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A tyrosinase-based chemically amplified biosensor, based on the substrate recycling of polyphenols driven by tyrosinase-catalyzed oxidation and chemical reduction by l-ascorbic acid (AsA), has been utilized for the highly sensitive detection of inhibitors of tyrosinase such as kojic acid, benzoic and SCN - ion. The amplified current response of immobilized tyrosinase-coupling oxygen electrode...
Alcohol dehydrogenase (ADH) has been immobilized on a nickel hexacyanoferrate modified microband gold electrode surface by a glutaraldehyde/bovine serum albumin (BSA) cross-linking procedure to provide a new amperometric sensor for the assay of ethanol. The resulting enzyme electrode exhibits excellent electrocatalysis for the oxidation of reduced nicotinamide-adenine dinucleotide (NADH). The amperometric...
The development of a glucose sensor suitable for use with whole blood is described. It is based on anodic oxidation at + 700 mV of hydrogen peroxide with a platinum electrode covered with a gas permeable membrane. Glucose reacts with glucose oxidase immobilised on the external side of the membrane, and forms hydrogen peroxide which is able to cross the gas permeable membrane due to its high vapour...
Poly(ethylene glycol)-modified glucose oxidase was immobilized in a poly(vinyl alcohol) cryogel membrane, obtained by a freezing-thawing cyclic process, to obtain a suitable amperometric glucose sensor. The covalent linkage between PEG and GOD molecule improved the physical immobilization of enzyme in the polymeric matrix, by decreasing its loss in time. Sensor behaviour was evaluated electrochemically...
A new sensing method (BAW-TAL technique), which combined the bulk acoustic wave (BAW) technique with the gelation reaction of Tachypleus amebocyte lysate (TAL), was used for viscosity and density measurement and applied to the detection of Escherichia coliform (E. coli). This method depended on the fact that the viscosity and density of the mixture increased, and as a result, the resonance frequency...
One of the most important parameters to be considered when developing a biosensor based on the use of oxidase enzymes is the selective determination of H 2 O 2 in the presence of easily oxidisable interferents. In this work one approach was taken to overcome this problem-the use of metallised carbon electrodes in conjunction with polymers. Polymers, both conducting and nonconducting,...
The screen-printing technology has several advantages over the others for industrial sensor production. In fact, it has the advantage of its heterogeneic nature, which is very similar to carbon paste electrodes, combined with the properties of solid electrodes. Carbon ink may be modified with metallic particles, mediators, biocomponents, etc. Carbon screen-printed electrode (SPE) may be coated with...
A sensor for H 2 O 2 amperometric detection based on a Prussian Blue (PB) bulk modified carbon screen-printed electrode was developed. It has been optimised with respect to the lowest limit of detection achieved. PB was made chemically by the reaction of FeCl 3 with K 4 [Fe(CN) 6 ]. The resulting powder, obtained by forced crystallisation induced by acetone,...
With the rapid development of micro-Total Analysis Systems (μTAS) and sensitive DNA recognition technologies, it is possible to immobilize DNA probes to small areas of surfaces other than silicon. To this end, photolithographic techniques were used to derivatize micron-sized, spatially segregated DNA recognition elements in Polydimethylsiloxane (PDMS) microfluidic structures. UV light was used to...
Three different methods for the amplified detection of a single-base mismatch in DNA are described using microgravimetric quartz-crystal-microbalance as transduction means. All methods involve the primary incorporation of a biotinylated base complementary to the mutation site in the analyzed double-stranded primer/DNA assembly. The double-stranded assembly is formed between 25 complementary bases...
An amperometric biosensor based on catalase enzyme for alcohol determination was developed. To construct the biosensor catalase was immobilized by using gelatin and glutaraldehyde on a Clark type dissolved oxygen (DO) probe covered with a teflon membrane which is sensitive for oxygen. The working principle of the biosensor depends on two reactions, which one is related to another, catalyzed by catalase...
A new amperometric biosensor based on urate oxidase-peroxidase coupled enzyme system for the specific and selective determination of uric acid in urine was developed. Commercially available urate oxidase and peroxidase were immobilized with gelatin by using glutaraldehyde and fixed on a pretreated teflon membrane. The method is based on generation of H 2 O 2 from urine uric acid by...
A sensor to detect markers of cardiac muscle cell death at less than 3ngml -1 and in less than 10min has been achieved. This fiber-optic-based surface plasmon resonance (SPR) sensor is being applied to detect myoglobin (MG) and cardiac troponin I (cTnI) in HEPES buffered saline solution. An in vivo sensor for the early detection of the onset of myocardial infarction (MI) will greatly...
Immunosensors and biochemical array detection systems based on electrochemical transducers have many advantages such as low detection limit, fast response, simple design and ease of miniaturization. However, further development of such sensors will depend on the availability of suitable substrates that can be converted by a labeling enzyme to an electrochemically active product. Here, we report the...
Stabilisation of electrochemically deposited Prussian blue (PB) films on glassy carbon (GC) electrodes has been investigated and an enhancement in the stability of the PB films is reported if the electrodes are treated with tetrabutylammonium toluene-4-sulfonate (TTS) in the electrochemical activation step following the electrodeposition. A multi-enzyme PB based biosensor for sucrose detection was...
An overview is presented which summarizes our accomplishment in the development of sensors and biosensors based on heterogenous carbon electrodes modified with manganese dioxide. Brief account of each sensor and biosensor has been given and example of real sample applications provided where appropriate.
The efficient and rapid detection of bioactive compounds in complex matrices of different origins (natural or synthetic) is a key step in the discovery of molecules with potential application in therapy. Among them, molecules able to interact with nucleic acids can represent important targets.In this study, an optical DNA biosensor, based on surface plasmon resonance (SPR) transduction, has been studied...
In this paper, it is demonstrated that a single-receptor biosensor can be used to quantitatively determine each analyte in binary mixtures using multivariate data analysis tools based on the dynamic responses received from flow injection peaks. Mixtures with different concentrations of two phenolic compounds, catechol and 4-chlorophenol, were measured with a graphite electrode modified with tyrosinase...
The intention of this article is to reflect the advances and describe the trends on biosensors for environmental applications. Biosensors are useful analytical tools for environmental monitoring, capable of providing results in real time, simple to use, portable and cost-effective. Some examples of biosensors in advanced stage of development, which have been applied to real samples, as well as of...
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