title: Enzyme-modified carbon-fiber microelectrode for the quantification of dynamic fluctuations of nonelectroactive analytes using fast-scan cyclic voltammetry.
abstract: Neurotransmission occurs on a millisecond time scale, but conventional methods for monitoring nonelectroactive neurochemicals are limited by slow sampling rates. Despite a significant global market, a sensor capable of measuring the dynamics of rapidly fluctuating, nonelectroactive molecules at a single recording site with high sensitivity, electrochemical selectivity, and a subsecond response time is still lacking. To address this need, we have enabled the real-time detection of dynamic glucose fluctuations in live brain tissue using background-subtracted, fast-scan cyclic voltammetry. The novel microbiosensor consists of a simple carbon fiber surface modified with an electrodeposited chitosan hydrogel encapsulating glucose oxidase. The selectivity afforded by voltammetry enables quantitative and qualitative measurements of enzymatically generated H2O2 without the need for additional strategies to eliminate interfering agents. The microbiosensors possess a sensitivity and limit of detection for glucose of 19.4 ± 0.2 nA mM(-1) and 13.1 ± 0.7 μM, respectively. They are stable, even under deviations from physiological normoxic conditions, and show minimal interference from endogenous electroactive substances. Using this approach, we have quantitatively and selectively monitored pharmacologically evoked glucose fluctuations with unprecedented chemical and spatial resolution. Furthermore, this novel biosensing strategy is widely applicable to the immobilization of any H2O2 producing enzyme, enabling rapid monitoring of many nonelectroactive enzyme substrates.
authors.affiliation: Department of Chemistry and ‡Department of Biology, North Carolina State University , Raleigh, North Carolina 27695, United States.
authors.forename: Leyda Z
authors.initials: LZ
authors.lastname: Lugo-Morales
authors.forename: Philip L
authors.initials: PL
authors.lastname: Loziuk
authors.forename: Amanda K
authors.initials: AK
authors.lastname: Corder
authors.forename: J Vincent
authors.initials: JV
authors.lastname: Toups
authors.forename: James G
authors.initials: JG
authors.lastname: Roberts
authors.forename: Katherine A
authors.initials: KA
authors.lastname: McCaffrey
authors.forename: Leslie A
authors.initials: LA
authors.lastname: Sombers
mesh_terms: D000818:Animals; D015374:Biosensing Techniques / Q000379:methods*; D002244:Carbon / Q000737:chemistry*; D000077482:Carbon Fiber; D055664:Electrochemical Techniques / Q000379:methods*; D004790:Enzyme Induction; D008297:Male; D008839:Microelectrodes; D051381:Rats; D017207:Rats, Sprague-Dawley; D013997:Time Factors
chemical_list: D000077482:Carbon Fiber; D002244:Carbon
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