Dissertations, Theses, and Capstone Projects

Date of Degree

9-2023

Document Type

Dissertation

Degree Name

Ph.D.

Program

Chemistry

Advisor

Ryan M. Williams

Committee Members

Rein V. Ulijn

Steven B. Nicoll

Subject Categories

Biochemistry | Biomedical Devices and Instrumentation | Biostatistics | Materials Chemistry | Nanoscience and Nanotechnology | Semiconductor and Optical Materials

Keywords

nanotechnology, bioconjugation, cancer, biomarkers, medical devices

Abstract

In recent years, nanosensors have emerged as a tool with strong potential in medical diagnostics. Single-walled carbon nanotube (SWCNT) based optical nanosensors have notably garnered interest due to the unique characteristics of their near-infrared fluorescence emission, including tissue transparency, photostability, and various chiralities with discrete absorption and fluorescence emission bands. Additionally, the optoelectronic properties of SWCNT are sensitive to the surrounding environment, which makes them suitable for in vitro and in vivo biosensing. Single-stranded (ss) DNA-wrapped SWCNTs have been reported as optical nanosensors for cancers and metabolic diseases. Breast cancer and cardiovascular diseases are the most common causes of death in the USA. Time-consuming clinical procedures limit the current screening tests for both diseases. Early diagnosis of these diseases significantly improves the outcomes of the treatment. Hence, rapid and minimally invasive biomarker-based early detection of breast cancer and cardiovascular diseases is desirable. Here, we have taken steps to construct and demonstrate rapid detection of relevant biomarkers by antibody-conjugated SWCNT-based nanosensors. We also focused on strengthening the performance of nanosensors by improving sensitivity and selectivity. We have constructed, characterized, and demonstrated the detection of interleukin-6 (IL-6) and estrogen receptor α (ERα), among the key proteins for the initiation and progression of cardiovascular diseases and breast cancer, respectively. We explored and improved a passivation strategy for screening out non-target proteins in human serum, resulting in the detection of clinically relevant IL-6 concentrations. This is the first study focused on improving passivation strategies and report on a new candidate, poly-L-lysine, for non-covalent passivation of nanosensor for successful IL-6 detection. In our next step, we constructed, demonstrated, and validated the performance of ERα nanosensor in breast cancer patient samples as a rapid detection alternative to conventional methods. We show that our ERα nanosensor can detect ERα with clinically acceptable selectivity, sensitivity, and precision. This is the first study where the detection of ERα in patient samples by an optical nanosensor has been studied and validated as a diagnostic method. Lastly, we explored an alternate method of conjugating the antibodies to SWCNTs, allowing preservation of its antigen binding abilities. We showed that engineering of N-glycan – a particular site on the non-binding region of antibodies - allows this preservation. We also compared and found discrete improvement in the detection abilities of the newly proposed nanosensor over conventionally conjugated nanosensor. This is the first research work utilizing N-glycan engineering tools for constructing optical biosensors and experimentally demonstrating its advantage over the conventional conjugation method. Overall, we present two new diagnostic tools aimed at early detection of pro-inflammatory diseases. We also present new strategies and solutions to improve the performance of nanosensors at a broader scale. We believe the work presented in this thesis will contribute towards improved clinical diagnostics and qualitative and quantitative impact on patient lives.

Download

Share

COinS