Scientists at Caltech have created the world’s smallest Mona Lisa. Their incredibly tiny version of the famous portrait was made using self-assembling DNA structures.

Scientists at the California Institute of Technology (Caltech) have likely created the world's smallest Mona Lisa.
Their incredibly tiny version of the famous portrait was made using self-assembling DNA structures and expands on the technique known as DNA origami, which makes it possible to fold strands into specific shapes.
DNA origami has well-served the nanotechnology field, allowing for a significant size reduction in programmable materials, but it has its limits. 
The Caltech researchers sought a way to offer more robust option and found a solution in, as a Caltech release notes, DNA origami that "self-assembles into large arrays with entirely customizable patterns, creating a sort of canvas that can display any image."
"The Caltech team developed software that can take an image such as the Mona Lisa, divide it up into small square sections, and determine the DNA sequences needed to make up those squares," the release further explained. "Next, their challenge was to get those sections to self-assemble into a superstructure that recreates the Mona Lisa." 
They found an efficient and economical solution in creating a limited number of edge shapes and assembling "the tiles in stages, like assembling small regions of a puzzle and then assembling those to make larger regions before finally putting the larger regions together to make the completed puzzle."  
The team ended up with a structure that's 64 times the size of the original DNA origami assembly and one very, very small Mona Lisa.