Biosensor configuration

Second-generation electrodes have biosensor configurations that use an electron acceptor (redox mediator), which is able to shuttle electrons from the redox center of the enzyme to the surface of the working electrode ... 

Figure 4-15 Examples of DNA biosensor configurations (A) direct electrooxidation detection of guanosine bases in target DNA after hybridization with immobilized capture probe on electrode surface (B) electrochemical detection of hybridization using exogenous redox species that intercalates into hybridized complex between immobilized capture DNA probe and target DNA.

In recent years, the development of biosensor configurations has been concentrated largely around the design of the transducer used. Further researchers attention, however, should be focused on the mechanism of molecular recognition and catalysis. The fundamental properties of the device must be better understood in order to optimize critical factors such as response time, selectivity, and stability. Immobilization technologies and new membrane materials may basically change the present performance of biosensors. 

As is briefly summarized in Fig. 13 this regeneration approach can be taken also for more complex architectures envisaged in biosensor configurations After binding of the streptavidin layer a layer of biotinylated Fab-fragments of Ad = 2.8nm is formed followed by a layer of HCG-antibodies of Ad = l.Snm. Again injection of free biotin removes the whole complexes and regenerates the free desthiobiotin surface (Fig. 13, left side). 

Figure 4 shows a response curve for the first NADH-based biosensor configured for the measurement of lactate. A steady-state fluorescence signal is measured as a steady-state concentration of HADH is established at the sensor tip. As expected, the magnitude of this signal increases with an increase in the lactate concentration. A detection limit (S/N >3) of 2 yM has been measured for this lactate biosensor. 

An internal enzyme biosensor configuration has been introduced in which the enzyme is not directly in contact with the sample. 

Mathematical modeling of biosensors has been successfully used to investigate the kinetic peculiarities of the biosensor action. The numerical simulation became a powerful framework for numerical investigation of the impact of model parameters on the biosensor action and to optimize the biosensor configuration [7]. Recently, the computational modeling of the laccase-based biosensor qualitatively explained and confirmed the experimentally observed synergistic effect of the mediator on the biosensor response [21]. The numerical simulation of an amperometric biosensor based on an enzyme-loaded carbon nanotube (CNT) layer deposited on a perforated membrane highlighted the dependence of the steady-state biosensor current on the anisotropic properties of CNT. It was also shown that the sensitivity of the biosensors... 

Figure 2 Amperometric biosensor configurations. Detailed descriptions are in the text. (A) Addition of substrate to a solution containing enzyme and cofactor. (B) Immobilized enzyme upstream from sensing electrode. (C) Enzyme immobilized directly on detecting surface.

The section below presents a brief review of the existent nanofiber biosensor configurations. Starting from the glucose sensor which was the earliest sensor developed in the history of biosensing, each realm is being replaced with nanofibers for improving sensor properties. An outline of the modifications made by incorporation... 

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