Cynthia G Zoski

Learn More
Catalase activity through hydrogen peroxide decomposition in a 1 mM bulk solution above Vibrio fischeri (γ-Protebacteria-Vibrionaceae) bacterial biofilms of either symbiotic or free-living strains was studied in real time by scanning electrochemical microscopy (SECM). The catalase activity, in units of micromoles hydrogen peroxide decomposed per minute over(More)
A simple chemical etching procedure based on the solubility of polycarbonate membranes in solvent mixtures is reported for fabricating 3D gold nanoelectrode ensembles. A solvent ratio of 50:50 dichloromethane/ethanol was found to be optimum for selective controlled etching of the surface layers of the polycarbonate membranes to expose up to 200-nm lengths(More)
Theoretical and experimental approaches to characterizing nanoelectrode (NE) ensembles of ultramicroelectrode dimensions (UME-NEEs) as a function of fraction of active area and random NE distribution are described. UME-NEEs were fabricated by addressing microregions of a gold-filled polycarbonate membrane through the UMEs of an underlying microfabricated(More)
Electrochemical reduction of H2O2 at pyrolytic graphite disc electrodes of radius 2.5 mm occurs at readily accessible potentials (600 mV versus the standard hydrogen electrode) in the presence of yeast cytochrome c peroxidase. Introduction of the enzyme into the electrolyte solution initiates large changes in the ellipsometric angles measured for the(More)
Electropolymerization, morphology characterization, and ion transport of poly(3,4-ethylenedioxythiophene) (PEDOT) films doped with different counterions (chloride, ferrocyanide (FCN), and poly(p-styrenesulfonate) (PSS-)) on a platinum electrode were investigated using scanning electrochemical microscopy (SECM) during both potential step (chronocoulometric)(More)
We discuss SECM tip voltammetry, where a UME tip is held above a conductive substrate within about a tip radius and a tip voltammogram is recorded as its potential is slowly scanned while the substrate is held at a fixed potential. When the potential of the substrate is changed, the series of steady-state tip voltammograms provide information about the(More)
An approximate theory for the feedback mode of the scanning electrochemical microscope (SECM) is developed to interpret the effects of substrate shielding on an ultramicroelectrode tip during a recording of iT versus d curves (approach curves) for reversible and quasireversible kinetics at a substrate surface. The resulting expressions for the tip current,(More)
An addressable nanoelectrode membrane array (ANEMA) based on a Au-filled track-etched polycarbonate membrane was fabricated. The Au-filled membrane was secured to a lithographically fabricated addressable ultramicroelectrode (UME) array patterned with 25 regularly spaced (100 microm center to center spacing), 10 microm diameter recessed Pt UMEs to create 25(More)
The investigation of steady-state diffusion-limiting currents at finite conical microelectrodes is reported. Such electrodes are of particular interest as probes in studies of kinetic reactions, measurements in microenvironments, and high-resolution electrochemical imaging. The diffusion-limiting currents were calculated using numerical (finite element)(More)