Comparative Study of Electrochemical Sensors Based on Enzyme Immobilized into Polyelectrolyte Microcapsules and into Chitosan Gel (original) (raw)
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Food Analytical Methods, 2013
In this study, we report the construction of amperometric screen-printed glucose biosensors for food analysis by using two procedures for Prussian Blue (PB) deposition and different membranes for enzymatic immobilisation. The comparison between the screen-printed electrodes modified with PB by electrochemical and chemical deposition showed higher analytical performance (detection limit of 1 μM, linear range from 0.5 to 500 μM and a sensitivity of 823 μA mM −1 cm −2) when the latter was employed. Then, the immobilisation of glucose oxidase (GOD) by silica sol-gel and polyvinyl alcohol (PVA) hydrogel was performed on electrochemically modified PB electrodes. The electrochemical response of two glucose biosensors was evaluated by flow injection analysis. Biosensors constructed by silica sol-gel entrapment showed a wider linear range (0.005-1 mM) and a detection limit (0.02 mM) that was 10-fold lower than using entrapped GOD in PVA. The selected glucose biosensor showed negligible interference from ascorbic acid when the Nafion membrane was used to cover the PB-modified electrode surface. Additionally, it exhibited an operating lifetime of 8 h under continuous glucose injections ranging from 0.01 to 2 mM. Finally, the biosensor was applied for specific determination of glucose in red and white wines, juices and dried fruit.
2020
In this study, we report the construction of amperometric screen-printed glucose biosensors for food analysis by using two procedures for Prussian Blue (PB) deposition and different membranes for enzymatic immobilisation. The comparison between the screen-printed electrodes modified with PB by electrochemical and chemical deposition showed higher analytical performance (detection limit of 1 μM, linear range from 0.5 to 500 μM and a sensitivity of 823 μA mM −1 cm −2 ) when the latter was employed. Then, the immobilisation of glucose oxidase (GOD) by silica sol-gel and polyvinyl alcohol (PVA) hydrogel was performed on electrochemically modified PB electrodes. The electrochemical response of two glucose biosensors was evaluated by flow injection analysis. Biosensors constructed by silica sol-gel entrapment showed a wider linear range (0.005-1 mM) and a detection limit (0.02 mM) that was 10-fold lower than using entrapped GOD in PVA. The selected glucose biosensor showed negligible inte...
Analytical and Bioanalytical Chemistry, 2008
Protective polymer coatings have been used to enhance the retention of enzymes in sol-gel films as immobilisation phases in electrochemical biosensors. Carbon film electrodes were electrochemically modified with poly(neutral red) (PNR). These electrodes were coated with oxysilane sol-gels incorporating glucose oxidase and an outer coating of carboxylated PVC (CPVC) or polyurethane (PU), with and without Aliquat-336 or isopropyl myristate (IPM) plasticizer, was applied. The biosensors were characterised electrochemically using cyclic voltammetry and amperometry, electrochemical impedance spectroscopy and scanning electron microscopy. Impedance spectra showed that the electrode surface is most active when the sol-gel-GOx layer is not covered with a membrane. However, membranes without plasticizer extend the lifetime of the biosensor to more than 2 months when PU is used as an outer membrane. The linear range of the biosensors was found to be 0.05-0.50 mM of glucose and the biosensor with PU outer membrane exhibited higher sensitivity (ca.117 nA mM −1 ) in the region of linear response than that with CPVC. The biosensors were applied to glucose measurement in natural samples of commercial orange juice.
ELECTROCHEMICAL GLUCOSE BIOSENSOR BASED ON ENZYME ENTRAPMENT WITH THE AID OF CHITOSAN
An environmentally friendly method with the aid of biomaterials was used to determine glucose in aqueous solutions. For this purpose, an electrochemical biosensor was fabricated by modifying the platinum electrode. The drop-dry deposition was used to immobilize enzyme on the surface of electrode. Glucose oxidase (GOx) was selected as the enzyme due to its excellent affinity to glucose. Then to immobilize GOx the electrode was coated by chitosan (CHIT) which is a biopolymer derived from chitin. Cyclic voltammetric experiment was carried out in absence and presence of glucose in 0.1 M phosphate buffer (PB) solution. Analysis of the cyclic voltammograms indicated that a catalytic reaction occurred on the modified electrode which was resulted from the oxidation of glucose by GOx. The electroactive surface area of the modified electrode was assessed by the cyclic voltammetry in 1 M KCl solution containing 5 mM K3[Fe(CN)6] at scan rates of 10-100 mVs−1 and calculated to be 0.012 cm2. Amperometric measurements were performed with an applied potential of +0.75 V at 25±0.2 °C in 0.1 M PB solution containing variable concentrations of glucose. The modified electrode showed an excellent performance for glucose detection with a high sensitivity of 38.5 μA mM−1 cm−2 and the detection limit of 17.4 μM glucose. The effect of temperature on the biosensor response and also the stability of biosensor were investigated. The fabricated biosensor showed accurate, fast and reliable responses for detection of glucose in aqueous phase.
Enzyme electrodes for the determination of carbohydrates in food
Sensors and Actuators B: Chemical, 1993
Characteristic features of screen-printed enzyme electrodes for glucose, lactose and sucrose are described. Glucose oxidase was immobilized on a screen-printed Pt electrode either by crosslinking with glutaraldehyde or by adsorption in an enzyme paste which incorporated either platinized graphite or graphite modified with the mediator tetrathiafulvalene. Thus, detection was based on either H,O, oxidation or mediator oxidation. The highest reproducibility was obtained with sensors based on the enzyme crosslinked with glutaraldehyde. Hence, this immobilization procedure was also used for the preparation of lactose and sucrose sensors. These sensors are based on co-immobilized j-galactosidase and glucose ox&se and invertase, mutarotase and glucose oxidase, respectively. Adding mutarotase to the enzyme mixture of the sucrose sensor enhanced sensitivity approximately 100 times. The linear range of the sensors could be increased by additional membranes fixed over the electrode surface. The greatest effect was observed using membranes with a reduced number of pores. This also led to a decrease in the sensitivity of the sensor. Additionally, these sensors showed a reduced response to ascorbic acid, the main electrochemically interfering compound in food. Hence, no interference was observed in juices without added ascorbic acid.
A new polymer composition was developed based on hybrid sol gel material for the immobilization of enzymes on the surface of screen printed carbon electrodes modified with Prussian blue. The existing and developed methods for the glucose oxidase (GO) immobilization are compared. Highly stable bioelectrodes were shown to be obtained by enzyme immobilization on a hybrid composition consisting of sol-gel/poly vinyl alcohol (PVA) (up to 60 sequential chains) and agar gel (up to 45 sequential chains). The range of glucose concentrations detected during enzyme immobilization in a hybrid sol gel/PVA composition or agar gel without dilution of a sample was 1.0–5.9 μM and 3.6–6.3 μM, respectively. An analysis of wine products was conducted. The results obtained using the proposed biosensors were shown to differ insignificantlyfrom those obtained by high performance liquid chromatography (the correlation coefficient was 0.9998).
A low cost, easy to fabricate, simple to operate, portable and disposable biosensor based upon the enzyme glucose oxidase (GOD) has been developed. A polymer matrix of Polyethylenemine (PEI) and Poly Carbamoylsulphonate (PCS) hydrogel has been used for the immobilization of GOD on a Platinum (Pt) tip of a screen printed graphite electrode. A multi channel potentiostat has been utilized in the electrode configuration for the amperometric measurement of glucose. The developed Pt/PCS+PEI/GOD glucose biosensor system could offer a reliable method of glucose determination in standard stock solutions. The designed glucose bio-sensor system has been duly characterized and the results obtained are presented. The biosensor has been found to show a sensitivity of 0.72 ± 0.15 nA/µM. Also, the specificity of the enzyme electrode and the storage stability of the GOD based biosensor system have been studied. The sensor system has also been tested with the real samples of fruit juice, soft drink and human blood. The biosensor system has been found to possess a potential for food analysis and clinical utility.
International Journal of Biological Macromolecules, 2005
Glucose oxidase was immobilized in conducting copolymers of three different types of poly(methyl methacrylate-co-thienyl methacrylate). Immobilization of enzyme was carried out by the entrapment in conducting polymers during electrochemical polymerization of pyrrole on the copolymer electrodes. Maximum reaction rate, Michaelis-Menten constants, temperature, pH and operational stabilities were determined for immobilized enzyme. The amount of glucose in orange juices of Turkey was investigated by using enzyme electrodes.
Carbon film electrodes for oxidase-based enzyme sensors in food analysis
Talanta, 2005
Carbon film resistor electrodes have been evaluated as transducers for the development of multiple oxidase-based enzyme electrode biosensors. The resistor electrodes were first modified with Prussian Blue (PB) and then covered by a layer of covalently immobilized enzyme. Electrochemical impedance spectroscopy was used to characterize the interfacial behaviour of the Prussian Blue modified and enzyme electrodes; the spectra demonstrated that the access of the substrates is essentially unaltered by application of the enzyme layer. These enzyme electrodes were used to detect the substrate of the oxidase (glucose, ethanol, lactate, glutamate) via reduction of hydrogen peroxide at +50 mV versus Ag/AgCl in the low micromolar range. Response times were 1-2 min. Finally, the glucose, ethanol and lactate electrochemical biosensors were used to analyse complex food matrices-must, wine and yoghurt. Data obtained by the single standard addition method were compared with a spectrophotometric reference method and showed good correlation, indicating that the electrodes are suitable for food analysis.
Fundamental and Application of Various Types of Biosensors in Food Analysis
A biosensor is a sensing device comprised of a combination of a specific biological element and a transducer. Microbial biosensor is an analytical device which integrates microorganisms with a physical transducer to generate a measurable signal proportional to the concentration of analytes. In recent years, a large number of microbial biosensors have been developed for environmental, food, and biomedical applications. Biosensors can essentially serve as low-cost and highly efficient devices for this purpose in addition to being used in other day-to- day applications. A “specific biological element” recognizes a specific analyte and the changes in the biomolecule are usually converted into an electrical signal by a transducer. Biosensors are an important alternative in the food industry to ensure the quality and safety of products and process controls with effective, fast and economical methods. Nowadays, a vast majority of the glucose meters are based on electrochemical biosensor technology. The use of enzymatic biosensor technology in food processing, quality control and on-line processes is promising compared to conventional analytical techniques, as it offers great advantages due to size, cost, specificity, fast response, precision and sensitivity. Enzymatic biosensors are a tool with broad application in the development of quality systems, risk analysis and critical control points, and the extent of their use in the food industry is still largely limited by the short lifetime of biosensors, in response to which the use of thermophilic enzymes has been proposed. Oxidase enzymes utilize molecular oxygen for oxidation of Substrate. In microorganisms, the enzymatic degradation of caffeine is brought about by sequential demethylation by an oxygenase, into theobromine or paraxanthine. Amount of caffeine converted by the microorganisms and the amount of oxygen consumed based on which, the amount of caffeine in the sample can be determined. Biosensor against caffeine is an new invention particularly in food Technology and other fields. Biosensors can have a variety of biomedical, industry, and military applications. In spite of this potential, however, commercial adoption has been slow because of several technological difficulties. For example, due to the presence of biomolecules along with semiconductor materials, biosensor contamination is a major issue. Potential applications within the supply chain range from testing of foodstuffs for maximum pesticide residue verification through to the routine analysis of analyte concentrations, such as, glucose, sucrose, alcohol, etc., which may be indicators of food quality/acceptability."Biosensors market is categorized as a growth market is expected to grow from 6.72billionin2009to6.72 billion in 2009 to 6.72billionin2009to14.42 billion in 2016." Biosensor adoption is increasing every year and the number of biosensor applications is continuously growing. Keywords: Specific biological element, Transducer, Analyte concentrations and adoption.