Sensors dopamine, detection

The ability of binaphthyl crown ethers such as (R)-74 to bind to various cations has been extensively studied by Cram et al. [18,62]. Optically active binaphthyl crown ethers have been used to resolve racemic amino ester salts. A racemic 74 has been polymerized on a platinum electrode to prepare a sensor to detect selectively dopamines, important neural transmitters [63,64]. However, because of the... 

Film devices are often developed based on polymer backbone or framework. For example, a poly-pyrrole film with borane in the backbone has been obtained by direct electropolymerisation. Boronic acid derivatised pyrroles have been employed to make molecular imprinted polymers (MIPs), for example for the detection of dopamine. Figure 8.8 shows the concept of polymer formation in the presence of analyte followed by extraction to provide highly selective pockets for dopamine to bind. The read-out in this case is based on the Fe(CN)/" redox probe. Poly-amino-boronic acid films without imprinting were employed for dopamine detection. Co-polymer sensor films based on poly(aniline-co-3-aminobenzeneboronic acid) and poly(acrylamidophenylboronic acid) have been reported. 

Levodopa (2-amino-3-(3,4-dihydroxyphenyl)-propanoic acid) (IV) is administered to Parkinson s sufferers to alleviate the reduced levels of dopamine commonly seen in such patients. Dopamine itself is not administered, as this compound cannot cross the blood-brain barrier unlike levodopa which is then converted in the body to dopamine [137]. Bergamini et al. [138] have utilised a gold screen-printed electrode as a sensor for monitoring levodopa both in stationary solution and in flow systems. This was achieved by using the oxidation of levodopa at +0.63 V in acetate buffer pH 3.0. A linear response was reported from 9.9 x 10-5 to 1.2x10 3M and an associated detection limit of 6.8 x 10-5M. The sensor was successfully used to detect the levodopa... 

Tissue and Bacteria Electrodes The limited stability of isolated enzymes, and the fact that some enzymes are expensive or even not available in the pure state, has prompted the use of cellular materials (plant tissues, bacterial cells, etc.) as a source of enzymatic activity (48). For example, the banana tissue (which is rich with polyphenol oxidase) can be incorporated by mixing within the carbon paste matrix to yield a fast-responding and sensitive dopamine sensor (Fig. 6.14). These biocatalytic electrodes function in a manner similar to that for conventional enzyme electrodes (i.e., enzymes present in the tissue or cell produce or consume a detectable species). 

These species have been used to modify electrodes to be used as sensors for the detection of molecules of pharmacological interest, such as dopamine. 

H.F. Cui, J.S. Ye, Y. Chen, S.C. Chong, X. Liu, T.M. Lim and F.S. Sheu, In situ temporal detection of dopamine exocytosis from 1-dopa-incubated nm9d cells using microelectrode array-integrated biochip, Sensors and Actuators B-Chemical, 115(2), 634-641 (2006). 

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