This dissertation includes five chapters. Chapter 1 introduces single molecule and nanoparticle imaging techniques and their applications. Chapter 2 is a study of electrophoretic migration and axial diffusion of single nanoparticles in cylindrical nanopores in which the liquid viscosity was successfully measured. Chapter 3 reports the use of gold nanoparticles as drug delivery carriers and imaging contrast probes to study stem cell proliferation. This is an effort to maximize the capabilities of the recently developed plasmonic nanoparticle imaging techniques in stem cell research. Chapter 4 reports a study of single molecule catalysis on a modular multilayer catalytic platform and demonstrates three-dimensional super-localization imaging of single turnover events on 200-nm nanocatalysts. Chapter 5 summarizes all of the contents in the dissertation.