Graphene Oxide Platform Research Articles

Prussian Blue nanoparticles supported on a hybrid platform of graphene oxide and cubic silsesquioxane applied to Diuron detection

This work describes the preparation and chemical modification of the graphene oxide platform with octa(aminopropyl)silsesquioxane, with subsequent deposition of Prussian Blue nanoparticles on its surface. The materials were characterized by Raman Spectroscopy, X-Ray Excited Photoelectron Spectroscopy and Transmission Electron Microscopy, which ensured the success of the proposed synthesis. The Differential Pulse Voltammetry technique was employed in order to apply the conventional electrode as a sensor for the detection of Diuron, a widely used pesticide due to its efficiency in controlling a wide range of weeds and grasses, but which has carcinogenic and genotoxic effects. The graphite paste electrode modified with the metallic complex was electroactive in the electrocatalytic detection of Diuron, with a detection limit of 4.96 nmol·L−1. Given this, it can be proposed that the material prepared in this work is included in the list of potential candidates for the development of electrochemical sensors for the detection of Diuron.

Development of fluorescent aptasensor for detection of acephate by utilizing graphene oxide platform

A fluorescent graphene oxide based aptasensing platform was developed for the detection of acephate. The aptamers specific to the acephate were screened through GO-SELEX (Graphene Oxide - Systematic Evolution of Ligands by EXponential enrichment) method for six rounds. The screened aptamers were analyzed for their binding affinity and specificity by using fluorescence-based assay. The aptamer AAPT3 that demonstrated highest affinity (Kd = 9 ± 1 nM) and an excellent selectivity, was employed in the development of fluorescent aptasensor. Under optimal conditions, the aptasensor showed low limit of detection (4 ng mL−1) and a wide dynamic linear range (5–80 ng mL−1). The aptasensor was also validated against water samples spiked with acephate, which showed fluorescence recovery from 94 to 107% and coefficient of variation 1–5%. These results indicate that the developed aptasensor can be used for sensitive, selective, and accurate detection of acephate in various samples.

Electrochemical Cytosensor Based on a Gold Nanostar-Decorated Graphene Oxide Platform for Gastric Cancer Cell Detection.

Effectively capturing and sensitively detecting cancer cells are critical to clinical diagnosis and cancer therapy. In this work, we prepared gold nanostar-decorated graphene oxide (GO-AuNSs) nanocomposites using a ultraviolet (UV)-induced strategy, and then modified them with a layer of bio-complex rBSA-FA (coupled reduced bovine serum albumin with folic acid) to generate GO-AuNSs@rBSA-FA nanocomposites. Herein, the application of GO and AuNSs not only strengthened the conductivity of the sensing platform but also guaranteed nanocomposites with biocompatible performance. Moreover, the adopted rBSA-FA layer could effectively enhance the stability and specificity towards gastric cancer cells (MGC-803). According to a systemic construction procedure, a novel electrochemical cytosensor based on GO-AuNSs@rBSA-FA was fabricated for MGC-803 cell detection. With the assistance of cyclic voltammetry (CV) and differential pulse voltammetry (DPV), the cytosensor reached a detection limit of 100 cell/mL in a wide linear range of 3 × 102~7 × 106 cell/mL towards MGC-803 cells. The good electrochemical characteristics for the cancer cell analysis indicate a promising prospect of this electrochemical cytosensor in clinical cancer diagnosis.

A probe-free electrochemical immunosensor for methyl jasmonate based on a Cu-MOF-carboxylated graphene oxide platform.

Methyl jasmonate (MeJA) is an important phytohormone which can regulate plant growth and stress tolerance. It is very necessary to develop sensitive and accurate detection methods for MeJA. In this work, a probe-free electrochemical immunosensor for MeJA detection was developed based on a Cu-MOF–carboxylated graphene oxide (COOH-GO) platform. The Cu2+ in the Cu-MOFs was used to provide redox signals, which avoids the application of an external redox probe in the electrolyte solutions as conventional immunosensors. COOH-GO was used to improve the structural stability and provide more sites for binding MeJA antibodies. The linear range of the MeJA immunosensor is from 10 pM to 100 μM, which can cover the whole concentration range of MeJA in most plants. And its detection limit is very low (0.35 pM), and it can detect very low concentrations of MeJA. This immunosensor is simple, low cost, and does not need redox probe solutions for measurements. It shows remarkable potential for on-site application in precision agriculture.

Development of Fluorescent Aptasensor for Detection of Acephate by Utilizing Graphene Oxide Platform

Development of Fluorescent Aptasensor for Detection of Acephate by Utilizing Graphene Oxide Platform

Graphene Bioelectronic Nose for the Detection of Odorants with Human Olfactory Receptor 2AG1

A real-time sensor for the detection of amyl butyrate (AB) utilising human olfactory receptor 2AG1 (OR2AG1), a G-protein coupled receptor (GPCR) consisting of seven transmembrane domains, immobilized onto a graphene resistor is demonstrated. Using CVD graphene as the sensor platform, allows greater potential for more sensitive detection than similar sensors based on carbon nanotubes, gold or graphene oxide platforms. A specific graphene resistor sensor was fabricated and modified via non-covalent π–π stacking of 1,5 diaminonaphthalene (DAN) onto the graphene channel, and subsequent anchoring of the OR2AG1 receptor to the DAN molecule using glutaraldehyde coupling. Binding between the target odorant, amyl butyrate, and the OR2AG1 receptor protein generated a change in resistance of the graphene resistor sensor. The functionalized graphene resistor sensors exhibited a linear sensor response between 0.1–500 pM and high selectively towards amyl butyrate, with a sensitivity as low as 500 fM, whilst control measurements using non-specific esters, produced a negligible sensor response. The approach described here provides an alternative sensing platform that can be used in bioelectronic nose applications.

Electrostatic Self-Assembly Approach to Fabricate Architectures of Carboxyl Functionalized Gold-Aryl Nanoparticles and Graphene Oxide Platforms

Graphene oxide (GO) was decorated with gold-aryl (Au-C) nanoparticles AuNPs-COOH by sodium borohydride reduction of aryldiazonium tetrachloroaurate(III) salt at room temperature in aqueous solutions. Brunauer-Emmett-Teller measurements supported GO anchoring by AuNPs modified with COOH; surface area dropped significantly. Morphology of AuNPs-COOH/GO nanocomposite (NC) was probed using AFM and TEM, showing NC’s surface roughness and wrinkling. XPS results suggest the clear reductive reaction of tetrachloroaurate anion into metallic gold in AuNPs-COOH/GO along with detailed interpretations of functional groups’ nature. Molecular dynamics calculations endowed support of favorable wrinkling at the edges and carboxyl intercalation to GO surface of types π- π, hydrogen bonding, and hydrophobic interactions. Solvent accessible surface area calculations of GO showed a decrease in total surface area. Environmental nanoremediation of the catalytic reduction of 4-nitrophenol, a priority pollutant listed by USEPA, was investigated. The apparent rate constants Kapp of four catalytic reduction cycles of nitrophenol were measured. The highest value is 1.17 × 10-1 min-1 for the first cycle which decreased to 4.49 × 10 -2 min -1 for the fourth cycle. The variations in rate constants were measured with different conditions, including NaBH 4 concentrations, NC loadings and NC incubating time in NaBH4.

Label-Free DNA Biosensor Using Modified Reduced Graphene Oxide Platform as a DNA Methylation Assay.

This work reports the use of modified reduced graphene oxide (rGO) as a platform for a label-free DNA-based electrochemical biosensor as a possible diagnostic tool for a DNA methylation assay. The biosensor sensitivity was enhanced by variously modified rGO. The rGO decorated with three nanoparticles (NPs)—gold (AuNPs), silver (AgNPs), and copper (CuNPs)—was implemented to increase the electrode surface area. Subsequently, the thiolated DNA probe (single-stranded DNA, ssDNA−1) was hybridized with the target DNA sequence (ssDNA-2). After the hybridization, the double-stranded DNA (dsDNA) was methylated by M.SssI methyltransferase (MTase) and then digested via a HpaII endonuclease specific site sequence of CpG (5′-CCGG-3′) islands. For monitoring the MTase activity, differential pulse voltammetry (DPV) was used, whereas the best results were obtained by rGO-AuNPs. This assay is rapid, cost-effective, sensitive, selective, highly specific, and displays a low limit of detection (LOD) of 0.06 U·mL−1. Lastly, this study was enriched with the real serum sample, where a 0.19 U·mL−1 LOD was achieved. Moreover, the developed biosensor offers excellent potential in future applications in clinical diagnostics, as this approach can be used in the design of other biosensors.

Synthesis of graphene oxide nanosheets decorated by nanoporous zeolite-imidazole (ZIF-67) based metal-organic framework with controlled-release corrosion inhibitor performance: Experimental and detailed DFT-D theoretical explorations

For the first time, the zeolite-imidazole (ZIF-67) framework, a new subfamily of metal-organic frameworks (MOFs), is synthesized on the graphene oxide (GO) platform. Co2+ (as a central atom) and 2-methylimidazole (as organic ligands) were assembled to fabricate ZIF-67/GO NPs for providing epoxy-based anti-corrosion coatings with both active (self-healing) and passive (barrier) performance. Also, the ZIF-67/GO NPs were modified by 3-Aminopropyl triethoxysilane (APS) to improve the particles compatibility with the epoxy matrix and control their solubility in saline media. The FE-SEM, FT-IR, UV–Vis, Raman, TGA, and low-angle XRD techniques were used to prove the successful ZIF-67 particles growth onto the GO platforms. Tafel (potentiodynamic) polarization test demonstrated that the ZIF-67/GO@APS NPs could protect the surface of steel through mixed anodic/cathodic type (O2 reduction/Fe oxidation) mechanisms and the corrosion current density of the iron sample decreased to 1.41 µA·cm−2. Interestingly, the epoxy coatings containing ZIF-67/GO and ZIF-67/GO@APS particles revealed long-term corrosion protection durability and outstanding self-healing anti-corrosion performance, which were well studied via EIS, salt spray, cathodic delamination, and pull-off techniques. The impedance value at the lowest frequency for the coating containing ZIF-67/GO@APS after 50 days decreased from 10.7 Ω·cm2 to 10.2 Ω·cm2 that showed the lowest reduction among the studied samples.

Enhanced Raman intensity of pollutants and explosives by using 2-mercaptoethanol controlled pyramid Ag–iron nanostructure embedded graphene oxide platform

In this study, a pyramid Ag–Fe embedded graphene oxide nanocomposite (PAFG) was synthesized and characterized using field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDS), and ultraviolet–visible (UV-V–visible (UV–vis) spectroscopy. FESEM images indicated the successful synthesis of exfoliated graphene sheets with a thickness of 7 nm, 30 nm Fe nanoparticles, and pyramid Ag nanostructures, where the sides measured from 100 nm to 600 nm. UV–vis analysis detected plasmon bands at 700 nm and 914 nm for PAFG. EDS analysis confirmed the presence of elemental Ag and C. Two PAFG phases were obtained after centrifugation, which were designated as PAFG1 and PAFG2. Surface enhanced Raman spectroscopy (SERS) analyses showed that the rhodamine 6G (R6G) peaks with PAFG1 were 1.75 times larger than those with trinitrotoluene (TNT) and 1.7 times larger than those with pyrene. SERS analysis of TNT with PAFG2 obtained 1.49 and 1.3 times greater peaks compared with those using pyrene and R6G, respectively. On average, the performance was around 1.4 times better with PAFG2 for each of the analytes. Measurements of the SERS spectra for TNT and pyrene with annealed PAFG (at mM and μM concentrations) showed that the enhancement factors (EFs) were 2.2 and 1.7 for the μM TNT and pyrene samples, respectively. Comparisons of the SERS spectra obtained for mM samples of the three analytes with annealed PAFG showed that the EFs were over three times higher than that with R6G.

Sharp-tip enhanced catalytic CO oxidation by atomically dispersed Pt1/Pt2on a raised graphene oxide platform

Sharp carbon-tip on defective graphene oxide induces strong local electric field on Pt-site, offering high catalytic performance.

Epoxy composite coating corrosion protection properties reinforcement through the addition of hydroxyl-terminated hyperbranched polyamide non-covalently assembled graphene oxide platforms

This paper presents the role of GO particle functionalization by different contents of hydroxyl-terminated hyper-branched polyamide on the epoxy coating corrosion protection properties. Raman spectroscopy, UV–visible analysis, and field emission scanning electron microscopy (FE-SEM) methods were applied to study the HB/GO interactions and morphology at different ratios. Then, by electrochemical impedance spectroscopy (EIS) and accelerated corrosion test (salt spray) the Epoxy-GO and Epoxy-HB/GO = 0.25, 0.5, 1.0 and 2.5 systems corrosion protection properties were investigated. Results obtained from Raman spectroscopy, UV–Visible analysis, and FE-SEM measurement proved that the GO sheets were successfully modified by HB molecules. SEM results evidenced that the GO particle dispersion quality in the epoxy matrix was significantly improved after modification by HB. Pull-off results revealed significant improvement in the epoxy film adhesion to the steel surface in the presence of HB/GO. Results disclosed that the epoxy composite coating reinforced with HB/GO = 0.5 and 1.0 showed the largest impedance (>1010 ohm cm2) and lowest delamination values. Generally, the modified GO sheets significantly improved the epoxy coating corrosion protection properties due to the role of HB in improving the dispersion state (proved by SEM results) and interfacial interactions between the GO and epoxy matrix.

Synthesis of a Novel Magnetically Retrievable Nanocomposite with Au Nanocatalysts for Hydration Reaction

Developing efficient catalysts with good recyclability is of great importance for its practical applications. In this study, a novel magnetically retrievable nanocomposite (Au-SiO2@Fe3O4-RGO) was synthesized for catalyzing hydration reaction. Active Au nanoparticles are deposited on core-shell SiO2@Fe3O4, which are further supported by a two-dimensional reduced graphene oxide (RGO) platform. The prepared Au-SiO2@Fe3O4-RGO was proven to be efficient as well as recyclable. An excellent catalytic performance, with 97% yield towards the hydration of phenylacetylene, was achieved for the catalyst in dioxane. Remarkably, the catalyst can be readily recycled through magnetic separation and achieved superior catalyst recovery and stability after seven cycles without any metal leaching. This work provides a strategy to fabricate recyclable and durable catalysts for industrial applications.

Nanoscale nickel metal organic framework decorated over graphene oxide and carbon nanotubes for water remediation

In this report, highly crystalline and well-dispersed nano-sized nickel metal organic framework (MOFs) was decorated over graphene oxide (GO) and carbon nanotubes (CNTs) platforms to form hybrid nanocomposites. These as-synthesized hybrid nanocomposites were synthesized through a one-pot green solvothermal method. The prepared nanocomposites were characterized by SEM, TEM, EDS, XRD, FT-IR, Raman and TGA techniques. XRD analysis revealed the crystalline structure of the hybrid nanocomposites. Morphological and elemental studies also verified successful decoration of nickel-benzene dicarboxylate (Ni-BDC) MOFs over GO and CNT platforms. Chemical analysis collected through IR, and thermal analysis collected through TGA technique, illustrated the presence of all the components in the hybrid nanomaterials. Methylene blue (MB) was used as a model organic pollutant to analyze the adsorption capacity of the prepared nanocomposites. According to the findings, a strong interaction exists between the MB molecule and the developed adsorbents at which due to the synergistic effect, the hybrid nanocomposites show several times higher adsorption capacity compared to that of parent materials. This improvement can be due to several reasons: high surface area of the MOFs in the composites resulting from the smaller size of MOFs, presence of the pores formed between the MOFs and the platforms and different morphological characteristic of Ni-BDC MOFs in hybrid nanocomposites, compared to bare Ni-BDC MOFs. Furthermore, the isotherm and kinetic studies revealed that the adsorption of MB onto the newly prepared adsorbents could best be explained by the Langmuir and Pseudo-second order kinetic models. A regeneration study demonstrated the highly stable nature of the hybrid nanocomposites.

A Biodegradable Multifunctional Graphene Oxide Platform for Targeted Cancer Therapy

AbstractThe design of multifunctional materials able to both selectively deliver a drug into cells in a targeted manner and display an enhanced propensity for biodegradation is an important goal. Here, graphene oxide (GO) is functionalized with the chemotactic peptide N‐formyl‐methionyl‐leucyl‐phenylalanine (fMLP) known to interact with the formyl peptide receptor, which is expressed in different cancer cells, including cervical carcinoma cells. This study highlights the ability of GOfMLP for targeted drug delivery and cancer cell killing and the subsequent degradation capacity of the hybrid. Biodegradation is assessed via Raman spectroscopy and transmission electron microscopy. The results show that GOfMLP is susceptible to faster myeloperoxidase‐mediated degradation. The hybrid material, but not GO, is capable of inducing neutrophil degranulation with subsequent degradation, being the first study showing inducible neutrophil degradation by the nanomaterial itself with no prior activation of the cells. In addition, confocal imaging and flow cytometry using HeLa cells demonstrate that GOfMLP is able to deliver the chemotherapeutic agent doxorubicin faster into cells, inducing higher levels of apoptosis, when compared to nonfunctionalized GO. The results reveal that GOfMLP is a promising carrier able to efficiently deliver anticancer drugs, being endowed with the ability to induce its own biodegradation.

A Multifunctional Graphene Oxide Platform for Targeting Cancer.

Diagnosis of oncological diseases remains at the forefront of current medical research. Carbonic Anhydrase IX (CA IX) is a cell surface hypoxia-inducible enzyme functionally involved in adaptation to acidosis that is expressed in aggressive tumors; hence, it can be used as a tumor biomarker. Herein, we propose a nanoscale graphene oxide (GO) platform functionalized with magnetic nanoparticles and a monoclonal antibody specific to the CA IX marker. The GO platforms were prepared by a modified Hummers and Offeman method from exfoliated graphite after several centrifugation and ultrasonication cycles. The magnetic nanoparticles were prepared by a chemical precipitation method and subsequently modified. Basic characterization of GO, such as the degree of oxidation, nanoparticle size and exfoliation, were determined by physical and chemical analysis, including X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), energy dispersive X-ray analysis (EDX), and atomic force microscopy (AFM). In addition, the size and properties of the poly-L-lysine-modified magnetic nanoparticles were characterized. The antibody specific to CA IX was linked via an amidic bond to the poly-L-lysine modified magnetic nanoparticles, which were conjugated to GO platform again via an amidic bond. The prepared GO-based platform with magnetic nanoparticles combined with a biosensing antibody element was used for a hypoxic cancer cell targeting study based on immunofluorescence.

Bi-enzyme functionalized electro-chemically reduced transparent graphene oxide platform for triglyceride detection.

Recently, increased attention has been drawn to application of graphene and its derivatives for construction of biosensors, since they can be used to rapidly detect the presence of bio-analytes. Present paper establishes the preparation of a unique transducer which relies on toluidine blue (TB), absorbed by electrochemically reduced graphene oxide (ERGO) transparent thin film onto the surface of the indium tin-oxide (ITO) glass electrode. The proposed TB/ERGO/ITO electrode shows excellent reversible electro-chemical properties. The novel platform has been explored to fabricate a triglyceride (TG) biosensor via co-immobilizing of lipase (LIP) and glycerol dehydrogenase (GDH) onto TB/ERGO/ITO electrode surface. The fabricated bioelectrode (LIP-GDH/TB/ERGO/ITO) directly oxidizes glycerol (produced by catalytic hydrolysis of tributyrin acting as a model TG) in the presence of GDH. The developed bioelectrode replaces unstable biological irreversible redox mediators NAD+/NADH, involved in the triglyceride breakdown reaction. NADH causes fouling on the bioelectrode surface in bi-enzymatic estimation of TG and reduces the shelf-life of biosensor. Electrochemical response studies carried out using cyclic voltammetry reveal that the fabricated electrode can detect tributyrin in the range of 50-400 mg dL-1 with high sensitivity of 29 pA mg-1 dL, low response time of 12 s, long-term stability and a low apparent Michaelis-Menten constant (Kappm) of 0.18 mM, indicating high enzyme affinity of LIP-GDH/TB/ERGO/ITO bioelectrode towards tributyrin. Furthermore, this modified bioelectrode has been explored for estimation of TG with negligible interference in human serum samples. The proposed bi-enzymatic bioelectrode for TG analysis offers an efficient and novel interface for application of graphene and its derivatives in the field of bioelectronic devices.

A comparative study of different electrodeposited NiCo2O4 microspheres anchored on a reduced graphene oxide platform: electrochemical sensor for anti-depressant drug venlafaxine.

Two different fabrication methods were performed and compared for preparation of binary metallic oxide microstructures supported on a reduced graphene oxide (rGO) modified graphite electrode. Nickel–Cobalt oxide microspheres (NiCo2O4 MSs) were prepared by two different deposition methods: wet chemical and in situ-electrical deposited methods. Different characterization methods were conducted, including cyclic voltammetry (CV), scanning emission microscopy (SEM), electrochemical impedance spectroscopy (EIS) and Raman spectroscopy. The deposition methods of NiCo2O4 MSs were found to affect the electrochemical behavior of the modified electrodes towards the oxidation of venlafaxine (VEN), an anti-depressant drug. The fabricated electrode showed linearity over the range 5–500 nmol L−1 and an excellent sensitivity with a limit of detection (LOD) and limit of quantitation (LOQ) of 3.4 and 10.3 nmol L−1, respectively. It was revealed that the wet-NiCo2O4@rGO modified electrode prepared by the wet chemical method showed an improved electrochemical behavior for determination of VEN in pharmaceuticals and human plasma with high recovery results in the range of 96.7–98.6% and 96.0–100.7%, respectively without any interference from the co-existing components.

A novel fluorescent aptasensor for the highly sensitive and selective detection of cardiac troponin I based on a graphene oxide platform.

Acute myocardial infarction (AMI) is one of the leading risks to global health. Thus, the rapid, accurate early diagnosis of AMI is highly critical. Human cardiac troponin I (cTnI) has been regarded as a golden biomarker for AMI due to its excellent selectivity. In this work, a novel fluorescent aptasensor based on a graphene oxide (GO) platform was developed for the highly sensitive and selective detection of cTnI. GO binds to the fluorescent anti-cTnI aptamer and quenches its fluorescence. In the presence of cTnI, the fluorescent anti-cTnI aptamer leaves the surface of GO, combines with cTnI because of the powerful affinity of the fluorescent anti-cTnI aptamer and cTnI, and then restores the fluorescence of the fluorescent anti-cTnI aptamer. Fluorescence-enhanced detection is highly sensitive and selective to cTnI. The method exhibited good analytical performance with a reasonable dynamic linearity at the concentration range of 0.10-6.0ng/mL and a low detection limit of 0.07ng/mL (S/N = 3). The fluorescent aptasensor also exhibited high selectivity toward cTnI compared with other interference proteins. The proposed method may be a potentially useful tool for cTnI determination in human serum. Graphical abstract A novel fluorescent aptasensor for the highly sensitive and selective detection of cardiac troponin I based on a graphene oxide platform.

Fluorometric graphene oxide-based detection of Salmonella enteritis using a truncated DNA aptamer

The work describes a fluorescence-based study for mapping the highest affinity truncated aptamer from the full length sequence and its integration in a graphene oxide platform for the detection of Salmonella enteriditis. To identify the best truncated sequence, molecular beacons and a displacement assay design are applied. In the fluorescence displacement assay, the truncated aptamer was hybridized with fluorescein and quencher-labeled complementary sequences to form a fluorescence/quencher pair. In the presence of S. enteritidis, the aptamer dissociates from the complementary labeled oligonucleotides and thus, the fluorescein/quencher pair becomes physically separated. This leads to an increase in fluorescence intensity. One of the truncated aptamers identified has a 2-fold lower dissociation constant (3.2nM) compared to its full length aptamer (6.3nM). The truncated aptamer selected in this process was used to develop a fluorometric graphene oxide (GO) based assay. If fluorescein-labeled aptamer is adsorbed on GO via π stacking interaction, fluorescence is quenched. However, in the presence of target (S. enteriditis), the labeled aptamers is released from surface to form a stable complex with the bacteria and fluorescence is restored, depending on the quantity of bacteria being present. The resulting assay has an unsurpassed detection limit of 25cfu·mL-1 in the best case. The cross reactivity to Salmonella typhimurium, Staphylococcus aureus and Escherichia coli is negligible. The assay was applied to analyze doped milk samples for and gave good recovery. Thus, we believe that the truncated aptamer/graphene oxide platform is a potential tool for the detection of S. Enteritidis. Graphical abstract Fluorescently labelled aptamer against Salmonella enteritidis was adsorbed on the surface of graphene oxide by π-stacking interaction. This results in quenching of the fluorescence of the label. Addition of Salmonella enteritidis restores fluorescence, and this effect is used for quantification of this food-borne pathogen.