Date of Graduation

5-2026

Document Type

Thesis

Degree Name

Bachelor of Science in Biomedical Engineering

Degree Level

Undergraduate

Department

Biomedical Engineering

Advisor/Mentor

Tung, Steve

Abstract

Hybrid structures formed between single-stranded DNA (ssDNA) and single-walled carbon nanotubes (SWCNT) have emerged as promising components in future direct DNA sequencing technologies due to their unique morphological and electronic properties. The nanoscale configuration of these hybrids, including the DNA wrapping angle, pitch, and contour behavior, directly influences their potential for stable electronic readout. This thesis presents an experimental study of DNA-SWCNT hybrid morphology using a fixed, reproducible wrapping protocol designed to minimize environmental variability and isolate the influence of DNA nucleotide sequence on hybrid structure. As described in prior work, this protocol produces well-dispersed hybrids suitable for high-resolution imaging. Using atomic force microscopy (AFM),  ssDNA-SWCNT hybrid structures were deposited onto freshly cleaved mica substrates and imaged under consistent conditions. Quantitative image analysis was conducted to obtain key morphological parameters including wrap number, helical pitch, and wrapping angle. These measurements enable a comparative assessment of how DNA base composition influences adsorption geometry and helical organization on CNT surfaces. AFM imaging confirmed successful formation of ssDNA-SWCNT hybrids across all four sequences tested, producing clear nanoscale structures suitable for analysis. Height and pitch measurements revealed irregular and variable wrapping morphologies along each nanotube, which was a consistent pattern across all sequences. These variations appear to arise from overlapping wraps and local base-stacking interactions rather than sequence-specific effects, indicating that wrapping behavior is largely sequence-independent under the conditions tested. All wrapping angle measurements were below 90°, indicating all sequences had matching helical orientation. These results provide a structural framework relevant to nanochannel-based sequencing platforms currently under development at the University of Arkansas in the Nano & Micro Systems lab. By clarifying how DNA sequences modulates hybrid morphology, this study offers insights that may improve the resolution, sensitivity, and reliability of future nanoscale biosensing and sequencing devices.

Keywords

carbon nanotubes; DNA-CNT hybrid structures; direct DNA sequencing

Download

Share

COinS