Author's School

Graduate School of Arts & Sciences

Author's Department/Program

Chemistry

Language

English (en)

Date of Award

Winter 1-1-2012

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Chair and Committee

Kevin D Moeller

Abstract

Microelectrode array has great potential as a platform for building "addressable" molecular libraries and being utilized to probe the ligand-receptor binding events in "real-time". To achieve this objective, a complete study would generally include three phases: 1) to enable and expand site-selective chemistry on the array; 2) to understand structural information of the molecules loaded; and 3) to develop research protocols of electrochemical analysis on the device to monitor those molecular interactions. While 2), quality-control analysis, is a core task of this thesis, the studies in other phases that drove this work or derived from it, are also discussed in detail.

In Chapter 2, the thesis starts with the effort towards expanding site-selective reaction methodologies by using electrodes to tune Lewis-acid: Sc: III)) catalyzed reactions. A confining strategy that involves redox cycle of the catalyst is introduced, as well as three types of reactions presented. A new challenge arises when the structures resulted from Diels-Alder reactions and Povarov-type multi-component reactions on the array are only confirmed by a careful design of the controlled experiments and the fluorescent tags at the moment. In addition, the important information regarding stereochemistry of those structures is missing. A new method to enable the complete characterization of the molecules on the array is required.

The new quality-control handle is derived from "safe-catch" linker. The linkers are attached to the array by means of an ester and contain either a protected amine or protected alcohol nucleophile that can be released using acid generated at the microelectrodes. By placing the substitutions on those linkers, it is allowed to collect the compounds generated from the site-selective chemistries and characterize with HPLC, LC-MS. Moreover, the arrays are kept intact during this procedure and could be recycled for reactions and analysis. In Chapter 3, a full story of the design, make and use of these linkers is to be discussed. The stereochemical question with respect to the reaction is thus answered and the role of the array in the reaction is revealed for the first time.

The work continues in Chapter 4 with a goal of developing a versatile tool to enable the quality control of not only the molecules but also the device before the signaling experiments. An amino-acid derived fluorescent linker is hereby prepared to replace the role of the tags used in the previous studies. The chemical reliability and compatibility of this fluorescent linker makes the first check possible before constructing libraries. Furthermore, it leads to a successful proof-of-principle signaling experiment in monitoring biotin-strepavidin interaction and a protocol to collect and analyze data from the Microelectrode Array. Lastly, the most recent efforts in combining features of chemically cleavable linkers and fluorescent linkers are introduced to conclude the chapter.

In the end, all progress and accomplishments are summarized in Chapter 5, followed by a couple of experiments proposed upon the linkers towards the construction of molecule libraries and assessment of ligand-receptor bindings on the array.

Comments

Permanent URL: http://dx.doi.org/10.7936/K7JM27NK

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