Date of Award

Fall 2018

Project Type

Dissertation

Program or Major

Chemistry

Degree Name

Doctor of Philosophy

First Advisor

W. Rudolf Seitz

Second Advisor

Roy P. Planalp

Third Advisor

Gonghu Li

Abstract

Molecular recognition can be thought as the process in which two or more molecules bind to one another in specific geometry through noncovalent bonding. Bioreceptors, such as antibodies, enzymes, and DNAs can specifically bind to its target with high binding affinity and selectivity. However, the bio receptors are suffering from low stability and tolerance to extreme pH, temperature and organic solvents.

To overcome the disadvantages of the bioreceptors, novel biomimetic molecularly imprinted polymers (MIPs) were developed by Seitz group. Different from the conventional MIPs with high percentage of covalent crosslinking, the biomimetic MIPs contain less than 5% mole percent covalent crosslinking. A second kind of non-covalent crosslinking was incorporated into the MIPs to keep the configuration of the binding sites. With the combination of covalent crosslinking and noncovalent crosslinking, the MIPs can bind to the template with high affinity and fast kinetics, just like bioreceptors.

The novel material was based on the Poly(N-isopropylacrylamide) (PNIPAm) which is a well known thermally responsive material. PNIPAms exist as well solvated coils at low temperature but aggregate out of solution when temperature is elevated above the critical temperature. This is similar to the denaturation of protein upon elevation of temperature.

The MIPs were prepared in the presence of the template molecules by Reversible Addition-Fragmentation Transfer (RAFT) polymerization. After removal of the template, binding cavities with a three-dimensional structure complementary to the template were left inside the polymer scaffold. RAFT polymerization is compatible with different kinds of monomers. This makes it convenient to make MIPs for various target molecules.

The MIPs with high physical stability, straight forward preparation, predictable binding affinity and low cost have been proved to be excellent receptors in fluorescent sensors. Sensors based on fluorescence resonance energy transfer (FRET) and “on/off” sensors with internal standard were developed in this dissertation.

Available for download on Wednesday, September 11, 2019

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