Date of Award

6-14-2013

Document Type

Thesis

Publisher

Santa Clara University

First Advisor

Ashley Kim

Abstract

In order to study neuromodulation in Cancer borealis, commonly known as the Jonah crab, we designed a microchip capillary electrophoretic (CE) device with micellar electrokinetic chromatography (MEKC) to separate bioamines and detect their concentrations using amperometric detection (AD). The analysis will be used to characterize the bioamines: dopamine, octopamine, tyramine, serotonin, norepinephrine, and gammaaminobutyric acid (GABA). The device measures the concentration of bioamines in microdialysate samples taken directly from the pericardial cavity of the crab. The research on Jonah crabs will be applied to enhance our understanding of the crab neurology. Since the structure and in some instances, the function of the neuromodulators are conserved, this research may be applicable to human studies. Researchers who use our device will be able to detect nanomolar concentrations of bioamines. This will help them to better understand the nervous system of crabs. This could also lead to a better understanding of the human nervous system and how to treat and manage neurodegenerative diseases. In order to obtain data, the device incorporates carbon paste electrodes modified with carbon nanotubes, which literature suggests should be able to detect 50 nanomolar concentrations using amperometry. Moreover, the buffer solution includes sodium dodecyl sulfate (SDS) micelles to separate two structural isomers of interest - octopamine and dopamine - by their difference in affinity. Combining these methods and applying voltage across the long channel separates bioamines via electroosmotic flow (EOF) based on their electrophoretic mobility. At the end of the CE channel there are electrodes to measure bioamine concentration via AD. An SU-8 mold was prepared by standard lithography techniques. Polydimethylsiloxane (PDMS) channels were formed from an SU-8 mold through replica molding. Carbon paste electrodes were screen printed into the PDMS electrode channel. We observed electroosmotic flow in CE by inserting fluoroisothiocyanate (FITC)-dextran dye and applying high voltage. Electrodes were placed in channel near the outlet to electrochemically detect the concentration of each bioamine. The limit of detection (LOD) for carbon paste electrodes was observed to be 10 mM using Cyclic Voltammetry (CV). Our device provides low cost fabrication, high time resolution, high sensitivity, and multi-analyte detection of bioamines in Cancer borealis.

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