Dopamine-sensor

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). 

Other researchers have followed related strategies as described above for detection of IL-6. For example, Wang et. al. [75] reported an amperometric immunosensor to detect interleukin-6 (lL-6) using a AuNP-Poly-dopamine sensor platform and multienzyme-antibody functionalized AuNPs on carbon nanotubes. They obtained a DL of 1 pg mL for lL-6 in buffer. Du et. al. [76] used AuNP-modified screen printed carbon electrode to detect p53 phosphorylated at Ser392 (phospho-p53 ) along with multi-enzyme labeled graphene oxide (GO). 

Only very few successful electrochemical applications of molecular imprinting were reported so far, but those reported are exciting and stimulating (Sayen, 2002 Collinson, 1999 Shustak, 2003). A description of Collinson s dopamine sensor is given in the applications section below. 

Liew, F. F. Hasegawa, T. Fukuda, M. Nakata, E. Morii, T. Construction of dopamine sensors by using fluorescent ribonucleopeptide complexes. Bioorg. Med. Chem. 2011, 79,4473 1481. 

FIGURE 6-12 The mixed tissue (banana) carbon-paste sensor for dopamine. PPO = polyphenol oxidase. (Reproduced with permission from reference 36.)... 

A poly(aniline boronic acid)-based conductimetric sensor for dopamine consisting of an interdigitated microarray electrode coated with poly(aniline boronic acid) has also been developed by the Fabre team. The sensor was found to show a reversible chemoresistive response to dopamine without interference by ascorbic acid from their mixtures.42... 

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... 

Figure 16.7 Schematic representation illustrating the selective diffusion of dopamine over glutamic acid and tyrosine into the mesopores of PLA-coated MSN-based fluorescence sensor system.

Additional improvements can be achieved through the use of multilayers (based on different overlaid films). Such combination of the properties of different films has been documented with bilayers of Nation/CA (14) and Nafion/collagen (29). The former allows selective measurements of the neurotransmitter dopamine in the presence of the slightly larger epinephrine and the anionic ascorbic acid (Figure 5). In addition to bilayers, mixed (composite) films, such as PVP/CA (75) or polypyrrole/Eastman Kodak AQ (30) layers can offer additional permselectivity advantages, such composites exhibit properties superior to those of their individual components. Also promising are sensor arrays, based on electrodes coated with... 

Negyessy L, Goldman-Rakic PS. 2005. Subcellular localization of the dopamine D2 receptor and coexistence with the calcium-binding protein neuronal calcium sensor-1 in the primate prefrontal cortex. J Comp Neurol 488 464-475. 

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