Biosensor-based methods proteins

The determination of H202 is very important in many different fields, such as in clinical, food, pharmaceutical, and environmental analyses [202], Many techniques such as spectrophotometry, chemiluminesence, fluorimetry, acoustic emission, and electrochemistry methods have been employed to determine H202. Electrochemical methods are often used because of their advantages. Among these electrochemical methods, the construction of the mediator-free enzyme-based biosensors based on the direct electrochemistry of redox proteins has been reported over the past decade [203— 204], The enzyme-based biosensors, which use cyt c as biocatalyzer to catalyze H202, were widely studied. 

For high-performance separation methods suffering of insufficient detectability in determination of MC in environmental samples for routine applications the most effective is preconcentration on immunosorbents. The new advantageous competitors in this field might be enzymatic assays and biosensors based on inhibition of protein phosphatase activity by MC. Some successful attempts in this field have been reported recently as colorimetric assays or electrochemical biosensors. 

Feng, X., et al. A hving cell-based biosensor utilizing G-protein coupled receptors principles and detection methods. Biosens. Bioelectron. 22(12), 3230-3237 (2007)... 

Biosensor-based analysis is becoming more and more important in the food industry, and one of the fields of application is in vitamins analysis. The method for vitamin analysis is a label-free, inhibition assay (Kalman et al., 2006). The SPR biosensor monitors interactions of a specific binding protein with the vitamin immobilized on a CMS sensor chip. The prepared samples are mixed with a fixed concentration of the vitamin binding protein by the autosampler and injected over the chip surface. The vitamin present in the sample binds to the protein and subsequently inhibits it from binding to the surface of the sensor chip. The higher the concentration of the vitamin is in the sample, the higher the level of inhibition, and hence the lower the response of the biosensor (O Kane and Wahlstrom, 2011). A regeneration step prepares the chip surface for the next sample. Quantification is performed by multilevel caHbration with the vitamin standards. 

Biosensors based on enzymes have high sensitivity and selectivity. A variety of microbial biosensors have also been developed. However, it still remains a great challenge to develop a rapid, inexpensive but sensitive method for real samples. Compared to enzymatic biosensors, development of a highly satisfactory microbial biosensor is still hampered because they suffer from long response time, low sensitivity, and poor selectivity. The trends for the development of biosensors lie in miniaturization of the devices, nanotechnology, and biotechnology. Disposable screen-printed sensors have been developed for industrial wastes or natural water. Metal nanoparticles can enhance the electron transfer between redox center in proteins and electrode surface and show promise for detection... 

There are also RMs which are prepared for a specific application and are used for validation of relevant methods. Cobbaert et al. (1999) made use of Ion Selective Electrode (ISE)-protein-based materials when evaluating a procedure which used an electrode with an enzyme-linked biosensor to determine glucose and lactate in blood. Chance et al. (1999) are involved with the diagnosis of inherited disorders in newborn children and they prepared a series of reference materials consisting of blood spotted onto filter paper and dried, from which amino-acids can be eluted and... 

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