Credit: TU Wien T-cells are an important component of our immune system: with the receptors they carry on their surface, they can recognise highly specific antigens. Upon detection of an intruder, an immune response is triggered. It is still unclear exactly what happens when antigens are recognised: How many antigens are necessary to elicit an immune response, and does the response depend on their spatial arrangement? These effects take place in the nanometer range - on the size scale of molecules, far below what can be seen with ordinary microscopes. To study all this, tiny tools are needed. Therefore, an unusual method was used at TU Wien: DNA molecules were folded in an ingenious way, similar to the paper folding art origami. In this way, not just a double helix is created, but a rectangular "molecular raft" that floats across a cell membrane and serves as a tool for novel measurements. The results have now been published in the scientific journal