UC Berkeley

Abstract

The Use of Liquid Phase Transmission Electron Microscopy for Quantifying Interactions Between Colloidal Nanoparticles and Visualizing Their Self-Assembled Structures

By

Hoduk Cho

Doctor of Philosophy in Chemistry

University of California, Berkeley

Professor A. Paul Alivisatos, Chair

This dissertation demonstrates the application of liquid phase transmission electron microscopy for quantifying interactions between colloidal nanoparticles and visualizing their self-assembled structures in their native solution state. Over a decade ago, the first liquid cells that could successfully enclose a thin layer of liquid while maintaining compatibility with the high vacuum conditions inside an electron microscope were developed. Subsequent commercialization of this technology by several companies greatly increased its accessibility and the research field has expanded rapidly as a result. The ability to directly visualize real-time nanoscale dynamics in solution has enabled researchers in physics, chemistry, biology, and materials science to investigate previously unexplored scientific phenomena. Thus far, the vast majority of research in this field has made use of the highly perturbative effect of the electron beam to initiate the dynamic process under study. Although this approach has yielded fruitful knowledge and insights, it has not been straightforward to extrapolate the conclusions formed from these studies to experiments conducted outside of the electron microscope. The effects of electron beam irradiation are still poorly understood, and ways to counteract them are limited. A more widespread application of liquid phase transmission electron microscopy would only be realized if the influence of the electron beam were well-known and could be tuned in a predictable manner. By understanding and controlling the effects of the electron beam on the encapsulated specimen during the imaging process, it will be possible to extract information relating to the behavior of colloidal nanoparticles in solution that can be generalizable to experiments carried out in the wet lab.

Chapter 1 introduces the basic concepts of nanoparticle self-assembly, interparticle interactions at the nanoscale, DNA-mediated nanoparticle assembly, liquid phase transmission electron microscopy, and radiation-induced effects that accompany electron microscopy imaging in liquid. Chapter 2 illustrates how the individual trajectories of nanoparticles moving in solution, obtained using liquid phase transmission electron microscopy, can be utilized for quantitative analysis of their interparticle interactions. Chapter 3 describes how the damaging effects of electron beam irradiation on DNA-assembled nanoparticles can be mitigated with the use of graphene and its derivatives as biocompatible radical scavengers. Chapter 4 summarizes the seminal findings that are reported in this dissertation and provides a brief outlook for the future.