Authors: Anupama Aggarwal Mengjia Hu Ingrid Fritsch
Publish Date: 2013/02/09
Volume: 405, Issue: 11, Pages: 3859-3869
Abstract
The electrochemical behavior of dopamine was examined under redox cycling conditions in the presence and absence of a high concentration of the interferent ascorbic acid at a coplanar microelectrode array where the area of the generator electrodes was larger than that of the collector electrodes Redox cycling converts a redox species between its oxidized and reduced forms by application of suitable potentials on a set of closely located generator and collector electrodes It allows signal amplification and discrimination between species that undergo reversible and irreversible electron transfer Microfabrication was used to produce 18 individually addressable 4μmwide gold band electrodes 2 mm long contained in an array having an interelectrode spacing of 4 μm Because the array electrodes are individually addressable each can be selectively biased to produce an overall optimal electrochemical response Four adjacent microbands were shorted together to serve as the collector and were flanked on each side by seven microbands shorted as the generator a ratio of 135 of electroactive area respectively This configuration achieved a detection limit of 0454 ± 0026 μM dopamine at the collector in the presence of 100 μM ascorbic acid in artificial cerebrospinal fluid buffer concentrations that are consistent with physiological levels Enhancement by surface modification of the microelectrode array to achieve this detection limit was unnecessary The results suggest that the redox cycling method may be suitable for in vivo quantification of transients and basal levels of dopamine in the brain without background subtractionMicroelectrode array chip design and assignment of electrodes used for determination of dopamine DA in the presence of large excess of ascorbic acid AA by redox cycling Analytes DA and AA are oxidized at the generator electrodes to form dopamineoquinone DAQ and dehydroascorbic acid AAo which diffuse to the nearest collector electrodes DA is selectively detected at the collector electrodes because DAQ can be reduced there but AAo hydrolyzes to a nonelectroactive form prior to arrivalFunding was provided in part by the National Science Foundation CHE0719097 and the Arkansas Biosciences Institute the major research component of the Arkansas Tobacco Settlement Proceeds Act of 2000 We thank Errol Porter for advice on microfabrication The use of the High Density Electronics Center microfabrication facilities is also acknowledged We express our appreciation to Adrian Michael of the University of Pittsburgh for insightful discussions about applications TS Hollingsworth is acknowledged for assistance in preparing this manuscript
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