A little happiness: "DNA origami" makes world's smallest Smiley Wed Mar 15, 1:30 PM ET PARIS (AFP) - A nanotechnologist has created the world's smallest and most plentiful Smiley -- a tiny face measuring a few billionths of a metre across that is assembled from strands of DNA. Fifty billion Smileys, each a thousand times smaller than the diameter of a human hair, can be made at a stroke under the technique pioneered by Paul Rothemund at the California Institute of Technology (Caltech). DNA, the molecule that comprises living things, has long been known for its versatility as a microscopic...