@article{spanos_gras-najjar_letchworth_sanford_toups_sombers_2013, title={Quantitation of Hydrogen Peroxide Fluctuations and Their Modulation of Dopamine Dynamics in the Rat Dorsal Striatum Using Fast-Scan Cyclic Voltammetry}, volume={4}, ISSN={["1948-7193"]}, DOI={10.1021/cn4000499}, abstractNote={The dopaminergic neurons of the nigrostriatal dopamine (DA) projection from the substantia nigra to the dorsal striatum become dysfunctional and slowly degenerate in Parkinson's disease, a neurodegenerative disorder that afflicts more than one million Americans. There is no specific known cause for idiopathic Parkinson's disease; however, multiple lines of evidence implicate oxidative stress as an underlying factor in both the initiation and progression of the disease. This involves the enhanced generation of reactive oxygen species, including hydrogen peroxide (H2O2), whose role in complex biological processes is not well understood. Using fast-scan cyclic voltammetry at bare carbon-fiber microelectrodes, we have simultaneously monitored and quantified H2O2 and DA fluctuations in intact striatal tissue under basal conditions and in response to the initiation of oxidative stress. Furthermore, we have assessed the effect of acute increases in local H2O2 concentration on both electrically evoked DA release and basal DA levels. Increases in endogenous H2O2 in the dorsal striatum attenuated electrically evoked DA release, and also decreased basal DA levels in this brain region. These novel results will help to disambiguate the chemical mechanisms underlying the progression of neurodegenerative disease states, such as Parkinson's disease, that involve oxidative stress.}, number={5}, journal={ACS CHEMICAL NEUROSCIENCE}, author={Spanos, Marina and Gras-Najjar, Julie and Letchworth, Jeremy M. and Sanford, Audrey L. and Toups, J. Vincent and Sombers, Leslie A.}, year={2013}, month={May}, pages={782–789} }
 @article{sanford_morton_whitehouse_oara_lugo-morales_roberts_sombers_2010, title={Voltammetric Detection of Hydrogen Peroxide at Carbon Fiber Microelectrodes}, volume={82}, ISSN={["1520-6882"]}, DOI={10.1021/ac100536s}, abstractNote={Hydrogen peroxide is a reactive oxygen species that is implicated in a number of neurological disease states and that serves a critical role in normal cell function. It is commonly exploited as a reporter molecule enabling the electrochemical detection of nonelectroactive molecules at electrodes modified with substrate-specific oxidative enzymes. We present the first voltammetric characterization of rapid hydrogen peroxide fluctuations at an uncoated carbon fiber microelectrode, demonstrating unprecedented chemical and spatial resolution. The carbon surface was electrochemically conditioned on the anodic scan and the irreversible oxidation of peroxide was detected on the cathodic scan. The oxidation potential was dependent on scan rate, occurring at +1.2 V versus Ag/AgCl at a scan rate of 400 V.s(-1). The relationship between peak oxidation current and concentration was linear across the physiological range tested, with deviation from linearity above 2 mM and a detection limit of 2 muM. Peroxide was distinguished from multiple interferents, both in vitro and in brain slices. The enzymatic degradation of peroxide was monitored, as was peroxide evolution in response to glucose at a glucose oxidase modified carbon fiber electrode. This novel approach provides the requisite sensitivity, selectivity, spatial and temporal resolution to study dynamic peroxide fluctuations in discrete biological locations.}, number={12}, journal={ANALYTICAL CHEMISTRY}, author={Sanford, Audrey L. and Morton, Stephen W. and Whitehouse, Kelsey L. and Oara, Hannah M. and Lugo-Morales, Leyda Z. and Roberts, James G. and Sombers, Leslie A.}, year={2010}, month={Jun}, pages={5205–5210} }