Date of Award

Spring 1-1-2020

Degree Type

Thesis

Degree Name

Master of Science In Chemical Engineering Degree

Department

Chemical And Biomedical Engineering

First Advisor

Ao, Geyou

Second Advisor

Dr. Xue-Long Sun

Third Advisor

Dr. Moo-Yeal Lee

Abstract

This thesis is a comprehensive study on the noncovalent complexation of singlewall carbon nanotubes (SWCNTs) using biopolymers, including single-stranded DNA and synthetic glycopolymers to explore their potential applications as optical sensors. SWCNTs are cylindrical structures of carbon lattice with diameters of~ 1 nanometer. They have unique electronic, chemical, and optical properties, which make them ideal candidates for bioimaging, biosensing, and drug delivery applications. The resulting biopolymerSWCNT complexes maintain the intrinsic properties of nanotubes and possess specific biological functionalities as well. Here, we have extensively studied the structure-property relationship oftwo types of biopolymer-complexed SWCNT systems, namely DNA- and glycopolymer-wrapped SWCNTs (i.e., DNA-SWCNTs and Glyco-SWCNTs). First, we investigated the optical properties of DNA-SWCNTs utilizing (GT)n sequences, where n = 6, 10, 15, 20, at controlled pH to examine the effect ofDNA nucleobase deprotonation on the near-infrared (NIR) fluorescence of SWCNTs and the subsequent SWCNT separation. When increasing the pH of aqueous dispersions ofDNA-SWCNTs to a basic region (i.e., pH ~ 12) the NIR emission intensity of nanotubes increased indicating the conformational change of DNA on the surface of nanotubes. The resulting DNA-SWCNT complexes distributed unevenly in a polymer aqueous two-phase system, allowing SWCNT separation at controlled pH. iv Next, we studied Glyco-SWCNT complexes and their ability to interact with carbohydrate-binding proteins (i.e., lectins). We utilized a disaccharide lactose-containing homopolymer with a polymer chain length of n = 400 (i.e., Lact-AM 400) to investigate the dispersion quality and carbohydrate-protein binding interactions of Glyco-SWCNTs. Various lectins were utilized including glucose and mannose-binding Concanavalin A (ConA) and galactose-binding Arachis hypogaea (PNA) to determine carbohydrate-protein interactions which were compared to mannose-binding Galanthus nivalis (GNA) and Bovine serum albumin (BSA) that does not bind specifically to carbohydrates. ConA showed a greater ability to cause the cross linking and aggregations of Glyco-SWCNTs while PNA reacted faster with Glyco-SWCNTs based on the kinetics of protein interactions. Taken together, our findings provide insights for creating biopolymer-SWCNT complexes with controlled optical properties and biological functionalities. This opens new possibilities for designing novel nanosystems for many applications, from nanotube purification to biological sensing and imaging to nanomedicine.

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