DNA undergoes large volume transition to organize several higher-order structures, including globular, rod-shaped, and ring-shaped (toroid) structures by polyion complexation with block copolymer comprising hydrophilic segment and polycations. This review discusses the origin of this versatile higher-order structure formation. The knowledge of underlying physical mechanisms might ultimately improve our understanding of the formation of hierarchically ordered structures in the nucleosomes and the operating principles governing how DNA functionality emerges, and also provide a solid strategy to prepare structured nonviral gene vectors.
