Access Type

Open Access Dissertation

Date of Award

January 2016

Degree Type

Dissertation

Degree Name

Ph.D.

Department

Chemistry

First Advisor

Jennifer L. Stockdill

Second Advisor

Parastoo Hashemi

Abstract

Detection of trace metals has great importance in environmental and biological applications. While traditional electrochemical techniques have played critical roles in this field, their usefulness is limited by temporal resolution, Hg toxicity and stability concerns. Recently, we developed a method using fast-scan cyclic voltammetry (FSCV) at carbon-fiber microelectrodes (CFMs) to achieve rapid measurement of metal ions with high sensitivity, selectivity, and stability. Through optimizations this method showed strengths in real-time trace metal analysis. ‬‬‬‬‬‬

‪Analytical selectivity was improved via covalent functionalization on CFMs. We employed diazonium electrochemical reduction followed by click chemistry to create robust covalent attachments. We showcased its application through grafting Cu(II) ionophores onto CFMs. The selectivity was further reinforced via inhibition of other species’ adsorption at surface oxygen groups. This stepwise functionalization approach served as a universal platform for elevating CFMs’ selectivity, while retaining sensitivity, response, stability, and lifetime.‬‬‬‬‬‬

In parallel work, pyrolyzed photoresist film (PPF) microelectrode arrays (MEAs) were fabricated to extend the borderlines of FSCV towards simultaneous multi-analyte analysis. The PPF MEAs maintained CFM’s carbon-fiber structures but provided more sensing channels. We employed a two-step pyrolysis process and a dual oxygen plasma treatment to improve fabrication repeatability, surface reactivity, and spatial geometry. Our technique has evident potential to achieve real-time simultaneous detection of various electroactive molecules and be employed for numerous applications in complex biological and environmental systems.‬‬‬‬‬

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