Date of Award

Summer 2017

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Chemistry and Biochemistry

School

Mathematics and Natural Sciences

Committee Chair

Wujian Miao

Committee Chair Department

Chemistry and Biochemistry

Committee Member 2

Paige Buchanan

Committee Member 3

Song Guo

Committee Member 3 Department

Chemistry and Biochemistry

Committee Member 4

Douglas S. Masterson

Committee Member 4 Department

Chemistry and Biochemistry

Committee Member 5

Karl J. Wallace

Committee Member 5 Department

Chemistry and Biochemistry

Abstract

This dissertation explored and investigated the coreactant electrogenerated chemiluminescent (ECL) properties of unmixed and mixed systems of highly efficient ECL emitters, such as 9,10-diphenylanthracene (DPA), rubrene (RUB), and tris(2,2′-bipyridine)ruthenium(II) [(Ru(bpy)32+)] species as well as their water-soluble derivatives, which can serve as ECL labels for sensitive bioanalysis of single or multiple analytes. The screening of most favorable common ECL coreactants, their concentration effects along with the effect of working electrode materials on ECL behavior, and energy transfer related interactions between ECL emitters were systematically investigated. In addition, a strategy for improvement of ECL signals with the use of nitrate salt as an ECL enhancing agent was employed. A highly sensitive and selective immunosensor for the detection of viruses (zika virus or ZIKV and dengue virus or DENV4) has been developed.

A well-adaptable spectral ECL instrument that can be used for undergraduate analytical chemistry or instrumental analysis laboratories was first constructed. ECL coreactant screening studies concluded that benzoyl peroxide (BPO) was the most suitable coreactant using Pt working electrode.

Water soluble analogues of DPA and RUB, i.e., DPAS and SRUB, were synthesized and characterized by electrochemical and ECL studies. ECL signals were enhanced by more than 10 times when a nitrate salt was added to anodic ECL systems. A nitrate radical was seen using electron paramagnetic resonance (EPR) spectroscopy, which supported the proposed ECL enhancement mechanism was obtained.

Efforts were made on looking for direct evidence of ECL coreactant intermediates using EPR spectroscopy. Benzyloxy free radical (C6H5CO2• or BPO•) and sulfate anion radical (SO4-•) were detected using solid or solution-phase coreactant with or without a spin trapping agent 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) under UV irradiation or through chemical reduction reactions.

Finally, zika virus (ZIKV) is a globally emerging mosquito-transmitted flavivirus that can cause severe fetal abnormalities. Any serotype of dengue virus (DENV1-4) shows flu like illness. As such, a highly sensitive and specific ECL based immunoassay was developed for detection of ZIKV and DENV-4 in human biological fluids with an impressive detection limit of 1 PFU of ZIKV in 100 μL of saline, human plasma, or human urine.

ORCID ID

0000-0003-0649-2424

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