and square wave voltammetry (SWV). The sensing devices used were two newly constructed enzyme biosensors, supported on single-layer carbon-nanotube-modified carbon screen-printed electrode (SPE/SWCNT) on whose surface tyrosinase (SPE/SWCNT/Tyr) and laccase (SPE/SWCNT/Lac) were immobilized, respectively. The active surfaces of the two biosensors were analyzed and characterized by different methods, cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and Fourier transform infrared spectroscopy (FTIR) and the results confirmed the efficient immobilization of the enzymes. SPE/SWCNT/Tyr was characterized by a low detection limit (LOD = 9.53 × 10⁻⁸ M) and a very good sensitivity (0.0718 μA·μM⁻¹·cm⁻²) over a wide linearity range from 0.49 to 11.22 μM. The process occurring at the biosensor surface corresponds to kinetics (h = 0.90), and tyrosinase showed a high affinity towards OLEU. The tyrosinase-based biosensor was shown to have superior sensitive properties to the laccase-based one. Quantitative determination of OLEU in EVOOs was performed using SPE/SWCNT/Tyr and the results confirmed the presence of the compound in close amounts in the EVOOs analysed, proving that they have very good sensory properties.

A single-walled carbon nanotubes-based electrochemical impedance immunosensor for on-site detection of Listeria monocytogenes

Real-time and sensitive detection of pathogenic bacteria in food is in high demand to ensure food safety. In this study, a single-walled carbon nanotubes (SWCNTs)-based electrochemical impedance immunosensor for on-site detection of Listeria monocytogenes (L. monocytogenes) was developed. A gold-plated wire was functionalized using polyethylenimine (PEI), SWCNTs, streptavidin, biotinylated L. monocytogenes antibodies, and bovine serum albumin (BSA). A linear relationship (R²  = 0.982) between the electron transfer resistance measurements and concentrations of L. monocytogenes within the range of 10³ -10⁸ CFU/ml was observed. In addition, the sensor demonstrated high selectivity towards the target in the presence of other bacterial cells such as Salmonella Typhimurium and Escherichia coli O157:H7. To facilitate the demand for on-site detection, the sensor was integrated into a smartphone-controlled biosensor platform, consisting of a compact potentiostat device and a smartphone. The signals from the proposed platform were compared with a conventional potentiostat using the immunosensor interacted with L. monocytogenes (10³ -10⁵ CFU/ml). The signals obtained with both instruments showed high consistency. Recovery percentages of lettuce homogenate spiked with 10³ , 10⁴ , and 10⁵ CFU/ml of L. monocytogenes obtained with the portable platform were 90.21, 90.44, and 93.69, respectively. The presented on-site applicable SWCNT-based immunosensor platform was shown to have a high potential to be used in field settings for food and agricultural applications. PRACTICAL APPLICATION: The developed immunosensor was developed for on-site detection of L. monocytogenes. The limit of detection of the sensor was 10³ CFU/ml with a detection time of 10 min. In order to facilitate the requirements for effective on-site screening for food safety, the sensor was integrated into a smartphone-controlled platform, so that the bio-molecular interactions were converted into impedance signals and transmitted wirelessly to a smartphone by a hand-held EIS transducer.

Advances in Nanomaterials-Based Electrochemical Biosensors for Foodborne Pathogen Detection

Electrochemical biosensors utilizing nanomaterials have received widespread attention in pathogen detection and monitoring. Here, the potential of different nanomaterials and electrochemical technologies is reviewed for the development of novel diagnostic devices for the detection of foodborne pathogens and their biomarkers. The overview covers basic electrochemical methods and means for electrode functionalization, utilization of nanomaterials that include quantum dots, gold, silver and magnetic nanoparticles, carbon nanomaterials (carbon and graphene quantum dots, carbon nanotubes, graphene and reduced graphene oxide, graphene nanoplatelets, laser-induced graphene), metal oxides (nanoparticles, 2D and 3D nanostructures) and other 2D nanomaterials. Moreover, the current and future landscape of synergic effects of nanocomposites combining different nanomaterials is provided to illustrate how the limitations of traditional technologies can be overcome to design rapid, ultrasensitive, specific and affordable biosensors.

Rapid electrochemical detection of Escherichia coli using nickel oxidation reaction on a rotating disk electrode

A standalone electrochemical method for detecting the bacterium Escherichia coli in water was developed using a nickel electrode and no biorecognition element. Electric current responses from different E. coli concentrations were recorded based on their interaction with a locally formed electrocatalyst. A rotating disk electrode was used to minimize the mass transport limitations at the interface. Results from experiments with the rotating disk electrode also paved the way for hypothesizing the detection mechanism. The operating conditions were established for sensing the electric current responses in the presence of E. coli. The least-squares linear regression model was fit to the data obtained from currents of some known E. coli concentrations. This probe had a detection limit in the order of 104 CFU/ml. The response time to detect the presence/absence of E. coli was less than half a second, while the total assay time, including quantification of its concentration, was 10 min. The electric current response from a solution mixed with E. coli and S. aureus showed current similar to E. coli only solution indicating the specificity of the sensor to respond to signals from E. coli. This electrochemical microbial sensor's uniqueness lies in its ability to rapidly detect E. coli by forming the catalyst locally on demand without the attachment of biorecognition elements.

(Bio)nanotechnology in Food Science-Food Packaging

Background: Bionanotechnology, as a tool for incorporation of biological molecules into nanoartifacts, is gaining more and more importance in the field of food packaging. It offers an advanced expectation of food packaging that can ensure longer shelf life of products and safer packaging with improved food quality and traceability. Scope and approach: This review recent focuses on advances in food nanopackaging, including bio-based, improved, active, and smart packaging. Special emphasis is placed on bio-based packaging, including biodegradable packaging and biocompatible packaging, which presents an alternative to most commonly used non-degradable polymer materials. Safety and environmental concerns of (bio)nanotechnology implementation in food packaging were also discussed including new EU directives. Conclusions: The use of nanoparticles and nanocomposites in food packaging increases the mechanical strength and properties of the water and oxygen barrier of packaging and may provide other benefits such as antimicrobial activity and light-blocking properties. Concerns about the migration of nanoparticles from packaging to food have been expressed, but migration tests and risk assessment are unclear. Presumed toxicity, lack of additional data from clinical trials and risk assessment studies limit the use of nanomaterials in the food packaging sector. Therefore, an assessment of benefits and risks must be defined.

Significant Effect of Sample Pretreatment on Ara h1 Extraction and Improved Sensitive SWCNT-Based Detection through Optimization

Single-walled carbon nanotube (SWCNT)-based nanobiosensors have received increasing attention from food researchers as a future instrument of food safety due to their high sensitivity. However, the pretreatment process of the sample applying to SWCNT-based nanobiosensor is required to be more delicate compared to other analyses. In this study, the pretreatment process of Ara h1 protein from its retained complex food matrix was optimized using various buffer compounds and the pretreated allergenic Ara h1 obtained for the optimized process was detected by SWCNT-based nanobiosensor. In the pretreatment process, the buffer extraction method with tris buffer (Tris-HNO3, pH 8.4) was developed and used to extract native peanut allergens from foods. The extraction procedure for Ara h1 from peanut butter foods was performed by varying the temperature, extraction time, and additives (NaCl and skim milk powder). The results of these tests using our SWCNT-based biosensor were analyzed to evaluate the allergenic nature of the extracts. The peak level of Ara h1 extraction was achieved as 84.60 ± 7.50 ng/mL at 21 °C/60 min with the mixture of Tris-HNO3 and 1 M NaCl. In addition, other significant Ara h1 extractions were found to be 29.59 ± 2.57 at 21 °C/15 min and 27.74 ± 1.33 ng/mL at 60 °C/15 min. This study emphasizes the importance of adjusting the extraction time and temperature with respect to the target allergen and food matrix components. After the optimization of the sample pretreatment, the precision of SWCNT-based nanobiosensor by the resistance difference (ΔR) of the SWCNT-based biosensor via linear sweep voltammetry in a potentiostat was identified using the pretreated Ara h1 sample from the processed food compared with the indirect enzyme-linked immunosorbent assay (ELISA) results.

Biosensors in Evaluation of Quality of Meat and Meat Products – A Review

Biosensors can find application in meat and meat products testing for safety, including microbial and other contaminants, and quality, including meat freshness, beef tenderness and pork quality defects. The available biosensors enable the evaluation of freshness, the classification of tenderness of meat products, the evaluation of the glycolysis extent and the presence of the microbial and other contaminants. Since biosensors depend on receptor types, the expansion of knowledge on metabolic transformations occurring in meat contributes to the development of new potential markers and indicators. Examples include assays for glucose, lactates, hypoxanthines, calpastastins, microbial and other contaminants in meat products, augmenting conventional methods. At the same time, biosensors rely on transducers for detection, requiring achievement in many fields including nanotechnology and optics, among others. Biosensors have potential to become a fundamental tool for monitoring and controlling safety and quality of meat products in the future. Hence the aim of the present paper is to present the current state of knowledge on the application of biosensors in meat.

A Paper-Based Near-Infrared Optical Biosensor for Quantitative Detection of Protease Activity Using Peptide-Encapsulated SWCNTs

A protease is an enzyme that catalyzes proteolysis of proteins into smaller polypeptides or single amino acids. As crucial elements in many biological processes, proteases have been shown to be informative biomarkers for several pathological conditions in humans, animals, and plants. Therefore, fast, reliable, and cost-effective protease biosensors suitable for point-of-care (POC) sensing may aid in diagnostics, treatment, and drug discovery for various diseases. This work presents an affordable and simple paper-based dipstick biosensor that utilizes peptide-encapsulated single-wall carbon nanotubes (SWCNTs) for protease detection. Upon enzymatic digestion of the peptide, a significant drop in the photoluminescence (PL) of the SWCNTs was detected. As the emitted PL is in the near-infrared region, the developed biosensor has a good signal to noise ratio in biological fluids. One of the diseases associated with abnormal protease activity is pancreatitis. In acute pancreatitis, trypsin concentration could reach up to 84 µg/mL in the urine. For proof of concept, we demonstrate the feasibility of the proposed biosensor for the detection of the abnormal levels of trypsin activity in urine samples.

Carbon nanotube-based thin-film resistive sensor for point-of-care screening of tuberculosis

For point-of-care diagnosis of tuberculosis (TB), current TB diagnostic approaches need to be further improved for achieving an accurate diagnosis that is rapid and low-cost. This paper presents an immuno-resistive sensor on a plastic film for inexpensive, simple TB screening. The sensor is composed of single-walled carbon nanotubes (SWCNTs) functionalized with polyclonal antibodies raised against the MPT64 surface antigen from Mycobacterium tuberculosis (MTB). The target analyte of either MTB or MPT64 is spiked in tongue swab and sputum samples. Under optimized conditions, targets are directly detected from tongue swab samples by resistive measurement. Target analytes spiked into human sputa are enriched with a magnetic bead protocol followed by resistive detection. This highly sensitive film sensor will facilitate rapid TB screening with the added benefits of a small form factor, simple operation, low power requirement, and low cost.

Rapid Detection of Escherichia coli by β-Galactosidase Biosensor Based on ZnO NPs and MWCNTs: A Comparative Study

The need for alternative approaches for identifying pathogens has led researchers to focus on nanobiotechnology. In this study, zinc oxide nanoparticles (ZnO NPs) and multi-wall carbon nanotubes (MWCNTs) were used as marker molecules. After measuring the best concentration of these nanomaterials to inhibit the lactase activity of the beta-galactosidase enzymes by binding to them, different concentrations of Escherichia coli were added to the medium and their detection ability was finally compared with each other. Due to small size and high reactivity, these compounds are able to detect very low amount of bacteria in the ambient. In fact, the bacteria are attached to the nanoparticles and detach them from the enzyme and lead to substrate decomposition by the enzyme. MWCNTs exhibited better performance than ZnO NPs in detection of bacteria at very low concentration of 10¹ CFU/ml in 15 min. As a result, they are very appropriate to be utilized especially in the food industry.

Applications of Nanotechnology in Sensor-Based Detection of Foodborne Pathogens

The intake of microbial-contaminated food poses severe health issues due to the outbreaks of stern food-borne diseases. Therefore, there is a need for precise detection and identification of pathogenic microbes and toxins in food to prevent these concerns. Thus, understanding the concept of biosensing has enabled researchers to develop nanobiosensors with different nanomaterials and composites to improve the sensitivity as well as the specificity of pathogen detection. The application of nanomaterials has enabled researchers to use advanced technologies in biosensors for the transfer of signals to enhance their efficiency and sensitivity. Nanomaterials like carbon nanotubes, magnetic and gold, dendrimers, graphene nanomaterials and quantum dots are predominantly used for developing biosensors with improved specificity and sensitivity of detection due to their exclusive chemical, magnetic, mechanical, optical and physical properties. All nanoparticles and new composites used in biosensors need to be classified and categorized for their enhanced performance, quick detection, and unobtrusive and effective use in foodborne analysis. Hence, this review intends to summarize the different sensing methods used in foodborne pathogen detection, their design, working principle and advances in sensing systems.

Carbon Nanotube-Based Electrochemical Biosensor for Label-Free Protein Detection

There is a growing need for biosensors that are capable of efficiently and rapidly quantifying protein biomarkers, both in the biological research and clinical setting. While accurate methods for protein quantification exist, the current assays involve sophisticated techniques, take long to administer and often require highly trained personnel for execution and analysis. Herein, we explore the development of a label-free biosensor for the detection and quantification of a standard protein. The developed biosensors comprise carbon nanotubes (CNTs), a specific antibody and cellulose filtration paper. The change in electrical resistance of the CNT-based biosensor system was used to sense a standard protein, bovine serum albumin (BSA) as a proof-of-concept. The developed biosensors were found to have a limit of detection of 2.89 ng/mL, which is comparable to the performance of the typical ELISA method for BSA quantification. Additionally, the newly developed method takes no longer than 10 min to perform, greatly reducing the time of analysis compared to the traditional ELISA technique. Overall, we present a versatile, affordable, simplified and rapid biosensor device capable of providing great benefit to both biological research and clinical diagnostics.

Carbon Nanomaterials for the Treatment of Heavy Metal-Contaminated Water and Environmental Remediation

Nanotechnology is an advanced field of science having the ability to solve the variety of environmental challenges by controlling the size and shape of the materials at a nanoscale. Carbon nanomaterials are unique because of their nontoxic nature, high surface area, easier biodegradation, and particularly useful environmental remediation. Heavy metal contamination in water is a major problem and poses a great risk to human health. Carbon nanomaterials are getting more and more attention due to their superior physicochemical properties that can be exploited for advanced treatment of heavy metal-contaminated water. Carbon nanomaterials namely carbon nanotubes, fullerenes, graphene, graphene oxide, and activated carbon have great potential for removal of heavy metals from water because of their large surface area, nanoscale size, and availability of different functionalities and they are easier to be chemically modified and recycled. In this article, we have reviewed the recent advancements in the applications of these carbon nanomaterials in the treatment of heavy metal-contaminated water and have also highlighted their application in environmental remediation. Toxicological aspects of carbon-based nanomaterials have also been discussed.

Carbon Nanotube Chemical Sensors

Carbon nanotubes (CNTs) promise to advance a number of real-world technologies. Of these applications, they are particularly attractive for uses in chemical sensors for environmental and health monitoring. However, chemical sensors based on CNTs are often lacking in selectivity, and the elucidation of their sensing mechanisms remains challenging. This review is a comprehensive description of the parameters that give rise to the sensing capabilities of CNT-based sensors and the application of CNT-based devices in chemical sensing. This review begins with the discussion of the sensing mechanisms in CNT-based devices, the chemical methods of CNT functionalization, architectures of sensors, performance parameters, and theoretical models used to describe CNT sensors. It then discusses the expansive applications of CNT-based sensors to multiple areas including environmental monitoring, food and agriculture applications, biological sensors, and national security. The discussion of each analyte focuses on the strategies used to impart selectivity and the molecular interactions between the selector and the analyte. Finally, the review concludes with a brief outlook over future developments in the field of chemical sensors and their prospects for commercialization.

Assessment of peanut allergen Ara h1 in processed foods using a SWCNTs-based nanobiosensor

The goals of this research were to develop a rapid single-walled carbon nanotube (SWCNT)-based biosensor and to employ it to commercial food products for Ara h1 detection. The SWCNT-based biosensor was fabricated with SWCNTs immobilized with antibody (pAb) through hybridization of 1-pyrenebutanoic acid succinimidyl ester (1-PBASE) as a linker. The resistance difference (ΔR) was calculated by measuring linear sweep voltammetry (LSV) using a potentiostat. Resistance values increased as the concentration of Ara h1 increased over the range of 1 to 105 ng/L. The specific binding of anti-Ara h1 pAb to antigen including Ara h1 was confirmed by both indirect ELISA kit and biosensor assay. The biosensor was exposed to extracts prepared from commercial processed food containing peanuts, or no peanuts, and could successfully distinguish the peanut containing foods. In addition, the application of present biosensor approach documented the precise detection of Ara h1 concentrations in commercially available peanut containing foods.

Nanotechnology: Review of concepts and potential application of sensing platforms in food safety

In recent years a number of new nanotechnology based platforms have been developed for detection of wide variety of targets including infectious agents, protein biomarkers, nucleic acids, drugs, and cancer cells. Nanomaterials such as magnetic nanoparticles, quantum dots, carbon nanotubes, nanowires, and nanosensors like giant magnetoresistance (GMR) sensors are used to quantitatively detect biomolecules with, experimentally, relatively good accuracy. There has been a growing interest in the use of magnetic fields in biosensing applications. Because biological samples have no ferromagnetic property and therefore there is no interference with complex sample matrix, detection of infectious agents from minimally processed samples is possible. Here, we provide a brief overview of the recent emergence of nanotechnology-based techniques for the detection and monitoring of foodborne diseases. In addition, the potential applications and future perspectives of nanotechnology on food safety are discussed. Ultimately, the review is expected to stimulate and provide directions to the development and application of nanotechnology-based tests for the early detection, and eventual control of foodborne diseases.

A sensitive and rapid immunoassay for Mycoplasma pneumoniae in children with pneumonia based on single-walled carbon nanotubes

Mycoplasma pneumoniae(MP) is a leading pathogen of respiratory infection, especially community-acquired pneumonia (CAP), in children worldwide. However, its diagnosis is frequently ineffective because bacterial culture and serology test are usually positive 1–2 weeks or more after the disease onset. To achieve a better detection efficiency, the single-walled carbon nanotubes(SWCNT) were coupled with the colloidal gold-monoclonal antibody immunochromatographic strips(CGIC). Interestingly, the SWCNT/CGIC assay allowed MP identification, with a detection limit of 1 × 10² copies/ml. Using referenced throat swabs of 97 MP and 40 non-MP cases, the assay yielded 72.2% sensitivity, 100.0% specificity, 100.0% positive predictive value (PPV), 59.7% negative predictive value (NPV). In summary, our assay was far more effective than any conventional methods for the diagnosis of acute MP. The ease of use, rapid and stability further enhance its feasibility for clinical use on-site.

A Protein Nanopore-Based Approach for Bacteria Sensing

We present herein a first proof of concept demonstrating the potential of a protein nanopore-based technique for real-time detection of selected Gram-negative bacteria (Pseudomonas aeruginosa or Escherichia coli) at a concentration of 1.2 × 108 cfu/mL. The anionic charge on the bacterial outer membrane promotes the electrophoretically driven migration of bacteria towards a single α-hemolysin nanopore isolated in a lipid bilayer, clamped at a negative electric potential, and followed by capture at the nanopore's mouth, which we found to be described according to the classical Kramers' theory. By using a specific antimicrobial peptide as a putative molecular biorecognition element for the bacteria used herein, we suggest that the detection system can combine the natural sensitivity of the nanopore-based sensing techniques with selective biological recognition, in aqueous samples, and highlight the feasibility of the nanopore-based platform to provide portable, sensitive analysis and monitoring of bacterial pathogens.

Recent Advancements in Nanobioassays and Nanobiosensors for Foodborne Pathogenic Bacteria Detection

Bacterial pathogens are one of the leading causes of food safety incidents and product recalls worldwide. Timely detection and identification of microbial contamination in agricultural and food products is crucial for disease prevention and outbreak investigation. In efforts to improve and/or replace time-consuming and laborious "gold standards" for pathogen detection, numerous alternative rapid methods have been proposed in the past 15 years, with a trend toward incorporating nanotechnology and nanomaterials in food pathogen detection. This article is a review of the use of nanotechnology in various detection and sample preparation techniques and advancements in nanotechnology applications in food matrices. Some practical considerations in nanobioassay design are discussed, and the gaps between research status quo and market demands are identified.

Simultaneous detection of E. coli K12 and S. aureus Using a Continuous Flow Multijunction Biosensor

Rapid detection and identification of potentially harmful bacteria is ideal for food manufacturers to prevent foodborne illness outbreaks. Continuous monitoring method of foodborne pathogens levels and trends in food gives real-time results. Therefore, the objectives of this study were to fabricate and characterize the continuous flow multijunction biosensor for simultaneous detection of Escherichia coli K12 and Staphylococcus aureus. Junction biosensors were fabricated using gold plated tungsten wires coated with polyethylenimine and single walled carbon nanotubes. Each junction was functionalized with streptavidin and biotinylated antibodies specific to E. coli K12 and S. aureus. Then, single or 2 biosensors for each targeted analyte were connected to tubing, perpendicular to the flow direction. Pure serial diluted samples of E. coli K12 and S. aureus and microbial cocktail samples were continuously pumped at a 0.0167 mL/s into the detection zone. Changes in the electric current by biorecognition reactions between antibody and antigens were calculated. The developed junction sensor coupled with the fluidic channel showed the enhancement of the electric signal responses for detection of E. coli K12, compared to the stationary sensor. A linear regression was observed for both the E. coli and S. aureus functionalized array sensors in the detection range of 10(2) to 10(5) CFU/mL. Multiplexed detection of bacteria at the sensing levels as low as 10(2) CFU/mL for E. coli K12 and S. aureus was achieved within 2 min. Therefore, the continuous flow multijunction biosensor shows potential for rapid and continuous multiplexed detection of foodborne pathogens.