Nanoscale DNA brick, molecular model. This triangular unit consists of three short lengths of DNA (deoxyribonucleic acid) that assemble into this shape due to the corresponding base units on each strand. One of the strands (top) is shown as a ball-and-stick model, while the other two are electron density models. The apexes of the triangle are used to bond to other triangles, allowing multiple units to be added together like bricks to form a 3D scaffold. This concept of sticky nanomolecular bricks was proposed by US chemist Nadrian C. Seeman in the 1980s.