Date of Graduation

12-2021

Document Type

Thesis

Degree Name

Master of Science in Microelectronics-Photonics (MS)

Degree Level

Graduate

Department

Microelectronics-Photonics

Advisor/Mentor

Jingyi Chen

Committee Member

Yong Wang

Second Committee Member

Yanbin Li

Third Committee Member

Yuchun Du

Fourth Committee Member

Matthew Leftwich

Keywords

chemical structures, dopamine, materials science, polydopamine

Abstract

Polydopamine (PDA) is described as a bioinspired polymer produced by a method involving the chemical oxidation of dopamine in a pH-dependent medium. It has been used for the functionalization of nanomaterials in diverse applications including drug delivery and biosensing because of its strong adhesiveness, functionality is easily modified, and biocompatibility with mammalian cells and tissues. The polymerization process is believed to be initiated by the autoxidation of dopamine to dopaminequinone. However, the repeating units, as well as the final structure of PDA, are not well understood. Hence, this work focuses on the characterizations of the PDA structures during formation and degradation under different conditions to understand how the structures affect the PDA properties and functionality.

A commonly used method was chosen for the study of the PDA formation process. The synthesis of PDA was conducted in tris buffer at pH 8.5. Different microscopic and spectroscopic tools were utilized to characterize the morphology and chemical structures of the dopamine polymerization process. The results indicate that the PDA repeating units consist of dopamine, 5,6-dihydroxyindole, and indole-5,6 quinone. These repeating units are covalently bonded together forming different degrees of oligomers. Additionally, the tris base might be incorporated in the oligomers that form the PDA structure. To study the stability of the PDA structures, the degradation of the PDA was performed in hydrogen peroxide over a period of time. The resulting products mainly contain dimer and trimer units of the PDA structures that are water-soluble. Finally, the PDA formation process was used to modify the surface of silica and their subsequent use for the synthesis of metal-silica composite materials.

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