The Experts below are selected from a list of 17946 Experts worldwide ranked by ideXlab platform
Gajjala Sumana - One of the best experts on this subject based on the ideXlab platform.
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Graphene quantum dots-based nano-biointerface platform for Food Toxin detection
Analytical and Bioanalytical Chemistry, 2018Co-Authors: Hema Bhardwaj, Chandan Singh, R. K. Kotnala, Gajjala SumanaAbstract:Due to the similar electrochemical properties to graphene oxide (GO), graphene quantum dots (GQDs) are considered as a highly potential candidate for designing an electrochemical biosensor. In this report, GQDs were synthesized having an average diameter of 7 nm and utilized for the fabrication of an electrochemical immunosensor for the detection of Food Toxin, aflaToxin B_1 (AFB_1). An electrophoretic deposition technique was utilized to deposit the chemically synthesized GQDs onto indium tin oxide (ITO)-coated glass substrate. Further, the monoclonal antibodies of AFB_1 were covalently immobilized onto deposited electrode GQDs/ITO using EDC-NHS as a crosslinker. The structural and morphological studies of GQDs and conjugated anti-AFB_1 with GQDs have been investigated using UV-visible spectroscopy, photoluminescence spectroscopy, Raman spectroscopy, transmission electron microscopy, scanning electron microscopy techniques, etc. The electrochemical impedance spectroscopy and cyclic voltammetry measurements were carried out for electrical characterization and biosensing studies. This simple monodisperse GQDs-based platform yields heterogeneous electron transfer (97.63 × 10^−5 cm s^−1), the time constant (0.005 s) resulting in improved biosensing performance. The electrochemical immunosensor shows high sensitivity 213.88 Ω (ng mL^−1)^−1 cm^−2. The limit of detection for standard samples and contaminated maize samples was found to be 0.03 ng mL^−1 and 0.05 ng g^−1, respectively, which is lower than the maximum acceptable limit according to the European Union. This result indicates its potential application for aflaToxin B_1 detection in Food contents. Graphical abstract ᅟ
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star shaped zinc sulphide quantum dots self assembled monolayers preparation and applications in Food Toxin detection
Sensors and Actuators B-chemical, 2016Co-Authors: Hema Bhardwaj, Chandan Singh, M K Pandey, Gajjala SumanaAbstract:Abstract We report the results of studies relating to the fabrication of an electrochemical immunosensor based on self-assembled of star shaped thioglycolic acid capped zinc sulphide quantum dots (ZnS QDs) synthesized by hot injection method. Structural and morphological investigations of ZnS QDs have been accomplished via transmission electron microscopy (TEM), X-ray diffraction spectroscopy (XRD), UV–visible spectroscopy (UV–vis) and Photoluminescence spectroscopic (PL) techniques. Further, monoclonal aflaToxin-B 1 antibodies (anti-AFB 1 ) have been covalently immobilized onto the ZnS/APTES/ITO electrode surface for the detection of aflaToxin-B 1, a potential Food Toxin using electrochemical impedance spectroscopy. The impedemetric response of the proposed immunosensor shows high sensitivity (176.58 Ω/(ng/mL)/cm 2 ), improved detection limit (0.02 ng/mL) and wide detection range (0.25–2.0 ng/mL). The ZnS QDs based platform provides an efficient platform for the fabrication of immunosensor for the detection of aflaToxin- B 1 and these results have implications in the design of highly efficient biosensors for other potential Toxins.
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graphene oxide based biosensor for Food Toxin detection
Applied Biochemistry and Biotechnology, 2014Co-Authors: Bansi D. Malhotra, Saurabh Srivastava, Azahar Ali, Sima Umrao, Upendra Kumar Parashar, Anchal Srivastava, Gajjala Sumana, Shyam S PandeyAbstract:We report results of the studies relating to the fabrication of a highly sensitive label free biosensor based on graphene oxide (GO) platform for the detection of aflaToxin B1 (AFB1) which is most toxic and predominant Food Toxin, using electrochemical impedance spectroscopy. The structural and optical characterization of GO/Au and anti-AFB1/GO/Au has been done by electron microscopy, Raman, X-ray diffraction (XRD), UV–vis and electrochemical impedance spectroscopy (EIS). The impedimetric sensing response of immunoelectrode as a function of AFB1 concentration reveals wider linear detection range (0.5–5 ng/ml), high sensitivity (639 Ω ng−1 ml), improved detection limit (0.23 ng ml−1) and good stability (5 weeks) for the label-free detection. Association constant (k a) for antigen–antibody interaction obtained as 0.46 ng ml−1 indicates high affinity.
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electrophoretically deposited reduced graphene oxide platform for Food Toxin detection
Nanoscale, 2013Co-Authors: Saurabh Srivastava, Azahar Ali, Anchal Srivastava, Gajjala Sumana, Vinod Kumar, Pratima R Solanki, Preeti S Saxena, Amish G Joshi, B D MalhotraAbstract:Reduced graphene oxide (RGO) due to its excellent electrochemical properties and large surface area, has recently aroused much interest for electrochemical biosensing application. Here, the chemically active RGO has been synthesized and deposited onto an indium tin oxide (ITO) coated glass substrate by the electrophoretic deposition technique. This novel platform has been utilized for covalent attachment of the monoclonal antibodies of aflaToxin B1 (anti-AFB1) for Food Toxin (AFB1) detection. The electron microscopy, X-ray diffraction, and UV-visible studies reveal successful synthesis of reduced graphene oxide while the XPS and FTIR studies suggest its carboxylic functionalized nature. The electrochemical sensing results of the anti-AFB1/RGO/ITO based immunoelectrode obtained as a function of aflaToxin concentration show high sensitivity (68 μA ng−1 mL cm−2) and improved detection limit (0.12 ng mL−1). The association constant (ka) for antigen–antibody interaction obtained as 5 × 10−4 ng mL−1 indicates high affinity of antibodies toward the antigen (AFB1).
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ring like self assembled ni nanoparticles based biosensor for Food Toxin detection
Applied Physics Letters, 2012Co-Authors: Prasanta Kalita, Gajjala Sumana, Pratima R Solanki, Jay Singh, Manish Kumar Singh, B D MalhotraAbstract:The self-assembled ring like nickel (RnNi ∼ 10-20 nm) nanoparticles have been prepared by pulsed laser ablation method and confirmed by transmission electron microscopy. These RnNi nanoparticles electrophoretically deposited onto the indium-tin-oxide (ITO) glass substrate have been functionalized with dimethyl sulfoxide (DMSO) for covalent immobilization of anti-aflaToxin (a-AfB1) monoclonal antibodies and bovine serum albumin as blocking agent. The electrochemical response studies of a-AfB1/DMSO/RnNi-film/ITO bioelectrode reveal linearity as 5-100 ngdL−1, detection limit of 32.7 ngdL−1, sensitivity of 0.59 μA/ng dL−1, and shelf-life of 60 days. The low value (1.3 × 1014 molL−1) of association constant (Ka) shows high affinity towards aflaToxin.
Chantal Mathieu - One of the best experts on this subject based on the ideXlab platform.
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cereulide Food Toxin beta cell function and diabetes facts and hypotheses
Diabetes Research and Clinical Practice, 2015Co-Authors: Roman Vangoitsenhoven, Michael Maris, Lut Overbergh, Joris Van Loco, Chantal Mathieu, Bart Van Der SchuerenAbstract:Abstract The incidence of both type 1 and type 2 diabetes is increasing and although environmental pollutants are believed to be potential culprits, the extent to which they can be held responsible remains uncertain. Some bacterial strains of the Bacillus cereus produce a Toxin, cereulide, which is frequently found in starchy meals and which is difficult to eradicate from the Food chain as it is highly resistant to heat, acidity and proteolysis. While cereulide is well known to cause acute emetic toxicity when ingested at high doses, several in vitro studies have shown that also extremely low doses of cereulide can be toxic, with beta cells being particularly sensitive. Mechanistically, such low doses impair the mitochondrial activity of the beta cells thereby leading to hampered insulin secretion and cell death, both key traits in the pathophysiology of diabetes. In vivo studies of chronic or repeated low dose exposure to cereulide are currently lacking, but should be performed to further clarify the true relevance of cereulide as a potential environmental contributor to the ongoing diabetes epidemic.
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Foodborne cereulide causes beta cell dysfunction and apoptosis
PLOS ONE, 2014Co-Authors: Roman Vangoitsenhoven, Dieter Rondas, Inne Crevecoeur, Wannes Dhertog, Pieter Baatsen, Mirjana Andjelkovic, Joris Van Loco, Christophe Matthys, Matilde Masini, Chantal MathieuAbstract:Aims/Hypothesis To study the effects of cereulide, a Food Toxin often found at low concentrations in take-away meals, on beta-cell survival and function. Methods Cell death was quantified by Hoechst/Propidium Iodide in mouse (MIN6) and rat (INS-1E) beta-cell lines, whole mouse islets and control cell lines (HepG2 and COS-1). Beta-cell function was studied by glucose-stimulated insulin secretion (GSIS). Mechanisms of toxicity were evaluated in MIN6 cells by mRNA profiling, electron microscopy and mitochondrial function tests. Results 24 h exposure to 5 ng/ml cereulide rendered almost all MIN6, INS-1E and pancreatic islets apoptotic, whereas cell death did not increase in the control cell lines. In MIN6 cells and murine islets, GSIS capacity was lost following 24 h exposure to 0.5 ng/ml cereulide (P<0.05). Cereulide exposure induced markers of mitochondrial stress including Puma (p53 up-regulated modulator of apoptosis, P<0.05) and general pro-apoptotic signals as Chop (CCAAT/-enhancer-binding protein homologous protein). Mitochondria appeared swollen upon transmission electron microscopy, basal respiration rate was reduced by 52% (P<0.05) and reactive oxygen species increased by more than twofold (P<0.05) following 24 h exposure to 0.25 and 0.50 ng/ml cereulide, respectively. Conclusions/Interpretation Cereulide causes apoptotic beta-cell death at low concentrations and impairs beta-cell function at even lower concentrations, with mitochondrial dysfunction underlying these defects. Thus, exposure to cereulide even at concentrations too low to cause systemic effects appears deleterious to the beta-cell.
Roman Vangoitsenhoven - One of the best experts on this subject based on the ideXlab platform.
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cereulide Food Toxin beta cell function and diabetes facts and hypotheses
Diabetes Research and Clinical Practice, 2015Co-Authors: Roman Vangoitsenhoven, Michael Maris, Lut Overbergh, Joris Van Loco, Chantal Mathieu, Bart Van Der SchuerenAbstract:Abstract The incidence of both type 1 and type 2 diabetes is increasing and although environmental pollutants are believed to be potential culprits, the extent to which they can be held responsible remains uncertain. Some bacterial strains of the Bacillus cereus produce a Toxin, cereulide, which is frequently found in starchy meals and which is difficult to eradicate from the Food chain as it is highly resistant to heat, acidity and proteolysis. While cereulide is well known to cause acute emetic toxicity when ingested at high doses, several in vitro studies have shown that also extremely low doses of cereulide can be toxic, with beta cells being particularly sensitive. Mechanistically, such low doses impair the mitochondrial activity of the beta cells thereby leading to hampered insulin secretion and cell death, both key traits in the pathophysiology of diabetes. In vivo studies of chronic or repeated low dose exposure to cereulide are currently lacking, but should be performed to further clarify the true relevance of cereulide as a potential environmental contributor to the ongoing diabetes epidemic.
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Foodborne cereulide causes beta cell dysfunction and apoptosis
PLOS ONE, 2014Co-Authors: Roman Vangoitsenhoven, Dieter Rondas, Inne Crevecoeur, Wannes Dhertog, Pieter Baatsen, Mirjana Andjelkovic, Joris Van Loco, Christophe Matthys, Matilde Masini, Chantal MathieuAbstract:Aims/Hypothesis To study the effects of cereulide, a Food Toxin often found at low concentrations in take-away meals, on beta-cell survival and function. Methods Cell death was quantified by Hoechst/Propidium Iodide in mouse (MIN6) and rat (INS-1E) beta-cell lines, whole mouse islets and control cell lines (HepG2 and COS-1). Beta-cell function was studied by glucose-stimulated insulin secretion (GSIS). Mechanisms of toxicity were evaluated in MIN6 cells by mRNA profiling, electron microscopy and mitochondrial function tests. Results 24 h exposure to 5 ng/ml cereulide rendered almost all MIN6, INS-1E and pancreatic islets apoptotic, whereas cell death did not increase in the control cell lines. In MIN6 cells and murine islets, GSIS capacity was lost following 24 h exposure to 0.5 ng/ml cereulide (P<0.05). Cereulide exposure induced markers of mitochondrial stress including Puma (p53 up-regulated modulator of apoptosis, P<0.05) and general pro-apoptotic signals as Chop (CCAAT/-enhancer-binding protein homologous protein). Mitochondria appeared swollen upon transmission electron microscopy, basal respiration rate was reduced by 52% (P<0.05) and reactive oxygen species increased by more than twofold (P<0.05) following 24 h exposure to 0.25 and 0.50 ng/ml cereulide, respectively. Conclusions/Interpretation Cereulide causes apoptotic beta-cell death at low concentrations and impairs beta-cell function at even lower concentrations, with mitochondrial dysfunction underlying these defects. Thus, exposure to cereulide even at concentrations too low to cause systemic effects appears deleterious to the beta-cell.
Chandan Singh - One of the best experts on this subject based on the ideXlab platform.
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Graphene quantum dots-based nano-biointerface platform for Food Toxin detection
Analytical and Bioanalytical Chemistry, 2018Co-Authors: Hema Bhardwaj, Chandan Singh, R. K. Kotnala, Gajjala SumanaAbstract:Due to the similar electrochemical properties to graphene oxide (GO), graphene quantum dots (GQDs) are considered as a highly potential candidate for designing an electrochemical biosensor. In this report, GQDs were synthesized having an average diameter of 7 nm and utilized for the fabrication of an electrochemical immunosensor for the detection of Food Toxin, aflaToxin B_1 (AFB_1). An electrophoretic deposition technique was utilized to deposit the chemically synthesized GQDs onto indium tin oxide (ITO)-coated glass substrate. Further, the monoclonal antibodies of AFB_1 were covalently immobilized onto deposited electrode GQDs/ITO using EDC-NHS as a crosslinker. The structural and morphological studies of GQDs and conjugated anti-AFB_1 with GQDs have been investigated using UV-visible spectroscopy, photoluminescence spectroscopy, Raman spectroscopy, transmission electron microscopy, scanning electron microscopy techniques, etc. The electrochemical impedance spectroscopy and cyclic voltammetry measurements were carried out for electrical characterization and biosensing studies. This simple monodisperse GQDs-based platform yields heterogeneous electron transfer (97.63 × 10^−5 cm s^−1), the time constant (0.005 s) resulting in improved biosensing performance. The electrochemical immunosensor shows high sensitivity 213.88 Ω (ng mL^−1)^−1 cm^−2. The limit of detection for standard samples and contaminated maize samples was found to be 0.03 ng mL^−1 and 0.05 ng g^−1, respectively, which is lower than the maximum acceptable limit according to the European Union. This result indicates its potential application for aflaToxin B_1 detection in Food contents. Graphical abstract ᅟ
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star shaped zinc sulphide quantum dots self assembled monolayers preparation and applications in Food Toxin detection
Sensors and Actuators B-chemical, 2016Co-Authors: Hema Bhardwaj, Chandan Singh, M K Pandey, Gajjala SumanaAbstract:Abstract We report the results of studies relating to the fabrication of an electrochemical immunosensor based on self-assembled of star shaped thioglycolic acid capped zinc sulphide quantum dots (ZnS QDs) synthesized by hot injection method. Structural and morphological investigations of ZnS QDs have been accomplished via transmission electron microscopy (TEM), X-ray diffraction spectroscopy (XRD), UV–visible spectroscopy (UV–vis) and Photoluminescence spectroscopic (PL) techniques. Further, monoclonal aflaToxin-B 1 antibodies (anti-AFB 1 ) have been covalently immobilized onto the ZnS/APTES/ITO electrode surface for the detection of aflaToxin-B 1, a potential Food Toxin using electrochemical impedance spectroscopy. The impedemetric response of the proposed immunosensor shows high sensitivity (176.58 Ω/(ng/mL)/cm 2 ), improved detection limit (0.02 ng/mL) and wide detection range (0.25–2.0 ng/mL). The ZnS QDs based platform provides an efficient platform for the fabrication of immunosensor for the detection of aflaToxin- B 1 and these results have implications in the design of highly efficient biosensors for other potential Toxins.
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Nanomaterial-Based Biosensors for Food Toxin Detection
Applied Biochemistry and Biotechnology, 2014Co-Authors: Bansi D. Malhotra, Saurabh Srivastava, Chandan SinghAbstract:There is an increased interest toward the development of bioelectronic devices for Food Toxin (mycoToxins) detection. MycoToxins are highly toxic secondary metabolites produced by fungi like Fusarium , Aspergillus , and Penicillium that are frequently found in crops or during storage of Food including cereals, nuts, fruits, etc. The contamination of Food by mycoToxins has become a matter of increasing concern. High levels of mycoToxins in the diet can cause adverse, acute, and chronic effects on human health and a variety of animal species. Side effects may particularly affect the liver, kidney, nervous system, endocrine system, and immune system. Among 300 mycoToxins known till date, there are a few that are considered to play an important part in Food safety, and for these, a range of analytical methods have been developed. Some of the important mycoToxins include aflaToxins, ochraToxins, fumonisins, citreoviridin, patulin, citrinin, and zearalenon. The conventional methods of analysis of mycoToxins normally require sophisticated instrumentation, e.g., liquid chromatography with fluorescence or mass detectors, combined with extraction procedures for sample preparation. Hence, new analysis tools are necessary to attain more sensitive, specific, rapid, and reliable information about the desired Toxin. For the last about two decades, the research and development of simpler and faster analytical procedures based on affinity biosensors has aroused much interest due to their simplicity and sensitivity. The nanomaterials have recently had a great impact on the development of biosensors. The functionalized nanomaterials are used as catalytic tools, immobilization platforms, or as optical or electroactive labels to improve the biosensing performance to obtain higher sensitivity, stability, and selectivity. Nanomaterials, such as carbon nanomaterials (carbon nanotubes and graphene), metal nanoparticles, nanowires, nanocomposites, and nanostructured metal oxide nanoparticles are playing an increasing role in the design of sensing and biosensing systems for mycoToxin determination. Furthermore, these nanobiosystems are also bringing advantages in terms of the design of novel Food Toxin detection strategies. We will focus on some of the recent results related to fabrication of nanomaterial-based biosensors for Food Toxin detection obtained in our laboratories.
Peter C Holland - One of the best experts on this subject based on the ideXlab platform.
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the basolateral amygdala is critical to the expression of pavlovian and instrumental outcome specific reinforcer devaluation effects
The Journal of Neuroscience, 2009Co-Authors: Alexander W Johnson, Michela Gallagher, Peter C HollandAbstract:Considerable evidence implicates the basolateral amygdala (BLA) in the formation of outcome representations that link cues to the incentive properties of reinforcers. Animals with BLA damage show impaired performance in reinforcer devaluation tasks, in which the value of the Food reinforcer is reduced by satiation or Food-Toxin pairings after the completion of cue or response training. Although intact animals spontaneously reduce their conditioned responding after such reinforcer devaluation procedures, animals with BLA lesions made before training typically do not, as evidenced across a range of species, training contingencies, and devaluation procedures. In contrast, the role of the BLA in devaluation task performance once such outcome representations are established is unclear. Whereas Pickens et al. (2003) found normal devaluation performance in rats when BLA lesions were made after pavlovian light-Food pairings but before devaluation by Food-Toxin pairings, Ostlund and Balleine (2008) found impaired devaluation performance when BLA lesions were made after instrumental training with multiple instrumental responses and Food reinforcers but before devaluation of one reinforcer by selective satiation. Those studies differed in their use of pavlovian or operant training contingencies, single or multiple reinforcers, and associative or motivational devaluation procedures. Here we found that, when multiple reinforcers were used, posttraining BLA lesions disrupted the expression of devaluation performance in rats, using either pavlovian or instrumental training procedures and either conditioned taste aversion or satiation devaluation procedures. Thus, BLA apparently plays a critical role in maintaining or using sensory associations of reinforcer value when multiple outcomes must be coded but not under single-outcome conditions.
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amount of training effects in representation mediated Food aversion learning no evidence of a role for associability changes
Learning & Behavior, 2005Co-Authors: Peter C HollandAbstract:Rats acquired aversions to Food pellets when a previously trained signal for that Food was paired with a Toxin, but only after minimal signal—Food training. After extensive signal—Food training, signal—Toxin pairings had no effect on Food consumption even after manipulations that enhanced the associability of the signal. By contrast, conditioned responding to the signal retained its sensitivity to devaluation of the Food reinforcer by Food—Toxin pairings after extensive training. These results suggest that the nature of associatively activated event representations changes over the course of training.
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Orbitofrontal lesions impair use of cue-outcome associations in a devaluation task.
Behavioral Neuroscience, 2005Co-Authors: Charles L. Pickens, Michela Gallagher, Michael P. Saddoris, Peter C HollandAbstract:The orbitofrontal cortex (OFC) has been implicated in the use of outcome expectancies to guide behavior. The present study used a devaluation task to examine this function. Rats first received light-Food pairings followed by Food-Toxin pairings designed to devalue the Food. After either excitotoxic or sham OFC lesions, responding to the light was reassessed. Sham-lesioned rats showed reduced responding to the light relative to behavioral controls, which had received Food and Toxin unpaired. In contrast, OFC-lesioned rats showed no such reductions. Combined with previous data (C. L. Pickens, M. P. Saddoris, B. Setlow, M. Gallagher, P. C. Holland, & G. Schoenbaum, 2003), these results indicate that the OFC is critical for the maintenance of information about the current incentive value of reinforcers or the use of that information to guide behavior.