Caltech -- Scientists at the California Institute of Technology (Caltech) have developed a simple process for mass producing molecular tubes of identical--and precisely programmable--circumferences. The technological feat may allow the use of the molecular tubes in a number of nanotechnology applications. The molecular tubes are composed of wound-up strands of DNA. DNA has been considered an ideal construction material for self-assembling molecular structures and devices because two complementary DNA strands can automatically recognize and bind with each other. DNA has been used to form rigid building blocks, known as tiles, and these tiles can further assemble into extended lattice structures, including tubes. However, it has been difficult to control the diameters of such tubes.