Dissertations, Theses, and Capstone Projects

Date of Degree

9-2019

Document Type

Dissertation

Degree Name

Ph.D.

Program

Chemistry

Advisor

Michael V. Mirkin

Committee Members

Malgorzata Ciszkowska

Teresa Bandosz

Huolin Xin

Subject Categories

Analytical Chemistry

Keywords

nanoelectrochemistry, carbon nanoprobes, single cell analysis, dopamine

Abstract

The progress in the field of nanoelectrochemistry requires preparation and characterization of nanometer scale electrochemical probes. The focus of my Ph.D. research was on development of carbon nanopipette-based electrodes with versatile and controllable geometry and their applications to nanoscale studies of chemical and biological systems. Carbon nanopipette (CNP) electrodes offer important advantages, including high sensitivity and improved analytical selectivity. They can serve as nanoreactors for sampling ultra-small solution volumes and studies of individual nanoparticles. CNPs were prepared by chemical vapor deposition (CVD) of carbon into the pre-pulled quartz capillaries. By changing pulling parameters and CVD conditions, we fabricated several types of carbon nanoprobes suitable for different experiments described in this thesis. After discussing the fabrication and characterization of carbon nanoprobes in Chapter 1, Open CNPs with the simplest geometry will be presented first (Chapter 2). Open CNPs can be used as multi-functional probes based on simultaneous recording of the ion current through the pipette and electronic current produced by oxidation/reduction of molecules at the carbon nanoring. They were employed as resistive-pulse sensors to detect gold nanoparticles (NPs) and NPs modified with antibodies and antigens. Open CNPs can also work as nanosensors for biological analytes. Both open CNPs and cavity carbon nanopipettes were applied in electroanalysis of dopamine and other neurotransmitters (Chapter 3). By depositing Pt into the nanocavity, we produced nanoelectrodes with a high surface area and increased catalytic activity for measurement of reactive oxygen and nitrogen species (ROS and RNS) in biological cells (Chapters 4, 5 and 6). These electrodes were employed as scanning electrochemical microscopy (SECM) tips for spatially resolved electrochemical experiments inside single biological cells and subcellular compartments. Disk-type nanoprobes were produced by filling the CNP cavity with carbon and served as a substrate for attaching single Au NPs and studying their electrocatalytic properties (Chapter 7). After polishing or focused ion beam (FIB) milling to obtain well-defined geometry, carbon disk electrodes became useful for quantitative SECM studies of surface reactions and electrochemical imaging.

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