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In vivo Electrochemical Techniques

Second, the in vivo electrochemical technique measures dynamic changes in concentration of electroactive species near the electrode induced by some physical or drug stimulation. In spite of the complexity of brain interactions, one can expect that not all of the electroactive species will necessarily change simultaneously. Selectivity based on the time of appearance of electroactive response is possible. [Pg.54]

In summary, the in vivo electrochemical technique appears applicable to many styles of neuroscience investigations. One can already see how... [Pg.63]

The first in vivo electrochemical measurements were performed in 1973 Since then bioelectrocheraists have spent much effort in developing in vivo methods of analysis. A major reason for this effort is the rapidity with which in vivo techniques... [Pg.34]

Differential pulse voltammetry has been widely used for in vivo electrochemical analysis This technique combines the linear sweep and pulsed potential... [Pg.37]

In 1976, Adams published a pioneering article on the voltammetric technique of in vivo determination of electrochemically active compounds in the brain [33]. It describes notably successful measurements on neurotransmitters such as dopamine (DA) and seretonin (5-HT) using carbon paste electrodes with tip diameters from 50 to 200 m implanted in the brain tissue of a rat. Thereafter, in vivo voltammetric technique attracted much attention from neuroscientists and electrochemists, and many papers have been published in the field [30, 34-47]. In this section microelectrodes suitable for the detection of neurotransmitters, the operation techniques for positioning electrodes, and some results are described. [Pg.476]

Enzyme linked electrochemical techniques can be carried out in two basic manners. In the first approach the enzyme is immobilized at the electrode. A second approach is to use a hydrodynamic technique, such as flow injection analysis (FIAEC) or liquid chromatography (LCEC), with the enzyme reaction being either off-line or on-line in a reactor prior to the amperometric detector. Hydrodynamic techniques provide a convenient and efficient method for transporting and mixing the substrate and enzyme, subsequent transport of product to the electrode, and rapid sample turnaround. The kinetics of the enzyme system can also be readily studied using hydrodynamic techniques. Immobilizing the enzyme at the electrode provides a simple system which is amenable to in vivo analysis. [Pg.28]

Electrochemical techniques in vivo use the standard three electrode voltammetric system described earlier with the electrodes implanted in the brain of the animal subject. Measurements are made by acquiring some stable baseline signal and then stimulating release of the biogenic amine neurotransmitters. The change in signal is then a measure of the concentration of neurotransmitter in the extracellular fluid. [Pg.35]

As with in vivo voltammetry, a variety of electrochemical techniques have been used for the stripping step. Because of its simplicity, linear sweep voltammetry has enjoyed widespread use however, the detection limit of this technique is limited by charging current. Differential pulse has become popular because it discriminates against the charging current to provide considerably lower detection limits. [Pg.40]

To date, electrochemical (amperometric) detection of NO is the only available technique sensitive enough to detect relevant concentrations of NO in real time and in vivo and suffers minimally from potential interfering species such as nitrite, nitrate, dopamine, ascorbate, and L-arginine. Also, because electrodes can be made on the micro- and nano-scale these techniques also have the benefit of being able to measure NO concentrations in living systems without any significant effects from electrode insertion. [Pg.25]

In order to maintain the advantage of the microfabrication approach which is intended for a reproducible production of multiple devices, parallel development of membrane deposition technology is of importance. Using modified on-wafer membrane deposition techniques and commercially available compounds an improvement of the membrane thickness control as well as the membrane adhesion can be achieved. This has been presented here for three electrochemical sensors - an enzymatic glucose electrode, an amperometric free chlorine sensor and a potentiometric Ca + sensitive device based on a membrane modified ISFET. Unfortunately, the on-wafer membrane deposition technique could not yet be applied in the preparation of the glucose sensors for in vivo applications, since this particular application requires relatively thick enzymatic membranes, whilst the lift-off technique is usable only for the patterning of relatively thin membranes. [Pg.263]

Investigation of in vivo environments with the use of very fast electrochemical techniques for the elucidation of biologically significant kinetic processes... [Pg.67]

Electrical properties of neurons are measured by a variety of techniques. A review of these methodologies is beyond the purview of this chapter. However, it is important to note that changes in the electrochemical potential, ionic diffusion or current, and membrane conductance or permeability can be determined experimentally by intracellular and extracellular recording techniques that can be performed in vitro and in vivo. Hubbard et al. (1969) describe in detail a variety of intracellular techniques, such as voltage clamping, and extracellular techniques, such as sucrose-gap recording. [Pg.90]

Electrochemical analysis methods assure, generally, the most reliable analytical information because of the simplicity of the sampling process which includes (1) sample dissolution in water or in organic solvents and (2) the possibility of measuring directly and continuously the activity of the species present in the solutions. The preconcentration step is not necessary, because of the sensitivities and limits of detection that characterize the electrochemical methods. The determined species are not necessary to be converted to other measurable species. The electrochemical methods can be successfully used for in vivo monitoring. Spectrometric analysis methods, on the other hand, nearly always require a complex sampling process because of the presence of interfering species. Therapy is necessary to adopt the best separation techniques that can assure, for each analytical method, the most reliable analytical information. Nondestructive techniques are used especially for environmental analysis, and surface analysis assures the best reliability of the analytical information. [Pg.28]

In conclusion, reproducible analytical information can be obtained through both electrometric and spectrometric methods and also through immunoassay techniques, but only electrochemical methods can be successfully used for in vivo assays because electrochemical methods assure the best reproducibility of the analytical information for clinical and pharmaceutical analysis. [Pg.52]


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Electrochemical techniques

In vivo Techniques

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