In this book, the author deals mainly with two topics: (1) single-molecule visualization of switching behaviors in the DNA nanoframe system utilizing different kinds of molecular switches through the use of high-speed atomic force microscope (AFM); (2) construction of photocontrollable DNA nanostructures in programmed patterns and direct visualization of the dynamic assembling process. Here, high-speed AFM was employed to observe the dynamic movements of single molecules. Compared to a traditional single-molecule analysis method, such as fluorescence spectroscopy or electron microscopy,...