top-down syntheses are limited by the entropic barriers presented by these materials. Currently, the number of different synthetic techniques used to make these particles is almost as diverse as the number of different types of nanorings themselves. One common method for synthesizing nanorings involves first synthesizing nanobelts or nanowires with an uneven charge distribution focused on the edges of the material. These particles will naturally self-assemble into ring structures such that Coulomb repulsion forces are minimized within the resulting crystal. Other approaches for nanoring synthesis include the assembly of a nanoring around a small seed particle which is later removed or the expansion and twisting of porphyrin-like structures into a hollow nanoring structure. References External links Nanorings: Seamless Circular Structures Could be Sensors, Resonators and Transducers for Nanoelectronics & Biotechnology (alternative link) Nanoparticles by morphology