The booming growth of nanoscience and nanotechnology is driven by our increasing capability of nanofabrication, new understanding of nanosized structures and materials, and new applications in material science and medicine. There are two methods for nanofabrication: top down and bottom up. The top-down method has been shrinking in size from the microscale to the nanoscale due to the use of shorter wavelengths in optical lithography. The bottom-up self-assembly method has been refined to fabricate more fancy and complicated structures.