Abstract
Single-molecule/particle detection avoids ensemble averaging, providing heterogeneous in-formation that is commonly inaccessible by conventional techniques. For decades, fluorescence microscopy has served as the workhorse for single-molecule/particle detection. However, despite its great ability to push the limits of detection sensitivity down to the nanoscale, this technique is also accompanied by several inherent restrictions. Interferometric scattering (iSCAT) microscopy offers an alternative approach for single-molecule detection without requiring extrinsic labels, with the current research focus primarily on protein biomolecules. This thesis details the implementation of iSCAT as a novel single-molecule technique to study nanoscopic structure and dynamics across different non-biological systems, including polymers and metal nanoparticles.Chapter 1 introduces single-molecule techniques, summarizing their mechanisms, advantages, and limitations. In this chapter, iSCAT is explicitly reviewed to provide a general background for my study. In Chapter 2, to demonstrate the capability of iSCAT in single particle detection, gold nanoparticles with known size were chosen as an example for iSCAT imaging. A calibration curve (iSCAT contrast vs. particle size) was developed, mapping the contrast of individual objects to their properties, such as diameter and mass. With this relationship established, Chapter 3 aims to investigate the kinetics of single polymer chain growth through real-time monitoring of its contrast evolution. Based on the same concept, in Chapter 4, the growth kinetics of individual gold nanoparticles are explored using iSCAT with a distribution of individual nanoparticle rate constants can be extracted. Following this, in Chapter 5, iSCAT was used to successfully observe the self-assembly process of crystallizable polymeric materials and served as a sensitive refractive index microscope to report changes in the optical properties within single nanoplatelets. Finally, Chapter 6 summarizes the work conducted in this thesis and discusses the future applications of iSCAT.
| Date of Award | 1 May 2024 |
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| Original language | English |
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| Supervisor | Mark Wallace (Supervisor) |