The nature of DNA allows building highly predictable nanostructures that have been applied in a wide range of areas like chemical sensing, material science, molecular data storage, and nanoelectronics. In the field of nanomedicine, DNA nanostructures proved a useful tool for diagnostic and therapeutic purposes. This chapter provides the protocols for the synthesis of self-assembled DNA nanostructures such as the DNA tetrahedron and the characterization of its assembly. Moreover, it also gives the protocols for the characterization of the internalization in mammalian cells both qualitatively and quantitatively.