Carbon Nanotube-Modified Carbon Fiber Microelectrodes for In Vivo Voltammetric Measurement of Ascorbic Acid in Rat Brain

Abstract

This study demonstrates a new electrochemical method for in vivo measurements of ascorbic acid (AA) in rat brain with multiwalled carbon nanotube (MWNT)-modified carbon fiber microelectrodes (CFMEs) based on the electrochemical property of MWNTs for facilitating AA oxidation. Cyclic voltammetry results indicate that the prepared MWNT-modified CFMEs possess a marked electrocatalytic activity toward AA oxidation and can be used for its selective measurement in the presence of other kinds of electroactive species coexisting in rat brain, such as 3,4-dihydroxyphenylacetic acid, uric acid, and 5-hydroxytryptamine. The selectivity of the MWNT-modified CFMEs toward AA measurement is further studied in vivo by exogenously infusing ascorbate oxidase into the brain, and the results confirm that the prepared electrodes are selective and can thus be used for reliable in vivo measurements of AA in rat brain, combined with their good stability during in vivo measurements. The basal level of striatum AA is determined to be 0.20 +/- 0.05 mM (n = 3). The application of the voltammetric method with the MWNT-modified CFMEs is preliminarily demonstrated for in vivo observation of homeostatic regulation of striatum AA with exogenous infusion of AA into the brain.

Development of a voltammetric technique for monitoring brain dopamine metabolism: compensation for interference caused by DOPAC electrogenerated during homovanillic acid detection

“…56,[61][62][63][64][65] In addition, lipids (and other surfactant media) 66,67 can remove surface pasting oil from CPEs, enhancing electron transfer kinetics and improving signal resolution. 64 The voltammetric behaviour of AA at very slow sweep rates at carbon electrodes has been described extensively, 56,63,[68][69][70][71][72][73] as has that of HVA under similar conditions, 29,30,74,75 and the ability of CPE PEA to resolve AA and HVA signals recorded at 10 min intervals in vivo at scan rates as low as 5 mV/s is clear. 29,33,76,77 However, because our aim was to develop a technique to monitor HVA with a time resolution of the order of seconds, the cyclic voltammetric response of AA and HVA at CPE PEA for a scan rate of 1 V/s was determined, initially in separate solutions (Fig.…”

Carbon Fiber-based Microelectrodes and Microbiosensors

“…By growing CNTs on CF microelectrodes, the nanostructure of CNTs inherently increases the effective interfacial area between microelectrode and neuron (Yeh et al, 2009). Cyclic voltammetry results indicate that the prepared multi-walled CNT-modified CF microelectrodess possess a marked electrocatalytic activity toward ascorbic acid oxidation and can be used for its selective measurement in the presence of other kinds of electroactive species coexisting in rat brain (Zhang et al, 2007). Application of single-walled CNTs on a CF microdisk electrode dramatically increased the sensitivity of CF microelectrode for nitric oxide (NO) as the detection limit proved to be about 10 times lower for NO than that of the bare carbon surface (Du et al, 2008).…”

“…Since the early times in CF applications for biorecording, a great variety of enzyme-modified CF microbiosensors has been introduced for the in situ determination of glucose, acetylcholine, choline, lactate, glutamate and other important compounds. The immobilization of DNA molecules (Millan & Mikkelsen, 1993) or carbon nanotubes (CNTs) (Zhang et al, 2007) onto CF microelectrodes has opened up new avenues in electrochemical detection of biologically significant species. A basic CF microelectrode is an elementary carbon filament built in a mechanically supportive and electrically insulating borosilicate glass or plastic sheathing.…”

Fabrication of Graphene Coated Carbon Fiber Microelectrode for Highly Sensitive Detection Application

“…Recently, much advancement has been achieved by using graphene in electrochemical applications, even electrochemical sensors or devices. [17][18][19][20][21] In the literature, 22 chemical reduction of graphene oxide was modified on the carbon fiber electrode by immersing the carbon fiber in a graphene mixture solution and the microsensor for DA showed good sensitivity and selectivity.…”