Modified Sawhorse Waveform for the Voltammetric Detection of Oxytocin

Carbon fiber microelectrodes (CFMEs) have been used to detect neurotransmitters and other biomolecules using fast-scan cyclic voltammetry (FSCV) for the past few decades. This technique measures neurotransmitters such as dopamine and, more recently, physiologically relevant neuropeptides. Oxytocin, a pleiotropic peptide hormone, is physiologically important for adaptation, development, reproduction, and social behavior. This neuropeptide functions as a stress-coping molecule, an anti-inflammatory agent, and serves as an antioxidant with protective effects especially during adversity or trauma. Here, we measure tyrosine using the Modified Sawhorse Waveform (MSW), enabling enhanced electrode sensitivity for the amino acid and oxytocin peptide. Applying the MSW, decreased surface fouling and enabled codetection with other monoamines. As oxytocin contains tyrosine, the MSW was also used to detect oxytocin. The sensitivity of oxytocin detection was found to be 3.99 ± 0.49 nA/µM, (n=5). Additionally, we demonstrate that applying the MSW on CFMEs allows for real time measurements of exogenously applied oxytocin on rat brain slices. These studies may serve as novel assays for oxytocin detection in a fast, sub-second timescale with possible implications for in vivo measurements and further understanding of the physiological role of oxytocin.

Novel, User-friendly Experimental and Analysis Strategies for Fast Voltammetry: 1. The Analysis Kid for FSCV

Fast-scan cyclic voltammetry at carbon fiber microelectrodes measures low concentrations of analytes in biological systems. There are ongoing efforts to simplify FSCV analysis and several custom platforms are available for filtering and multi-modal analysis of FSCV signals but there is no single, easily accessible platform that has capacity for all these features. Here we present The Analysis Kid: a free, open-source cloud application that does not require a specialized runtime environment and is easily accessible via common browsers. We show that a user-friendly interface can analyze multi-platform file formats to provide multimodal visualization of FSCV color plots with digital background subtraction. We highlight key features that allow interactive calibration and parametric analysis via peak finding algorithms to automatically detect the maximum amplitude, area under the curve and clearance rate of the signal. Finally, The Analysis Kid enables semi-automatic fitting of data with Michaelis Menten kinetics with single or dual reuptake models. The Analysis Kid can be freely accessed at https://analysis-kid.herokuapp.com/. The web application code is found, under an MIT license, at https://github.com/sermeor/The-Analysis-Kid.

Amine-Functionalized Carbon-Fiber Microelectrodes for Enhanced ATP Detection with Fast-Scan Cyclic Voltammetry

Here, we provide evidence that functionalizing the carbon-fiber surface with amines significantly improves direct electrochemical adenosine triphosphate (ATP) detection with fast-scan cyclic voltammetry (FSCV). ATP is an important extracellular signaling...

Electrochemical Evaluation of Laccase Activity in Must

As laccase (produced by Botrytis cinerea) can significantly alter the properties of wine, winemakers frequently use commercially available colorimetric kits and spectrophotometers to measure the activity of this enzyme in grapes, must and wine. Although the used kits are based on electrochemically active substrates (such as syringaldazine and 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid), ABTS), the electrochemical determination of laccase activity as an alternative to the colorimetric determination was not thoroughly investigated up to now. Therefore, in the present work, we explored the electrochemical determination of laccase activity. Laccase activity measurements were carried out using either carbon fiber microelectrodes or screen-printed electrodes as working electrodes, either syringaldazine or ABTS as the electrochemically active laccase substrate, and either cyclic voltammetry or constant potential amperometry as the electrochemical method. The best performing approach, which combines ABTS, screen-printed gold electrodes, and constant potential amperometry, allowed identifying laccase positive must sample (i.e., must samples with › 3U/mL laccase) in about 5 min.