177,067 research outputs found
Screening and resolution of carbamic and organophosphate pesticides mixture in Extra Virgin olive oil with a bi-enzymatic amperometric sensor
No full textQuantitative screening and resolution of carbamic and organoposphate pesticides mixture in Extra Virgin olive oil by acetylcholinesterase-choline oxidase sensor.
No full textLabel-free impedimetric biosensors for the control of food safety–a review
No full textThe guarantee of food safety requires fast and accurate control for all contaminants, chemicals and bacteria, which are harmful to human health. Ensuring the safety and quality of food is the main interest both for the food industry and for consumers. In the food industry, the safety of a food product is evaluated through chemical and microbiological analysis: these procedures conventionally use the technique as chromatography, spectrophotometry and electrophoresis that are time-consuming, require highly trained personnel, are expensive and require steps of sample pretreatment, increasing the time of analysis. Consequently, among food and beverage industries, exists a growing demand in biosensing technologies as simple, rapid, accurate, low - cost and portable analytical devices for the monitoring and detection of chemical and microbiological contaminants (toxins, mycotoxins, pathogenic bacteria, pesticides and allergens) that endanger the food safety. Among biosensors, the label-free biosensors, characterised by direct detection of the analyte of interest, exploiting the advantages of an impedimetric transduction technique, seem to be the most promising devices for the future. In the last years, the potential use of Electrochemical Impedance Spectroscopy technique has been widely considered in the biosensor field; it is, in fact, a powerful, non-destructive and informative technique which can be used to study the electrical properties of the sensing device interface and to trace the reactions that occur on it. For these reasons, the application of impedimetric technique as a transduction technology has allowed the label-free detection and sensitive quantification of the bio interaction in different application and thus for the development of food hazards biosensors too. This review provides the current situation in the literature on label-free impedimetric biosensors in food safety
Entirely automated glucose monitoring system based on a flow injection analysis apparatus
No full textA process for waste whey treatment, fully based on membrane technologies, has been studied and developed in a pilot plant scale, with the aim to recover chemicals from farm wastes (fats, whey proteins, lactose, salts and water). This process, described in its essential steps, includes a hollow fiber membrane reactor for the hydrolysis of lactose with an immobilized β-galactosidase. The bioreactor performances are studied, in a lab scale, with an entirely automated glucose monitoring system based on a flow injection analysis apparatus. The monitoring system shows interesting performances concerning signal stability, extended linearity (up to 150 mmol l-1) and long term monitoring (up to 3 months without manual operations). The performances of the glucose monitoring system are described. © 1994, Taylor & Francis Group, LLC. All rights reserved
Disposable label - Free immunosensor on screen - Printed electrodes for the detection of Aflatoxin B1 in food
No full textAn impedimetric label - free immunosensor on disposable screen-printed carbon electrode (SPCE) for Aflatoxin B1 detection has been developed in this work. SPCE surface was modified with gold nanoparticles and the monoclonal anti-AFB1 was immobilized on the working electrode through a cysteamine layer. After each coating step, the modified surface was characterized by Cyclic Voltammetry and Electrochemical Impedance Spectroscopy. The charge transfer resistance (Rct) was chosen as the best parameter that describes the reproducible change in electrical properties of the electrode surface at different AFB1 concentrations and it was used to investigate the analytical parameters of the developed immunosensor. Under optimized conditions, the immunosensor showed a linear relationship between 0.01 and 4 ng/mL with a low detection limit of 0.01 ng/mL, making it suitable to detect AFB1 amount in many common food products. Lastly, the immunosensor was used to measure AFB1 in nuts samples with good results
Label-free impedimetric immunosensors for sensitive detection of aflatoxin B1 in food
No full textAflatoxin B1 (AFB1) is one of the mycotoxins highly resistant to food processing that enters the food chain and provide a threat to human health. In this paper, different immobilization techniques of the monoclonal anti-AFB1 on gold electrodes were tested and compared, in order to develop a label-free immunosensor able to detect AFB1 amount imposed by European legislation for adult and infant foods. Different materials, coupled with Electrochemical Impedance Spectroscopy as transduction technique, were used to improve immunosensors analytical parameters, such as linear range, sensitivity and limit of detection. Through the use of ferrocene molecules, the immunosensor showed linearity in the range 0.01-10 ng/mL and the lowest limit of detection (0.01 ng/mL), allowing the possibility to use it in a wide range of food products, including infant foods
Self assembled and electrochemically deposed layers of thiols on gold compared with electrochemical impedance spectroscopy and atomic force microscopy
No full textSelf-Assembling is based on a spontaneous process in which organic molecules (alkanethiols, silanes) are adsorbed on a substrate (gold, glass, silicon). Although the implementation is extremely easy, it shows a big disadvantage in timing, because the solution has to be in contact overnight with the substrate under mild shaking. An alternative method of molecular deposition is the Electrochemically Deposed Multilayers commonly used in our laboratory for further immobilization of biological molecules in order to obtain specific biosensors for several analytes. It consists in applying a constant potential on gold working electrode (1.3 V vs. Ag/AgCl) for driving molecules in proximity of the electrode and allow them to react on the surface and form a layer similar to self assembled ones. Both the layers, self assembled and electrochemically deposed ones, were tested with Electrochemical Impedance Spectroscopy and Atomic Force Microscopy. The substrate electrochemically covered shows a higher and a more homogeneous deposition than self assembled one and the deposition time is extremely reduced from several hours to a few of seconds (50 s)
Impedimetric label - free immunosensor for rapid detection of Ochratoxin A in beer and wine
No full textIn this work, the development of an impedimetric label-free immunosensor for the detection of Ochratoxin A in food products is reported. Two different immobilization schemes of a monoclonal antibody for OTA detection were investigated and compared, with the aim to develop an analytical device able to detect an OTA amount equal to the maximum levels imposed by European legislation for food products. activated ferrocene as electron-transferring mediator, improved the electrical properties of the immunosensor, which showed a limit of detection equal to 0.25 ng/mL. This immunosensor was used to analyze wine and beer samples spiked with known OTA amounts
In-line determination of metabolites and milk components with electrochemical biosensors
No full textComparison of TEOS (tetraethyl orthosilicate) and PVA (polyvinyl alcohol) for immobilization of glucose oxidase on screen-printed electrodes
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